An investigation into the damage development and residual strengths of open-hole specimens in fatigue

Abstract

An extensive experimental program was carried out to investigate and understand the sequence of damage development throughout the life of open-hole composite laminates loaded in tension-tension fatigue. Quasiisotropic carbon/epoxy laminates, with stacking sequence [45 2 /90 2 /-45 2 /0 2 ] S , [45/90/-45/0] 2S and [45/90/-45/0] 4S were examined. These were selected on the basis that under quasi-static loading the [45 2 /90 2 /-45 2 /0 2 ] S configuration exhibited a delamination dominated mode of failure whilst the [45/90/-45/0] 2S and [45/90/-45/0] 4S configurations showed a fibre dominated failure mode, previously described as "pull-out" and "brittle" respectively. Specimens were fatigue loaded to 1x10 6 cycles or catastrophic failure, which ever occurred first. A number of tests were interrupted at various points as the stiffness dropped with increasing cycles, which were inspected using X-ray Computed Tomography (CT) scanning. A static residual strength program was carried out for run-out specimens of each configuration.

Generation of micro-scale finite element models from synchrotron X-ray CT images for multidirectional carbon fibre reinforced composites

“…[3][4][5]. X-ray CT image-based numerical models (most commonly the finite element (FE) method) have also been recently built to investigate the mechanical behaviour of some multi-phase materials, such as homogenisation of elastic properties of fibre reinforced concrete [6], damage evolution of carbon-carbon composites [7], and complicated nonlinear fracture in concrete [8,9].…”

Fibre failure assessment in carbon fibre reinforced polymers under fatigue loading by synchrotron X-ray computed tomography

“…Green et al [16] observed delaminationdominated failure (ply-level scaling) and fibre-dominated failure (sub-laminate level scaling) under quasi-static load depending on the quasi-isotropic configuration considered, albeit without direct observations of fibre failure. However, when the same material systems were considered under fatigue loading on a sub-laminate level, the observed failure modes were delamination-dominated, except for load levels higher than 90%, which showed fibre-dominated failure [17]. Wright et al [18] observed fibre M A N U S C R I P T…”

Predicting Fatigue Damage of Composites Using Strength Degradation and Cumulative Damage Model

“…Archard et al [35] presented a discrete ply model approach to experimentally quantify damage under static loading for a composite plate with a hole under tensile loading. Nixon-Pearson et al [36] presented an extensive experimental framework to show the sequence of damage development throughout the life of open-hole quasi-isotropic IM7/8552 carbon fiber/epoxy laminates loaded in tension-tension fatigue. Work of Nixon-Pearson et al [36] showed that there is delamination between 0/45 and 45/90 layers during fatigue cycles.…”

“…Nixon-Pearson et al [36] presented an extensive experimental framework to show the sequence of damage development throughout the life of open-hole quasi-isotropic IM7/8552 carbon fiber/epoxy laminates loaded in tension-tension fatigue. Work of Nixon-Pearson et al [36] showed that there is delamination between 0/45 and 45/90 layers during fatigue cycles. For the open hole tension specimen, we have depicted the reduction in the strength and stiffness The effect of the interlaminar failure and damage patterns are shown by researchers for open hole composite specimens under tensile loading.…”