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Squeal noise is a harsh, high-pitched sound that occurs when railways are running at sharp curve tracks. The cause of squeal noise is known to be the transient lateral traction force between wheel and rail. Field measurements are too difficult to control the parameters. Thus, the scaled test rig

A fatigue life is one of the key design factors for crawler excavators because they are usually operated in a very harsh working condition. In order to evaluate the fatigue life, the fatigue loads in various working conditions should be decided in advance. In case of the attachments such as boom and arm, the forces at the bucket tip due to digging and lifting are primary fatigue loads, which can be calculated relatively easily using design specifications. However, the forces at the track need to be considered additionally for the upper and lower frames. And it is almost impossible to measure the forces at track in a field test. In this study, a dynamic model of excavator including track system is implemented and dynamic load simulations are carried out to investigate the distribution of the reaction forces at each roller for the typical working scenarios. The model and the simulation technique are verified by comparison with the results of measurement in view of weight balance, cylinder forces, accelerations of counter weight and stresses at concerned points. The normalized distribution of the reaction forces at each roller in digging and lifting working mode are presented and the distribution is expected to be used as the baseline of fatigue load estimation for the upper and lower frames of various class crawler excavators. To get the multibody dynamic simulation results by the excavator motion, we used the commercial software such as Recurdyn for kinematic and dynamic modeling. Especially the track modeling of the excavator is composed using Track_LM module of the Recurdyn. And stress analysis of the frame is carried out using the NX-Nastran program.

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Fretting fatigue tests were conducted to investigate the effect of contact pressure on fretting fatigue behavior in aluminum alloy A7075-T6. Test results showed that when the contact pressure is so low that gross or partial slip occurs at the pad/specimen interface, fretting fatigue damage increases with the contact pressure. However, when the contact pressure is high enough to prevent slip at the interface, fretting fatigue damage decreases with the contact pressure. In order to understand how the contact pressure influence the fretting fatigue damage, finite element analyses were conducted and the analysis results were used to evaluate critical plane fretting fatigue damage parameters and their components. It is revealed that fretting fatigue damage estimated with the parameters exhibits the same variation as that in the tests. Moreover, the variation of fretting fatigue damage is closely related with that of the maximum normal stress on the critical plane rather than the strain amplitude on the critical plane.