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提出一种方法,可以确定直至结构破坏时,与单元长度相关的应力、应变关系,并适用于有限元分析模型。采用已测出的表面位移计算结构直至破坏时的应变。从颈缩处已测出的力和横截面面积可以推导出应力的数值。此外,由于光学测量的数字特性,将应变的参考长度清晰地定义为像素的函数。在数值模拟中有限单元的长度与这个参考长度相等。此法可以对拉伸试验进行精确的数值模拟,除非在结构破坏时曲线无法拟合,或者缺少根据所取的分隔尺寸来调整材料关系的迭代方法。精确的材料关系有助于提高非线性数值模拟的准确性。
A method is proposed to determine the relationship between stress and strain related to the unit length up to the failure of the structure and to be applied to the FEA model. The measured surface displacements were used to calculate the strain of the structure until failure. The value of the stress can be derived from the measured force and cross-sectional area at the neck. In addition, due to the digital nature of optical measurements, the reference length of strain is clearly defined as a function of pixels. The length of the finite element in the numerical simulation is equal to this reference length. This method allows for accurate numerical simulation of tensile tests unless the curve fails to fit in the event of structural failure or an iterative method of adjusting the material relationship depending on the separation size taken. Accurate material relations help to improve the accuracy of nonlinear numerical simulation.