模拟平面四连杆机构，建立模型并仿真，程序源文件(MATLAB Planar four connecting rod)

车辆二自由度（三种方式），三自由度，四自由度车辆模型，参数齐全，可完美运行，绝不忽悠！(Vehicle two degrees of freedom (three ways), three degrees of freedom, four degrees of freedom vehicle model, complete parameters, perfect operation, never fooling!)

一受均匀拉力的板，中心带贯穿裂纹，裂纹长2a，使用4节点单元计算裂尖应力分布和应力强度因子(A uniform tensile plate with a through crack in the center and a crack length of 2a is used to calculate the stress distribution and stress intensity factor at the crack tip using a four node element)