Effect of variable core stiffness on the impact response of curved sandwich plates

Abstract

An extensive analytical model to determine behaviour of curved sandwich plates with variable stiffness cores and face-sheets under low velocity impact with foam core is presented in this paper. A developed method is introduced to determine effective dynamic stiffness of the facesheets and core with variable stiffness. A modified spring-mass-dashpot model was used to obtain the contact force function related to effective dynamic stiffness and effective dynamic frequency to determine the contact force histories by impact of a hemispherical-nose impactor. A parametric study was also performed to understand the effects of several factors such as impactor velocity, face-sheet thickness, core thickness (constant and variable stiffness), layup orientation and curvature on the contact force histories of curved sandwich plates. Different geometries of curved sandwich plates are analysed to study their performance under impact loading. Numerical analysis was performed in LS-DYNA to further validate with the developed analytical models.

Analytical development on impact behaviour of composite sandwich laminates by differentiated loading regimes

“…The loading stage is concerned to the onset of the impact, where no prior damage exists in the panel. As stated by previous authors ( [13], [17]), the indentation behaviour in these conditions can be subsequently divided into three regions depending on the maximum dent magnitude and the subsequent dominant response of the facings. Initially, for small indentations, and provided that the core remains in the elastic range, the target behaves like a plate on a Winkler foundation (see Ref.…”

“…Therefore, a novelty of the herein proposed formulation is the consideration of the lower facesheet local deflection through the non-linear stiffness parameter K b , which allows for extending the applicability of the analytical method to larger impact velocities by introducing material damage in that instance, thus eliminating the impact velocity limit stated by Arachchige and Ghasemnejad [17]. Although no facesheet damage is considered in the present study, the proposed formulation may be accordingly modified to account for those in subsequent studies.…”

“…This behaviour supports the interest for the use of non-conventional core geometries in an aim for improving the low velocity impact performance of sandwich panels. Eventually, one of the most recent studies concerning the low velocity impact modelling of sandwich structures was performed by Arachchige and Ghasemnejad [17], who proposed a new formulation that accounted for the uneven distribution of stiffness across curved sandwich panels. This methodology, which was simultaneously validated against results available in the literature and finite element models, posed a great breakthrough by allowing the analytical modelling of complex sandwich structures.…”

Curved grid‐scored foam core sandwich composites under low‐velocity impact loads: Effects of curvature, stacking sequence, and core finishing

“…The use of lattice materials as a core in curved sandwich structures was found to improve impact resistance, reduce the contact force and residual kinetic energy of the bird, and reduce the deformation of the back face sheet. Arachchige and Ghasemnejad 26 developed an analytical model to simulate the low‐velocity impact response of curved sandwich composites with a foam core. The relation between the increase in plate curvature and the increase in energy absorption of curved sandwich structures was verified by comparing numerical and analytical models.…”

Impact and compression-after-impact behavior of sandwich panel comprised of foam core and wire nets/glass fiber reinforced epoxy hybrid facesheets

“…Sandwich structures are highly susceptible to impact events that may be caused by tool drops, runway stones, hails, etc. [5,6]. Compared to high-velocity impact, low-velocity impact is more of concern since it gives rise to barely visible impact damage, which might lead to significantly strength reduction of sandwich structures without any visible damage signs at the surface [2,7–9].…”