Abstract An experimental study has been performed on a representative prototype-sized pipe bend made of SS 316 LN material to generate the relevant material parameters required for fatigue crack growth (FCG) simulation. Traditionally, FCG numerical simulation material parameters are generated based on specimen level test. In the literature there are many prototype pipe bend test results can be found. However, this paper takes a new look for generating FCG material parameters based on prototype-sized pipe bend test results. A semi-elliptical shaped pre-cracked pipe bend is used for the crack growth studies. Advancement of the crack profile has been measured in a periodic interval of cyclic testing, and the essential crack dimensions are derived to extract the FCG material parameters. FCG response curve derived, based on the prototype sized pipe bend test result, is well below the similar response curve obtained from the conventional material properties. The major reason behind this difference in FCG response is attributed to the influence of the residual stress locked during pipe bend fabrication. Based on these findings, it is recommended to adopt the material parameters derived based on the component-level test for more accurate prediction. Further studies are required to generalise the role of fabrication assisted effects in the material parameters in the case of prototype sized components.

中文翻译：

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疲劳裂纹扩展材料参数——基于原型弯管试验与常规参数对比

摘要 对由 SS 316 LN 材料制成的具有代表性的原型尺寸弯管进行了实验研究，以生成疲劳裂纹扩展 (FCG) 模拟所需的相关材料参数。传统上，FCG 数值模拟材料参数是基于试样水平测试生成的。在文献中有很多原型管弯曲试验结果可以找到。然而，本文对基于原型尺寸的弯管测试结果生成 FCG 材料参数进行了新的探索。半椭圆形预开裂弯管用于裂纹扩展研究。在循环测试的周期性间隔中测量裂纹轮廓的进展，并导出基本裂纹尺寸以提取 FCG 材料参数。导出的 FCG 响应曲线，基于原型尺寸的弯管测试结果，远低于根据常规材料特性获得的类似响应曲线。FCG 响应差异背后的主要原因是弯管制造过程中残余应力锁定的影响。基于这些发现，建议采用基于组件级测试得出的材料参数，以进行更准确的预测。需要进一步的研究来概括制造辅助效应在原型尺寸组件的材料参数中的作用。基于这些发现，建议采用基于组件级测试得出的材料参数，以进行更准确的预测。需要进一步的研究来概括制造辅助效应在原型尺寸组件的材料参数中的作用。基于这些发现，建议采用基于组件级测试得出的材料参数，以进行更准确的预测。需要进一步的研究来概括制造辅助效应在原型尺寸组件的材料参数中的作用。