Cad Two Marks Org

8/2/2019 Cad Two Marks Org

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NOORUL ISLAM COLLEGE OF

ENGINEEING KUMARACOIL

DEPARTMENT OF CIVILENGINEEING

QUESTION ANSWERBANK

CE1029 COMPUTER AIDED DESIGN FOR

STRUCTURES EIGTH SEMESTER


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Unit 1

INTRODUCTI

ON

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1. Define CAD.

Computer Aided Design involves any type of design

activity which makes use of computer to develop, analyze or

modify an engineering design. Modern CAD systems are

based on interactive computer graphics.

2. Define data structure.

A data structure is defined as a scheme, logic or a

sequence of steps developed to achieve a certain

graphics, non- graphics and a programming goal.

3. What is a database?

A database is defined as an organized collection of

graphics and non graphics data stored on secondary storage

in the computer.

4. Define automated drafting.

Automated drafting involves the creation of hard

copy engineering drawings directly from the CAD data

base. Graphic features of computer aided design can

increase productivity in drafting function.

5. Define model co ordinate system.

It is defined as the reference space of the model

with respect to which all the model geometric data is stored.

Three types of co ordinate systems are needed in order to

input, store and display model geometry and graphics.

6. Write the functions of design work station.

The functions of design work station are:

i) It must interface with the central processing unit.

ii) It must generate a steady graphic image for the user.

iii) It must provide digital descriptions of the graphic image.

iv) It must translate computer commands into operating


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functions.

v) It must facilitate communication between the user andthe system.


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7. What is a geometric model? Mention its types.

A geometric model is a graphical representation of

an object, using the mathematical database in the

computer. Solid model, surface model and wireframe model

are the types of geometric model.

8. Write the various design tasks performed by CAD system.

The design tasks performed by CAD system

are geometric modeling, engineering analysis, design

review and evaluation and automated drafting.

9. What is the graphic configuration of a

graphic system? The graphic configuration ofa graphic system is,

i) It interacts with the graphics terminal

to create and alter images on the screen.

ii) Construct a model of something

physical out of

the images on the screen. The

models

are sometimes called application models.

iii) Enter the model into computermemory and

or secondary storage.

10. What are functions of a graphic package?

The functions of a graphic package are

generation of graphic elements, transformations,

display control and windowing functions, segmenting

functions and user input functions.

11. List the types of output devices used in conjunction

with computer aided design system.

Pen plotters, hard copy units, Electrostatic

plotters, Computer-output-to-microfilm (COM) units

are the output devices

used in conjunction with computer aided design

system.

12. What are the modules of ICG?

The interactive computer graphics software is

divided into three modules as the graphics package,

application software and application database.


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13. Write the display devices used in computer graphics

application.

Raster scan monitor, LCD monitors and plasma

panel display are the display devices used in

computer graphics application.


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14. Write the display devices used in computer graphicsapplication.

The display devices used in computer graphics

application are Raster scan monitor, LCD monitor and

Plasma panel display.

15. List any two types of output devices used inconjunction with CAD

system.

Graphic Displays and Hard copy Printersand Plotters.

16.Define Recognition of need.

Recognition of need involves the realization by

someone that a problem exists for which some corrective

action should be taken. This might be identification ofsome defect in current machine design by an engineer or

the perception of a new product marketing opportunity by

salesperson. Definition of the problem involves a thorough

specification of the item to be designed. The specification

includes physical and functional characteristics, cost,

quality and operating performance.

17.Write the analysis step of design process

Synthesis and analysis are closely related and highlyiterative in the design process. A certain component or

subsystem of the overall system is conceptualized by the

designer, subjected to analysis, improved through this

analysis procedure and redesigned. The process is repeated

until the design has been optimized within the constraints

imposed on

the designer. The components and subsystems are

synthesized into the

final overall system in a similar iterative manner.

18. what is evaluation?

Evaluation is concerned with measuring the design

against the specifications established in the problem

definition phase. This evaluation often requires the

fabrication and testing of prototype model to assess

operating performance, quality, reliability and other

criteria. The final phase in the design process is the

presentation of design. This includes documentation of the

design by means of drawings, material specifications,


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assembly lists and so on.

19. Write a note on engineeringdesign?

Engineering design has traditionally been accomplished

on drawing boards, with design being documented in the form

of a detailed engineering


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drawing. Mechanical design includes the drawing of the

complete product as well as its components and

subassemblies.

