Prediction of dynamic stresses using flexible multibody system algorithms: Application to tracked vehicle upper structure

Abstract

The objective of this investigation is to develop a general procedure for predicting the dynamic stresses when the nonlinear floating frame of reference formulation is used to model flexible components in multibody system applications. The procedure utilizes the concept of the floating frame of reference intermediate finite element coordinate system and the general continuum mechanics approach to develop accurate definitions of the floating frame of reference kinematic equations that enter into the formulations of the strains. These general equations are used to design a computational algorithm for the calculation of the dynamic stresses. In order to demonstrate the use of the procedure developed in this investigation for the stress prediction, a tracked vehicle system is used as the study model. Taking into consideration the actual endurance test, a model for a bulldozer upper structure is developed using computer aided engineering solution framework which includes flexible multibody system algorithms. In order to obtain the dynamic stresses, the flexible structure of the tracked vehicle is modeled using Mindlin shell finite elements. The equations of motion are developed using the finite element/floating frame of reference formulation that allows for effectively reducing the number of degrees of freedom by neglecting high-frequency modes of vibration using component mode synthesis techniques. The stresses are obtained using a procedure that takes into consideration the dynamic coupling between the rigid body motion and the elastic deformations. The use of the general continuum mechanics theory to formulate the strain and stress equations allows for applying the procedure developed in this paper to other element types. Kinematic relationships are used to formulate several components and elements of the undercarriage including the idler cushion system and the maximum reverse angle. Numerical results are presented in order to demonstrate the use of the general floating frame of reference procedure in the stress analysis of the tracked vehicle undercarriage system.