Impact Analysis of Aluminum-Fiber Composite Lamina *

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1 [ 溶接学会論文集第 33 巻第 2 号 p. 166s-170s (2015)] Impact Analysis of Aluminum-Fiber Composite Lamina * by Yehia Abdel-Nasser**, Ninshu Ma***, Hidekazu Murakawa*** and Islam El-Malah** Hybrid materials of fiber composite and aluminum alloys have a great potential in reducing the weight of transportation vehicles. It has been become an alternative solution to steel panels because they can provide high strength and improve energy absorbing capability under impact and collision loading. Developing a new composite material based on experiment by changing mechanical properties is quite expensive and takes long time. Therefore, numerical simulation with the aid of FEM is often performed, since its results have been proved to be close to the experimental ones. There are many different ways to combine the fiber into the resin. In this paper, the effect of lining arrangements of composite materials and the orientations of the layers on the strength was simulated using FEM in which the adhesive bond between fiber composite/metal is assumed as a tie constraint. Impact strength and failure modes of several plate panels with different lining arrangements were investigated. The results of analyses are presented and their trends are discussed. Key Words: FEM, Hybrid Plate Panels, Lining Arrangements, Impact Analysis, Penetrations 1. Introduction A composite material is fabricated by combining two or more distinct materials together but remaining uniquely identifiable in the mixture. The most common example is, a fiberglass composite material, in which glass fibers are mixed with a polymeric resin 1). Composite materials are becoming increasingly more attractive in a variety of structural engineering applications, such as airplane fuselages, turbine blades, patrol boats and car bodies. The challenge at hand is to use a composite material that is optimized to provide the same or better strength and stiffness as that of traditional isotropic materials. The amount of fracture load at which a piece of fiber glass breaks, depends on the size of the piece of fiberglass, its thickness, width, length, and also the loading direction 2). It also depends on what the fiberglass is made of such as layers orientations of fibers and amount of polymeric resins. The goal of this paper is to analyse the strength of hull structures made of composite materials as an alternative solution to replace the heavy steel structure. It is anticipated that the use of the composites will save on overall weight in order to maximize potential payload capacity. The optimal composite design is expected to be both lighter than the steel configuration, and exhibited resistance to more severe loading conditions such as impact loadings 3). It is possible to design a composite material such that it has the attributes desired for a specific application. * Received: ** Faculty of Engineering, Alexandria University *** Member, Joining and Welding Research Institute, Osaka University For example, fiber-metal Laminates (FMLs) are a hybrid of metal and composite laminates that are increasingly being used in aerospace structures 4). This is consisting of alternating layers of thin metallic sheets and fiber-reinforced epoxy. Two main types of FML are aramid fiber-reinforced epoxy /aluminum laminates (ARALL) and S2 glass fiber-reinforced epoxy/aluminum laminates (GLARE). The combination of mechanical properties of monolithic metal and fiber-reinforced composite provides FMLs with mechanical advantages such as low density, high strength, and high damage tolerance. Impact damage is a key concern for the safety of transportation vehicles 5). Therefore it is necessary to accurately predict internal impact damage to FMLs and other composite materials 6). Therefore, the goal of this project is to rearrange lay-up of aluminum-fiber composite lamina through changing mechanical properties and lining arrangements of the layers, and comparing results of the arrangements to obtain higher performance of the plate lamina against impact and blast loadings. These changes can be virtually done by numerical simulation using FEM-software such as ABAQUS 7). However, the numerical results required to be verified through laboratory experiments. 2. Failure criteria The failure of a composite panel will be resulted from either a critical strain or stress exceeded in the matrix or fiber. The composite behaves elastically and reaches to the point of failure, primarily because the glass fibers and the polymeric resin were both linear elastic solids with a brittle fracture mode, i.e., no

