A frequency response function-(FRF-) based direct decoupling method is proposed and applied to inverse analysis of a multicoordinate coupled system. The general formulation of inverse substructuring method for multicoordinate coupled multisubstructure system is derived. The proposed method is validated by a lumped mass-spring-damper model; the predicted FRFs of substructures are compared with the direct computations, showing exact agreement. The developed method offers an approach to back out the unknown substructure-level FRFs from purely system-level FRFs.

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The finite element model of bulging at elevated temperature was established by using of pam-stamp 2007. The bulging tests of boron steel sheets were also performed on the self-designed and manufactured tool system. The simulated results of bulging height, limit strain and the minimum temperature of specimens are consistent with that of tests. It demonstrates the validity and accuracy of the finite element model established in pam-stamp. The influences of the friction coefficient, the temperature and the stamping velocity on the hot bulging are analyzed numerically. The friction condition should be improved and the minimum temperature gradient is recommended in practical hot stamping production.