STYLE GUIDELINES FOR DESIGN REPORTS

For the students of ME 2110

The George W. Woodruff School of Mechanical Engineering

Jeffrey Donnell

May, 2005

TABLE OF CONTENTS

REPORT FORMAT ...................................................................................................................................................1

FORMAT, SUBSTANCE AND ORGANIZATION ............................................................................................2

SPEAKING TO FIGURES .......................................................................................................................................5

STYLE IN ENGINEERING REPORTS.................................................................................................................7 STYLE IN PARAGRAPHS.......................................................................................................................................7 STYLE IN SENTENCES ..........................................................................................................................................9

STANDARDS...........................................................................................................................................................11

STANDARDS FOR FORMATTING AND INTEGRATING FIGURES .......................................................12 GUIDELINES FOR DRAWINGS AND TEXT DISCUSSION OF DRAWINGS ..................................................12

EXAMPLE 1: A SIMPLE DRAWING ...............................................................................................................13 EXAMPLE 2: A SIMPLE SYSTEM DESCRIPTION........................................................................................14

STANDARDS FOR GRAPHS...............................................................................................................................15 EXAMPLE 3: THE FEATURES OF A SIMPLE GRAPH.................................................................................16 EXAMPLE 4: TECHNICAL DISCUSSION OF A GRAPH..............................................................................17 EXAMPLE 5: PRICE VS WEIGHT OF VARIOUS AUTOMOBILES ............................................................18

STANDARDS FOR TABLES................................................................................................................................19 EXAMPLE 6: COMMON FEATURES OF A TABLE .....................................................................................20 EXAMPLE 7: A TABLE WITH SUBSTANTIVE DISCUSSION.....................................................................21

PAGE DESIGN AND DOCUMENT ASSEMBLY............................................................................................22

REPORT MODEL #1: REPORT SHOWING A CALCULATION .................................................................25

REPORT MODEL #2: REPORT SHOWING A SPAGHETTI BRIDGE......................................................35

OVERVIEW This Guide provides an introduction to the basic requirements of professional reports. In this Guide, those requirements are presented under the headings of Format, Style and Standards. The Format section on pages 1-6 of this Guide provides an overview of document organization and a set of prompt questions to help students provide the right kinds of information in each section of their documents. The Style section, on pages 7 and 8, speaks briefly to sentence and paragraph structure, with emphasis on the impersonal style that is required in most engineering reports. Finally, the Standards section of this guide specifies our expectations for the preparation of figures (pages 11-18) and tables (pages 19-21), and it provides some examples of appropriate text discussion of sample figures and tables. At the end of the Standards section, on pages 22-24, is a brief checklist for page design and for the assembly of finished documents. Brief sample reports, starting on pages 25 and 35, demonstrate appropriate reporting style and organization, reasonable Abstracts and appropriately integrated drawings. A separate document, “Communicating with Concept Drawings: How to make and use simple line drawings,” explains how to prepare and present information in simple concept drawings.

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REPORT FORMAT On any kind of project, the engineering professional must take the following steps: 1) Identify a need and translate that need into a problem that can be solved 2) Adopt an orderly and focused approach to solving that problem 3) Develop a good solution to the problem 4) Validate that solution with analysis (as appropriate) 5) Describe that solution in a report In project reports, the information collected above is repackaged and described. Professional reports generally use the headings provided here. Below each heading is a listing of the questions that must be answered in that headed section. The next pages of this section will describe what kinds of information should be provided in response to these questions.

Abstract What project is addressed in the report? What result was obtained? What deliverables are presented in the report? Introduction (or problem Statement) What are the functional objectives of this project? What are the constraints on the project? What design challenges are presented by the objectives and constraints? What design is described in the report? Design Overview (or Presentation of Deliverables) What design was developed? What design-related deliverables were developed? Methods and/or Evaluation By what method was the design solution developed? What alternative designs were explored? How were alternatives evaluated and ranked? What performance was obtained? How is this performance evaluated? Conclusion What design (or progress) was described in this report? What performance was obtained by the completed design?

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FORMAT, SUBSTANCE AND ORGANIZATION Readers expect to find certain kinds of information under certain headings and subheadings in your reports. This section of the guide describes the kinds of information that readers need to see under each subheading of your reports. ABSTRACTS People read abstracts to answer a simple question: “What is presented in this report?” Abstracts need to be short, and they should answer that question without discussion. Specifically, the Abstract should be limited to these statements:

Description of the project objective or need Description of the result that was developed or obtained Description of the materials that are presented in the report

The Abstract should be 4 to 6 sentences long. It should offer no discussion, pose no questions and cite no figures. For this class, the Abstract should appear alone on an unnumbered sheet, placed before the Introduction to the report. Example abstracts are found in the two report models attached at the back of this Guide. INTRODUCTIONS The Introduction to a design report responds to these questions in the following order:

1. What need is presented? 2. What design challenges must be addressed in order to meet that need? 3. What accomplishments or results are presented in the report?

Your introductions should briefly address these questions in the following steps: 1. What need is presented?

Briefly describe the project objective(s) as outlined by the instructor/client.

What is a design challenge? A design challenge is a problem that you must solve by using your skills as a professional engineer. In ME 2110 students are often presented with design challenges like these:

A) Support a heavy weight using weak materials; B) Move a large object while using a small device.

These design challenges are also called design problems. Professionals solve design problems by using engineering expertise to develop and validate clever systems.

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2. What challenges, or problems, must be addressed?

Characterize the design challenges raised by the need or objective. 3. What accomplishments or results are presented in the report?

Design accomplishments are generally presented as drawings, charts, tables and analyses. Each of these kinds of figure characterizes a step in the design process. The close of the Introduction section should indicate what project-related deliverables are described in the present report.

DESIGN OVERVIEW (OR PRESENTATION OF DELIVERABLES) The introduction briefly lists the project-oriented deliverables that are presented in the report. The following section of the report then describe those deliverables; generally one brief component of the report is devoted to each deliverable item. Deliverables are usually presented as graphical information, such as drawings, tables, charts and graphs. Graphical information is not self-explanatory. It is the job of the professional engineer, as author of the report, to describe each graphic clearly and responsibly, highlighting and explaining crucial elements of information. Such explanations can be developed by following this information checklist:

1) Figure Citation

2) Objective statement

3) List of features

4) Description of features as they pertain to objective

5) Discussion of challenges or open questions

This checklist is expanded and explained on pages 5 and 6 of this Guide, and quick guidelines for figures, tables and sketches will be presented later in this guide. In addition, the ME 2110 web site also provides a full guideline for the presentation of concept drawings in reports: “Communicating With Concept Drawings: How to Make and Use Simple Line Drawings.” METHODS AND EVALUATION After a design has been presented, a report should respond to questions such as these:

1. How was the design developed? 2. What result was obtained? (--or-- What result was expected?) 3. How might the design be improved?

