NASA challenges you to design a handrail clamp assembly for The International Space Station!

About this Challenge

NASA is seeking to challenge the GrabCAD Community by sponsoring an open competition where participants utilize the new additive manufacturing capability on the International Space Station (ISS). The competition will be to design a complementary Handrail Clamp Assembly (HCA) which is currently utilized by astronauts to provide rigid mounting locations required in a microgravity environment for normal daily operations. The complementary HCA design will be referred to as the CHAMP (Clamp for Handrail with Additively Manufactured Parts). The printed part will be analyzed to further our understanding of the effects of microgravity on the fused deposition method of manufacturing.

Handrail Clamp Assembly (HCA) Overview

The HCA is currently utilized on the ISS to provide a seat track interface by creating a structural connection on the ISS handrail located throughout the station. It should be noted that the seat track interface is what needs to be reproduced in the CHAMP. The seat track is consistent with those utilized on commercial airlines. The interface does NOT have to be considered a separate feature. It must however provide the interior cross section and access to that interior profile consistent with the provided dimensions so as to be a functional connection point for the mating adaptor (must be at least 1.750” long with 0.785” holes, etc.). The cross section should be considered a smooth and consistent surface. The following picture show the HCA as well as the HCA in-situ.

Addition to NASA GrabCAD Challenge (as of January 22)

The overall function of the clamp assembly is to provide a seat track interface in order to mount hardware onto the handrails. This Challenge is not focused on creating a carbon copy of the existing ISS handrail clamp, but to design a device that attaches to the handrail and provides a seat-track-like interface specifically optimized for 3D printed material. The handrail itself does not need to be redesigned. The existing seat track is metallic and has small features with high strength capability that would be very difficult to replicate with ABS plastic. While a new seat-track-like device could be designed the goal is to design the device to interface with the Stud specified in MS33601, available here . Please note we understand the spec is outdated, but the NASA interfacing components meet this spec.

The current clamp assembly (shown for reference) has a required kick load of 125 lbf. We understand that this requirement may be unfeasible given ABS material and the size limitations, but try to make the designs as strong as possible. Maximum loads from mechanical properties we have obtained so far from ABS parts made by FDM are as follows:



Z Tensile (build direction): 50 lbf,





XY Tensile (-45,45 layup): 121 lbf,





XY Tensile (0,90 layup): 120 lbf,





Flex (-45,45): 359 lbf,





Flex (0,90): 323 lbf,





Z Compression: 1433 lbf,





XY Compression (-45,45): 1316 lbf,





XY Compression (0,90): 1457 lbf.





A factor of safety is not accounted for with the listed numbers. Crew tools on the ISS must have a FOS of at least 2.

Seat Track Explanation

We understand that many designs are works-in-progress, but we wanted to make sure that everyone in the challenge was aware of how seat track functions. Please take a moment to watch this video showing how the stud and seat track connect. Your design should allow for the stud fastener to be attached and secured. Thanks again to Philip LaRoach for finding and sharing this video.