20. Define Electrical design of CAD

Electrical design is concerned with the presentation of

circuit diagrams, specifications of electronic components, and so

on. In each engineering discipline, the approach has traditionally

been to synthesis a preliminary design manually and then to

subject that design to some form of analysis.

UNIT

2

GRAPHICSPACKAGE

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1. Define segmentation.

Segmentation or curve splitting is defined as replacing

one existing curve by one or more curve segments of the

same curve type such that the shape of the composite curve

is identical to that of the original curve.

2. Define transformations.

Transformations are used to change the image on the

display screen and to reposition the item in database.

Transformations are applied to the graphic elements in

order to aid the user in constructing an application model.

3. What is a frame buffer?

A viewing surface of a raster scan display is divided

into an array of pixels. Every pixel in the viewing screen

must be associated with one bit of memory. In this graphics

memory, one bit is associated with each pixel on the display

surface. This memory is called frame buffer.

4. What is a digitizer?

It is an input device used for inputting a serious of x-y


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coordinate pairs. In a CAD environment, digitalizes are used

for two functions viz, inputting maps and drawings into

the system and for creating tablet menus.


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5. Define scanner.

The input device used for inputting images directly is

the scanner, which converts a page into an array of dots

depending on the resolution of the scanner. These dots are

converted to pixels that can be used as inputs.

6. What are the methods adopted to generate text in graphics?

In computer graphics two methods are adopted

to generate text primitive. They are vector generated text

and raster generated.

7. Define scaling.

The image displayed can be reduced or enlarged

using scaling. Scaling can be done either in x or y directionor in both directions simultaneously. Scaling factors can be

specified in x and y directions to carry out scaling.

8. Write the properties of graphical work station.

The properties of graphical workstation are:

i) It has one display surface with a fixed

resolution. ii) The display spaces are

rectangular.

iii) No image is displayed outside the specified display space.

iv) It supports several line types, marker types , text

fonts, character spacing etc.

v) It has one or more logical input devices.

vi) It stores and manipulates segments.

9. List the GKS work stations.

GKS defines six categories of workstations viz,

Output workstation which has display surface for

displaying images. Input workstation with atleast onelogical input device.

Output / Input workstation with a display surface &

atleast one logical input device.

Workstation independent segment

storage (WISS) GKS metafile input &

output.

10. What is a GKS metafile?


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A graphics metafile is defined as mechanism for the

transfer and storage of graphics data, which is both

applicant independent and device independent.

11. Define wireframe model.

A wireframe model is the simplest geometric

modeling type, where an object is described by points,

lines, circles, and curves in 3D representation.

12. Define surface model.

Surface model is similar to wireframe model where an

object is described by surface entities such as B- spline,

Bezier patches, coons patches, ferguson, surfaces,etc.

13. Define solid model.

Solid model is a complete representation of a

surface model where the object is described by solidentities such as blocks, cylinder, cone, sphere, wedge etc.

It can also be compared with an actual or existing

model.

14. Write the functions of GKS.

Regeneration and transformation of imagesImage generated in user co-ordinateControlling the activities of work stationStructuring the cell arrays and there bygenerating images

15. State the advantages of AUTOCAD

Smooth arcs can be drawn to connect two lines.

Objects can be filled with specified pattern or crosshatched.

Aspect ratios can be varied at any time.

Objects can be dragged to vary their locations andsizes.

16. Define pivot point.

The point about which the image is rotated is calledpivot point.

17.What are the types ofmodel

Wireframe model

Surface model

Solid model

18. Define wire framemodeling.

Wireframe models are the simplest of the


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three types of models. They are easy to create and use. They

provide sufficient information on


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solid object. They are normally used to create models of simple

objects. Wire frame models are generated by continuing line

segments

19. Define Surface

Modeling

Surface entities are introduced to the wire frame model in

the surface modeling. Surface models define part geometry

more precisely, compared to wire frame models. An object

generated through surface modeling can be displayed on a screen,

in such a way that it look like a solid object .

20. DefineRotation

The transformation is used to rotate objects or images aboutany point in the world space either clockwise or anticlockwise

direction. The point about which the image is rotated is called

pivot point. These steps are required to perform this operation.

