Finite element modelling of low velocity impact of composite sandwich panels

Besant, T.; Davies, G. A. O.; Hitchings, D.

doi:10.1016/s1359-835x(01)00084-7

Cited by 104 publications

(56 citation statements)

References 4 publications

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“…The sandwich structure considered in this work is made of an aluminium honeycomb core and carbon composite skins, this last being a typical combination of materials employed in some real-world aerospace engineering applications, like those presented in [8,9,12,25]. The material properties of the aluminium alloy used for the honeycomb core as well as those of the elastic air (these last taken from [2]) are listed in Table 3.…”

Section: Numerical Studymentioning

confidence: 99%

A multi-scale approach for the optimum design of sandwich plates with honeycomb core. Part I: homogenisation of core properties

Catapano

Montemurro

2014

Composite Structures

114

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This work deals with the problem of the optimum design of a sandwich panel. The design process is based on a general two-level optimisation strategy involving di erent scales: the meso-scale for both the unit cell of the core and the constitutive layer of the laminated skins and the macro scale for the whole panel. Concerning the meso-scale of the honeycomb core, an appropriate model of the unit cell able to properly provide its e ective elastic properties (to be used at the macro-scale) must be conceived. To this purpose, in this rst paper, we present the numerical homogenisation technique as well as the related nite element model of the unit cell which makes use of solid elements instead of the usual shell ones. A numerical study to determine the e ective properties of the honeycomb along with a comparison with existing models and a sensitive analysis in terms of the geometric parameters of the unit cell have been conducted. Numerical results show that shell-based models are no longer adapted to evaluate the core properties, mostly in the context of an optimisation procedure where the parameters of the unit cell can get values that go beyond the limits imposed by a 2D model.

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Section: Numerical Studymentioning

confidence: 99%

A multi-scale approach for the optimum design of sandwich plates with honeycomb core. Part I: homogenisation of core properties

Catapano

Montemurro

2014

Composite Structures

114

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“…Conventionally, modelling of this phenomenon is either based on an equivalent material law, which could be of the perfectly plastic type [22] and [23], or on a discrete crushing law (with a peak) for honeycomb blocks [24] and [25]. In this area, Horrigan [26] used an isotropic continuum damage model, but this modelling was limited to small indentations, since the continuity of the damage model and the plastic stress flow did not represent the real damage in the core.…”

Section: -Introductionmentioning

confidence: 99%

Modelling of low-energy/low-velocity impact on Nomex honeycomb sandwich structures with metallic skins

Castanié¹,

Bouvet²,

Aminanda

et al. 2008

International Journal of Impact Engineering

100

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Abstract.In the aircraft industry, manufacturers have to decide quickly whether an impacted sandwich needs repairing or not. Certain computation tools exist at present but they are very time consuming and they also fail to perfectly model the physical phenomena involved in an impact. In a previous publication, the authors demonstrated the possibility of representing the NomexTM honeycomb core by a grid of nonlinear springs and have pointed out both the structural behaviour of the honeycomb and the influence of core-skin boundary conditions. This discrete approach accurately predicts the static indentation on honeycomb core alone and the indentation on sandwich structure with metal skins supported on rigid flat support. In this study, the domain of validity of this approach is investigated. It is found that the approach is not valid for sharp projectiles on thin skins. In any case, the spring elements used to model the honeycomb cannot take into account the transverse shear that occurs in the core during the bending of a sandwich. To overcome this strong limitation, a multi-level approach is proposed in the present article. In this approach, the sandwich structure is modelled by Mindlin plate elements and the computed static contact law is implemented in a non linear spring located between the impactor and the structure. Thus, it is possible to predict the dynamic structural A c c e p t e d m a n u s c r i p t response in the case of low-velocity/low-energy impact on metal-skinned sandwich structures.A good correlation with dynamic experimental tests is achieved. Keywords.Sandwich structures, low velocity/low energy impact, finite element nonlinear analysis, indentation. 1-IntroductionSandwich structures exhibit static properties such as high stiffness-to-weight ratio and high buckling loads which are of great importance in the aeronautics field. Nevertheless, the current applications on commercial airplanes remain mainly limited to secondary structures like control surface or floor panels. In the field of helicopters where stress levels are lower, full sandwich structures are already in flight. In fact, one of the main limitations is linked to a lack of knowledge on the effects induced by impact damages [1]. However, in service, such structures are exposed and are often impacted during taxiing manoeuvres or take-off. They can also be damaged by tool drops during maintenance operations [2] and [3]. In such circumstances, the aircraft manufacturer has to inform the users very quickly of whether the impacted structure needs a repair or not. The study presented in this article is a step toward the final objective, which is to provide the aerospace industry with an inverse method. In this method, a 3D picture of the damage is first made by the airline company. Then, based on the shape of the impact, the impactor's shape is found and both the impact damage and the residual strength would be computed. All the approaches presented have a common feature which is to consider the honeycomb as a homogeneous material. Recent...

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“…Consider now the sample case formerly studied by Kärger et al [7] (Sample case #3), for which experimental results are available for the contact force and for the damage. A rather sophisticate computational model based on a three-layer description for the stress and strain field across the sandwich thickness is used in [7]; the core damage is represented using the criterion of Besant et al [11] and the elasto-plastic crushing of the core considering the contribution to the work of the inner force, degrading the out-of-plane properties of the core after failure. No failure of the face sheets have been accounted for, although the authors observed that the face sheet degradation could provide a more accurate contact force time history prediction.…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

“…At low energies, sandwich composites fail by invisible core crushing under combined shear and compression stresses, as it appears, e.g., by the experimental work of Besant et al [11]; thus a model of this core material degradation has to be implemented in the computer codes. Since the laminated faces can behave quite differently with respect to the metallic faces considered by Besant et al, also the criteria for matrix cracking, fibres failure and delamination are implemented in the present paper.…”

Section: Damage Criteria and Post-failure Degradation Modelmentioning

confidence: 99%

Impact analysis of laminated and sandwich composites using a plate finite element with strain energy updating

Icardi

Ferrero

2008

WIT Transactions on the Built Environment

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This paper deals with finite element simulation of low velocity-low energy impacts on sandwich composites with laminated faces. A refined zig-zag model with a high-order piecewise representation of in-plane and transverse displacement components is used as a structural model in order to accurately simulate the effects of the transverse normal stress and strain. The goal is to develop a tool for improving the accuracy of conventional plate models, so as to enable the impact analysis of sandwich composites. A strain energy updating process is used for this purpose. As is customary, the Hertzian law and the Newmark implicit time integration scheme are used. The contact radius is computed within each load step by an iterative algorithm, which forces the impacted top surface to conform, in the least-squares sense, to the shape of the impactor. Then, the failure analysis is performed and the material properties of the failed areas reduced. Nonlinear strains of von Karman type are used because the transverse displacement can be quite large even when the plate deflection is small. Comparison with numerical and experimental results published in literature show the present model to be able to accurately predict the impact force and the damage it induces.

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Finite element modelling of low velocity impact of composite sandwich panels

Cited by 104 publications

References 4 publications

A multi-scale approach for the optimum design of sandwich plates with honeycomb core. Part I: homogenisation of core properties

A multi-scale approach for the optimum design of sandwich plates with honeycomb core. Part I: homogenisation of core properties

Modelling of low-energy/low-velocity impact on Nomex honeycomb sandwich structures with metallic skins

Impact analysis of laminated and sandwich composites using a plate finite element with strain energy updating

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