Numerical Analysis and Material Testing of Failure Coach Axle

• Main Author: Siburian, Parningotan
• Format: Theses
• Language: Indonesia
• Subjects: Teknik (Rekayasa, enjinering dan kegiatan berkaitan)
• Online Access: https://digilib.itb.ac.id/gdl/view/44423
• Institution: Institut Teknologi Bandung

Axle is an important component of a train and directly related to train operation safety. There are two forms of passenger train axle failure the first axle broken with the fracture surface perpendicular to axle axis, showing fatigue failure and the second axle broken in the bearing area with a form that shows axle suffered wear, heat treatment and plastic deformation (hot axle). To prevent and avoid similar failures happening again it is necessary to conduct root cause analysis study of passenger train axle failure. Through this study is expected the axle failure phenomenon can be understood. The root causes of the hot axle and broken axle can be found. The final objective is an alternative step and recommendations on corrective and prefentif required. In this research, literature study about previous axle failures on the train has been, conducted to study the phenomenon of axle failures. Surveys and interviews conducted on the wheel sets maintenance facilities to determine condition of axle maintenance and to observe axle failure mode. Stress analysis of axle conducted to get the performance of axle on normal loading conditions, in bad condition of rail connections and damaged on wheel roundness profile. Microstructure and hardness testing of failed axle specimens is performed to determine the material condition of the failure axle. Through the above activities we can obtain axle failure main cause. The stress analysis of axle on ideal loading conditions shows the maximum principal stress 89.9MPa. On loading with acceleration in the vertical direction for 2.5g (g is the acceleration of gravity) on the axle stress greater than the endurance limit, so the axle age is limited. Micro structure testing shows there are several layers of different micro-structures on axle, micro-structural changes showed the effect of heat in the axle. The results of tests on hot axle specimens found Widmanstatten structure which is an indication that the axle material warming until 1000oC and then cooled in air. Heat comes from friction between the bearing and the axle due to poor fit between bearings and axle. Friction caused wear and high heat and cause axle failure. In broken axle sampel observed axle fatigue failures caused by imperfections in the surface hardening process that resulted in material softening on some position produce lower strength. Low strength can not withstand the stress from the tensile residual stress in chrom plating and bending stress due to load on the axle. To avoid the same failures happen improvement on axle and bearing maintenance procedures and axle chromium plating procedures.