A compact system for accurate measurement of true stress-strain curves in transparent materials subject to extensive deformation

• Published in: Measurement : journal of the International Measurement Confederation Vol. 223; p. 113799
• Main Authors: Chen, Zhenning, Tang, Xinqiao, Zhao, Huatao, Zhou, Yan, Liu, Rumeng
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2023
• Subjects: Digital image correlation; Large strain; Transparent materials; True stress-strain curve; Transparent materials; True stress-strain curve; Digital image correlation; Large strain
• ISSN: 0263-2241
• DOI: 10.1016/j.measurement.2023.113799

•Multispectral 3D-DIC correlation reconstructs two surface profiles.•Refractive distortion correction helps deformed cross-sectional area measurement.•Proposed method effectively evaluates true stress-strain of transparent materials.•Direct and theoretical results align, offering accurate results at large strains. Accurate quantification of the true stress-strain curve over an extensive strain range is pivotal for elucidating material mechanical properties and simulating non-linear plastic deformation. A novel experimental approach was developed to directly measure true stress-strain behavior in transparent materials. Our setup featured a single 3CCD camera and mirrors, capturing images of both specimen surfaces with bicolored fluorescent speckle patterns. Initially, we determined and corrected the specimen’s refractive index using a point-by-point least squares method. Subsequently, we used multispectral dual 3D digital image correlation (DIC) to reconstruct surface profiles and correct refractive distortions. This allowed precise computation of the deformed cross-sectional area over an expansive strain range. True stress was calculated from the measured engineering stress and computed deformed area. Validity was confirmed by deforming a fluorescent elastomer, and results aligned with the theoretical predictions. This compact experimental setup effectively evaluates true stress-strain relationships in transparent materials under extensive deformation.