NDT of composite components for automotive applications

Non Destructive Testing (NDT) of composite materials has been a topic of great interest for the global scientific community. The final aim of engineers is the Structural Health Monitoring (SHM) of composite components in real applications. Building block approaches are necessary for this target, starting with NDT studies on coupon specimens and moving towards the testing of larger scale components. In this study, NDT of carbon/epoxy sub-components has been undertaken in order to assess the occurring damage mechanisms. V-shape components were initially tested under static and fatigue, tensile and compressive loads in order to examine the mechanical response of the corner section of a square beam component with a potential usage in a vehicle frame for a suspension mount. The square beam component was then tested in a progressive manner under static and fatigue compressive loads. Conventional strain gauge measurements were compared in all cases with the more innovative Digital Image Correlation (DIC) and Acoustic Emission (AE) methods, in order to explore the benefits and limitations of all of them. The last two techniques were proven to provide, in all cases, a more sensitive and conservative estimation of the onset of damage. DIC, when applied through the thickness of the V-shape components, could provide specific strain profiles leading to failure, whereas it could indicate the location of the occurring damage when applied to the external surface of the square beam components. AE was proven to provide the exact location of damage as well as the migration of the locus of damage during testing through advanced localization algorithms. All results were compared with the AE findings of tests on coupon specimens to explore the potential of acoustic methods for damage identification and classification in composite structures.