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一、引言在工程上,高温结构的设计是以零件的设计应力要低于许用应力为依据,而许用应力是根据材料的持久强度或蠕变极限来确定。目前,都用光滑圆棒试件测定材料的持久强度和蠕变极限。如果零件已存在缺陷,则这种测试方法不能保证安全可靠。高温零件的断裂事故证明:断裂是由零件裂纹源所引起的。近年来,国外对接近高温零件工作状况的模拟试验特别重视,尤其是对具有缺口应力集中的高温断裂研究更为突出。
I. INTRODUCTION In engineering, the design of high temperature structure is based on the design stress of the part to be lower than the allowable stress, and the allowable stress is determined according to the long-term strength or creep limit of the material. At present, the durable strength and creep limit of materials are determined by smooth round bar test pieces. If the part is already defective, this test method can not be guaranteed to be safe and reliable. Fracture of high temperature parts proved: fracture is caused by the source of crack components. In recent years, foreign countries have paid special attention to the simulation tests near the working condition of high-temperature parts, especially the study of high-temperature fracture with notched stress concentration.