Aemission spectrometer,micro-hardometer,optical microscope and scanning electron microscope were used to analyze the reason of crack on connecting rod unit assembly for piston of car engine.

Based on the three-dimensional modeling of multilateral junction assembly,designating the material and the mechanical property parameter and determining the multilateral well simulation method,the three-dimensional model was meshed with ICEM and the nonlinear simulation of multilateral well preliminary forming process was carried on with the finite element commercial software.