They are

Translate the pivot point xp,yp to the origin

Rotate the translated points by e about the origin

Translate the centre of rotation back to the pivot point

In the first step the points (x,y) get transformed to (x,y),and inthe zsecond step (x,y).In the third step to (x,y).all the line

segments on the objects has to be transformed to get the

complete image rotated about the pivot point xp,y

UNIT 3

STRUCTURALANALYSIS

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1. Define discretization.

The basic concept of the finite element method is that

a body or a structure is divided into smaller elements of

finite dimension called finite elements.


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2. Mention some commercially available software

packages of finite element analysis.


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ABACUS, ADINA, ANSYS, ASKA, COSMOS, GT-

STRUDL, NISA, PAFEC, SAP, SESAM-80 are some of the

available software packages of finite element analysis

3. What is meant by banding of a stiffness matrix?

The adjacent elements of the diagonal matrix

are non zero numbers and the elements far away from

them are non zero numbers.

4. Define nodal point.

The point at which two nodal planes meet is called

node (or) nodal point. Nodes are points at which

different elements are connected to generate the

structure or system.

5. Define general type pre and post processor.

The types of pre and post processors are general

and specific purpose. General purpose type processors canbe coupled to many finite element packages and many even

offer facility to process problems in the field of engineering.

6. Define special purpose type pre and post processor.

The special purpose processor work in connection with

specific finite element analysis package and is usually

available in an integrated form with that package.

7. What is duplication?

Portions of an existing model or the entire model can

be translated, rotated, mirrored or scaled to generate

another portion of the model is called duplication.

8. Write the functions of pre and post processor.

A preprocessor creates the finite element model and

the input necessary for a finite element analysis

program. A post processor program accepts the results of

the analysis and generates tables, diagram/pictures etc for

the interpretation of results.

9. Write the basic steps of finite element analysis.

The basic steps of finite element

analysis are:i) Discretization of a given body or structure into an

assemblage of finite elements.

ii) Derivation of element equations for various types ofanalysis.

iii) Assemblage of elements to obtain the governing

equation for the whole problem.

iv) Solution of the assembled

equations v) Post-processing of

results.

10. What is FEM.


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FEM is a numerical technique for solving boundary value

problem in which one divides the domain of the problem into little

pieces over which the solution is approximated using polynomials.

11. Define shape function.

Shape function is defined as one whose values at a

particular node is unity and other nodes zero.

12. What are the properties of shape function?

i) There will be as many shape functions as there are nodes.

ii) It will have unit at the node in question and zero values at

other nodes. iii) The sum of all the shape functions is unity.

13. List out the advantages of FEM?

Advantages

Since the properties of each element are evaluated

separately we4can incorporate different material properties of

each element

There is no restriction to the shape of the medium.

Any type of boundary condition can be accommodated.

14. List out the disadvantages of FEM?

Disadvantages

The computational cost is more.

The solution is approximate.

15. Define displacement function?

Simple functions which are assumed to approximate the

displacement for each element are called displacement functions.

It may be a function of polynomials, trigonometry or others.

16.Name the types of noded elements

2-noded elements-line

3-noded elements-triangle

4-noded elements-quadrilateral

17. List the Hardware requirements of pre and post processor

Computers-VAX family

Prime family

DEC

HARRIS

APPOLLO

CDC cyber

18. List the various co ordinates of FEM.

I) Local or element co

ordinates


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ii) Natural coordinates

iii) Simple natural co

ordinates iv) Area co

ordinates

v) Generalised coordinates.

19. What are the factors that govern the selection type of finiteelement?

Geometry of the body

Number of independent space coordinates

Nature of stress variation

20. What are the properties of shape function?

No. of shape function=no. of nodes

Values of the nodes in the question =1 and all others mustbe zero

The sum of the shape function is unity

Unit-4

DESIGN ANDOPTIMIZATION

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1. Define objective function.

A function for which an extreme is sought, in theoptional design

process. It is also referred to as merit function. Usually weight,

cost or volume of the structure/solid/component is chosen as the

objective function.

1. What is a design variable?Design Variables are those quantities defining a system andthese are varied to achieve an extremism of the objectivefunction. Generally the Cross-sectional dimensions, thickness,etc are taken as design variables.