2 溶接学会論文集 第 33 巻 (2015) 第 2 号 167s plastic deformation. We would also note from the mechanical tests that the elastic modulus of the composite also varied with the amount of fiber added to the resin. Hashin s failure criteria 8) for Unidirectional Fiber Composites will be considered in this work. These are interacting failure criteria where more than one stress components have been used to evaluate the different failure modes. Usually Hashin criteria are implemented within two dimensional classical lamination approach for stress calculations with ply discounting as the material degradation model. After that, he extended the criteria to three dimensional problems where the maximum stress criteria are used for transverse normal stress component. 3. Description of FE models The paper addresses the numerical simulation of impacts on plate panels by applying FEM. The plate panels are composed from hybrid material (S2 glass fiber-reinforced epoxy/ aluminum laminates). The research work is aimed to optimize the arrangement of composite layers which sustained the maximum impact load. Other loads such as in-plane loads are not considered here. The FE simulation of the impact analysis encompasses a number of individual problems such as mesh size, element type and time increments, which should be given appropriate attention during the analysis. In the analysis, a fine mesh is generated especially at the contact areas (mesh size=3x3x0.5mm) to acquire accurate results and to represent real failure modes during impact. Whereas coarse mesh may be applied for areas located far from collision region to reduce CPU time. Also appropriate element type (8 node break element) is selected to achieve accurately FE analysis and increase the reliability of numerical models. The adhesive bond between the glass/epoxy plies and aluminum layers was modeled using the tie constraint module in Abaqus software to express the delaminating failure. Abaqus/Explicit can be applied to model nonlinear material behavior in a composite laminate. Other problem such as modeling of the material damage criteria is explained in Refs. 9). Abaqus/Explicit version is used to simulate the impact of plate panels with a striking object such as ball or cylinder at different velocity. The plate panels are modeled using solid elements (C3D8R). The impactor (ball or cylinder) is modeled using rigid elements (R3D4). This assumption is chosen because we are interested in comparing the effect of the impact on the different plate panels with no reference to the impactor. Different configurations of lining arrangement are investigated. The absorbed energy and contact force for each arrangement of the plate panel are calculated after damage. The following assumptions are considered in the models: Volumetric ratio of composite (fiber/resin) is 50%. The plies are symmetric laminated composites. Unidirectional fiber or Random fiber is assumed. Adhesive bond between Fiber/Metal is assumed as a tie constraint. Wu 10) 4. Validation of FE models conducted a series of low velocity impact tests to evaluate the deformation and damage responses of FMLs. A comparative study is conducted using these experimental impact results to validate a basic numerical model. The model consists of two layers of Al 2024-T3 Aluminum alloy sheets and one layer of [0/90/90/0] S2 glass/epoxy composite. Here, Al is referred to the material of aluminum and /0/90/90/0/ is referred to 4plys of the composite material as shown in Fig.1. A steel spherical impactor of 12.3 mm diameter and with a mass of 6.29 kg impacted the plate panel with different impact energies such as 12.7J, 16.3J and 24.3J respectively. The hybrid plate panel (Aluminum-Fiber composite) of (0.076x0.076m) with total plate thickness 1.56mm is analyzed using FEM. The plate panel is clamped at all edges. The mechanical properties of S2 glass/epoxy 4) are as shown in Table 1. The Aluminum 2024-T3 is assumed to be an elastic material and its characteristics are as follows: Young s Modulus E= MPa and Poisson s ratio ʋ=0.33. Hashin failure criteria are applied to trace the failure state of the composite material while the ductile failure criterion is applied for the aluminum. The tie constrained law is applied to express the adhesive bond between fiber composite and aluminum 7). The time of impact is taken about 6 x10-3 second. Table 1 Mechanical properties of S2 glass/epoxy. Material Parameter values (GPa) S2 E11 E22 E33 G12 G23 V12 V23 glass/ epoxy Parameter values (MPa) σl U,t σl U,c σt U,t σt U,c τlt u The mesh model of the plate panel and the impactor are shown in Fig.2. The impactor is moving with a constant velocity towards

3 168s 研究論文 YEHIA et al.: Impact Analysis of Aluminum-Fiber Composite Lamina the plate panel. The numerical results show that the maximum deformation is observed at the center of the plate panel. Figure 3 shows relationships between contact force and time for different levels of energy. At low energy such as 12.7J the numerical results have the same value in the contact force curve when compared with the experimental results. However, for 16.3J and 22.3J energy, at the elastic state the same results are attained but the deviations are observed after damage. Here, the numerical results show higher contact forces than those attained by the experimental ones. This is because the debonding of the Aluminum layers and the composite layer was constrained using the tied constraint. During the impact analysis of the plate panel, failure modes such as plastic deformation of the metal layers (Aluminum) and matrix cracking and fiber failure of the composite layer are observed. Figure 4 shows relationship between deflection at the center of the plate panel and the time. The central deflection is reached to about 4.5mm and it is increased as the impact energy increases. The effect of fiber dimensions and orientations are not considered in this study 11). 