In ME 2110 you will mainly present design alternatives and evaluation tables in this section of a report. When you discuss such deliverables, you should briefly account for all of the information presented in those drawings and tables. In discussions of design alternative sketches, you should provide brief (1-3 sentence) responses to the questions shown above for describing figures. In discussions of tables and graphs, you should explain how input values were determined for all numbers shown on the table or graph, and you should explain the calculations that are represented by any results shown on the table or graph. In discussion of the table, you should comment on any uncertainty in the assignment of values, you should explain how you interpret the results, and you should indicate whether the results are reliable.

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CONCLUSIONS The end of an engineering report is not the right place to speculate or to explain. In this class, the conclusion of a report should only summarize the main points made in the report without offering new discussion. What was designed or delivered? How did the design perform?

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SPEAKING TO FIGURES Engineering reports are filled with non-textual information in the form of drawings, tables, graphs, calculations, and so forth. When you provide such information in a report, it is your job to describe that figure or table, and you can best do that by responding to the questions that any reader will ask about any figure. Readers generally expect you to both describe the information and then to evaluate it. The questions pertinent to description and evaluation are listed below:

Description 1) What is shown in this figure or table? 2a) What is it supposed to do? (for a design drawing) 2b) What does it demonstrate? (for a table or graph) 3) What are the features of this drawing, table or graph? Evaluation 4) How do these features respond to your needs/goals? (as needed) 5) What complications/problems do these features raise? (as needed)

When you write in response to these questions, you will create the following components of a figure description:

1) Figure Citation

2) Objective statement

3) List of features

4) Description of features as they pertain to objective

5) Discussion of challenges or open questions

To exemplify a figure description and its components, a photograph of a torpedo is provided on the next page, followed with a brief description of that photograph. In that brief discussion, 4 of the 5 elements of a figure description are provided, and they are numbered according to the checklist presented here. It is noteworthy here that items 1 and 2, the Citation and the Objective statement, are given complete sentences in this example; most good authors can provide this information in a single sentence. Item 3, the list of figures is key to the description, for it lists the words that govern the remaining sentences of the description. Item 3 connects features of the drawing to functions of the system, and it lists the words that will be important in the rather long set of statements under Item 4. In this example, those important words are highlighted by combinations of boldface, underline and italics. Those important words also form the labels shown on the photograph of the torpedo.

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Example figure presentation:

[1]Figure A displays the basic elements of a torpedo. [2]A torpedo needs to do 4 things: it must

find the target, it must propel itself toward that target, it must guide itself on its path, and it must

detonate near the target. [3]To meet these goals, the torpedo has 4 main components: a nose

section containing sonar, a motor and fuel tank, a guidance system, and a warhead. [4]When the

torpedo is launched, the nose sonar locates the target and notifies the guidance system, which

receives constant updates from the sonar. The fuel tank and the motor simply propel the torpedo

forward until the warhead is detonated, either on a signal from the sonar or from contact with the

target.

Courtesy Saab Bofors Dynamics

Figure A. Cutaway view of a torpedo, showing the target acquisition, guidance, propulsion and detonation subsystems.

Nose Guidance Warhead

Fuel

Afterbody, with motor

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STYLE IN ENGINEERING REPORTS Engineering reports must be orderly and objective. Your reports will appear orderly to the extent that your paragraphs are well constructed. Your reports will appear objective to the extent that your sentences are logically ordered and impersonally presented. This section on Style explains how to prepare orderly and objective reports by speaking first to paragraph formation and subsequently to the issues of sentence construction STYLE IN PARAGRAPHS A paragraph has three information components: an ISSUE or topic announcement, a POINT announcement, and a DISCUSSION section, which provides explanation or comment on the point. Each of these paragraph structures conveys a certain kind of information to the reader, and readers expect to receive that information in a certain order. The schematic representation of a paragraph shown below highlights the relative placement of these three paragraph components. The discussion section is by far the largest part of the paragraph, but it keys heavily on particular terms provided in the point statement.

1. Problem or objective.

2. Claim or result, offering terms

a, b, and c, for future discussion.

3a. Discussion of a.

3b. Discussion of b.

3c. Discussion of c.

Issue

Point

Discussion

Figure B. Schematic representation of paragraph organization.

The Issue section of a paragraph typically raises one of two problems:

1) What problem is addressed here? Or 2) What part of the project is addressed here?

The Point statement of a paragraph should announce the answer to the question(s) above, and it should list the terms that will govern the subsequent discussion.

The Discussion section of a paragraph either explains, substantiates or elaborates on the point made in the paragraph. So long as the discussion emphasizes the key terms listed in the point section, the paragraph can be characterized as focused and cohesive. On the next page, a graph is presented, with a one-paragraph description. In that description, the Issue, Point and Discussion sections are marked and the key terms for discussion are highlighted with circles to display the linguistic link between point and discussion sections. The point, the information hat the author supports or explains, is highlighted with a rectangle.

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y = 0.0197x2 - 105.23x + 152889

R2 = 0.9824

10000

20000

30000

40000

50000

2000 2500 3000 3500 4000

Weight of vehicle in pounds

Pric

e of

veh

icle

in d

olla

rs (M

SRP)

Price in dollars (MSRP) 2nd order trendline Figure C. The relationship between weight and price for an assortment of model year 2001 sedans.

[Issue]To characterize the relationship between price and weight in automobiles, data for ten 2001 model sedans were collected and placed in a spreadsheet for analysis. [Point]The result of this analysis is displayed in Figure 1, which graphically relates [term a]weight to [term b]price for these automobiles, displaying data points and a [term c] trendline, and [claim] which demonstrates that sedan prices rise exponentially with increases in weight. [Discussion, term a] Vehicle weight is represented, using units of pounds, on the X-axis, which is offset from the origin by 2000 pounds to indicate that none of the automobiles evaluated here weighs less than 2000 pounds. The Y-axis represents the [Discussion, term b] price of each vehicle using the Manufacturer’s Suggested Retail Price (MSRP). The Y-axis is offset from the origin by 10,000 dollars, to indicate that none of the vehicles is priced below $10,000. The supplied [Discussion, term c, support for claim] trendline characterizes the overall relationship of price to weight in this data set as a second order equation, which is displayed on the plot area, along with the line’s R2 value. This R2 value is 0.98, indicating that the calculated trendline characterizes this particular set of data accurately.

