A New Direct Method for Updating Mass and Stiffness Matrices with No Spillover

Abstract

A direct method for model updating of mass and stiffness matrices of structures without spillover is presented, which requires the knowledge of only the few eigenpairs to be updated of the original undamped model. Upon a necessary and sufficient condition, proposed previously by authors, for the incremental mass and stiffness matrices that modify some eigenpairs while keeping other eigenpairs unchanged, the finite element model updating problem that preserves symmetry and avoids spillover is formulated as a semi-definite programming problem, which can be efficiently solved by existing semi-definite programming algorithms. Numerical examples are given to demonstrate the accuracy and effectiveness of the presented updating method.

Finite Element Modelling of Laser Stitch Welding Joints for Structural Dynamic Predictions

“…Thus, it is important to understand the dynamic behaviour of a jointed structure due to laser welding so that the dynamic behaviour of the overall automotive structure can be predicted accurately [4][5][6][7][8]. However, to numerically model the structure jointed by laser welding for finite element (FE) analysis is very difficult, challenging and time consuming due to the involvement of uncertainties that are produced during the joining process, such as frictional damping, localised stiffness and heat affected zone (HAZ) on the joint itself [9][10][11][12][13]. There are several researches regarding the employment of suitable element connector to represent laser weld joints.…”