Evaluation of the survivability of CFRP honeycomb-cored panels in compression after impact tests

Elena Strungar,Oleg Staroverov,Valery Wildemann

doi:10.3221/igf-esis.56.01

Elena Strungar, Oleg Staroverov + Show 1 more

Open Access

https://doi.org/10.3221/igf-esis.56.01

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Abstract

This paper is oriented to the experimental research of the mechanics of the CFRP sandwich plates, glass and carbon fiber sample panels with a large-cell honeycomb core. The method for testing polymer composite sample plates in compression after impact (CAI) tests with joint use of a testing machine and a video system for deformation field registration was tested. Analysis of the experimental data obtained highlighted the impactive sensitivity zone for the test specimens. A quantitative assessment of the load-bearing capacity of glass and carbon fiber sample panels in CAI tests with the different levels of the drop weight impact energy was performed. Photos of samples after impact have been provided. Vic-3D non-contact three-dimensional digital optical system was used to register the displacement and deformation fields on the surface of the samples. The video system was used to evaluate various damage mechanisms, including matrix cracking, delaminations, and rupture of the damaged fibers. The paper studied the evolution of non-homogeneous deformation fields on the surface of the composite samples during the post-impact compression tests and analyzed the configuration of non-homogeneous deformation fields.

Highlights

The low-velocity impact is a serious threat to the use of composite materials in engineering applications, as they cause minute damages that can go unnoticed
The main objectives of this study were to obtain new experimental data on changes in the residual strength of polymeric large-cell composite samples in post-impact compression tests with joint use of a system for registering deformation fields to analyze the kinetics of crack propagation on the surface of the samples
The use of the video system for registration of displacement and deformation fields during the compression tests after the impact of carbon fiber sample plates allowed to record and track the process of initiation and propagation of cracks caused by out-of-plane impact in the stress concentrators area

Summary

Introduction

The low-velocity impact is a serious threat to the use of composite materials in engineering applications, as they cause minute damages that can go unnoticed. In paper [12], the authors measured the deformation of composite samples under post-impact compressive loads using the electronic speckle pattern interferometry This method is not suitable for measuring out-of-plane displacements. Using the Vic-3D non-contact optical video system, a DIC-based mathematical apparatus, it becomes possible to solve the problems of strain measurement under the combined stress and fracture kinetics analysis in the process of cracks propagation during the compression of samples [15,16,17,18,19,20,21]. The main objectives of this study were to obtain new experimental data on changes in the residual strength of polymeric large-cell composite samples in post-impact compression tests with joint use of a system for registering deformation fields to analyze the kinetics of crack propagation on the surface of the samples

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Conclusion