Passive infrared thermography measurement of transverse cracking evolution in cross‐ply laminates

Over the last decades, various experimental methodologies have been used to study the matrix crack density evolution in cross‐ply laminates. The main drawback of these techniques is their difficult use at intermediate and high strain rates. In this study, a new experimental protocol to evaluate matrix crack density evolution at intermediate strain rates is proposed and applied to [0/903]s carbon/epoxy laminate. It is based on the use of passive infrared thermography to monitor the matrix cracking appearance. This methodology is used to first demonstrate that the crack appearance in the 90° ply remains instantaneous from side to side with the increase of the strain rate. Finally, the rate insensitivity of the crack density as a function of the applied stress for the studied material in the studied range of strain rates (8.3 × 10−4 up to 6.69 × 10−2 s−1) is demonstrated.