FINITE ELEMENT ANALYSIS OF COMPOSITES UNDER DIFFERENT LOAD CONDITIONS WITH THE EFFECT OF HYBRIDIZATION OF GLASS REINFORCEMENT ON KEVLAR FIBRES

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1 International Journal of Mechanical Engineering and Technology (IJMET) Volume 9, Issue 11, November 2018, pp , Article ID: IJMET_09_11_043 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed FINITE ELEMENT ANALYSIS OF COMPOSITES UNDER DIFFERENT LOAD CONDITIONS WITH THE EFFECT OF HYBRIDIZATION OF GLASS REINFORCEMENT ON KEVLAR FIBRES Anu Jacob Paul Associate Professor, North Malabar Institute of Technology, Kerala, India Research Scholar, Karunya Institute of Technology and Sciences, Coimbatore, India S Darius Gnanaraj Professor, School of Mechanical Engineering, VIT University, Vellore, Tamil Nadu, India ABSTRACT In the recent trends, several researches are happening in the area of Composite Materials especially in the case of hybrid composites to avail the higher properties of the hybridized fibres. It has become more challenging in the Aerospace industry as it is essential to develop a material which satisfies all property strength and to attain better strength to weight ratio. In this line of research, properties such as tensile, compression, shear and flexural are considered for the materials with the hybridization of E-glass in Kevlar 49 fibres at different orientation. Initially experimental analyses were done on these materials at a constant volume fraction of varying orientation and obtained the property strength values as per ASTM standard of composite material test procedure. In continuation to this experimental work, detailed Finite Element Analysis on same configuration is conducted using ANSYS. The primary objective is to do static structural analysis of the hybrid composites under tensile, compression, shear and flexural load and to validate with the experimental results. Key words: Hybrid composites; Kevlar glass fibre; Epoxy LY5052, FEA; Mechanical properties; ANSYS. Cite this Article: Anu Jacob Paul and S Darius Gnanaraj, Finite Element Analysis of Composites Under Different Load Conditions with the Effect of Hybridization of Glass Reinforcement on Kevlar Fibres, International Journal of Mechanical Engineering and Technology 9(11), 2018, pp editor@iaeme.com

2 Anu Jacob Paul and S Darius Gnanaraj 1. INTRODUCTION Hybrid composites are developed by incorporating two or more fibres in a matrix. It may also have two resin systems also. Hybrid Composites in short named as hybrids. There are many researches happening in the automobile and aerospace application. The utilization of hybrid composites is expanding rapidly, and they have been acknowledged as structural materials with superior properties [1]. Much research has been done through the investigation of hybrids with the mix of carbon and glass fibre. There are several configurations of hybrids like, fibre by fibre mixture, tow by tow and layer by layer mixtures. In this research work, hybridization of E-glass fibre with Kevlar49 in an epoxy resin matrix system LY5052. Kevlar 49 used here is in the form of bidirectional fibre with mild varying properties in wrap and weft directions of the woven mat. Kevlar forms a strong and flexible material. Kevlar fibres are strengthened with the layers of resin to develop a rigid material which is light having high strength compared to steel [4]. E-glass, very commonly used as reinforced fibre in composites, creates textures with incredible dimensional stability under different kinds of loading conditions. Glass fabrics show good heat resistance at relatively low cost. Glass fibres are durable, and exhibits better thermal conductivity and chemical resistance. LY5052 epoxy commonly used in Aerospace industry having low viscosity provides better mechanical and dynamic behaviour even when cured at room temperature. The results of the experimental analysis and the finite element analysis (ANSYS) of the laminates of above hybrid configuration are studied to validate the strength values of this reinforced composite material. The significant application of the developing composite material is in aircraft wing box construction [3]. It makes stronger, lighter weight, and a thicker frame to build a wing. A wing box made of 3 basic components like skin, ribs and spars is designed to react mainly the bending and the shear loads developed in the wing. Wing box also acts as a torque box which resists the torsional loads. 2. EXPERIMENTAL WORK Layer by layer lamina are stacked to develop the laminates of thickness approximately 3.2mm [2]. For the experimental analysis of the properties, nine laminates of different orientations were prepared as shown in Table1. Layers of Kevlar, E-Glass and the corresponding bonding material LY5052 are taken to process the laminates [2]. Table 1 Stacking sequence of the laminates with orientations K0 0 G0 0 K90 0 G90 0 K0 0 G45 0 K90 0 G45 0 K0 0 G90 0 K90 0 G0 0 K45 0 G0 0 K45 0 G90 0 K45 0 G layers of Kevlar and 5 layers of E glass arranged alternatively. Top and bottom layer as Kevlar Laminates are processed using vacuum bag technique. Raw materials weight and volume fraction in all laminates are kept constant and only orientation has been changed. Further tests like tensile, flexural, compression, shear and impact were conducted in our previous work [2] to obtain the strength and modulus values in both longitudinal and lateral direction of the laminates editor@iaeme.com

