Week 8

     This week during class, we discussed some of the articles we had researched the previous week. We would like to look into the bone's response to mechanical stimuli more, and see if there is a minimum threshold required to prevent bone loss. We also got the thumbs-up for using the Instron tensile test machine, so we ran some tests on our elastic bands.
     The elastic bands were cut into strips that were 10 cm long and 1.5 cm wide. Each elastic band (there are five different ones) was cut up to provide three samples for testing. Shown below are pictures of this process.

Shown are the small elastic band strips used for tensile testing.

The Instron machine pulling one of the black elastic band samples.

Testing the different elastic bands.

     Isaac later compiled the data gathered from the tests and organized them into an excel file. Shown below are plots generated for each different color band.

This is an example of one of the results from a black elastic band.

Black elastic band results.

Blue elastic band results.

Green elastic band results.

Red elastic band results.

Yellow elastic band results.

      During the week, we met as a group to delegate duties and discuss Deliverable 5. We started on some Solidworks, updated the excel mathematical model, and constructed the critical module test using elastic bands.

Version 1 of the harness drawn in Solidworks.

Version 1 of the ankle brace drawn in Solidworks.

 The critical module test utilized several different bands in order to provide sufficient load. We tried to make the elastic band module as similar to the spring model as possible (in regards of things like anchor point locations and force) so that fair testing and comparison between the two methods would be possible.

This was for the inside of the arm. It contains two black bands and one blue band, all stacked on top of each other.

This is the outside of the arm. Bands were attached to the wooden model via duct tape.

The final product.

Example of the math model for the constant force spring system.

Moment about the inside of the arm using the spring system.

Moment about the outside of the arm using the spring system.

Using both the inside and outside spring system.

Moment about the inside of the arm using elastic bands.

Moment about the outside of the arm using elastic bands.

Using both the inside and outside elastic band system.

     Our team had some questions about the architectural design portion of the Deliverable, so we emailed/met with our professor. Dr. Gordon said that he was surprised we hasn't asked for an extension on the deliverable, and told us that he would prefer we wait to submit the deliverable and focus on doing more research. The research should concentrate on whether there is a minimum force needed to stimulate the bones and should also provide alternative/additional options for targeting the astronauts' legs. (This had always been a point of concern, and Jake had emailed a former professor and astronaut who confirmed that astronauts do not use their legs extensively while in zero gravity).