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

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.

Thermal Diffusivity Mapping of Graphene Based Polymer Nanocomposites

“…It also states that the energy pulse is instantaneous and uniformly illuminates the front face of the specimen. In order to avoid these assumptions, Clark and Taylor 29 examined the thermogram at different points before the maximum temperature was reached and developed a correction factor, ( C R ): The corrected value for thermal diffusivity becomes This method has been used to measure the diffusivity for non-destructive evaluation (NDE) inspecting porosity 30 , 31 , bonding defects 30 and impact damage 32 in composite laminates. The mapping of the thermal diffusivity requires its calculation for each pixel.…”

Early Damage Detection in Composites during Fabrication and Mechanical Testing

“…Non-destructive inspection/evaluation (NDI/E) techniques are often employed for the detection, localisation, and quantification of flaws and damage. Widely researched methods include the use of X-rays [ 1 ], ultrasonic waves [ 2 ], eddy currents [ 3 ], shearography [ 4 , 5 , 6 ], and infrared thermography [ 7 , 8 , 9 , 10 ]. Though they improve safety and often minimise premature replacements, inspections can represent significant down-time and labour costs.…”

Evaluation of the influence of preliminary low-velocity impacts on the residual fatigue life of CFRP composites

“…The use of additional infrared thermal scanning equipment, registration of acoustic emission signals (Munoz et al, 2016;Chandarana et al, 2017;Zhou et al, 2020;Wu et al, 2022), control of displacement and deformation fields, supported by the results of the microstructure analysis, provide a full picture of damage accumulation and composite material fracture, which correlates well with the experimental data.…”