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Hill在1952年首先提出板料拉伸失稳有分散性失稳(difluse necking)和集中性失稳(Localized necking)两种。他指出最大拉伸载荷(Swift失稳条件)时材料开始出现分散性失稳,然后才产生集中性失稳,并从理论上推算出出现集中性失稳的条件。在单向拉伸试验时,出现集中性失稳的时刻远比理论预示值要早。因此分散性失稳现象,往往容易被忽视,一般常袭用最大载荷的出现时刻称为细颈点。本文用理论分析和实验结果解释了单向拉伸失稳的机理说明了集中性失稳提前到来的原因。
Hill first proposed in 1952 that the plate destabilized had two kinds of difluse necking and localized necking. He pointed out that when the maximum tensile load (Swift instability condition) began to appear dispersion instability, and then produce a centralized instability, and theoretically calculate the conditions of the emergence of centralized instability. In the uniaxial tension test, the time of concentrated instability is far earlier than the theoretical predictions. Therefore, the phenomenon of decentralized instability, often easily overlooked, the general attack with the emergence of the maximum load is called the neck point. In this paper, the theoretical analysis and experimental results to explain the uniaxial tensile instability mechanism illustrates the reasons for the early arrival of concentrated instability.