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Burst/Leak Testing

UPDATE: New arm segment pressure tests are currently underway to reflect an increased operational pressure of 3psid. Results will be posted upon completion of the tests.

Burst Testing
The first arm to be tested (under the old operating pressure of 2 psid) demonstrated excellent strength during burst testing. The goal of such testing is to reach three times operating pressure without failure. The results of the first test are summarized below.

 

Goal Reach 3x operating pressure without failure.
   
Pressure Results
6 psid 3x MX-2 operating pressure of 2 psid
12.9 psid 3x EMU operating pressure of 4.3 psid
12.3 psid Failed axial restraint line, no catastrophic failures.



With improved restraint line design, we are confident new burst testing will demonstrate the same success.

Quality Assurance & Leak Testing
Each arm manucatured for operation must also pass a strength test as a form of quality assurance. The goal of such testing is to hold 1.66-2.0 operating pressure while minimizing leakage rates. The results from the first two arms tested (under the old operating pressure of 2 psid) are summarized below.

Goal Test identical arms to 1.66x - 2x operating pressure. Maintain arm leakage < 1% suit flow.
Sample Conditions,Results
Arm A 3.7 psid, no defects
Arm B 4.0 psid, no defects
Total Arm Leakage < 990 sccm (1% = 1,700 sccm)





Joint Torque/Range of Motion

The goal of providing the capability to replicate the joint angle limitations and torque requirements of an actual pressure suit for some selected body joints is perhaps the most difficult goal to accomplish for this project. The design and fabrication of fabric mobility joints has been the focus of much research in industries and in space agencies around the world. It is not the goal of this project to invest an equivalent amount of time and money into this research, but rather to provide a reasonable approximation to the limitations and abilities of actual pressure suit joints.
 

 




 


 

To do this, a bench top experiment has been developed to help characterize joint toque behavior. This same setup examines range of motion as well. Joint segments (currently only elbow segments) are built and pressurized. A digital force gauge records force exerted at the end of the segment while motion capture software records the motion of the arm segment. This information can then be reduced to joint torque and rotation angle. While much more testing is needed, an example of some preliminary data is illustrated above and to the left.





 


Future Testing
Our team is currently working to have a fully pressurized system up in the near future. From here, the following tests will begin in order to prepare for our manned dives:

  • Unmanned air system checkouts

  • Emergency procedures training and simulation

  • Tethered buoyancy checkouts

 
   
Questions? Comments? Contact Shane Jacobs