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STYLE IN SENTENCES In technical reports, sentences need to be Impersonal, Empirical, Objective, and Logical. These sentence qualities are directly linked to the grammatical structures from which all sentences are constructed: subjects, verbs and modifiers. Using these sentence elements, professionals assemble information for their colleagues; to do this they build every sentence around answers to the following questions:

Question GRAMMATICAL STRUCTURE

What happened? VERB

What caused it to happen? Subject What quantities were involved? Modifier How does this information pertain to the sentences surrounding it?

Connector, conjunction

In technical writing, certain kinds of words are reserved for use in the responses to these questions. Sentence subjects, for example, should incorporate terms pertaining to systems, forces, and theories; for modifiers, specific numbers are preferred to adjectives and adverbs. Sentences are best connected using conjunctive terms that display logic while performing the grammatical function of linking clauses. Sentence subjects should be Impersonal Members of the design team (that's you) should not appear in sentences describing their projects. The subjects of your sentences should be the things (or forces) you are studying. Avoid this: "We found that the pressure varied with changes in temperature." Do this: "Pressure varied with changes in temperature." Verbs are used to maintain an Empirical stance The verb answer sthe questions "What Happened?" or "What did [the subject/agent] do?" The answers commonly involve active verbs--things 'deflect,' 'break,' 'boil,' 'cool,' etc. Experiments require observation, so verbs associated with seeing are acceptable. Phenomena are 'observed,' 'seen,' 'found' and 'shown,' for example, and values are 'calculated' and 'determined. But because professionals do not get to appear as subjects in their sentences, the so-called passive verb construction is used to maintain an impersonal stance while recounting the work faithfully. Passive constructions appear often in impersonal texts. Avoid this: "We used Equation 4 to determine the Reynolds number." Do this: "Equation 4 was used to determine the Reynolds number." Or do this: "The Reynolds number was determined using Equation 4." Modifiers are avoided in order to maintain Objectivity The best known modifiers are adjectives and adverbs, which inexactly characterize number in observations. Typical adverbs and adjectives speak to simple questions such as “How many?” “How

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fast?” “How large,” and so forth. When numbers are available to answer these questions, they must be used. Avoid this: "A large sample was heated to a high temperature for a long time; then it was cooled

quickly." Do this: "A 70 gram sample was heated to 200 degrees F for 4 hours. It was then cooled to 0

degrees F over the course of 20 minutes." Logic is displayed in the connections between clauses The words listed below are the most common and most powerful logical markers in the language. When they are used correctly in sequences of sentences, these words describe the relationships between the ideas contained in those sentences.

and that/which however after, before but who/whom therefore as, while or, nor whether thus but if how, when, where although yet since why because unless until whenever hence so that in addition wherever otherwise similarly nevertheless on the contrary consequently : ;

The sample paragraph below demonstrates how connectors are used at the beginnings of sentences in order to establish logical continuity. In most cases, this connection is established with a single word, Connections between ideas can also be established with short introductory clauses which describe the objective of an action, as does the introductory clause in the first sentence below:

To explain the much larger observed heat leak conductance, it was noted that the cylinder is

equipped with 16 pairs of 24 gage thermocouple leads, one pair of 12 gage power leads, and a 12

gage grounding conductor. A 50 mm 12 gage copper lead has a conductance of .026 W/C, and a

24 gage lead has a conductance of .0016 W/C. Consequently the total of the electrical leads

could allow a heat leak conductance of at least .104 W/C, which is 54 % of the lowest observed

value. In addition, the supports and the grounding lead are directly exposed to the air stream and

are sure to experience some lateral conduction and ultimately convection heat loss. Furthermore,

the power leads are connected directly to the resistance heater, which is much warmer than the

convection surface itself, exacerbating the heat leak by this path. These effects could easily

account for the enhanced conduction heat leak. Additionally, the fin effect explains the

unexpected dependence on the wind speed.

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STANDARDS The following pages of the Guide provide checklists for the formation of figures, both drawings and graphs, and tables. Following these checklists we offer sample drawings, graphs and tables, along with text discussions of each. These checklists and examples are designed to outline our minimum expectations for presenting these basic elements of engineering reports. Students need to remember that text descriptions are as important as are the graphs, tables and drawings discussed below. Your reports are comprised of text AND figural/tabular information. In the examples below, suggestions are provided for both the written text and for the formation of figures and tables.

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STANDARDS FOR FORMATTING AND INTEGRATING FIGURES Professional reports generally use two kinds of figures: drawings and graphs. For purposes of

citation, attachment and labeling, we treat drawings and graphs the same way. A few special cautions concerning graphs are provided in items 5 and 6, below, as well as in the discussion of graphs on pages 15-18. Each figure must have a figure number and a descriptive caption. 1. Figures should be numbered in the order of citation in the report. 2. The figure number and caption are placed on the same line, below the figure. The figure number is

placed to the left of the caption. 3. Figure captions must be technically descriptive. The caption on Figure 1, below, appropriately

provides technical descriptions of each of the lines represented as well as a description of what test results are shown in the figure. The caption on Figure 2, below, describes the point made in the figure.

4. In graphs, the axes must be labeled, and each label must show the units used on that axis. 5. A legend should be provided for each graph. This legend should provide a short, substantive

description of each line shown on the graph. 6. If figures are attached at the back of a report, they must still be numbered and arranged in order of

use. 7. When figures are integrated into the body of a report, authors should cite the figure in the text above

the point where it is displayed on the page. 8. In citations, figure numbers are capitalized, as in this reference to Figure 1, below. 9. When landscape-oriented figures and tables are presented in a document, they should be attached with

the bottom of the figure or table on the reader’s right-hand side. GUIDELINES FOR DRAWINGS AND TEXT DISCUSSION OF DRAWINGS

The samples below show two kinds of drawings that you might make in ME 2110. The first is a variety of crude sketch that you might make in haste to document one of the early in-studio projects such as the spaghetti project or the newspaper project. The second drawing is taken from a patent, and is provided as an example of excellence in concept illustration.

