Monitoring and defect detection in production and maintenance of thick composite componentes

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In order to exploit the full potential of fiber reinforced plastics, it is inevitable to understand their failure mechanisms and the effects of defects.One focus of this research project will be the production of thick glass fiber reinforced plastic laminates with high pressure resin transfer molding (HP-RTM). Another focus will be investigations of the dependence of laminate thickness and mechanical properties. Research activities of the IKT (University of Stuttgart) will be the nondestructive test- and detectability of thick laminates from production to failure.One objective of the IKT is the detection of the resin flow front during (HP-RTM). The laminate thickness will be between four and ten millimeters. The nondestructive Phased Array Matrix Ultrasonic Testing method will be used. Especially the influence of changing reflections of the ultrasound signal will be emphasized. All preparations and results will be evaluated in cooperation with the ILK (Dresden University of Technology).Also an objective of the IKT is non-destructive investigation of the influence of local fiber waviness and global layer waviness on the mechanical properties of thick laminates. Air-coupled Ultrasound and Ultrasound Matrix Phased Array will be utilized as nondestructive testing methods to detect defects like cracks and delaminations. The damage extend will be monitored depending on the imperfection of the laminate. Additionally, nondestructive testing data of the laminate stiffness using the Differential Time of Flight method will establish a basis for simulation of residual stresses conducted by the IPC (Hamburg University of Technology).A further objective of the IKT is investigation of the influence of laminate thickness on the strength and fatigue behavior. Nondestructive testing methods Air-coupled Ultrasound and Ultrasound Matrix Phased Array will again be used, whilst mechanical testing with static and dynamic load. Results will form the basis for simulations performed by the IFL (Braunschweig University of Technology) and are matched to Acousting Emission testing.