Background: The non-conforming contact usually induce stress concentration as the interaction only occurs at a small interface. Theoretical and numerical investigations have shown that the contact stress distribution and maximum pressure are closely related to the length of the contact interface. Objective: Therefore, the characterization of the contact length is a key issue in studying the contact behavior and the corresponding structural safety. Methods: In this paper, we propose an indirect experimental identification approach that can reliably characterize the contact length between non-conforming frictionless surfaces. The relationship between the contact length and the local displacement is established based on the contact theory, and a modified digital image correlation method is implemented to acquire the displacement field near the contact area. The contact length is then identified with the established model and the measured displacement gradient through an identification algorithm, which can be easily calculated and does not require an optimization process. Results: Both simulations and experiments are performed to evaluate the precision and applicability of the proposed approach. The identification error maintains within a very low level during different load steps. Conclusions: The results indicate that the proposed method can accurately identify the contact length and has the ability to against the inevitable measurement inaccuracy of the displacement field.

中文翻译：

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非合格无摩擦接触中接触长度识别的间接实验测量方法

背景：非一致接触通常会引起应力集中，因为相互作用仅发生在很小的界面上。理论和数值研究表明，接触应力分布和最大压力与接触界面的长度密切相关。目的：因此，接触长度的表征是研究接触行为和相应结构安全性的关键问题。方法：在本文中，我们提出了一种间接实验识别方法，可以可靠地表征不合格的无摩擦表面之间的接触长度。根据接触理论建立接触长度与局部位移的关系，并采用改进的数字图像相关方法获取接触区域附近的位移场。然后通过识别算法使用建立的模型和测量的位移梯度来识别接触长度，该算法可以轻松计算并且不需要优化过程。结果： 进行模拟和实验以评估所提出方法的精度和适用性。在不同的负载步骤期间，识别误差保持在非常低的水平。结论：结果表明，所提出的方法能够准确识别接触长度，并具有克服位移场不可避免的测量误差的能力。然后通过识别算法使用建立的模型和测量的位移梯度来识别接触长度，该算法可以轻松计算并且不需要优化过程。结果： 进行模拟和实验以评估所提出方法的精度和适用性。在不同的负载步骤期间，识别误差保持在非常低的水平。结论：结果表明，所提出的方法能够准确识别接触长度，并具有克服位移场不可避免的测量误差的能力。然后通过识别算法使用建立的模型和测量的位移梯度来识别接触长度，该算法可以轻松计算并且不需要优化过程。结果： 进行模拟和实验以评估所提出方法的精度和适用性。在不同的负载步骤期间，识别误差保持在非常低的水平。结论：结果表明，所提出的方法能够准确识别接触长度，并具有克服位移场不可避免的测量误差的能力。进行模拟和实验以评估所提出方法的精度和适用性。在不同的负载步骤期间，识别误差保持在非常低的水平。结论：结果表明，所提出的方法能够准确识别接触长度，并具有克服位移场不可避免的测量误差的能力。进行模拟和实验以评估所提出方法的精度和适用性。在不同的负载步骤期间，识别误差保持在非常低的水平。结论：结果表明，所提出的方法能够准确识别接触长度，并具有克服位移场不可避免的测量误差的能力。