5. The impact behavior In this section, the hybrid plate panel of 0.5x0.5m is modeled with solid elements. The cylinder is modeled with 3D rigid elements. The cylinder is moving towards the center of palate panel with a high energy of about 2000J. The dynamic explicit solver was used to account for the time-dependent loading and the complex interaction between the cylinder and the composite plate panel. The model with different arrangements of fiber glass and Aluminum laminated layers are investigated to determine the best arrangement that able to prevent cylinder penetration and absorb the high energy (2000J). These model arrangements are suggested as follows, (See Fig.5) 3GL (3 layers of Aluminum each layer has 4 mm thick and 2 layers of fiber glass/epoxy each layer has 3mm thick). 4GL (4 layers of Aluminum each layer has 3 mm thick and 3 layers of fiber glass/epoxy each layer has 2mm thick). 5GL (5 layers of Aluminum each layer has 2 mm thick and 4 layers of fiber glass/epoxy each layer has 2mm thick). Each layer of the composite material is consisted of 4 plies Rigid ball Fiber layers Fig. 1 The hybrid plate panel. Fig. 2 Mesh model of the hybrid plate panel. Fig. 3 Relationships between the impact force and time. Fig. 4 Relationships between the deflection and time.

4 溶 接 学 会 論 文 集 4 研究論文 第 33 巻 2015 第 2 号 他 169s with final zero velocity. For 5GL model, the cylinder could not penetrate the plate panel. It approaches zero velocity and totally 3GL 4GL Fiber Al 5GL Fig. 5 Different arrangements of hybrid plate panels. lost its ballistic energy. It is noticed that with increasing number of (Al) layers as in cases 4GL and 5GL arrangements; the velocity of the cylinder is drastically decelerated. Table 3 shows a comparative analysis for the previous arrangement using the specified material properties. with equal ply thickness and unidirectional of the stack sequences In this analysis, the weight parameter defined by the weight per (0/90/0/90). The local co-ordinate systems are defined to account area WP (kg/m2) of the plate panel is a little bit high. The weight for orientations of individual plies and to model the laminate and parameter WP (kg/m2) may be reduced by utilizing higher material behavior precisely. The material properties of the strength of composite materials to get less plate thickness13). It composite are given in Table 1. While properties for Aluminum can be safely assumed that at high loading rates, as normally are taken from Ref. The cylinder of mass 8g and length 39 mm observed in ballistics impact, the metal layers and glass fibers impacts the center of the plate panel in the axial direction with a undergo considerable hardening before failure thus providing constant velocity of 700m/s as shown in Table 213). Here, due to extended resistance. 12) the high energy, the time of impact is taken about 12x10-5 second. Table 2 Characteristics properties of the cylinder 13). Designation 7.62x39mm Weight Velocity Energy g m/s J The developed FE model is shown in Fig. 6. Fine mesh is generated at the center of the plate panel. Table 3 Characteristics of plate panel arrangements during analysis. Time of Model Plate Thick penetration Arrangement (mm) (s) End Weight Failure of Velocity (kg /m2) layers (m/s) 3GL 5.2x All 138 4GL 6.1x Not All 0 5GL Not 43 Not All 0 Rigid Cylinder Figure 7 shows the penetration of the cylinder into the plate panel. It is noticed that for 3GL and 4GL arrangements, after the plastic deformation spreads at the center of the face layer (Al) of the plate, failure starts at the face layer (Al) then the cylinder penetrates the face (Al) layer and reaches the composite layers causing brittle damages in its plys. Finally, the cylinder penetrates the second layer (Al) of the plate panel after causing large Fig. 6 Mesh model of the plate panel before and after penetration. deformation in this layer (Al). This process is repeated for remaining layers of the plate panel. Figure 8 shows the ductile fracture of aluminum layers and brittle fracture of the composite layers. Figure 9 shows relationships between moving velocity of the cylinder and time. At the beginning, the cylinder is moving with a velocity of 700m/s, then its velocity gradually decreases. For 3GL model, the cylinder penetrates the plate panel at time of 5.2x10-5 second and it still has a kinetic energy with a velocity of about 138m/s. At the end a complete penetration is occurred. Regarding 4GL model, the cylinder penetrates the plate panel at time 6.1x10-5 second and its kinetic energy is gradually dissipated Penetration Fig. 7 Penetration of the cylinder into plate panel arrangements.

