Characterization of the Mechanical Behaviour of Carbon Fiber Composite Laminate under Low Velocity Impact

Abstract

The main purpose of the present investigation was to determine the damages generated by the low velocities with the help of the experimental method (Impact by a drop test) and the finite element method. The commercial transient finite element package LS-dyna used to model the effect of slug impactor and circular notch induced damage in composite material IntroductionThe fibrous composites are being increasingly used in load bearing structures due to number of advantages over conventional materials: high specific strength and stiffness, good fatigue performance and corrosion resistance. A serious obstacle to more widespread use is their sensitivity to impact and static loads in the thickness direction. As composites have demonstrated to be very venerable to out of plane impact, which cause barely visible impact damage (BVID) reportedly contributes up to 60 % loss in structures' compressive strength and major reason of catastrophic failures. The energy absorbed during impact is mainly dissipated by a combination of matrix damage, fibre fracture and fibre-matrix de-bonding, which leads to significant reductions in the resistance. In ballistic impacts the damage is localized and clearly visible by external inspection, while low velocity impact involves long contact time between impactor and target, which produces global structure deformation with undetected internal damage at points far from the contact region. Low velocity impact is often simulated by simple static indentation-flexure tests, neglecting the influence of dynamic effects. It is also suggested the complete model to take into account the full dynamic behavior of the laminates. Abrate et al. [1] have investigated the delamination of two laminated composite graphite/PEEK and graphite/BMI under low velocity impact. The range number of layers varies from 9 to 95 plies. The obtained result shown a higher delamination threshold load and higher damage resistance. The resulting damage is not normally visible on the specimen surface nor is easily detected and grows rapidly during normal service. The area has been under active research for a quite some time. Some of the relevant articles addressing this issue found in the literature are presented below. The strategy of reducing the stiffness of damaged plies to a certain fraction without considering the degree of damage was used by some investigators [2,3]. Other researchers applied damage theory of continuum mechanics to address the internal damage. They initiated the stress-strain relation for the actual damaged by introducing a fourth-order damage operator to transform the compliance matrix according to the damage states. Based on this work, several investigations

3D printing-assisted interphase engineering of polymer composites: Concept and feasibility

“…have outstanding mechanical performance in-plane by contrast to out-of-plane type loading [2]. To improve the latter, various approaches have been proposed (needling, stitching, pinning, interleaving etc.)…”

Multifunctional application of carbon fiber reinforced polymer composites: Electrical properties of the reinforcing carbon fibers – A short review

“…Barakati and Zhupanska [57] studied how the dynamic mechanical properties of the CFRP at low-velocity impact test are affected by an electromagnetic field or flowing electric current. The mechanical behavior of CFRP tested with low-velocity impact when it is not in an electromagnetic field is described elsewhere [58]. Barakati and Zhupanska [57] claimed that if the test is carried out in an electromagnetic field, the mechanical damping of the specimen is greater, and the oscillation of the specimen will disappear sooner.…”

Comparison of static and fatigue interlaminar testing methods for continuous fiber reinforced polymer composites

“…The catastrophic failure of a composite is caused in most cases by the synergy of multiple failure processes: fiber breakage, matrix fracture, fiber-matrix debonding/pullout and delamination [1]. While in the case of dynamic loading the first two processes are dominant, in the case of cyclic loading, interfacial/interlaminar failure processes play greater role [2][3][4][5].…”