These drawings are presented along with brief text descriptions of the sort you should develop for

your reports. These drawings are offered as demonstrations of basic standards for formatting and integrating drawings into reports. As you read the examples, please pay particular attention to the way the figures are cited, the way they are numbered and captioned, to the placement of numbers and captions, and to the way the text description speaks to each labeled feature in the drawings. This section of the Guide is devoted to format and integration of drawings; for tips on how to capture information in drawings, read Example Report 3, “Communicating with Concept Drawings.

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EXAMPLE 1: A SIMPLE DRAWING Figure 1 shows an umbrella design for a non-lethal squirrel trap. The first goal of the umbrella design that it must work without springs, which proved to be unreliable in other alternative designs. A secondary goal was that this trap must be easily moved about the homeowner/user’s yard. The umbrella design has three main sections: a base, the umbrella structure itself, and a trigger. The base section is composed of a flat, circular metal plate to which are fixed two arches made of smooth metal tubes or heavy wires. The umbrella section is to be composed of a strong, but slick fabric supported by thin plastic ribs, which are fixed to a central ring located at the center of the umbrella fabric. The trigger section is built around a central rod, which is fixed to the very top of the arching frame. This rod supports the central ring for the umbrella ribs, allowing this ring to travel smoothly up and down. At the bottom of this rod, a bait bag is attached to a trigger that can release the umbrella. At the top of the rid is a handle, allowing the homeowner to carry the trap easily. The umbrella trap works simply. To reach the bait, a squirrel must stand in the center of the base plate, under the arching frame. When the bait is touched, the trigger releases the central ring, which slides down the support rod. The umbrella fabric is forced open as it slides smoothly down over the metal frame, trapping the squirrel. The umbrella trap was ultimately abandoned, however, because squirrels can chew through most fabrics and plastics. Handle for carrying Umbrella structure With lines representing ribs Support rod Trigger cable Bait Arched Frame Base Figure 1. Umbrella-shaped squirrel trap, showing base plate, frame, umbrella-shaped confinement structure and convenient carrying handle.

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EXAMPLE 2: A SIMPLE SYSTEM DESCRIPTION The objective of the invention presented below is to link two, or more, single-color printing

presses in such a way that a four-color picture can be printed in a single step. Figure 1 provides a general

view of the invention as it might be used to link two color printing presses. This drawing shows the

invention and the two color presses in side view, showing only the main rollers. The two printing presses

are labeled as “First Printing Unit” and “Second Printing Unit.” These presses are represented by four

rollers, labeled “Form Cylinder,” “Blanket Cylinder,” “First/Second Impression Cylinder,” and “Pick-up

Cylinder/Sheet Delivery Mechanism.” The invention linking these printing units is linked to the three

cylinders in the middle of the drawing, labeled as “First Transfer Cylinder (T1),” “Second Transfer

Cylinder (T2)” and “Third Transfer Cylinder (T3).” The small arrows on the cylinders indicate the

direction of rotation for each cylinder and suggest the path followed by a sheet of paper as it moves from

the Feed Board on the right of the drawing, over the first unit’s form cylinder, and then passes between

the blanket cylinder and the First impression cylinder. The sheet then passes over the three Transfer

Cylinders to the Second Printing Unit’s Form Cylinder, Blanket Cylinder and Impression Cylinder. The

Second Unit’s Sheet Delivery Mechanism then sends the finished sheet out of the machine.

Figure 1. Overview of a multi-color printing press system.

US Patent # 2,757,610

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STANDARDS FOR GRAPHS In order to present graphical data clearly and accurately, you must determine the range of your axes, and you must determine what kinds of lines to use to best characterize your data. Two technically unrelated graphs are shown below, and two different text discussions demonstrate how you should speak to the features in your graphs. Figure 1 is discussed in the text section concerning Scatter Plots; Figure 2 is presented with a technical description drawn from a laboratory report.

Sales and ranges for axes: Select the ranges for y and x axes with care. An overly wide range can distort overall patterns by compressing the data excessively. When possible, avoid offsets that omit the (0,0) point; such omissions can distort proportions and obscure scaling relations.

Straight lines: Straight lines should be used to connect data points in order to illustrate simple

trends, as in Figure 2, below. Straight lines should also be used to connect data points when a graph displays multiple data sets for purposes of comparison.

Curved lines or smooth lines: Smooth lines and curved lines generally indicate that some mathematical model has been used to generate the line. Such lines are best described as comparison curves when they represent the model, or predicted values against which experimental data is compared. A curved line or smooth line might also represent a regression model developed to account for the data you have collected.

Scatter Plots: Never force your data to fit on a curved line or a smooth line. Instead use a scatter

plot of unconnected data points, such as that shown in Figure 1, on the next page.

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EXAMPLE 3: THE FEATURES OF A SIMPLE GRAPH

Figure 5 shows the elements of a simple graph, which students should use as a basis for developing their own graphs and text discussions of those graphs.

In Figure 5, a smooth line, without markers, runs near the unconnected data points; the graph’s

legend describes this line as a regression model. The regression model shown in Figure 5 is accompanied by dotted error bands; when feasible, such error bounds on a regression line curve should be plotted along with the line itself. Use a distinct line type, such as a dashed line, to indicate the upper and lower limits of the error band.

Figure 5 also shows a smooth line, described by the legend as a “Lit. Model.” This line shows the

predictions made before the experiment. Such prediction lines should be shown whenever predictions have been made, for they provide the starting-point for all analysis of error.

Below Figure 5 is a crucial 2-line identifier: Figure Number and Descriptive caption. The figure

number is always placed on the left, followed by a colon. The descriptive caption contains a compact description of the main points of the figure, generally indicating what is shown in the figure and what features of the figure merit notice from the reader. Captions should be limited to 2 lines.

0

500

1000

1500

2000

2500

3000

10.0 20.0 30.0 40.0 50.0 60.0

Temperature (C)

Hea

t Cap

acity

(J/k

g-K

)

Data Regress Model Lit Model

Upper Lim Lower Lim

Figure 5: Heat Capacity Data (markers) and Regression Model (solid line) with Error Band (dotted lines) for Lubrication Oil Compared with Model from Tempco (1992, broken line).

