Cross-Influence between Intra-Laminar Damages and Fibre Bridging at the Skin–Stringer Interface in Stiffened Composite Panels under Compression

Abstract

In this paper, the skin–stringer separation phenomenon that occurs in stiffened composite panels under compression is numerically studied. Since the mode I fracture toughness and, consequently, the skin–stringer separation can be influenced by the fibre bridging phenomenon at the skin–stringer interface, in this study, comparisons among three different material systems with different fibre bridging sensitivities have been carried out. Indeed, a reference material system has been compared, in terms of toughness performance, against two materials with different degrees of sensitivity to fibre bridging. A robust numerical procedure for the delamination assessment has been used to mimic the skin–stringer separation. When analysing the global compressive behaviour of the stiffened panel, intra-laminar damages have been considered in conjunction with skin–stringer debonding to evaluate the effect of the fibre and matrix breakage on the separation between the skin and the stringer for the three analysed material systems. The latter are characterised by different toughness characteristics and fibre bridging sensitivities, resulting in a different material toughness.

An analytical study on low velocity impact resistance behaviors of general bio‐inspired helicoidal composite plates

“…30 The numerical results of the considered damage model have been compared with experimental cases to ensure the accuracy of the modeling. 31 To date, as mentioned above, systematic studies have been carried out on such subjects experimentally or/and numerically, but the procedure was always notoriously time-consuming and/or costly 25,32 , especially as so many influencing factors needed to be considered. Computationally efficient analytical solutions have always been desired; unfortunately, the complexity of LVI responses of the bioinspired helicoidal laminates precluded simple analytical solutions.…”

A Numerical Study on the Influence of Nanosilica‐Reinforced Epoxy Resin on the Delamination Behavior of Composite Laminates

“…Indeed, fiber‐reinforced polymers (FRPs) are widely sensitive to delamination and debonding, [ 1,2 ] triggered by service loads, impact phenomena, and/or production flaws. [ 3–5 ] The development of toughening mechanisms to increase the fracture resistance, and consequently reduce the delamination susceptibility of epoxy resin based composite materials, is an urgent demand in the use of FRPs for aeronautical structural applications. [ 4,6 ] Nanocomposites fall into this context, as the addition of low content of nano‐dimensioned particles and/or tubes has demonstrated to enhance the physical and mechanical properties of the epoxy matrix‐based materials, offering promising results in the improvement of delamination growth resistance in FRPs.…”

“…[3][4][5] The development of DOI: 10.1002/masy.202100458 toughening mechanisms to increase the fracture resistance, and consequently reduce the delamination susceptibility of epoxy resin based composite materials, is an urgent demand in the use of FRPs for aeronautical structural applications. [4,6] Nanocomposites fall into this context, as the addition of low content of nanodimensioned particles and/or tubes has demonstrated to enhance the physical and mechanical properties of the epoxy matrixbased materials, offering promising results in the improvement of delamination growth resistance in FRPs. [7][8][9] The improvement of the fracture toughness of FRP due to the nanofillers addition [10,11] can be attributed to two principal mechanisms: the localized plastic shear banding and the debonding of the nanofillers, which produces plastic voids around the nanoparticles.…”

Stability and failure of compressed thin‐walled composite columns using experimental tests and advanced numerical damage models

“…60 Regarding the above, it is necessary to employ interdisciplinary research methods enabling the description of failure of the composite materials. [61][62][63][64][65] Additionally, the numerical investigations presented in work constitutes a complex issue, through globally occurring cohesive zones between all layers in thin-walled composite structure.…”