The stress distribution of an S-shaped micro spring fabricated by the micro-electro-mechanical-system (MEMS) technology was analyzed by the finite-element method (FEM) using ANSYS software, which showed that the stress concentration is located in the inner corner of the turning round. To reduce the maximum stress but not change the spring coefficient, an optimization S-shaped micro spring with the slope cross section was designed. The width of one end of the turning round is increased from the original 80μm to 100μm, while the other is decreased from 80μm to 21.5μm. The spring coefficient formula of the optimization S-shaped micro spring was calculated out by the Castigliano second law, and the difference between the formula and the FEM is 2.7%. At the same time the FEM simulation shows that the maximum stress of the optimization S-shaped micro spring can be reduced by 32.7% while the spring coefficient is the same comparing with the primary S-shaped micro spring, which shows that the mechanical performance of the optimization S-shaped micro spring is better than that of the primary S-shaped micro spring.

Based on virtual modeling technology and multi-body dynamics theory, three-dimensional virtual design and dynamics simulation was completed in this paper. Basic flow and general method of layout design of product using of 3D computer aided design software was presented. The frame model of layout was completed based on the structure and performance requirements of the dual-side-load trailer and 3D software’s CAD technology including parametric and variational technology and top-down design method. Based on the frame model, the layout design of the trailer was completed and the three-dimensional digital model was established. Took the lifting mechanism of the trailer as an example, based on its structure and operation principle, kinematics and dynamics simulation to each of the typical operation processes was completed.

Based on the method of power bond graph, the simulation model of the hydraulic system of the hydraulic breaker is presented. Treanor’s numerical method is applied to calculate the dynamic response of the hydraulic breaker in time domain. The dynamic Characteristics of the piston and the spool is achieved. The influence regularity of the working parameters on the performance of hydraulic breaker is shown.