A finite element analysis (FEA) procedure has been developed to estimate the loss of contact forces in connector beams due to stress relaxation of copper alloys at high temperatures. ABAQUS, a commercial nonlinear FEA solver, was used to model this phenomenon using its classical metal CREEP formulation. A user-defined creep law was developed based on the relaxation test data and input into ABAQUS using its CREEP subroutine. Actual testing of raw material coupons (Olin's Phosphor Bronze Alloy 510) at different temperature and initial stress-levels provided the material data required for the FEA models. Three different temperatures (25°, 75°, & 125℃) and four initial stress-levels (two below, one at, and one above the yield point) were considered. Molex parts, made from the same alloy, were later tested in lots of twenty-one beams each for 1000 hours. The same temperature and initial stress conditions were maintained for this test, using a test fixture custom designed for this study. Initial stress levels were established by calculating and maintaining the deflections required at the point of contact on these beams. Normal forces were recorded at 1, 100, 200, 300, 400, 500, and 1000 hours for each of the twelve (3 temperatures x 4 initial-stresses) setups. Finally, the FEA results were compared and correlated with the test data.
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