ASSESSMENT OF MATERIAL STATE FOR PREDICTING THE DURABILITY OF COMPOSITES

Abstract

**Please note that the full text is embargoed** ABSTRACT: The long term behavior of composites have been extensively studied for the last four decades. Given the heterogeneity of these materials, the damage accumulation mechanisms lead to superior fatigue performance of composites compared to metals. However, due to the ‘sudden death’ behavior controlled by defect coupling, the precursor to fracture plane development of these materials, the challenge remains on how to assess the real-time material state and predict when it becomes critical? In the recent past, broadband dielectric spectroscopy (BbDS) has been used successfully to assess the material state and predict the material state change (triggered by defect coupling) for quasi-static loading. In this work, we perform insitu monitoring of material state change for tension-tension fatigue loading (low cycle fatigue) and attempt to capture the material state change for quasi-isotropic laminates. The insitu response can be used to predict the formation of a ‘critical’ material state- the final frontier to predict the durability of composites and discuss the repeatability of the methodology.