5 170s 研究論文 YEHIA et al.: Impact Analysis of Aluminum-Fiber Composite Lamina attained. This may be reduced by utilizing higher strength composite materials to get less plate thickness and weight. Reference (a) Ductile damages in Aluminum layers Fiber (b) Brittle damages in composite layers Fig. 8 Failure damages in the plate panel. Fig. 9 Relationships between the impact velocity and time. 6. Conclusions Aluminum The paper refers to the simulation impact of aluminum-fiber composite plate lamina using FEM which provided close results compared with the experimental ones. It is found that by increasing number of (Al) layers in the lay-up arrangement of the hybrid plate lamina will drastically decelerate the velocity of the impacted cylinder and absorb higher impact energy (2000J). However, higher weight parameter WP (43kg/m 2 ) of the hybrid plate lamina is 1) D. Hull and T.W. Clyne: An Introduction to Composites Materials, Cambridge University Press (1996). 2) D. Roylance: Introduction to Composite Materials", Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA (2000). 3) C. Akin and M. Senel : An Expermental Study of Low Velocity Impact Response for Composite Laminated Plates, Dumlupinar University, Tr. (2010). 4) M. Rathnasabapathy, A.P. Mouritz and A.C. Orifici : Numerical Investigation of Fiber-Metal Laminates, TH International Conf. on Composite Materials Subject to Impact damage, (2008), Edinburgh, UK. 5) R. Kalavalapally, R. Penmetsa and R. Grandhi : Multidisciplinary optimization of a lightweight torpedo structure subjected to an underwater explosion, Finite Elements in Analysis and Design 43 (2006), ) S. Hyoungseock, J. Hundley, H.T. Hahn and J.Yang : Numerical Simulation of Glass-Fibre-Reinforced Aluminium Laminates with Diverse Impact Damage, AIAA Journal, Vol. 48, No. 3 (2010), pp ) Abaqus : Damage and Failure Of Laminated Composite Plates, User manual Dassault System Rhode Island US. 8) Z. Hashin : Failure criteria for unidirectional fiber composites, Journal of Applied Mechanics Material Science and Technology, Vol. 47(1) (1980), pp ) P. CAMANHO AND C. ROSE : Failure Criteria for FRP Laminates, MS 240, NASA Langley Research Center Hampton, VA 23681, USA. 10) G. Wu :The Impact Properties and Damage Tolerance of Bidirectionally Reinforced Fibre Metal laminates, Journal of Material Science and Technology, Vol. 42, No. 3 (2005), pp ) P. Kumrungsie, K. Maneeratana and N. Chollacoop : Effects of Fiber Orientation on Ballistic Impact upon Polymer Composite Plate, The 21st Conference of Mechanical Engineering Network of Thailand (October 2007), Chonburi, Thailand. 12) M. Luo, Ductile Fracture Characterization of an Aluminum Alloy Sheet using Numerical Simulations and Tests, Term Project Report of 2.094, MIT, (2008). 13) V. Phadnis, K. Pandya, N. Naik, A Roy and V. Silberschmidt : Ballistic impact behaviour of woven fabric composite: Finite element analysis and experiments, Journal of Physics: Conference Series 451, (2013).