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EXAMPLE 4: TECHNICAL DISCUSSION OF A GRAPH

0.0

0.1

0.2

0.3

0.4

4.0 6.0 8.0 10.0 12.0 14.0 16.0

Wind Speed (m/sec)

Hea

t Lea

k C

ondu

ctan

ce (W

/C)

Data model model + 2 std err model - 2 std err Figure 6: Heat Leak Conductance Data, Model and Error Band

A linear regression model for the heat leak conductance data as a function of wind speed was prepared and is shown along with the experimental data in Figure 6. The model is expressed in dimensional terms by Equation 2 for the wind speed, V, in m/s,

VUAL ⎟⎟⎠

⎞⎜⎜⎝

⎛+=

smCW01483.CW1244.0 (2)

As is evident in the figure, the model represents the data well. The largest deviation of the model from the data is only -4.6 %. Overall, the R-squared is almost 98 %, indicating near perfect agreement between the data and the model. The model has an alpha risk of only 1 % implying a negligibly small probability that the observed correlation between the conductance and the air speed could be due to mere chance. This alpha risk is well below the conventional upper limit of 5 % and indicates that the regression model is statistically significant. A quadratic model was also attempted. As detailed in the attachment, this model returned only a slightly higher R-squared but has an entirely unacceptable alpha risk of 54 %. This high alpha implies that the additional fit is most likely only an adjustment to random error in the model and indicates that the quadratic term is statistically insignificant and should not be used. The linear regression analysis also returned a value of only 0.010 W/C for its standard error of estimate. To illustrate the tightness of the regression estimate as implied by this standard error, an experimental error band with the half-width of two standard errors of estimate is also plotted on the figure. Obviously, all of the experimental data are either within or very near this error band, another indication that the model represents the data well and that the data includes no suspicious outliers.

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EXAMPLE 5: PRICE VS WEIGHT OF VARIOUS AUTOMOBILES To characterize the relationship between price and weight in automobiles, price and weight data were collected for ten 2001 model vehicles. This data was placed in a spreadsheet and a graph was generated, as described below.

Figure 7 graphically relates weight to price for these automobiles, displaying data points and a trendline, which indicates that sedan prices rise exponentially with increases in weight. Ten data points are shown here, and a trendline is supplied in order to characterize the data visually. Vehicle weight is represented on the X-axis using units of pounds. The X-axis is offset from the origin by 2000 pounds, indicating that none of the automobiles evaluated here weighs less than 2000 pounds. The Y-axis represents the price of each vehicle using the Manufacturer’s Suggested Retail Price (MSRP). The Y-axis is offset from the origin by 10,000 dollars, indicating that none of the vehicles is priced below $10,000. The supplied trendline characterizes the overall relationship of price to weight in this data set as a second order equation, which is displayed on the plot area, along with the line’s R2 value. This R2 value is 0.98, indicating that the calculated trendline characterizes this particular set of data accurately.

y = 0.0197x2 - 105.23x + 152889

R2 = 0.9824

10000

20000

30000

40000

50000

2000 2500 3000 3500 4000

Weight of vehicle in pounds

Pric

e of

veh

icle

in d

olla

rs (M

SRP)

Price in dollars (MSRP) 2nd order trendline

Figure 7. The relationship between weight and price for an assortment of model year 2001 automobiles.

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STANDARDS FOR TABLES Tables are to be treated with the same care and precision as are figures. Two tables, with associated

text discussions, are offered below. Table 1 provides a discussion that draws attention to the kinds of information that may be provided in a table. Table 2 presents an evaluation matrix, with associated discussion, drawn from a previous ME 2110 section.

1. Tables must have numbers and descriptive captions. 2. Tables must be numbered in the order of citation in the report. 3. The table number and caption are placed above the table; the number goes on the left of the caption. 4. The rows and columns of tables must be clearly defined and labeled. Units must be visible either at

the tops of the columns or at the left edges of the rows. 5. The left-hand column usually lists the independent variables or the categories used in the table. 6. The first row of the table usually shows text entries called "heads" that identify the columns. These

heads commonly contain units. 7. If tables are attached at the back of a report, they must still be numbered and arranged in order of

citation. 8. Always cite the table in the text before it is displayed on the page. 9. When landscape-oriented figures and tables are presented in a document, they should be attached with

the bottom of the figure or table on the reader’s right-hand side. 10. The table number and the first word of the caption are capitalized, as shown in Table 1, on the next

page.

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EXAMPLE 6: COMMON FEATURES OF A TABLE Table 1, below, and the accompanying discussion demonstrate how tabular information is displayed and explained in a report.

Table 1. Estimate of Bias in Shaft Power Measurement

Measurement uma Influence Coefficient,

ixW

∂∂ & σ

∂

∂m mm

uW

x2

2

=⎛

⎝⎜⎜

⎞

⎠⎟⎟

& Basis Source

shaft speed, N

5 RPM &.

W

N= =

6283

10006 28

W

RPM

W

RPM 987. W2 Resolution (A)

arm length, r

1 mm &.

W

r= =

6283

30020 9

W

mm

W

mm 439. W2 Measure-

ment (B)

force, F

2.5 N &.

W

F= =

6283

200315

W

N

W

N 6170. W2 Calibration (C)

sum of variances = 7590. W2 uncertainty (1 σ) = 87.1 W limitb of accuracy (2 σ) = 174 W or 170 W

Sources: (A) physical inspection, (B) precise measurement, see text, (C) conducted by Ace Labs (1997)

a Uncertainty in individual direct measurement, b 95 % confidence limit.

The table number and descriptive caption are placed above the table in printed reports. The top row and the left column generally provide heads or labels for the rows and columns. The bottom rows may be set aside to show the sums of columns or to show the results of analyses, as are the bottom three rows of Table 1.

Tables may be immediately followed by footnotes. When a table is borrowed in whole or in part,

an overall source footnote should be used. A specific source footnote may be desired when a data has been borrowed or used for purposes of comparison. Engineering tables commonly include brief explanatory notes within a table; longer explanations can be presented in footnotes or they can be included in the regular text of the report. Source or explanatory footnotes that refer to parts of the table may be indexed with a capital letter in parenthesis, as illustrated in the right column of Table 1, shown on the next page. Notes identifying or explaining a specific entry may be indexed with a superscripted lower case letter, as also shown in the heads to columns 2 and 4 of the example. In such references letters are preferred to numbers, in order to avoid confusion with exponents, page footnotes or entries in the list of bibliographic references.

