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In recent years, due to the increasingly powerful functions of tablets, more and more people have used tablets. The failure of the screen caused by debonding failure between the screen and the case of the tablet due to drops will affect the normal use of the tablet. However, there have been few studies on the debonding methods of the screen and the case of the tablet, as well as the factors influencing the debonding between the screen and the case of the tablet. Numerical analysis software was used in this paper to simulate the iPad Air (Air) drop process, and the cohesive zone model and tiebreak contact were used to simulate the debonding process between the screen and case of the Air tablet, respectively. When the results are compared to the experiments, the results show that the cohesive zone model is superior. The effects of various rounded corner radii, drop postures in the XY plane, materials of the outer case, and strain rates of PC/ABS on the localized debonding between the outer case and outer glass of the Air during the drop process were investigated. The degree of debonding between the Air model's outer case and outer glass is defined by t, which is the ratio of the area of the deleted cohesive elements to the total area of the cohesive elements. The results show that the rounded corner radius and the strain rate of PC/ABS have less influence on t; the t of the Air model dropped at 45° in the XY plane is 37.7% of that dropped at 0° and 90°; and the t of the Air model with glass as the outer case material is 48% of that with aluminum alloy as the outer case material. These studies serve as a foundation for tablet design and material selection. [ABSTRACT FROM AUTHOR]

This study describes the numerical simulation results of aluminum/carbon-fiber-reinforced plastic (CFRP) hybrid joint parts using the explicit finite-element solver LS-DYNA, with a focus on capturing the failure behavior of composite laminates as well as the adhesive capacity of the aluminum–composite interface. In this study, two types of adhesive modeling techniques were investigated: a tiebreak contact condition and a cohesive zone model. Adhesive modeling techniques have been adopted as a widely commercialized model of structural adhesives to simulate adhesive failure based on fracture mechanics. CFRP was studied with numerical simulations utilizing LS-DYNA MAT54 to analyze the crash capability of aluminum/CFRP. To evaluate the simulation model, the results were compared with the force–displacement curve from numerical analysis and experimental results. A parametric study was conducted to evaluate the effect of different fracture toughness values used by designers to predict crash capability and adhesive failure of aluminum/CFRP parts.

In order to study the interfacial adhesive material simulation method of a sandwich structure with aluminum alloy panels and a low-density foam core under edgewise compression condition, two finite element models were defined using material model no. 185 (MAT 185) adhesive element and tiebreak contact, respectively, by LS-DYNA. Under the conditions of different loading rates, and element sizes, the effects of peak load, energy absorption, failure mode of adhesive layer and the influence degree of the changing condition on the calculated results were compared between the two models, and then compared with the experiment results and theoretical results. The higher the loading rate was, or the smaller the element size was, the higher the peak load was. The simulation results obtained using MAT 185 were closer to the experimental results under the edgewise compression condition.

Maximising impact protection of fibre reinforced plastic (FRP) laminated composite structures and predicting and preventing the negative effects of impact on these structures are paramount design criteria for ground and space vehicles. In this paper the low velocity impact response of these structures will be investigated. The current work is based on the application of explicit finite element software for modelling the behaviour of laminated composite plates under low velocity impact loading and it explores the impact, post impact and failure of these structures. Three models, namely thick shell elements with cohesive interface, solid elements with cohesive interface, and thin shell elements with tiebreak contact, were all developed in the explicit nonlinear finite element code LS-DYNA. The FEA results in terms of force and energy are validated with experimental studies in the literature. The numerical results are utilized in providing guidelines for modelling and impact simulation of FRP laminated composites, and recommendations are provided in terms of modelling and simulation parameters such as element size, number of shell sub-laminates, and contact stiffness scale factors. [ABSTRACT FROM AUTHOR]