3 Finite Element Analysis of Composites Under Different Load Conditions with the Effect of Hybridization of Glass Reinforcement on Kevlar Fibres 3. FINITE ELEMENT ANALYSIS The scope of work is static structural analysis of hybrid composites [5] under loading conditions of tensile load, compressive load, shear load and flexural load. Here again nine laminates of the same stacking sequences as of experimental work are taken (Table 1). Dimensions of test piece are also taken as same as experimental work as per ASTM standards. All laminates are modelled according to the input details available for the raw materials as per the details given in Table 2. Table 2 Input details of Raw Material sproperties Properties Kevlar 49 E-Glass EpoxyLY5052 Density (Kg/m 3 ) E x Young s Modulus[GPa] E y E z V xy Poison s ratio V xz V yz G xy Shear modulus [Gpa] G xz G yz Layer Thickness [mm] (avg) Analysis of mathematical model of laminates was carried out. The procedures adopted are, Input study & Identifying geometry details of model for analysis; Generate new FE model based on the dimensions; Structural analysis with applied force and further deformation and von misses stress are evaluated on various cases FEA on Tensile Property For comparison of FEA with experimental strength values on tensile property, all nine laminates are prepared as per ASTM dimensions (ref fig 1a). Each laminates are modelled separately (sample model of laminate-1 is referred in Fig 1b) and gradually applied loads were considered at the boundary condition till the peak load is obtained. The peak load taken with respect to the loads obtained during the experimental work and these loads (in N) of each laminates are 11240, 13578, 12211, 11493, 10017, 15950, 10499, 2487, and 3709(N) respectively. Figure 1 a) Specimen dimension as per ASTM standard b) Sample model of laminate editor@iaeme.com

4 Anu Jacob Paul and S Darius Gnanaraj These laminates under varying gradually applied load were further simulated and analysed the stress- strain and the load-deflection behaviour of the developed composites to obtain the tensile strength value (ref fig 2a and 2b). For the laminate 1, the tensile strength in longitudinal fibre direction is 333 MPa. Similarly the strength values are obtained for all the laminates and the comparison with its experimental values are illustrated graphically below (ref fig 3). Sample deformation and equivalent stress plots of laminate-1 analysed in ANSYS are also presented in Fig 4. The comparison of deformation of all laminates is shown in Fig 5. Figure 2 a) Load deflection behaviour for laminate-1, b) Stress strain behaviour for laminate-1 Figure 3 Comparison of FEA Tensile strength value in longitudinal direction of all laminates with Experimental values Figure 4 a) Sample deformation plots of laminate -1 in ANSYS b) Sample equivalent Von mises plots of laminate editor@iaeme.com

5 Finite Element Analysis of Composites Under Different Load Conditions with the Effect of Hybridization of Glass Reinforcement on Kevlar Fibres Figure 5 Comparison of deformation under tensile load of all laminates 3.2. FEA of Compressive strength property Static structural analysis with boundary condition of compressive forces applied at both ends. It is modelled again as per the geometry of ASTM standard on compressive test in reinforced polymers, which is a rectangular shape of 100x12.5mm with 3.2mm thickness (ref fig 6). Maximum compressive load as per the experimental test to delamination is again considered as the peak load in FEA compressive analysis by applying it gradually at certain intervals. For all laminates the load taken in N are 1425, 1895, 559, 573, 791, 1090, 1816, 1257 and 664 N respectively. The comparison of compressive strength is given in figure=7. Deformation and stress plots using ANSYS of laminate 1 are given in f figures 8a and 8b. The comparison of deformation under compression for all laminates is given in figure 9. Figure 6 Sample model of laminate 1 as per ASTM geometry Figure 7 Comparison of FEA Compressive strength value in longitudinal direction of all laminates with Experimental values editor@iaeme.com

