Analysis of Camshaft Failure in Multi-Purpose Vehicle Car

Camshaft in an internal combustion engine is responsible for precisely controlling the timing of the intake and exhaust valves. When this operation does not proceed ideally, it can lead to camshaft failure. Therefore, this research aimed to investigate the causes of camshaft failure in MPV (Multi-Purpose Vehicle) by conducting a series of analyses including hardness test, chemical composition analysis, microstructure observation, SEM (Scanning Electron Microscopy), and numerical analysis. The hardness test was conducted along both x-axis and y-axis, yielding an average value of 102.15 HRB and 101.55 HRB, respectively. The chemical composition analysis classified camshaft material as gray cast iron category according to ASTM A159-1993. Microstructure observations of camshaft material showed the presence of gray cast iron with elongated flakes of perlite and graphite. Subsequently, SEM analysis showed that camshaft failure occurred due to defects on the shaft’s surface, leading to crack propagation. The numerical method applied was the finite element method using FEMAP software to analyze the stress intensity factor KI. The analyzed sections were subjected to loads on the valve and the defective surface. In the valve load analysis, the areas of maximum stress and the defective surface had average K1 values of 40.1875 MPa·m1/2 and 20.0975 MPa·m1/2, respectively. Meanwhile, the load on the defective surface had an average K1 value of 115.2 MPa·m1/2. All of these values met the criteria for crack propagation, where KI ≥ KIC (crack toughness value) for camshaft is 20 MPa·m1/2.