Engineers at Silicon Graphics designing the company’s new Altix[R] 3700 BX2 supercomputer used software to find the reasons for shock and vibration problems in the design. The problems stemmed from planar packaging of the pc boards, which made it difficult to build in structural elements for handling the shock and vibration. Deflection of the hardware created a shear load on the joints. Software pinpointed the problem and showed the path to the solution.
Using a combination of in-house testing (vibration and dye-and-pry tests) and PTC’s Pro/Mechanica finite element analysis software, engineers found the point of maximum deflection. They had measured different sites along the boards with accelerometers. Their conclusion was that the failure was in connectors under the stiffener in the chassis.
The original stiffener design they used was rigid enough, says team leader Steven Dean. But they had substituted a sheet material to reduce costs, and found the material couldn’t handle the movement. Dean compared the problem to the harmonic-frequency issues automakers and jet-engine manufacturers have.
The solution: Reconfigure the stiffener elements.
“It was a hard problem to find,” Dean says. The software was essential to resolving the issue.