中心圆孔方板循环安定极限试验及屈服强度参数影响分析
CYCLIC SHAKEDOWN LIMIT TESTING AND ANALYSIS OF THE INFLUENCE OF YIELD STRENGTH PARAMETERS ON SQUARE PLATES WITH A CENTRAL CIRCULAR HOLE
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摘要: 循环载荷作用下结构可通过有限塑性变形及残余应力重分布进入安定状态. 现有安定性分析通常采用单向拉伸试验获得的屈服强度作为材料参数, 但对循环载荷下结构安定极限预测的适用性仍需进一步验证. 本文首先通过单向拉伸试验和应变控制循环加载试验获得316L不锈钢的单调屈服强度与循环屈服强度; 其次, 以同材料的带中心圆孔方板为研究对象进行结构分级多次循环加载试验, 通过结合孔边危险区域应变演化及平均应变率等关键因素, 识别结构安定极限载荷区间; 最后, 基于理想弹塑性有限元数值分析模型, 对比不同屈服强度参数对安定极限预测的影响. 结果表明: 316L材料的循环屈服强度低于单调屈服强度, 结构试验识别得到的安定极限载荷为151.85 ~ 162.96 MPa. 采用单调屈服强度时, 预测值偏高达12.30% ~ 20.51%; 采用循环屈服强度时, 预测偏差仅为1.86% ~ 9.31%. 显然, 屈服强度参数的选取对带孔板安定极限预测结果影响较大, 循环屈服强度更适用于安定性分析.Abstract: Under cyclic loading, structures can reach a stable state through limited plastic deformation and redistribution of residual stress. Existing stability analyses usually use the yield strength obtained from uniaxial tensile tests as a material parameter, but its applicability for predicting the stability limit of structures under cyclic loading still needs further verification. This paper first obtains the monotonic yield strength and cyclic yield strength of 316L stainless steel through uniaxial tensile tests and strain-controlled cyclic loading tests; second, performing hierarchical multiple cyclic loading tests on square plates with a central circular hole made of the same material, the stability limit load range of the structure is identified by combining key factors such as strain evolution in the dangerous area around the hole and the average strain rate; finally, based on an ideal elastic-plastic finite element numerical analysis model, the effects of different yield strength parameters on predicting the stability limit are compared. The results show that the cyclic yield strength of the 316L material is lower than the monotonic yield strength, and the stability limit load identified by structural testing is 151.85 ~ 162.96 MPa. When using the monotonic yield strength, the predicted values are overestimated by 12.30% ~ 20.51%; when using the cyclic yield strength, the prediction deviation is only 1.86% ~ 9.31%. Clearly, the choice of yield strength parameters has a significant impact on the predicted stability limit of perforated plates, and cyclic yield strength is more suitable for stability analysis.
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