21

EXAMPLE 7: A TABLE WITH SUBSTANTIVE DISCUSSION Table 2, below, is an example of the kind of table that might be found in an undergraduate design report. Table 2 shows the first evaluation matrix for the CD mover project. The three main concepts are evaluated against a datum; the gravity-powered system of Concept 5 is used for the datum, and is not represented in this table. The criteria emphasize estimated performance of the system, although the items Build Time, Build Cost and Repeatability address the team’s concerns about ease of fabrication and ease of use. According to this evaluation, the 3-stage Arm Extension is preferred, but the distinctions are not strong, so these three concepts required further investigation.

Table 2: First evaluation matrix for CD mover, rating three concepts against a datum.

Concepts Criteria Rolling (Pushed)

Vehicle with Extending and Retracting Arm

3 Stage Arm Extension: Extend to CD, Turn to Target, Extend to Target

Rolling Vehicle (Powered) with Forward-Sweeping Arm.

Build Time D + S - Build Cost A + + + Reaches CD T + + + Moves toward Target U + + + Powered to Target M - + + 2 Stage Sequence + - - Repeatability - + + Total + 5 5 5 Total - 2 1 2 Overall total 3 4 3

22

PAGE DESIGN AND DOCUMENT ASSEMBLY Reports are commonly prepared in parts by project team members. But the final submission must

look like a single document prepared by a single author during a single writing session. Unless they receive explicit instructions to the contrary, all authors should observe the following guidelines for page design and for assembling reports. 1. Use Times New Roman font, 12 point. 2. Set Line Spacing for 1.5. 3. Set left and right line margins to 1.0 inches. 4. Insert one blank line between paragraphs. 5. Indent ½ inch for the first line of each paragraph. 6. Titles of reports and of report chapters should be centered and bolded. Titles are preceded and

followed by at least one blank line. 7. Section headings should be left aligned, bolded and presented in all caps, as is the heading at the top

of this page. Section headings are preceded by one blank line, and they are followed by a line of text, as shown at the top of this page.

8. Secondary headings should be left-aligned and bolded, with an initial capital letter. 9. Tertiary headings should be left-aligned and underlined with an initial capital letter, and they should

be followed by a period. Such headings are uncommon, and are used as an alternative for side-headings.

10. Side-headings should be underlined, and they should be followed by a period or a colon. The first

sentence of a paragraph immediately follows the colon or period. 11. Headings, subheadings and side-heads may include numerical or alphabetical markers, as required by

some instructors. 12. Side-headings should be indented 5 spaces. 13. Report pages should be numbered, beginning with the first page of the introduction. The title page is

not numbered, the table of contents and the abstract may be numbered with lower-case Roman numerals.

14. Landscape-oriented figures and tables should be attached to the report such that the bottom of the

figure or table is on the reader’s right side.

23

Demonstration of headings and subheadings

TITLE

The title of a report or of a report chapter appears alone on a line. It is presented in allcapital letters, it is centered and it is bolded, as shown above. A title is placed at the top of apage, and it is followed by at least one blank line before text lines are inserted.

PRIMARY HEADINGA primary heading can also be described as a section heading, for it marks the largest

chunks, or sections, of text within a report or report chapter. Section headings appear alone onlines, they are left aligned, bolded and presented in all capital letters, as is the section heading atthe top of this paragraph. Section headings always follow a blank line (the empty space after theprevious paragraph); text is inserted on the line immediately below the section heading.

Secondary headingSecondary headings mark out so-called subsections of text. Like primary headings, they

appear alone on lines, they are left aligned and bolded. Secondary headings are presented inlower-case letters, with an initial capital only. Secondary headings always follow a blank line,and text is inserted on the line immediately below the secondary heading.

Tertiary headings.Tertiary headings, when required, appear alone on lines, where they are left-aligned and

underlined. Tertiary headings are presented in lower-case letters with an initial capital only.Tertiary headings are followed by punctuation, either a colon or a period. Tertiary headingsalways follow a blank line, and text is inserted on the line immediately below the tertiary heading.

Side-head. The side-head is the lowest subdivision of a report. Side-heads are presentedin lower-case letters, underlined, with an initial capital only. Side-heads are followed bypunctuation, either a colon or a period. Side-heads follow a blank line, but they otherwise aretreaded like the first phrase of a paragraph, for they are indented, and they are immediatelyfollowed by text, as is the side-head at the beginning of this paragraph.

24

ASSEMBLING YOUR REPORT

Figu

re 1

: Spa

ghet

ti ca

r

Introduction

Design overview

1

Abstract

No page number

Cover Sheet:

Title

Names

Date

No page number

REPORT MODEL #1: REPORT SHOWING A CALCULATION

26

ME 2110-L

Studio Project 9:

Determination of Shaft Diameter

Submitted to:

Instructor: J. S. Coon

GTA: G. P. Burdell

Date: November 18, 1997

Submitted by Team L-2:

M. Howard

L. Fine

J. Howard

27

ABSTRACT

The goal of this project was to determine the diameter of an 18-inch pulley shaft subjected to

axial loads. A shaft diameter of 1.22 in. was determined to be minimally acceptable, and a shaft size of

1.25 in. is recommended. In support of these conclusions, this report provides calculations of the sums of

moments, maximum loading, moment of inertia and maximum loading. These calculations are supported

by an overall system sketch, a loading diagram, a shear force diagram and a moment diagram.

28

INTRODUCTION

Figure 1 shows the solid round shaft of interest. This shaft is 18 inches long, and is supported by

self-aligning roller bearings at the ends. Mounted on the shaft are a V-belt sheave, which contributes a

radial load of 400 lb to the shaft, and a gear, which contributes a radial load of 150 lb. The two loads are

in the same plane, and have the same directions. The bending stress is not to exceed 10 kpsi. The

objective is to determine the diameter for this solid round shaft.

Figure 1. The size for this shaft is to be determined.

ASSUMPTIONS The following assumptions govern this calculation: • The weight of the shaft is neglected.

• Because the bearings are self-aligning, the shaft is assumed to be simply supported, and the loads and

bearing reactions are assumed to be concentrated.

• The normal bending stress is assumed to govern the design at the location of the maximum bending

moment.

METHOD Figure 2 shows a loading diagram for this problem, based on the drawing and assumptions

outlined above, and Figures 3 and 4 show the shear-force diagram and the moment diagram for this

system. Based on these diagrams, R1 and R2 are first determined by summing the moments around O and

C. Second, using the values of R1 and R2, the maximum bending moment for the shaft will be calculated

6” 8”

18”

y

x

Pulley 400 lb Gear 150 lb

29

in order to determine which part of the shaft undergoes the greatest stress. Third, using the calculated

value for the maximum bending moment, the diameter of the shaft will be determined using common

expressions for the section modulus and the maximum stress.

