Fatigue Testing of Continuous GFRP Composites Using Digital Image Correlation (DIC) Technique a Review

Abstract

Usage of Glass Fiber Reinforced Polymeric (GFRP) composites is increasing drastically in many fields from Aerospace to Sporting good due to light weight and low cost. An effective design of GFRP composites requires detailed understanding of material and the way of testing. Fatigue is the single largest failure that occurs in composites suddenly without any warning, and this failure is catastrophic in nature. In the past years the composites were tested under fatigue loads so that the fatigue behavior can be identified. But this can’t detect the crack behavior of material at the time of testing which is a very important phenomena in identifying the stress concentration of the material. This paper discusses the application of Digital Image Correlation (DIC) technique for fatigue testing of GFRP material in order to capture anisotropic damage. DIC is a non-contact and non–destructive unique exploring full field optical method used to measure accurate displacement, surface strains usually called as speckle pattern for anisotropic material undergoing motion and deformation. In this paper we explained DIC by using Newton- Rapshon (NR) correlation analysis. DIC technique uses high speed, high resolution and accurate Charge-Coupled device (CCD) cameras for measuring displacement components on the surface of the testing material having speckle patterns. Images were captured at the time of testing at every stress cycle and these deformed patterns were correlated with a reference pattern and determining the displacements of the so called subsets. Because of fast data acquisition this technique is well suited for characterization of material properties.