Effect of fibre architecture on the specific energy absorption in carbon epoxy composite tubes under progressive crushing

This paper presents the progressive crushing performance of composite tubes with varied fibre architecture. The effect of lay-up configuration and influence of percentage of unidirectional (UD) and woven fabric (WF) fibre architectures on the specific energy absorption (SEA) is investigated using experiments. Composite tubes with internal diameter 42 mm and wall thickness to diameter of 0.05 were manufactured for a range of specimens with different ratios of axial and hoop fibres. The samples were chamfered at an angle of 70 degrees. Progressive crushing of specimens under quasi-static (20 mm/min) and dynamic (4.48-6.7 m/s) loading were performed. A new factor Axial Fibre Mass Fraction (AFMF) was introduced to describe the mass fraction of axial fibres to reflect upon the SEA response. To investigate the influence of AFMF and loading rate on the crushing mechanism of composite tubes, computer tomography (CT) was additionally. The calculated SEA for different loading conditions indicate a drop of 10%-20% for dynamic cases depending on the fibre architecture of the samples. The CT-scans present a relationship between debris length and AFMF. The average length of debris decreases with the increase of AFMF which indicates more intense fibre breaking, reduced integrity of the 'petals' and hence increased SEA.