User:7ajacobs/Project1

Project Preference

 * 1) MakerBot PLA Material Characterization
 * 2) Autonomous power wheel
 * 3) Bioengineering project

Problem Statement
The project's objective is to test the different resistances ( CTE, strenght , stress , stiffness , strain , ductility ) of the material that the maker bot uses, that is the PLA

Project Plan
week zero : each team member has a resistance that they have to look into Samantha Smallwood : Eke Agbai         : Anthony Jacobs    : CTE ( coefficient of expansion ) Kimberly Cooper   :

Week 1 Narrative
I looked into the CTE ( coefficient of thermal expansion ), found the equation to find the coefficient of linear expansion and came up with two ways of experimenting the expansion coefficient :

first test : rising the heat
by using an oven to expose the PLA object that we'll have created with the maker bot to high temperatures, we will be able to find the coefficient by using the following equation : ΔL= αΔTL , and deduce how much the PLA expanded , and find out how heat affects the PLA

second test : lowering the heat
by using a freezer to expose the PLA object that we'll have created with the maker bot to low temperatures, we will be able how the cold affects the PLA. Then, by using the same equation as the one in the oven test , we will be able to determine how the cold affected the PLA.

during the research, I thought about doing chemistry tests : resistance to acids and corrosion since the PLA will probably have a melting point low , mixing the CTE with the effects of acid on it would be quite instructive , and usefull to future project with the maker bot.

The CTE is important because the different pieces made of PLA might expand or refract depending on how they are used, therefore they might fail to achieve the purpose for which they where created in the first place if their sizes or stiffness ( if the piece melts ) changes.

update : after discussion and research, the group concluded that researching the CTE was useless because the melting point of the PLA is of 180°C , and no experiment conducted in the engineering department that uses PLA parts will atteign this temperature , or temperature that could provoke significant change in the PLA size or shape.

Week 2 Narrative
During this week, my objective was to research and design experiments to test the strenght/stiffness limitations of the material used by the maker bot : the PLA. During my research I found out about Young's modulus and the equation to find stiffness : k = P/dX where k = stiffness, P = load and dX = change of deflection

afterwards I thought about 2 tests the team could do to test the stiffness and apply the equation :

• first test : create a PLA bolt, and put half of it on a stable surface , and half of it unsupported , and hang a weight the part that is not on the surface , and higher the weight until the bolt breaks. • second test : create a PLA bolt pierced on the two extremes, and hang on side on the ceiling or any other stable palce , and hang a weight on the other hole, and higher the weight until the bolt breaks.

using these two tests, we can obtain data , and then use this data in the equation above , thus finding it's stiffness constant K.

Week 3 Narrative
This week I had to design a test for the 3-point bending as we discussed it in class and with the team. After discussion with instructor Edelen, the easier three-point binding test would be to have the strength pulling down instead of pushing down ( from above ). The test itself is quite simple to conceive and cheap.Using the PLA rectangle we'll have printed as our test subject, the rectangle will be fixed to two tables with a space between them large enough so that we can suspend a calculated weight ( the weight is the strength pulling down using strength = weight x gravity ). We can use two claws ( located in the storage room ) to fix the test object to the tables, some simple string to attach the weight in the precise middle of the PLA , and some simple lead weight ( costing 20$ on amazon ). the purpose the test is to find the relation between the PLA's resistance to strength and the maximum weight it can support before breaking. Using a test on small measures will be useful because the stress ( calculated by T = F/A, T being the stress ) and thus allowing us to calculate the maximum strength the PLA can sustain before breaking

Week 4 Narrative
During this week I've mainly focused on the CDIO project and try to have as much detail as possible on the different formulas used during the project. The formulas used are Young's modulus and o=P/A and k= F/l. I've also done more research on the three-point bending, and the tensile test , using my teammate's research as research material Samantha787. With those research and in class discussion with team mates, I had a better understanding of the three-point bending , and was able to draw an initial test of the three-point binding



Using a PLA test subject printed in class. As said in week3 update, the test is cost - efficient and will even be under 20$. Seeing the result samantha787 had in her test with a wooden test subject, and the great margin of error she encountered , it is obvious that the test needs to be run several times , and then all of the results need to be crossed-check to obtain the most precise results possible. Also discussed in class, the test should be run with PLA subjects that have their layers printed in different directions , and then observe the difference in the binding observed , to see if the way the layer was printed could influence the binding of the PLA. Using the formula k= P\dx where p = load, and dx= the change of deflection , we can find k=Stiffness