2. What is meant by InequalityConstraints?

These constraints usually ensure safety against a failure modeor satisfactory behaviour under the given loading conditions. Thelimits imposed on stress at a section/point not to exceed the


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allowable value and displacement at a node not to exceed thepermissible limits is typical examples for inequality constraints.

3. Define EqualityConstraints.


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These are conditions that must be strictly satisfied

for the design to be acceptable. In the case of solids, the

conditions of equilibrium are to b imposed as equality

constraints, but they are implicit as part of analysis

procedure and are not stated. So it may be noted that the

inequality constraints such as limits in press cannot be

expressed explicitly since it requires a finite element

analysis.

4. What are Side Constraints?

The upper and lower bounds on the design variables are

usually referred to as side constraints. Generally the idle

constraints impose geometric restrictions on the design

variables 10


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generate and test approach.

8. Write short notes on constrained optimization techniques?


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A constrained optimization is concerned with obtaining a

minimum(or maximum) of the objective function to constraints.

The methods of optimization can be classified into two broad

categories: (i)Direct Methods and (ii)Transformation or Indirect

Methods.

9. Write short notes on unconstrained optimization techniques.An unconstrained optimization problem aims at

minimization ( or maximization) of the objective function inthe absence of constraints. The unconstrained optimizationtechnique can be broadly classified into two categories , i)single variable/ unidirectional search techniques and ii) multi-variable optimization techniques.All the algorithms

10. Define Transformation/Indirect Method

These methods transform the constrained optimizationproblem into a sequence of unconstrained optimizationproblems with the motivation to use well establishedunconstrained optimization techniques discussed in theearlier section. The general approach of the indirectmethods will be to minimize (or maximize) the objectivefunctions as an unconstrained function but provide penaltyto limit the constraint violation.

11. Define meta-knowledge.The term meta knowledge refers to knowledge about

knowledge. As the size of the knowledge base grow larger andlarger, and controls strategy become more complex. An ideal

way in this situation is to logically divide the knowledge intosmaller ones, and have a higher level knowledge base, whichcontaining the knowledge about the lower level knowledgebases and problem solving strategy. Knowledge base athigher level is called meta-knowledge.

12. Write the architecture of KBES development tool.

The architecture of KBES development tool consists of Rulebase inference engine which consists of Knowledgeacquisition facility, Data base management system, Framemanagement system, Engineering design synthesis and

Design critic.13. Write the functions of preprocessor?

Reads control parameter.

Reads or generates nodal Coordinates boundaryconditions.

Reads or generates element connectivity and

element loads.

Reads material constants constitutive matrixcoefficients.

Reads nodal loads and loading conditions.14. Write the functions of postprocessor?

Prints/plots deflection shape.


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Prints/plots contours of displacements.

Calculates strains and stresses.


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Prints/plots contours of stresses, Displaysstress bands, maximum and minimumvalues.

15. Write the different gradient based

methods?

Methods od Steepest descent/Ascent

NewtonSearch Method

Conjugate Gradient Method

Method of Flecture and reevs

Quasi-Newton/Variable Metric Methods and under this

category, Davidon-Fletcher-Powell (DFP) method is

reported to be stable and reliable for use.

16. Name the methods ofconstraints

Cutting plane method

Move Limit Method

Method of Feasible Directions

Zontendijk's Method

Gradient Projection Method

Generalized Gradient Projection Method

Pschenichnny's Linearization Method

Quadratic Objective function and Linearized Constraints Sequential Quadratic Programming

Recursive Quadratic Programming

17. What are the Principles of RC design.

Find the strengthconsidering

(A) Strength in yielding of gross area.

(B) Strength in rupture of critical section and

(C) Strength in block shear.

Minimum edge distance and minimum pitch

distances are maintained, strength in yield is the least

value, hence the design is safe.

18. What are the Principles of compression member design.

Select a section togive effective are required and calculate rmin.

Knowing the end conditions and deciding the type of connection

determine effective length. find


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the slenderness ratio and hence the design stress and load

carrying capacity. Revise the section if calculated Pd differs

considerably from the design load.

19. Write the types of optimization techniques.

The types of optimization techniques are constrained

optimization techniques and unconstrained optimization

techniques

20.Define Explanation Facility

Explanation facility is one of the most important

components of the expert system. This provides a mechanism for

the user of the expert system, to get more information on the

inference process. Primarily a user will be looking for four

different pieces of information during and after the inference

process.

