| Abstrakt: |
Nondestructive testing (NDT) is widely used in research and industry to evaluate the quality of a variety of materials including composite structures. NDT, as the name indicates, has the benefit that it does not alter or destroy the sample like other techniques, such as cross-section imaging. In this work, two nondestructive techniques, ultrasound and micro computed tomography (micro- CT), were used to characterize carbon fiber epoxy composites, particularly reused composite oriented strand board (COSB) and conventional laminates. The void content and morphology of samples cured using a range of materials and process parameters was determined using NDT and conventional microscopic analysis of cross-sections. The mass distribution of fiber and resin within each sample was also determined. The primary objective of this work was to evaluate the feasibility of NDT methods in the assessment of composite laminates, specifically COSB made from reused prepreg scrap. To this end, the advantages and limitations of ultrasound and micro- CT are discussed. High resolution micro-CT provides the most detailed information on composite microstructure, including void size, morphology, distribution, and overall void content. Conventional micro-CT, however, is ill-suited to scanning large samples because of long scan times and large file sizes. To enhance the capabilities of micro-CT for evaluation of composite structures, we developed a micro-CT post processing method using stitching computer programming algorithms. The method presented here markedly increases the resolution that micro-CT NDT can achieve, as well as the maximum feasible sample size, thus overcoming some of the primary drawbacks to conventional micro-CT. The results shows that with stitching up post processing, micro-CT can be used to detect global void morphology, structure-wide, making the technique competitive with ultrasound, yet with greater resolution and equivalent scan size. In this work, we apply the technique to a novel composite product form - composite oriented strand board, fabricated from production scrap. [ABSTRACT FROM AUTHOR] |
