Characterisation of Damaged Tubular Composites by Acoustic Emission, Thermal Diffusivity Mapping and TSR-RGB Projection Technique

Neha Chandarana,Henri Lansiaux,Matthieu Gresil

doi:10.1007/s10443-016-9538-8

Abstract

An increase in the use of composite materials, owing to improved design and fabrication processes, has led to cost reductions in many industries. Resistance to corrosion, high specific strength, and stiffness are just a few of their many attractive properties. However, damage tolerance remains a major concern in the implementation of composites and uncertainty regarding component lifetimes can lead to over-design and under-use of such materials. A combination of non-destructive evaluation (NDE) and structural health monitoring (SHM) have shown promise in improving confidence by enabling data collection in-situ and in real time. In this work, infrared thermography (IRT) is employed for NDE of tubular composite specimens before and after impact. Four samples are impacted with energies of 5 J, 7.5 J, and 10 J by an un-instrumented falling weight set-up. Acoustic emissions (AE) are monitored using bonded piezoelectric sensors during one of the four impact tests. IRT data is used to generate diffusivity and thermal depth mappings of each sample using the thermographic signal reconstruction (TSR) red green blue (RGB) projection technique. Analysis of AE data alone for a 10 J impact suggest significant damage to the fibres and matrix; this is in good agreement with the generated thermal depth mappings for each sample, which indicate damage through multiple fibre layers. IRT and AE data are correlated and validated by optical micrographs taken along the cross section of damage.

Highlights

Fibre reinforced polymer composite materials have become attractive for use in structural applications since they can provide advantages over traditional materials
Non-destructive evaluation (NDE) techniques are often adopted for periodic inspection of composite structures while they are in service
Common methods of non-destructive evaluation (NDE) include the use of x-rays, ultrasonic waves [1], eddy currents [2], shearography [3,4,5], and infrared thermography [6,7,8,9,10,11,12,13,14,15,16,17]

Summary

Introduction

Fibre reinforced polymer composite materials have become attractive for use in structural applications since they can provide advantages over traditional materials. The relative inexperience designing with composites means that industries are reliant on models and predictions regarding the response of these materials in service and how damage affects component lifetimes. This inexperience can often translate into conservative actions, leading to overdesigning and premature replacements of parts, which greatly affects the cost saving capability of a moving to composites. Non-destructive evaluation (NDE) techniques are often adopted for periodic inspection of composite structures while they are in service. Where the use of SHM and NDE are combined, it becomes possible to carry out Bfocused^ inspections using non-destructive techniques, saving both time and money

Methods

Results

Conclusion