Figure 2. Loading diagram for the shaft system shown in Figure 1.

Figure 3. Shear-force diagram for the shaft system shown in Figure 1.

Figure 4. Moment diagram for the shaft system shown in Figure 1.

Sum of moments. Values for R1 and R2 must be determined first. These values are found by

summing the moments about points O and C, according to Equation 1:

R2

C BA O x

y

R1

400 lb 150 lb

xO

V 300

250

xO

M

30

∑ =n

eM1

0 (1)

For R1 the moments sum as follows:

∑MC = -18 R1 + 12(400) + 4(150) = 0

R1 = 300 lb

For R2 the moments sum as follows

∑MO = -18R2 + 6 (400) + 4(150) = 0

R2 = 250 lb

These values will next be used to determine the maximum bending moment.

Maximum bending moment. The maximum bending moment is determined using the values of

R1 and R2. In this case the maximum bending moment is found between O and A in Figure 2, so the

value of R1 is of primary interest:

M = 300 lb (6 in) = 1800lb · in

This value for the maximum bending moment will be used later in the final calculation of Maximum

Stress.

Section modulus. The section modulus for the shaft is characterized in Equation 2:

33

0982.032

ddcI

==π

(2)

where I is the second moment of inertia, c is the distance from the neutral axis, obtained elsewhere, and d

is the diameter of the shaft, which is of interest. The shaft diameter will be determined using this

equation in connection with the Maximum Stress equation.

Maximum stress. The maximum stress is related to the section modulus according to equation 3:

31

ZM

=σ (3)

where Z is the section modulus I/c from equation 2, M is the bending moment determined earlier, and σ is

the bending stress, which has been specified. Since the bending stress is not to exceed 10 kpsi, σ is set to

be 10,000. The bending moment value has been determined to be 1800 lb. in, and the section modulus

known to be is related to shaft diameter according to equation 2. The diameter of the shaft can now be

determined using Equations 2 and 3 as follows:

3)10000(0982.0

1800=d = 1.22 in.

CONCLUSION A shaft diameter of d = 1.25 in is selected.

32

DISCUSSION OF THIS ANALYSIS PRESENTATION ABSTRACT

The abstract for a report should be treated as a very short description of the report’s contents. It

should very briefly state the problem that is addressed, the result that was obtained and the deliverables,

usually illustrations or equations, that are presented in the report.

THE ANALYSIS PRESENTATION An engineering analysis has 5 crucial parts:

1. A layout drawing of the component to be considered in the analysis;

2. A loading diagram of the component, showing the locations of forces and reactions;

Other diagrams may be included, as required for the calculation;

3. A list of the assumptions that will govern the analysis;

4. A brief summary of the solution approach to be used in the analysis;

5. A display of the equations and solution steps.

While most students prefer to leap straight to step 5, steps 1-4 perform 2 vital functions. First,

these steps, when followed carefully, constrain the student to think through the analysis problem clearly

and logically and to proceed through the solution steps in an orderly fashion. Second, these first four

steps allow the student to communicate the solution steps clearly to colleagues, instructors and

supervisors.

The communication role of the first four steps is vital; every engineering calculation must be

communicated to a colleague or a supervisor; when students omit these vital four steps, they often find

that their instructors cannot understand the equations that are displayed. When this happens, the student

often finds that s/he is unable to recall what is represented and is unable to produce a satisfactory

explanatory sketch.

Below, the elements of these 5 steps in analysis are discussed in some detail.

1. A layout drawing of the component to be considered in the analysis

Engineering analyses present solutions to problems. Consequently they must begin with full

statements of the problems to be addressed. Those problem statements include a drawing and a prose

description of the problem.

The drawing should show an overview, or layout drawing illustrating the problem. In the case of

the problem presented above, the drawing in Figure 1 presents only those elements of the overall system

33

that pertain to the problem under consideration: the shaft, the bearings that support it, and the pulley and

gear on that exert forces on the shaft. The associated prose statement of the problem appropriately lists

the central features of the drawing as they pertain to the problem at hand.

This drawing is used as a reference point as the engineer moves through steps 2 through 5. When

such a drawing is displayed to the audience, steps 2 through 5 are easily presented. When such overview

drawings are omitted, review discussions usually grind to a halt.

2. A loading diagram of the component, showing the locations of forces and reactions

A loading diagram, such as Figure 2, is next provided, to represent the assumptions graphically.

This diagram should display all pertinent forces on the system under consideration, and it should indicate

with variables what values are to be determined through calculation. In the case of the simple system

considered in our example, the loading diagram shows only 4 forces; two of these forces are known and

the others are determined as part of the solution to the problem.

The loading diagram is a simplification of the overview drawing, based on the assumptions that

govern the analysis. Consequently, the loading diagram and the overview drawing should be placed close

to each other, they should have the same orientation, and they should be the same size.

During a review of your work, instructors and supervisors will consider your overview drawing,

your assumptions and your loading diagram together. Based on these three pieces of information, they

will try to verify that the diagram accurately represents the case under consideration, that all forces are

appropriately balanced, and that the analysis will indeed address the stated problem.

3. A list of the assumptions that will govern the analysis

After the problem is presented in an overview drawing, a short list of assumptions is provided.

These assumptions might also be called the model or case being used to address the problem, and they

outline, in this case, what forces or weights, are to be neglected, how the component is believed to be

supported, and what force or stress is of primary interest in the calculation.

This list of assumptions is critical for the student and for all technical reviews of a calculation.

Formulation of such a list of assumptions helps the student to develop an organized approach to the

problem, to select an appropriate case or model from a reference book, and to locate an appropriate set of

equations for developing a useful solution.

Because a list of assumptions acts as a gloss on the overview drawing, technical reviewers can

use the list to determine whether a solution approach is reasonable and appropriate.

34

4. A brief summary of the solution approach to be used in the analysis

The method of reaching a solution to the problem should be outlined briefly. This outline should

consist of a very few sentences indicating what values are to be determined and in what order they are to

be determined. In the above example, this information is presented in 3 sentences, which outline the 4

main steps in the solution procedure.

This information is entirely reader-oriented. Engineering problems generally require a number of

intermediate calculations, and the breaks between these calculations are not always apparent on a sheet of

equations. In the calculation represented above, the solution steps are enumerated in the Approach

paragraph, and they are subsequently distinguished from one another by paragraphing. Each step is

marked with a new paragraph, showing indented and underlined side-headings, displays of equations and

text explanations of the variables.

