Homework

 

Problem set 5, Due Wednesday, November 19, 2003 (HTM)

Problem set 5, Due Wednesday, November 19, 2003 (PDF) The last one! 

Problem set 4, Due Wednesday, November 5, 2003 Solutions

Problem set 3, Due Wednesday, October 22, 2003 Solutions

Problem set 2, Due Wednesday, October 8, 2003 Solutions

Problem set 1, Due Wednesday, September 17, 2003 Solutions

 

Project

Completed Reports: Nice job on a difficult assignment.
Mike Dewald and Vinay Gill
Jean Gullickson and Julie Waters
Eric Keaveny
Don Ward and Brian Burke

The assignment: Design and perform simple, tabletop experiments to determine an elastic potential that characterizes the behavior of latex rubber sheets over a range of finite deformations.

You can work in pairs or alone, but please let me know if you will be working alone or with a partner by Wednesday, 11/12.

For the experiments, use inexpensive, portable equipment and materials to make your measurements, rather than standard mechanical testing devices such as the Instron. Use things such as rulers, calipers, weights, clamps, etc.  The measurements are not expected to be incredibly precise, although you should quantify the level of accuracy in the measurements.

To begin, address some of the basic constitutive issues. You might first check (or assume!) material symmetry for the latex. Test to see if the latex seems to be compressible or incompressible. 

Once you have addressed these fundamental questions, then test the sheets in other ways, and collect whatever stress-stretch data you think would be helpful. 

Finally, choose candidate forms for the elastic potential, and fit any parameters in these forms to the data. For ₁) is a function of the first ₁, and fit, say polynomial form for W(I₁). You might have to try a few forms before finding an elastic potential that matches well with your data. You may wish to attempt to characterize the  plane stress elastic potential directly, along with a the function giving the out-of-plane stretch as a function of the in-plane deformation invariants. 

Each pair will be required to make a 20-30 minute presentation in class during the week of December 1. Describe and demonstrate your experimental set ups. Discuss the types of deformations to which you subjected the rubber, and explain how and why you chose these deformations. Show data. Finally, describe the form of the

And if you need more rubber, just ask! Good luck--I know this assignment is a bit of a stretch for some of you.  (ha, ha)