The procedure for the head check initiation life prediction of railway rails has been developed. It is mainly performed by three-dimensional finite element (FE) analyses that account for the local material response generated by the contact load between wheel and rail. Both wheel and rail are modeled by FE mesh, and the wheels are loaded then rotated to the rolling direction on the rails repeatedly. The Chaboche and Lemaitre model is used to simulate the material response that is important in rolling contact situations. The results obtained from FE analyses are combined with the theory of critical distance and the critical plane approach to predict fatigue crack initiation life in the railhead. Parametric studies are performed to investigate the influence of several factors on the crack initiation life. Finally, the predictions are compared with the data obtained from the investigation in the field.

A study on the countermeasure method for gauge corner cracking by applying the worn profiles of rail AbstractIn Japanese railway networks, the gauge corner cracking (GCC) occurs to the head hardened rail of the high rail in curved sections of R600 to R800m. In case of the GCC propagates deeply, it will be a possibility of causes rail broken. Therefore, the appearance of GCC is considered a serious problem from the viewpoint of safety transportation. Since GCC appears mixed with head checks, it is very difficult to find GCC in the early stages. Furthermore, GCC appears in the cluster conditions, it is very difficult to remove all cracks of GCC. Hence, it is very important to control the initiation of GCC. However, the countermeasure method for GCC initiation has not been developed. The aim of this study is to examine the reduction method for GCC initiation due to the relief of the contact pressure between wheel/rail. Therefore, the wear development of rail was focused, the influence of the worn profiles of rail on wheel/rail contact condition was examined. In the beginning of this study, rolling contact fatigue (RCF) test were conducted by use of the twin disc test equipment. Secondly, wear analysis of rail with multibody dynamics which was modeled the locations of GCC appearance was conducted. Finally, the effect of the worn profiles of rail on wheel/rail contact and the suppression of RCF initiation was examined by the wheel/rail contact analysis. In summary, the worn profiles of rail were confirmed the suppression effect for RCF by reducing the contact pressure between wheel/rail.

Rail wear is one of the phenomena caused by rolling contact of rail and wheel. Situation of rail wear changes with complexity because the contact of rail and wheel changes gradually according to the running condition of vehicles and track geometry condition. Therefore, it is important to predict the wear profile of rail continuously. However, predicting the change of rail profile due to wear has been mostly examined based on one contact condition of rail and wheel. SIMPACK, which is one of the Multi-Body Dynamics (MBD) software is very useful to analyze vehicle dynamics, contact conditions of rail and wheel and so on. In this research, the authors constructed a model for predicting of worn profile of rail incorporated in SIMPACK and carried out the analysis under the several conditions. Furthermore, we examined about the influential factor of wear of rail.2・4 摩耗則 車輪とレールの転がり接触による摩耗は，主に凝着摩耗であると考えられる．凝着摩耗を表す摩耗則はこれま でにいくつか提案 (10-12) されているが，本研究ではそのうちの一つである，Archard (12) の摩耗則を適用した．Archard の摩耗則は式(3)で与えられる．

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The rights-of-way of urban railway systems contain many sharp curves. Since sharp curves can contribute to wheel and rail wear, the ability to predict the development of wheel wear is crucial to maintaining safe operation of such systems. Observation of wear development in practical railway systems is inefficient and time consuming. In order to efficiently predict wheel wear, numerical analysis using multi-body dynamics software, such as Simpack, is proposed. Contact pressure, slip ratio, and other necessary parameters are determined from Simpack's vehicle motion analysis. Wear depth is derived to create a worn wheel profile. The current wheel profile is updated using the wear profile, and is then adopted as the new wheel profile in Simpack. The rail vehicle modeled in our numerical analysis is based on a typical Japanese commuter rail vehicle. Wear depth is calculated based on the Archard wear theory. Wear development in the wheel/rail contact area is calculated, and nodes are replaced by calculated wear depth. Validity of the wear coefficient used in the simulation is discussed. The results of the numerical analysis are compared with experimental results to assess the amount of wear from the viewpoint of mechanical and tribological contact problems.