5. A display of the equations and solution steps

Steps in the actual calculation of values should follow the norms for presenting calculations in

laboratory reports; equations should be appropriately displayed and numbered, and the sources of

variables and values should be made clear.

35

REPORT MODEL #2: REPORT SHOWING A SPAGHETTI BRIDGE

Sample “Good Report”

36

ME 2110-X

Studio Project 1:

Spaghetti Bridge

Submitted to:

Instructor: J. S. Coon

GTA: G. P. Burdell

Date: January 18, 1997

Submitted by Team X-2:

M. Howard

L. Fine

S. Howard

J. Howard

Sample “Good Report”

37

ABSTRACT This report describes two spaghetti structures that were built to span a distance of three feet and

to bear weight. These spaghetti structures are here characterized using three drawings, and the results of

the project are as follows: each of the two spaghetti structures successfully spanned the required distance;

the first structure bore a weight of four ounces, and the second bore a weight of sixteen pounds.

Sample “Good Report”

1

INTRODUCTION The objective of this project was to build a bridge between two tables placed 3 feet apart. This

bridge was to be constructed using only one box of dried spaghetti noodles and one roll of clear tape.

After the bridge was constructed, weights were to be hung from the bridge to determine how much of a

load the structure would hold before failing.

The challenges posed by this project stem from the materials to be used. Spaghetti flexes and

breaks easily, so it must be reinforced in order to be useful in construction. Tape can provide

reinforcement for spaghetti in some circumstances, but it cannot prevent bending. Tape was found,

however, to have tensile strength. Both of the bridges described in this report were designed to exploit

tape’s strengths while compensating for the weaknesses of spaghetti. In the first bridge, the design

focused on the use of tape-reinforced spaghetti structures, while the second bridge was designed entirely

to exploit the strengths of tape.

OVERVIEW OF BRIDGE WITH SPAGHETTI AS STRUCTURAL ELEMENT The first spaghetti bridge, represented in Figure 1, was designed to use spaghetti as the main

structural element, while using tape as a reinforcement for the weak characteristics of spaghetti. This

bridge consists of a long central span of taped spaghetti bundles, two table anchors, also made of taped

spaghetti bundles, and eight tape supports, which were introduced to prevent swaying and to prevent the

bridge from collapsing under its own weight. The long central span was designed to be strong by using

reinforced spaghetti bundles, which are represented in Figure 2. Each component of this span was

composed of three tape-wrapped bundles of spaghetti, which were themselves wrapped together, forming

a double-tape-wrapped central span member. Such members were then fixed together until reaching a

length of 40 inches. Similarly wrapped members were taped to the tables to function as bridge anchors, to

which the ends of the central span were taped. The support strands of tape were then strung from the

table to four locations along the span in order both to stabilize the span and to prevent it from sagging and

pulling itself loose from the anchors.

The bridge thus fabricated was able to hold four ounces of weight before it failed. Failure

occurred when the spaghetti strands in the central span broke and pulled apart. When failure occurred,

however, the reinforcing tape strands remained intact, simply unwinding from the remaining spaghetti

elements of the central span. This failure revealed that tape was by far the better material for holding

weight; this information came to govern the second design.

Sample “Good Report”

2

OVERVIEW OF BRIDGE USING TAPE AS PRIMARY ELEMENT The second spaghetti-tape bridge, shown in Figure 3, was designed to use tape, rather than

spaghetti, to bear weight. This bridge had a central span made of spaghetti cable, a primary support web

of individual tape threads and a secondary support frame of tape. The spaghetti cable, the tape frame and

the tape web all converged at a central point, which was designated as the support point for weights.

The spaghetti cable was built of three spaghetti bundles, as represented in Figure 2. Three

bundles were developed, each bundle being composed of six spaghetti strands wrapped in tape. The three

bundles were then wrapped in a tape sheath to form a member of the spaghetti cable. Members were

added to this cable until it reached a length of 40 inches.

As a primary support for this central spaghetti cable, a tape support web was formed of four long

pieces of tape that ran diagonally between the two tables, crossing below the central span exactly at its

mid point. These four pieces of tape were fixed to the tables in long strips, marked as “adhesion surfaces”

in Figure 3. These long tape strips offered support to the design by expoliting the tape’s tensile strength.

The tape strips crossed each other at the cable’s midpoint, the location of the maximum expected load.

Below this tape web a heavy, secondary frame of tape was strung between the two tables and

beneath the spaghetti cable and the web, providing support for both. As shown in Figure 3, this tape

frame consisted of two long strands of tape, doubled, that were fixed to the tables and that ran parallel to

the central span. Cross-pieces of tape then were strung below the cable, forming a support cradle near the

center point.

This design was able to support 16 lb. Although the spaghetti in the cable failed quickly, the two

tape support structures never failed. Loading was terminated when the tables themselves were pulled

together by the weights suspended between them.

METHODS While design alternatives were not developed, two assumptions governed the development work

on this project. It was first assumed that loads would either stretch or shear the spaghetti noodles, and it

was second assumed that tape could be used to solve this stretching/shearing problem. A successful

design would need to balance the strengths of tape and the weaknesses of spaghetti. While both designs

used these assumptions, the first design used the tape in the wrong way. The failure of the first design

revealed both that spaghetti could not be easily reinforced to bear a load and that tape need not be entirely

integrated with spaghetti in a successful design. The second design was governed by these insights, as the

role of spaghetti in the design was reduced, while the role of tape in the design increased greatly.

Sample “Good Report”

3

CONCLUSION Two bridge structures were developed using spaghetti and tape. The first such structure, shown

in Figure 1, supported a load of four ounces. The second such structure, shown in Figure 3, supported a

load of 16 pounds.

Sample “Good Report”

4

Spaghetti bridge,main span

Tape supports

Spaghettianchors

Table Table

Figure 1. Spaghetti bridge using a single central span and eight tape-support cables.

Sample “Good Report”

5

Tape outerwrapping Tape wrapping

for strands

Individualspaghetti noodles

Figure 2. Cross sectional 0f the Central Span cable for the tape reinforced spaghetti bridge.

Sample “Good Report”

6

Table Surface

Light Web Support

Heavy Bridge Support (tape)

Spaghetti Cable

LargeAdhesionSurfaces

3’

Figure 3. Spaghetti-tape bridge, using a tape web to support weight.