Strain Analysis on 2D Specimen Under Tensile Load – Unexpected Negative Strain in Y-Direction

[[Ha...]]

Hello everyone,

I'm currently performing strain analysis on a 2D specimen subjected to a uniaxial tensile load using Digital Image Correlation (DIC). I’ve encountered an issue: the strain in the Y-direction appears negative on the upper half of the specimen, which is unexpected under tensile loading.

I suspect this might be due to specimen slipping during the test, possibly at the grips.

Has anyone experienced a similar issue?
Is there any post-processing method or correction technique in DIC software (e.g., filtering, coordinate transformation, reference frame adjustment) that could help address this?

I've attached an image of the experimental setup and the strain result for reference.

Any advice or insights would be greatly appreciated!

Thank you in advance.

Edited May 21

[[Mo...]]

Hello Harith,
It appears that the upper part of the sample may be moving away from the camera, causing the software to calculate an apparently negative strain. This could be due to the sample slipping during the test or incorrect positioning of the camera.

i recommend checking the alignment and securing of the sample, as well as the positioning of the camera, to ensure that the measurements are accurately captured.

Best regards
Mohamed