Abstract: The simulation of the delamination process in composite structures is quite complex, and requires advanced FE modelling techniques. Failure analysis tools must be able to predict initiation, size and propagation of delamination process. The objective of the paper is to present modelling techniques able to predict a delamination in composite structures. Four different ways of modelling delamination growth of a double cantilever beam test (DCB) are proposed. The first two approaches were based on a cohesive zone model: the interface being represented either by using delamination elements or non-linear springs. The idea of the third approach was to use a fracture mechanics criterion, but to avoid the complex moving mesh techniques it often implies. The interface between the two layers was simulated with solid elements representing the matrix, which were eliminated when their energy release rate exceeded the critical value. The energy release rate was computed using the virtual crack closure technique (VCCT). In the last approach, the interface behaviour was modelled by a tiebreak contact. Coincident nodes were tied together with a constraint relation and remained joined, until when the maximum interlaminar stresses was reached. Once this value was exceeded, the nodes associated with that constraint were released to simulate the initiation of delamination. The comparison of the results of the first three modelling techniques with experimental data showed that very good correlation was achieved. Poor results were obtained using tiebreak contact. It was due to the criterion used, since when the critical interlaminar stress was reached, the delamination was experienced before the critical energy release rate was reached. [Copyright &y& Elsevier]

This study describes the numerical simulation results of aluminum/carbon-fiber-reinforced plastic (CFRP) hybrid joint parts using the explicit finite-element solver LS-DYNA, with a focus on capturing the failure behavior of composite laminates as well as the adhesive capacity of the aluminum–composite interface. In this study, two types of adhesive modeling techniques were investigated: a tiebreak contact condition and a cohesive zone model. Adhesive modeling techniques have been adopted as a widely commercialized model of structural adhesives to simulate adhesive failure based on fracture mechanics. CFRP was studied with numerical simulations utilizing LS-DYNA MAT54 to analyze the crash capability of aluminum/CFRP. To evaluate the simulation model, the results were compared with the force–displacement curve from numerical analysis and experimental results. A parametric study was conducted to evaluate the effect of different fracture toughness values used by designers to predict crash capability and adhesive failure of aluminum/CFRP parts. [ABSTRACT FROM AUTHOR]

In order to study the interfacial adhesive material simulation method of a sandwich structure with aluminum alloy panels and a low-density foam core under edgewise compression condition, two finite element models were defined using material model no. 185 (MAT 185) adhesive element and tiebreak contact, respectively, by LS-DYNA. Under the conditions of different loading rates, and element sizes, the effects of peak load, energy absorption, failure mode of adhesive layer and the influence degree of the changing condition on the calculated results were compared between the two models, and then compared with the experiment results and theoretical results. The higher the loading rate was, or the smaller the element size was, the higher the peak load was. The simulation results obtained using MAT 185 were closer to the experimental results under the edgewise compression condition. [ABSTRACT FROM AUTHOR]

The paper presents a new approach for failure modeling of a cellular structure manufactured with a 3D printing technology. For this purpose, the honeycomb topology was designed and fabricated using fused deposition modeling of ABSplus material. The proposed method was based on the tiebreak contact for connecting plastic joints with cell walls. Additionally, two methods based on constitutive models were also analyzed. In the first case, an elasto-plastic material model was adopted, whereas in the second case an elasto-visco-plastic material model with damage was included. Firstly, the mechanical properties of ABSplus material were determined and numerically correlated with experimental outcomes. Subsequently, a contact parametric study was performed, and the optimal contact parameters were evaluated. The quasi-static experimental compression tests were simulated using LS-Dyna software. The results of actual tests and numerical analyses with three different methods for honeycomb structure modeling were compared in terms of deformation, force history, failure behavior and energy absorption capabilities. It was shown that the contact-based method resulted an in an increase of the results quality with better reproduction of force characteristic and progressive failure behavior during the deformation process, compared to other two methods. Unlabelled Image • A new approach for failure modeling based on tiebreak contact algorithm is proposed • The proposed approach is compared with two standard constitutive model based methods • Contact parametric study is performed to assess failure parameters of tiebreak based algorithm • Crashworthiness properties of the Honeycomb cellular structure are investigated in experimental and numerical tests [ABSTRACT FROM AUTHOR]