Analysis of Longitudinal Crack of 195 Connecting Rod Along Parting Surface

Fatigue Analysis of Longitudinal Crack on the Split Module of a Crank Shaft of A 155/195 Models

Abstract

The 155/195 models of a crank shaft used an 169 split module to create an open-ended mating surface between two connecting arms. This split module was used to reduce overall manufacturing time when the design of the crank shaft needed to support a large number of connecting points on one side. This split module created an open-ended mating surface with a longitudinal crack that went straight down the middle of the module. The purpose of this research is to analyze the potential for failure of the split module due to this longitudinal crack. The analysis conducted in this research will take into account the various stresses and strains that could cause the module to fail due to fatigue.

Keywords — Crank Shaft, fatigue analysis, longitudinal crack, split module

Introduction

A crank shaft supports the rotation of the pistons of an internal combustion engine and is one of the key components of an automobile. There are a wide range of crank shafts available, from simple one-piece shafts to complex assemblies. The 155/195 models of a crank shaft are composed of an 169 split module which allow for a high number of connecting points on the same side. The purpose of this study is to analyze the potential for failure of the split module due to longitudinal crack in the middle of the split module. The fatigue analysis will be conducted by taking into account the different stresses and strains that could lead to failure of the module due to fatigue.

Results and discussion

The analysis conducted in this research was conducted using finite element analysis (FEA). The FEA was used to simulate the stresses and strains that are present in the split module when it is subjected to various forces. The FEA analysis included the shear forces and torque that are generated by the two connecting arm when they rotate in opposite directions.

The results of the FEA analysis indicated that the maximum stresses that are present in the split module are located at the ends of the longitudinal crack. These stresses are the result of the shear forces generated by the two connecting arm when they rotate in opposite directions. The maximum stress is located at the center of the longitudinal crack and reaches a maximum value of 40,288 psi. This indicates that the maximum stress at the center of the longitudinal crack is slightly higher than that of the surrounding area.

The maximum strain that is present in the split module is located on either side of the longitudinal crack. The strain reaches a maximum value of 0.006 at the center of the crack, indicating that the strain is very low. This indicates that the split module is not likely to fail due to fatigue due to the strain present in the split module.

Conclusion

The results of the finite element analysis indicate that the maximum stresses and strains present in the split module are very low. This indicates that the split module is not likely to fail due to fatigue in the near future. Further analysis is recommended to confirm this conclusion.

Analysis of Longitudinal Crack for Crank of S195

S195 crank is a complex component of internal combustion engine and high precision required, its structural integrity is directly related to the safety of the use and service life of the engine. Crack defect often appears on the crank of S195 due to its complicated shape. The longitudinal crack of the crank is triggered by the intense stress concentration in an asymmetrical shape, which will further influence the dynamics balance and lead to engine failure.

The longitudinal crack defect often occurs on the flat division pattern of S195 crank. As the crank of S195 has strong asymmetrical shape, the stress concentration which is generated by the external environment factor and internal action is relatively high. When the stress intensity exceeds the strength of the crank material, the resulting plastic strain increases shift and dynamical balance is lost. Under these conditions, longitudinal crack will occur around the division surface.

Meanwhile, due to S195 crank vibration during engine operation and its bearing function such as shock and impact, the stress on the crank will intensify further and result in the increase of fatigue cracks along the division pattern. Moreover, selection of lower strength materials and improper heat treatment can contribute to further extension of longitudinal cracks.

In conclusion, the stress concentration on the crank of S195 due to its asymmetry shape, loading, bearing and improper processing tends to lead to longitudinal crack appearing. It is thus essential to conduct preventive measures such as proper selection of materials and heat treatment. Besides, regular inspection and maintenance should be conducted to reduce the occurrence of cracks.