An Indirect Experimental Measurement Method for Contact Length Identification in Non-conforming Frictionless Contact

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.