Modeling of Damage in Coilable Composite Shell Structures

Abstract

Coilable composite shell structures, composed of ultra-thin laminates, are ideal for deployable space structures applications. Their ability to be flattened and coiled for packaging, and deployed in their operational configuration makes them suitable for many space missions. Due to the complex states of stresses that occur in a composite shell during these processes (coiling, stowage, and deployment), material failure may be induced. This in turn would negatively affect the deployment, cause shape distortions, reduce the stiffness of the shell, or even lead to catastrophic failure of the mission. Therefore, predicting the failure modes and mechanisms of ultra-thin laminates at the structural scale is critical for design and certification purposes. However, this is often complicated by the complex microstructure and the multiple length-scales (micro and meso) associated with composites. This study presents a finite element model with progressive damage that effectively captures the ply failure modes. This is done through a damage constitutive model, where local cracks in the shell are smeared within a finite element. The fracture properties of interest are experimentally measured and incorporated into the model. The salient features of the model needed to capture failure are identified by comparing the simulation results with experiments. This is achieved by analyzing the coiling of a TRAC longeron shell structure.

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