5389 15360 15370 018600 018600 018600 ratio 1003 1001

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Unformatted text preview: e initial static force is calculated as k∆ = 30 lb and the damping coefficients are calculated as c = 2ξsqrt(km) = 3.52636, 1.76318, 0.352636, and 0.0 lb-sec/in for the four damping ratios (ξ) given in the test case, respectively. The node locations are arbitrarily selected. The integration time step (0.001 sec) is based on ≈ 1/180 of the period to allow the step changes in acceleration to be followed reasonably well and to produce sufficient printout for the theoretical comparison. The maximum time of 0.095 sec covers about 1/2 the period. One master degree of freedom (MDOF) is selected at the mass in the spring direction. A static solution is done at the first load step. POST26 is used to extract results from the solution phase. Results Comparison t = 0.09 sec Target ANSYS Ratio u, in (for damping ratio = 2.0) 0.47420 0.47637 1.005 u, in (for damping ratio = 1.0) 0.18998 0.19245 1.013 u, in (for damping ratio = 0.2) -0.52108 -0.51951 0.997 u, in (for damping ratio = 0.0) -0.99688 -0.99498 0.998 Figure 71.2...
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