Week Nine

The bones that we requested in Week 8 were received this week. They are shown in the picture below. As a recap, we printed four pairs of bones: a set of healthy bones with no modifications, another set of bones with minimal modification, one more pair with slightly more modification, and a final pair of bones that had the most modified dimensions.

4 set of bones printed in red ABS plastic. As laid out above, the bones
decrease in scale of modification. The bones farthest to the right have not been modified at all.

The majority of the time in lab was spent in treating the bones with acetone. Out of the eight bones, all of the modified bones as well as one healthy bone were soaked in acetone for sixty seconds. The remaining healthy bone, which was not treated, will serve to be a control group. Furthermore, the data that we collect after testing this bone will serve as a back-up set of data to the original data we have. This way we can check for any outliers, if they should so arise. Further testing of data and data-analysis will follow on Friday of this week (5/31/13).

Pouring 100% in a soap dish

Bone undergoing treatment for 60seconds

--- FRIDAY UPDATE---

After waiting a couple days for the acetone treated bones to dry, we went back to the lab today and tested the eight bones. Though the data we received was consistent, it was surprising to find that these bones, unlike the ones printed several weeks ago, were not hollow. Instead, they had a second layer of thick plastic inside the bone. 

Week Eight

           Between last week and the beginning of this week, we have collected the results from the Three Point Flexural Test, figured out the Bending Stiffness and Young's modulus, and analyzed data. 

             We noticed that the Young's modulus and the Bending Stiffness decrease as the amount of time that the bones are submerged in 100% acetone increases. This holds true for the hollow cylindrical, normal bones and the scaled bones. However, there is one exception: in the loading test #8, the data we obtained for the modified femur that is treated with acetone for 60 seconds did not turn out as expected. The obtained Young's modulus and Bending Stiffness increased. As we examined this modified bone model after the test, we noticed that the breaking point was not in the middle of the bone's length. Instead, it was between the mid-shaft and the trochanter of the bone. Meanwhile, in the remaining models, the breaking point happened to be in the middle. This error may have affected the accuracy of our data in loading test #8. So, we've decided to overlook the result from loading test #8. 

             At the end of this week's lab, we returned to our bone model on AutoCad to re-modify the dimensions of its frontal and transversal planes. We sent out the adjusted model with the new dimensions for 3D printing.