Vibration-buckling tests on heated composite plates

Abstract

This paper presents an experimental investigation on vibrations of heated composite plates leading to thermal buckling. The tests were performed considering two main goals: the application of the Vibration Correlation Technique for the detection of thermal buckling in composite plates; and the exploration of the frequency variations before and after the occurrence of a mode jump in post-buckling regime. Two test setups were used. The setups shared a low thermal expansion frame, while they differentiate on the type of heating source and mechanical boundary conditions. Two composite plates with layups [30/−30/5/−5]s and [35/−35/10/−10]s were tested. The plates were excited acoustically using a loudspeaker, and the vibration frequencies were monitored and stored using a laser vibrometer. Buckling temperatures were successfully detected using the Vibration Correlation Technique. Frequency changes, potentially related to the mode jumping, were also detected.