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本报告应用断裂力学方法,对铝合金贮箱箱底进行了初步的分析。应力计算主要考虑了箱底在内压作用下的薄膜应力和由边缘效应引起的弯曲应力以及假定的焊接残余应力。断裂分析包括对表面裂纹临界尺寸的线弹性和弹塑性计算,给出了母材和焊缝处的临界裂纹尺寸;确定了加载20次到201次时所允许的最大初始裂纹尺寸。对一维和二维裂纹扩展模型进行了比较,指明二维扩展模型更为合理。最后对验证实验以及超声波检查配合使用进行了简单的讨论。给出了在本文条件下,贮箱箱底的无损检验标准和确定验证试验的方案。
This report uses the fracture mechanics method to conduct a preliminary analysis of aluminum alloy tank bottom. The stress calculation mainly considers the film stress under the internal pressure of the box bottom and the bending stress caused by the edge effect as well as the assumed welding residual stress. Fracture analysis includes linear elastic and elasto-plastic calculations for the critical crack size and the critical crack size at the base metal and weld; the maximum initial crack size allowed for 20 to 201 loadings is determined. The one-dimensional and two-dimensional crack propagation models are compared, indicating that the two-dimensional model is more reasonable. Finally, the verification experiment and the combination of ultrasonic examination were briefly discussed. In this paper, the non-destructive test standard of tank bottom and the scheme of confirming verification test are given.