Świłło Sławomir, Cacko Robert
Faculty of Mechanical and Industrial Engineering, Institute of Manufacturing Technologies, Warsaw University of Technology, 02-524 Warszawa, Poland.
Materials (Basel). 2023 Jan 6;16(2):558. doi: 10.3390/ma16020558.
The paper presents an experimental evaluation of deformation of flat samples during uniaxial tensile testing, including uniform deformation and post-necking phases. The authors recommend a specially designed vision extensometer and simplified image processing method for analytical correction of triaxial test results for extended stress-strain curve estimation. A modified correction model is proposed, based on the application of Gaussian functions, to determine the neck geometry of the tested sample. The vision extensometer can monitor a specimen's elongation using two fibre-optic gauges inserted into the material. Measurements taken from the vision extensometer are compared with readings from analogue gauges within the range of uniform deformation. The analytical correction model's ability to correctly assess the extended true stress-strain curve in the post-necking phase was investigated. Image processing forms the basis of an efficient method for identifying the contour of the specimen's neck. Digital image correlation (DIC) was used to verify the proposed solutions and assess the results obtained for the uniform and post-neck deformation phases. The change in thickness of the sample was experimentally measured throughout the tensile test with a digital gauge sensor and compared with the results of the digital image correlation.
本文介绍了扁平样品在单轴拉伸试验过程中的变形实验评估，包括均匀变形和颈缩后阶段。作者推荐了一种专门设计的视觉引伸计和简化的图像处理方法，用于对三轴试验结果进行分析校正，以估计扩展应力 - 应变曲线。基于高斯函数的应用，提出了一种改进的校正模型，用于确定测试样品的颈缩几何形状。视觉引伸计可以使用插入材料中的两个光纤应变片来监测试样的伸长。在均匀变形范围内，将视觉引伸计的测量结果与模拟应变片的读数进行比较。研究了分析校正模型在颈缩后阶段正确评估扩展真实应力 - 应变曲线的能力。图像处理是识别试样颈部轮廓的有效方法的基础。使用数字图像相关（DIC）来验证所提出的解决方案，并评估均匀变形和颈缩后变形阶段获得的结果。在整个拉伸试验过程中，使用数字应变片传感器对样品厚度的变化进行了实验测量，并与数字图像相关的结果进行了比较。
