COMPARATIVE STUDY BETWEEN INFRARED THERMOGRAPHY AND LASER DOPPLER VIBROMETRY APPLIED TO FLAWS INDENTIFICATION IN COMPOSITE MATERIALS

There are many NDT techniques available but only a few allow in situ analysis. Thus, the requirements for non-destructive evaluation are continuing to be driven by the need for lower cost methods and instruments with greater reliability, sensitivity, user friendliness and high operational speed as well as applicability to increasingly complex materials and structures [1]. Both infrared termography and laser Doppler Vibrometer accomplish these characteristics and, for this reason, are widely employed in the NDT sector. In this work, a comparative study between laser Doppler vibrometry and infrared thermography applied to the damage detection in composite material is presented. A mathematical model was implemented in order to validate the results obtained experimentally through the thermographic technique. The thermal measurements uncertainty and the noise of the LDV system, which are limitations of each methodology, are also discussed. The experimental procedure was carried out in the Mechanical and Thermal Measurements laboratory of the Mechanical Engineering Department of the Università Politecnica delle Marche. The honeycomb panel used in this work has its four layered top part made with a combination of glass-fibre fabric type RE 200 and E277 epoxy resin. Three wax inclusions were inserted in certain positions among the layers during its manufacturing process in order to create the flaws. After, by warming, the wax inclusions were eliminated from the panel to simulate real delaminations. Figure 1 shows the geometry and th