Experimental Study of the Influence of a Tensile Preload on Thin Woven Composite Laminates Under Impact Loading

In this work, the influence of a tensile preload on the impact behavior of thin woven composite laminates is investigated. These kinds of laminates are usually parts of more complex structures, for example, skins of structural sandwich panels or helicopter blades. These structures are generally subjected to external loads, and can also be impacted in operation. The objective of this study is to identify a correspondence between the preload of the structure and the resulting impact damage. This preliminary work is a first step of a more global study that aims at predicting impact damage in structural composites in order to optimize the design process. Experimental tests are carried out on carbon/epoxy and glass/epoxy mixed thin laminates and on sandwich structures. The samples are loaded uniaxially using a specially designed test rig. The effect of the preload on the impact damage size and shape and the peak load is experimentally quantified and discussed.