Research On The Mechanical Behavior Of Fiber Placement Composite Stiffened Structure

Fiber placement is an advanced automated composite manufacturing technology whichovercomes the disadvantages of low-productivity, high-cost and unstable-quality of the traditionalcomposite manufacturing technology. Fiber placement composites have been used in aircraftfuselage、wings、inlet and many other components. Buckling instability is the most common failuremode in aircraft fuselage, wings and inlet and it can be improved by adding stiffener. Therefore, it istheoretically significant and practically valuable that researches on the mechanical properties ofstiffened fiber placement composite structures.In the paper, experimental and theoretical researches on the fiber placement composites had beencarried out. The results indicated that, for fiber placement composite laminates, the first-order sheartheory was suitable and Hashin-based failure criteria could be used to predict the failure onset.According to the researches in mechanical properties of fiber placement composite, finite elementmodels were presented to study the buckling and postbuckling behaviors of stiffened curved panel andstiffened hyperbolic paraboloidal panels based on ABAQUS/CAE software. The material stiffnessdegradation model was established. In the model, cohesive elements were adopted to simulate thedebonding failure between the skin and stiffener, and Quads failure criteria and Hashin-based failurecriteria were used to predict the damage of cohesive elements and composite laminates, respectively.The buckling, postbuckling behaviors and failure propagations under compression had been studied indetail. Effects of height, configuration, number of stiffeners and panel radius on buckling and ultimateloads of fiber placement composite stiffened curved panels and stiffened hyperbolic paraboloidalpanels had been investigated. The results indicated that the buckling and ultimate loads increased asincreasing the height and number of stiffeners, decreasing the radius of the curved panels andincreasing the axial radius of the hyperbolic paraboloidal stiffened panels.