关于拉伸试验中真实收缩率和延伸率间偏差和颈缩分析

Analysis on Deviation and Necking Formula between the Elongation and Reduction in Tensile Test

摘要: 根据拉伸试验中试件收缩率和延伸率间一定的适用公式，可以推倒出它们之间的公式。由偏差关系得出在小于0.09时收缩偏差较好，在中间一段延伸偏差较好，大于一定值收缩率偏差又变好的规律。在110%偏差率时收缩率的值小于延伸率，它的真实性高1.83倍。根据试件拉伸前后的延伸率得出在拉伸后的颈缩公式ψ > kε，在这里k是大于等于2的参数，颈缩变大k值也变大。

Abstract: According to density invariability of elongation and reduction of specimens in the tensile, by adapting formulas we can calculate the mathematical compare relation of them. Conditions to cause necking formula and deviation rules are gained. From deviation relations of reduction and elongation we find that in the case of smaller than 0.09 reduction deviation it will become good with compare to elongation one. In the case of bigger than certain value reduction one of 110 will be good too. They are 1.83 times good to compare with the strain. Additionally the formula of necking is gained with ψ > kε. In general the k will be larger than 2. If the necking becomes big, the k will become big too. It is thought that Twin causes necking and dislocation causes strain.