Your load is more important than your speed (University of Washington)

Strain gages from Micro-Measurements® were used by the University of Washington ECOCAR 3 team to validate the design of the front electronics shelf and generator structure mount in the car. The gages allowed the team to develop a framework for validation of future ECOCAR structures. Knowing the bounds of maximum stress experienced in the harshest of driving conditions will allow the team to further load these structures. From seeing how well the FEA results correlate with the measured stress in the car the addition of components will not require further structure reinforcement. FEA and experimental mechanics can work as a team! This will allow UW ECOCAR to save considerable amounts of design and manufacturing time.


Computer models are useful tools for predicting structural performance, but they only tell part of the story. Strain gage testing is performed to correlate the actual response of the part to test inputs with the generated computer model. Many uncontrollable realities can affect the FEA model, including complex structural design (not easily modeled), insufficient FEA mesh density, unknown or unaccounted for residual stresses in the part (often caused by the manufacturing and/or assembly processes), errors in material constants, unexpected interactions from other assemblies, and uncertainty in the applied loads (inaccurate boundary conditions). Perhaps one of the best questions to ask concerning strictly analytical design (no experimental verification) is: Would you want to ride on a car that had no design requirements verified by physical measurement (only computer-generated data was used to qualify the plane)?


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Yuval Hernik

StrainBlog Editor in Chief