SUMMARYThis paper considers a layered thick shell finite element procedure for determining the dynamic transient nonlinear response of plates and shells. The degenerated three-dimensional isoparametric shell element with independent rotational and translational degrees-of-freedom is employed and a layered formulation is adopted to represent the steel reinforcement and to simulate progressive concrete cracking through the thickness. The dynamic yielding function is assumed to be a function of the current strain rate, in addition to being total plastic strain or work dependent. The concrete model also simulates both compressive crushing and tensile cracking behaviours and an implicit Newmark algorithm is employed for time integration of the equations of motion. Several numerical examples are presented for both slab and shell structures and the results obtained compared with those from other sources wherever available.

The low frequency horizontal vibration of engineering vehicles is a part of multidimensional vibration, which causes driver's occupational disease. Therefore, the design of low frequency horizontal vibration isolation is of great significance. The principle of rolling vibration isolation is applied to seat suspension for low frequency horizontal vibration isolation in this paper. The natural frequency characteristic model of horizontal suspension and the seat-human system dynamics model with horizontal suspension based on the Lagrangian equation are established. The dynamic characteristics of rolling horizontal suspension are studied on account of the established models. Results show that this horizontal suspension can achieve very low natural frequency so as to isolate the low frequency vibration in horizontal direction by the matching design of the rollers and concave dimensions. The vibration isolation characteristics of the front and back seat–human system are improved with the reduction of the rollers’ radius. The vibration isolation characteristic of the front and back seat - human system increases with the increase of the concave surfaces’ radius.