| Chery car engine connecting rod bending fracture events happened in after-sales, this caused a serious economic loss to the company and great reputation damage. For this purpose, Therefore, a research team has been set up in company to solve connecting rod bending fracture failure. After comprehensive analysis, possibility of insufficient connecting rod fatigue strength, unqualified processing and manufacturing quality, liquid into cylinder, movement interference between piston and valve, connecting rod bending fracture which caused by knock have been excluded, while insufficient buckling strength of connecting rod which lead to connecting rod buckling and fracture during work has been focused on. This thesis use failure connecting rod as research object, study connecting rod buckling strength problem with formula calculate and method that combines finite analysis and test measurement, aim to judge whether connecting rod buckling strength is enough, and select and develop method which suitable for connecting rod buckling analysis and test.This thesis has mainly work and conclusion as bellows:According to the after sales problem analysis of an engine connecting rod, all possible factors which lead to connecting rod bending has been summarized, and insufficient buckling strength might be one of the main reasons in this after sales problem.Various methods of buckling strength calculation has been summarized, calculate and contrastive analysis for after sales failure connecting rod had been carried out.Buckling strength calculate and contrastive analysis for connecting rod under uniform rod, non-uniform rod and eccentric load conditions have been carried out, with finite element Riks method and MR+ eigenvalue method.Compression test for failure batch connecting rod has been arranged, measured compression yield strength, compression modulus of elasticity and compression stress-strain curve. Connecting rod buckling compression test has been carry out on pressure testing machine with two methods of center load and eccentric load, got connecting rod buckling ultimate load, and contrast the test data with finite calculation result. The contrasts shows that connecting rod buckling strength result of finite Riks method has well agree with test result.From calculation and test above, connecting rod in this study has no buckling strength problem. Riks finite element method can be used as a precise method for connecting rod buckling strength check. While in the early design stage, formula J.C.JOHNSON can be used for evaluate whether the connecting rod buckling strength in two directions are similar, and get rapid buckling strength check according to formula J.C.JOHNSON result, with safety factor 1.41. |
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