EFFECT OF STRUCTURAL VARIATIONS ON THERMAL DEFORMATION OF SINGLE CURVATURE COMPOSITE SANDWICH PANELS
Abstract
Composite structures cured at a high temperature in a contoured female mold have a tendency to deform or spring-in when brought down to room temperature from cure temperature. This thesis investigates the effects of various structural parameters on the spring-in of the curved shape of a composite sandwich panel due to thermal deformation. A finite element model of a single curved composite sandwich panel is developed using 3D shell elements and validated against other published articles and classical lamination theory. Using a control structure of AS4/3501-6 carbon/epoxy with half inch Nomex honeycomb core with a layup of [0°/90°/0°/90°/Core/90°/0°/90°/0°]T, structural parameters are varied including core thickness, face sheet thickness, face sheet ply orientation, asymmetric face sheets, temperature delta, and structure radius. Core thickness variations using the control layup were found to decrease the total spring-in as core thickness (as well as bending stiffness) increased; however, as face sheet thickness increases for a constant core thickness, total spring-in increases. Cases using other quasi-isotropic face sheets other than 0°/90° layups were analyzed and found to correspond to the results from the face sheet thickness study.