No abstract

In this study, a statistical estimation of S-N curves for high-strength steels from their static mechanical properties was attempted. First, the fatigue data of high-strength steels were extracted from the "Database on fatigue strength of metallic materials" published by the Society of Materials Science, Japan (JSMS), and the S-N curves of respective steels were determined from the JSMS standard, that is, the "Standard evaluation method of fatigue reliability for metallic materials: Standard regression method of S-N curve". The correlations between the regression parameters obtained here and the static mechanical properties were investigated. Thus, significant correlations were found between the regression parameters and static mechanical properties (e.g., fatigue limit E and tensile strength s B). Based on these correlations, the S-N curves of high-strength steels were successfully predicted from their static mechanical properties, similar to structural carbon steels and aluminum alloys in previous studies. Moreover, from the distribution of the fatigue limit E, the percentile points for the estimated S-N curve were predicted. It was finally confirmed that 84 % of the S-N data series fall within the estimated interval of ±2s, where s represents the standard deviation of the fatigue limit.

Owing to the population aging, it is expected that the number of patients undergoing acetabular bone and hip joint disease will increase. A total hip arthroplasty (THA) is one of the treatments for serious disease of hip joint. However, in the situation of massive acetabular bone loss, an acetabular reconstruction cage is additionally needed to reconstruct the hip joint. In this study, we focus on the acetabular reconstruction cage. The conventional cage is mainly made of metal. However, due to the lack of mechanical biocompatibility, there is a serious problem of 'stress shielding' of metal. The acetabular reconstruction cage made of CFRP could be possible to reduce the stress shielding, but the applicability for strength should be guaranteed. Therefore, the purpose of this study is to develop a numerical modeling method for acetabular reconstruction cage, and estimate the mechanical behaviors of bone and the cage. According to the numerical simulation, relative displacement of CFRP cage to bone was almost the same as Ti-6Al-4V cage. Moreover, strain energy density of CFRP was higher than Ti-6Al-4V in a wide range. Therefore, it was concluded that CFRP enables to design acetabular reconstruction cage which is more excellent for restraint of bone atrophy and promotion of bone remodeling than ready-made without influence on micromovement.

As a joint project of Committees on Fatigue and Reliability Engineering in the Society of Materials Science, Japan (JSMS), an electronic database on fatigue strength of metallic materials fabricated in Japan had been constructed and published in 1996. Book style of the same data compilation had been published at the same time by the JSMS and Elsevier. About twenty years have passed since the above publications of database and databook. Thus, a lot of new fatigue test data have been obtained during such a long period including many data on the very high cycle fatigue such as gigacycle regime. Based on such a circumstance, the JSMS has organized a new project to construct an electronic database on very high cycle fatigue. A lot of numerical data obtained by fatigue tests would be compiled together with many photographs of fracture surfaces. In this paper, fundamental view and compilation concept of the database are briefly introduced by showing a typical example of proto-type database constructed from domestic data in Japan.

The aim of this study is to develop a statistical estimation method of S-N curve for iron and structural steels by using their static mechanical properties. In this study, firstly, the S-N data for pure iron and structural steels were extracted from "Database on fatigue strength of Metallic Materials" published by the Society of Materials Science, Japan (JSMS) and S-N curve regression model was applied based on the JSMS standard, "Standard Evaluation Method of Fatigue Reliability for Metallic Materials -Standard Regression Method of S-N Curve-". Secondly, correlations between regression parameters and static mechanical properties were investigated. As a result, the relationship between the regression parameters and static mechanical properties (e.g. fatigue limit E and static tensile strength σB) showed strong correlations, respectively. Using these correlations, it is revealed that S-N curve for iron and structural steels can be predicted easily from the static mechanical properties.