EXPERIMENTAL METHOD OF INTERLAMINAR CHARACTERIZATION IN FILAMENT WOUND THICK COMPOSITE STRUCTURES

摘要

Interlaminar properties are among the most important material allowables controlling structuralrnintegrity and damage tolerance of laminated composite structures. Existing methods of theirrnexperimental characterization are primarily based on testing of beam-type composite couponsrnspecifically manufactured to mimic the laminated lay-ups. However, their application to filamentrnwound composite structures (WCS) may be quite challenging due to difficulties generatingrnsimilar flat coupons, i.e., the ability to capture interlaminar damage specific to the windingrnmanufacturing process. Additional challenges can also be noted for relatively thick WCS withrnmuch more complex 3D stress distributions. The objective of this work, therefore, isrndevelopment of an experimental in situ approach to characterize interlaminar shear (ILS)rnproperties in thick WCS. The proposed approach is designed to represent a shear failure modernand can be easily applied to a wide range of composite lay-ups and geometries. To address thern3D nature of stress distributions, integration with FEA is applied in an efficient way.rnDemonstration of the approach is considered on a representative thick-wall WCS made ofrncommercially available carbon-fiber composites. Simplicity of implementation and robustness ofrngenerated results are shown. Details of the implementation and the lessons learned arernsummarized in the form of practical recommendations.