嘉宾简介： 野田尚昭教授为日本九州工业大学大学院工学研究院、机械智能工学研究系教授。现为日本机械工程学会会士(JSME Fellow)、日本自动车技术会会士(JSAE Fellow)、日本材料学会破坏力学委员会委员、日本机械学会材料力学部门弹性数理解析发展普及及利用研究会委员、日本微电子封装学会委员、科学研究费委员会审查委员、社团法人日本钢铁协会委员会员、日本塑性加工学会会员。在日本国内及国际学术期刊共发表论文 400 余篇，其中 EI、SCI 收录近 200 篇，出版著作 11 部。 曾在多个国际会议(EMA2013、FFW2014、FFW2015、FFW2016、DAMAS2017、FFW2017、MSAM2018、PCM2018)担任大会主席，获得日本机械学会材料力学部门奖贡献奖(2017)、日本材料学会学术贡献奖(2010)、日本素形材中心(SOKEIZAI)工业技术奖(2010)及中华人民共和国驻福冈总领事馆表彰(2016)。 报告内容： In a wide industrial field, the bolt-nut joint is unitized as an important machine element and widely used. To ensure the safety of the structure and reduce cost, low-cost bolt-nut connections with good anti-loosening performance and high fatigue strength are always required especially in automotive engineering. To improve the strength of the bolt-nut connections, previous researchers mainly focus on stress reduction at the root of the thread by changing the shape of the bolt, and the effect of the materials on the fatigue strength has also been researched. In this study, a slight pitch difference between bolt and nut is considered, and both fatigue experiment and finite element analyses are conducted. The cracks in the bolt specimens are observed and the improvement mechanism of fatigue life is considered by comparing the experimental results with the finite element analytical results. The analytical results can explain the experimental results of the crack positions as well as the improvement mechanism of fatigue life. Furthermore, to improve the fatigue life more effectively, lager root radiuses ρ of bolts and nuts are considered both experimentally and analytically. It is found that the fatigue life of the bolts can be improved by enlarging the radius of the root comparing with standard M16 bolts. In addition, experiments and analysis of slight pitch difference bolt joints with larger root radius have also been conducted, and the fatigue life of the bolt joints is significantly improved by introducing a pitch difference and enlarging the root radius. |
