The New Constraint Algorithm Based on Efficient Inverse Isoparametric Mapping

There is no explicit formulation of inverse mapping about the isoparametric element, so inverse mapping should be avoided in finite element analysis. But for some complex construction , inverse mapping for irregular element shapes is often mett. Through analyzing the analytical character of inverse isoparametric mapping based on the typical four-nodal isoparametric element, an automatic multi-node constrain algorithm is developed for inconsistent mesh base on the efficient inverse isoparametric mapping algorithm.Taking an intermediate point as bridge, each constraint function is built with the new constrain algorithm is between one node in one surface and all the nodes of the approximate element in the other surface. Comparing with contact algorithm, the new constrain algorithm is has only a little increase in the stiffness of the structure, and achieves satisfying displacement and stress solutions with great efficiency and speed.