UNIT-5

EXPERTSYSTEM

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1.Define Inference Mechanism.

It is impossible to compile the knowledge in a database.

Hence certain components directs to implement it in theknowledge base. It is a search technique. This can be done in 2

types Forward chaining, Backward chaining

2.Define Backward chaining:

In Backward chaining inference mechanism the data

required fed in steps in which it is required. It selects the goal

and scans until the goal is reached.

3. What is an Inference Engine?


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The inference engine, which is nothing but the

implementation of one or more inference mechanisms, carries out

the search through the knowledge base either to prove

hypotheses or to arrive at a conclusion. Depending on the nature

of problem to be solved and the nature of knowledge

contained in the knowledge base, a proper inference

mechanism is I selected and the search is


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carried out. When a prototype expert system is developed

the knowledge engineer decides on the inference strategy to be

selected.

4.Define production rule.

Production rule are based on control knowledge orhieuristic knowledge. The antecedent has a course of action andit is satisfied only then the course of action of antecedent issatisfied.That is RHS is equal to LHS only if the course of action of LHSis satisfied then only the course of action of RHS is satisfied.

Example:IF the environment iscorrosive THEN avoidusing steel columns. IF

flow is open channelAND fraude number is 1THEN flow is critical.

5.What are the common ways of knowledge representation?Knowledge can be represented in many ways. They are

1.Quantitative Method2.Qualitative Method3.Compiled Method

6.What is meant by forward chaining?

In forward chaining, inference mechanism rules arescanned until a goal is achieved. It is done if a rule matches with

the goal or the process is repeated. No data is fed during the

process. The inference mechanism uses the data only from the

working memory.

7.What is meant by Artificial Intelligence?

Artificial Intelligence is the method of acquisition of human

or other animals behavior in solving complex problems. It is the

study in which human act in such a way that he can do all theactivities.

8.Define decision tables.

It is a simple and effective method for controlling the

knowledge-based techniques. It consists of both heiuristic and

initative knowledge basis. The decision table consists of four parts.


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Goal Rule I Rule II Rule III Rule I

9.Write the stages of expert system.

The stages of expert system are identification,

formulation, conceptualization, implementation testing

and validation.

10.Write about the search methods of artificial intelligence.

The search methods used in the area of Artificial Intelligence

are broadly classified into five types. They are,

1. Simple search

2. Evaluation based search

3. Games search

4. Constraint search

5. Controlled search

11. List the common ways of knowledge representation.

The most common ways of knowledge representation are,

Production rules, decision tables, frames, semantic networks,predicate logic, conventional programs.

16. What is RDBMS?

A relational database management system (RDBMS) consists

of a set of programs which can relate relations and manipulate the

data stored in the relations. In a standalone mode, the structured

query language (SQL) is used to query the database to get

required information. In language interface mode, generally SQL

queries are embedded in language.

17. What are the components of KBES?

There are two main components of any KSEB are theknowledge base and inference engine. The inference engine

acts on the knowledge stored in the knowledge base to

carry out reasoning. As the nature of database processing

and knowledge processing is different, the strategy adopted

for embedding DBMS in programming language cannot be

adopted here; Databases are created either in standalone

mode or through programs.

18. What is hill climbing techniques


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Hill climbing is an example of an informed search method

because it uses information about the search space to search

in a reasonably efficient manner. If you try to climb a

mountain in fog with an altimeter but no map, you might use

the hill climbing generate and test approach.

19. Define Working Memory

Working memory, which is also sometimes called context, is

nothing but a workspace for the problem, generated by the

inference engine, from the information provided by the user. Many

hypotheses and facts are established during the reasoning

process. These are stored in the working memory. The information

available in the working memory are used for continuing with the

inference process using the knowledge contained in the

knowledge base. The explanation facility also uses the information

in the working memory, to answer the queries of the user.

20.Define Knowledge Acquisition Facility

A knowledge acquisition facility is an optional component

of an expert system. This very much depends on the expertsystem development tool used to implement the system. Any text

editor can be viewed as a knowledge acquisition facility, since it

provides an environment for the knowledge engineer or the expert

to input the coded knowledge into the system. Many development

shells allow the development engineers to code the formal

presentation of the knowledge in a text file, following a specified

syntax. Later, the knowledge in the text files are converted into a

form of data and stored in a data structures for carrying out

reasoning process.

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