Identifying Delamination in Composite Materials Using Impulse Response Analysis of Infrared Thermography

The paper concerns with the transient response analysis of the nondestructive infrared thermography test to detect thedelaminationsin the laminated composites. A thermal pulse flow is applied to the surface of composite samples and the dimension and position of delamination defects are determined based on the temperature distribution analysis of the heating surface. The transient thermal response is determined by finite element model of laminated composite subjected to heat flux of halogen lamp in a short time period and natural cooling convection flow on the specimen surfaces at long time. The thermography model is implemented for a laminated composite sheet with different size delaminations located at multiple depths. Thin aluminum layers are considered on the composite surfaces to uniform heat transfer. The numerical results show that temperature gradient is observed at specific time range on heating surface due to considerable thermal resistance variation of defects and the temperature distribution can be used to detect the small size delaminating in the laminated composites The temperature distribution and spatial derivation result in the exact size of damage regions and the optimum inspection time leading to appropriate results in impulsive infrared thermography test.