Crack spacing threshold of double cracks propagation for large-module rack
来源期刊：中南大学学报(英文版)2015年第7期
论文作者：ZHAO Tie-zhu SHI Duan-wei YAO Zhe-hao MAO Hong-yong CHENG Shu-xiao PENG Hui
文章页码：2533 - 2539
Key words：large-module rack; double cracks; fatigue crack propagation; crack spacing threshold; moving load
Abstract: Large-module rack of the Three Gorges shiplift is manufactured by casting and machining, which is unable to avoid slag inclusions and surface cracks. To ensure its safety in the future service, studying on crack propagation rule and the residual life estimation method of large-module rack is of great significance. The possible crack distribution forms of the rack in the Three Gorges shiplift were studied. By applying moving load on the model in FRANC3D and ANSYS, quantitative analyses of interference effects on double cracks in both collinear and offset conditions were conducted. The variation rule of the stress intensity factor (SIF) influence factor, RK, of double collinear cracks changing with crack spacing ratio, RS, was researched. The horizontal and vertical crack spacing threshold of double cracks within the design life of the shiplift were obtained, which are 24 and 4 times as large as half of initial crack length, c0, respectively. The crack growth rates along the length and depth directions in the process of coalescence on double collinear cracks were also studied.
ZHAO Tie-zhu(赵铁柱), SHI Duan-wei(石端伟), YAO Zhe-hao(姚哲皓), MAO Hong-yong(毛宏勇), CHENG Shu-xiao(程术潇), PENG Hui(彭惠)
(School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China)
Abstract:Large-module rack of the Three Gorges shiplift is manufactured by casting and machining, which is unable to avoid slag inclusions and surface cracks. To ensure its safety in the future service, studying on crack propagation rule and the residual life estimation method of large-module rack is of great significance. The possible crack distribution forms of the rack in the Three Gorges shiplift were studied. By applying moving load on the model in FRANC3D and ANSYS, quantitative analyses of interference effects on double cracks in both collinear and offset conditions were conducted. The variation rule of the stress intensity factor (SIF) influence factor, RK, of double collinear cracks changing with crack spacing ratio, RS, was researched. The horizontal and vertical crack spacing threshold of double cracks within the design life of the shiplift were obtained, which are 24 and 4 times as large as half of initial crack length, c0, respectively. The crack growth rates along the length and depth directions in the process of coalescence on double collinear cracks were also studied.
Key words:large-module rack; double cracks; fatigue crack propagation; crack spacing threshold; moving load
