ME 277K Project Proposal

Date: 6 / 01 / 05

To: Mechanical Engineering Undergraduate Office

From: Trevor Page

Subject: Proposal for Solid Freeform Fabrication Research Project

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PROJECT STATEMENT

In the late 90’s, Joseph J. Beaman and many other talented professors introduced Solid Freeform

Fabrication (SFF) to the Mechanical Engineering Department. The SFF concept has driven the

development of various techniques for freeform fabrication. The proposed research utilizes a

selective laser sintering (SLS) technique, which is currently used to fabricate customized

prototypes or functional parts, part assemblies, molds, and other products. One of the inherent

limitations of the SLS machine is the restricted size of its build volume.

This research project is motivated by the overall goal of building large parts in a nominal build

volume. The objective of this research project primarily focuses on determining the feasibility of

creating deployable SFF structures with a SLS machine. The research project focuses on

transforming a condensed structure, manufactured in the small build volume currently in the SLS

machine, to a much larger deployed structure by heating and pressurizing techniques. The

transformation would be similar to inflating a balloon. The ability to mimic this balloon-like

behavior with SLS technology and materials, supplemented with techniques for controlling the

overall shape of the final part, will alleviate part size limitations of the current build volume and

significantly increase SFF capability.

The proposed research project will explore the feasibility of deploying very simple SFF

structures built with available SLS machines and materials. The first part of research focuses on

researching the material properties of SLS material. Since materials have different properties,

one may work better over another, which may suggest important experimental techniques during

the deployment procedure. The current material of choice is Nylon 11, which is used to develop

relatively functional, precise components in the SLS machine. An in depth investigation of

material properties and an analytical analysis will be required to determine the compliance of

Nylon 11 or any other selected material that is subject to the forces, pressures, and temperatures

implemented during the deployment process. Knowledge of the material properties will inform

our design of the pressurized, heated deployment process. Second, 3-D solid model software

such as Pro-E will be used to construct solid models of a compressed/condensed/deflated version

of a simple freeform structure to be made in the SLS machine. The details of the solid models of

the condensed structures will be developed with the experimental deployment procedures in

mind. Solid models will be updated based on the result of experimental trials, in an iterative

process, where the configuration and dimensions of the condensed solid models are continually

modified as new problems arise and experimental parameters change. Third, I will face the

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open-ended task of devising a testing experiment for the deployment process, which will exploit

the material research, CAD knowledge as well as other practical engineering principals. The

experimental objective is to use heat to make the condensed SFF structure physically compliant,

then use air pressure to expand the deflated structure. In the initial tests, each step is crucial and

must be done carefully, then properly recorded for further tests. Many parameters are pertinent to

each step in the experiment and must be methodically analyzed, then modified throughout testing

to ensure desired results. For instance some parameters include; heating technique, heating

temperature, heating rate, deployment technique, compressed air temperature and pressure,

pressure seal, condensed SFF structure geometry and volume, part wall thickness, part curvature

thicknesses, etc. A main parameter of the deployment process requires strict control of a heating

chamber temperature to make the free formed object compliant enough to possibly use an air

compressor to initiate expansion of the freeform structure. In addition, the rate of increase of this

temperature must be closely monitored so that the part maintains shape and does not either

become hardened or melt. Another important factor is the deployment technique, but even more

important is the timing and temperature of the structure while initiating this technique. In

addition, part walls and curvature thicknesses will contain varying compliant behaviors, forcing

deployment procedures to adapt. These parameters will play critical roles in understanding the

deployment techniques used on SFF structures. After much iteration of tests, modification of

parameters and solid models, and examination of the experiment from a practical perspective, a

deployment technique will be realized.

With comprehensive knowledge gained through research of these aspects, iterative testing, and

the collaboration of Dr. Seepersad and other professors involved in this project, I propose that

this research project will form a foundation for research leading to the validation that large scale

deployable SFF structures can be developed.

PROJECT SCHEDULE

This research project will be completed in three phases with a minimum of 10 hours of dedicated

work per week. I will meet weekly with Dr. Seepersad to inform her on the projects’ status. All

tasks are clearly identified in the attached Gantt Chart.

The first phase will consist of gathering research resources and experimental materials necessary

to conduct experiments efficiently. Research resources include reference material on SLS

techniques and materials, as mentioned in the Project Statement. Experimental materials include

SLS build material and any heating mechanisms, air compressors or tools needed from other

departments. This first phase should only take about a week and a half.

In the second phase of this research project, I will be interpreting the results of material research,

developing CAD configurations of simple condensed geometries (e.g. Deflated basketball), and

conducting preliminary deployment experiments on simple freeform structures. This phase of

research will be presented in a progress report which is to be completed prior to mid-semester.

In the third phase, I will conduct a series of iterative experiments, comprehend the affects of

parameter modification, and determine the feasibility of creating deployable SFF structures with

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a SLS machine. This phase of the research project will be documented in a final report due

before the end of the summer session.

PROJECT REQUIREMENTS:

Computer (MELRC lab applicable)

SLS Machine

Small lab space on first floor near the SLS machine

Nylon 11 build powder / other material powders

Thick gloves for handling heated parts

Special Shop Services:

Heating chamber (Mechatronics lab) – 1 hr/part

Source of compressed air – 1 hr/part

Long shafted tools – 1 hr/part

PROJECT BUDGET

Dr. Seepersad and the Laboratory for Freeform Fabrication will cover the costs of the powder

required for the SLS machine. All other equipment and supplies are available for use within the

department and do not require additional funds.

REQUESTED CREDIT

By taking on this responsibility I will be involved in a research project that roughly equals the

time and workload required of a 2-hour laboratory course, but it will require much more in-depth

planning, execution, and interpretation and documentation of results. Similar to a laboratory

course, I will gain experience formulating and conducting experiments, but in this case I will

plan the experiments myself for a relatively open-ended problem. The iterative experimentation

will help me learn how to plan strategic experiments, collect experimental results, critically

analyze the results to fully understand what is taking place in the experiment, and use that

knowledge to modify the experiments accordingly. Experience handling this type of problem

will greatly benefit me in my professional career. Also, this experience will provide an

opportunity to gain formal expertise with CAD software and allow me to further develop my

design skills. In addition, I will become fluent in prototype manufacturing with SLS techniques

and learn about the properties of SLS materials. This research project will establish a foundation

for future research projects focused on more complex, deployable SFF structures.