An analysis of the UGent model of the stress–strain curve of elastoplastic materials is proposed. The UGent model describes the properties of materials that have a section with positive curvature on the stress–strain curve. The stress–strain curve, according to this model, is composed of three segments. In the first and third segments, a Ramberg–Osgood law with different power exponents is postulated. On the second segment, a curve postulated that smoothly connects the curves of the first and third segments. Therefore, the stress–strain curve is differentiable over the entire strain interval. The authors of the UGent model have implemented this good idea with a number of logical flaws. The spline has modified to correct these shortcomings. The modified deformation law in the second segment contains a linear combination of two linear polynomials and two power functions that describe the deformation laws in the first and third segments. New boundary conditions are also formulated for the initial and final points of the third section of the stress–strain curve. The proposed model is ten-parametric. The physical meaning of all ten parameters is shown. The model has been tested on various materials. As an example, the article proposes testing for Russian steel 35 (A682 Grade 1035 USA/ASTM). The coordinates of the point of ultimate strength on the true curve were chosen as normalizing factors. The remaining eight characteristics were determined from the requirement of a minimum objective function using the gradient descent method. The standard deviation was chosen as the objective function. The standard deviation of the constructed curve from the sample of experimental points for steel 35 (A682 Grade 1035 USA/ASTM) is 1.8%.

提出了对弹塑性材料应力-应变曲线的UGent模型的分析。UGent 模型描述了在应力-应变曲线上具有正曲率截面的材料的特性。根据该模型，应力-应变曲线由三个部分组成。在第一和第三部分中，假设了具有不同幂指数的 Ramberg-Osgood 定律。在第二段上，假定一条曲线平滑地连接第一段和第三段的曲线。因此，应力-应变曲线在整个应变区间上是可微的。UGent 模型的作者实现了这个好主意，但存在许多逻辑缺陷。样条已修改以纠正这些缺点。第二段中的修正变形规律包含两个线性多项式和两个幂函数的线性组合，描述了第一段和第三段中的变形规律。还为应力-应变曲线第三部分的起点和终点制定了新的边界条件。所提出的模型是十参数的。显示了所有十个参数的物理意义。该模型已在各种材料上进行了测试。例如，文章建议对俄罗斯钢 35（A682 Grade 1035 USA/ASTM）进行测试。选择真曲线上极限强度点的坐标作为归一化因子。其余八个特征是根据使用梯度下降法的最小目标函数的要求确定的。选择标准差作为目标函数。对于钢 35（A682 Grade 1035 USA/ASTM）的实验点样本，构建曲线的标准偏差为 1.8%。