6 Anu Jacob Paul and S Darius Gnanaraj Figure 8 a) Sample deformation plots of laminate -1 in ANSYS b) Sample equivalent Von mises plots of laminate-1 Figure 9 Comparison of deformation under compressive load of all laminates 3.3. FEA of Flexural Property Three point bending test and analysis of 3D model of FRP are carried out. Static structural analysis carried out on beams supported at both ends under various bending loads applied at mid-point of the beam. Geometry is taken as per ASTM as 130x12.7x3.2mm. The displacement of Uz is constrained on both ends of beam as shown in figure 10. Bending loads are applied gradually at the mid-point of the simply supported beam to the experimental peak load withstood by the specimen before the onset of delamination or failure took place. And the loads considered for all laminates are 226, 290, 119, 156, 176, 217, 309, 144 and 109 N respectively. Comparison of flexural strength obtained through FEA of each laminate with experimental values is shown in figure 11. Deformation and stress plots of laminate 1 using ANSYS are shown in figs 12a and 12b. The comparison of mid-point deformation under bending load for all laminates are illustrated is shown in figure 13. Figure 10 Sample model of laminate 1 with boundary condition as per ASTM geometry editor@iaeme.com

7 Finite Element Analysis of Composites Under Different Load Conditions with the Effect of Hybridization of Glass Reinforcement on Kevlar Fibres Figure 11 Comparison of FEA Flexural strength value in longitudinal direction of all laminates with Experimental values Figure 12 a) Sample deformation plots of laminate -1 in ANSYS b) Sample equivalent Von mises plots of laminate-1 Figure 13 Comparison of mid-point deformation under bending loads of all laminates 3.4. FEA of Shear Property 3D model with dimensions 50x16x3.2mm are analyzed. The boundary conditions are applied. The displacement constraints of Uy & Uz are fixed. Shear forces are applied along X direction of the beam as shown in fig 14. Shear forces of 7080, 6433, 6034, 5292, 6323, 8164, 8222, 7041 and 9137 N respectively are applied on laminates with respect to the peak load from experimental results. Shear strength values are obtained and the comparison between experimental values and values obtained through simulation is shown graphically in figure15. Deformation and stress plots of laminate-1 using ANSYS are shown in figs 16a and 16b. Comparison of deformation under shear load for all laminates is shown in figure editor@iaeme.com

8 Anu Jacob Paul and S Darius Gnanaraj Figure 14 Sample model of laminate 1 with boundary condition as per ASTM. Figure 15 Comparison of FEA Shear strength value in longitudinal direction of all laminates with Experimental values. Figure 16 a) Sample deformation plots of laminate -1 in ANSYS b) Sample equivalent Von mises plots of laminate-1 Figure 17 Comparison of deformation under shear loads along X Direction of beam in all laminates editor@iaeme.com

9 Finite Element Analysis of Composites Under Different Load Conditions with the Effect of Hybridization of Glass Reinforcement on Kevlar Fibres 4. DISCUSSIONS Both experimental and the FEA results were compared. In most of the cases, the values are comparatively closer to each other. However in few cases, compression test in laminate-7 and tensile test in laminate-9 show larger differences. From the above results, it is seen that the laminates 2 and 6 are comparatively better in tensile strength having lesser deformation. Laminates 2 and 8 are better in compressive strength with more deformation. Laminates 2 and 7 have higher bending strength; deformation of laminate 2 is smaller but the deformation of laminate 7 is very high. Laminates 5 and 6 have high shear strength but the shear deformation is high. It can be said that laminate 2 is the best composite compared to all other composites. Laminate 2 has orientation of K90 /G90. It has been observed that the hybridization of E-glass with a constant Kevlar orientation of 90 o is much superior in most of the properties compared to other laminates. Also, the volume fraction for all laminates is same as we have taken the same number of layers of Kevlar and E-glass. 5. CONCLUSIONS Finite element analysis carried out on 9 laminates of hybrid composites with different orientations. Simulations were made using tensile, compressive, bending and shear loads. The results were compared with experimental results and comparison is closer for many laminates. Laminate-2 with orientation K90 /G90 was found to have good tensile, compressive and bending properties compared to other laminates. REFERENCES [1] M.N. Gururaja and A.N. Hari Rao, A review on recent applications and future prospectus of hybrid composites, International Journal of Soft Computing and Engineering (IJSCE), vol. 1, no. 6, pp ISSN: , January 2012 [2] Anu Jacob Paul and Darius Gnanraj S, The Effects of Hybridization of Glass Fiber on the Mechanical Properties of Kevlar Composites with LY5052 Epoxy Polymer Matrix, Proceedings of International Conference on FEAST, NIT Trichy, Vol-2, ISBN , 2017 [3] Immanuvel D, Arulselvan K, Maniiarasan P, Senthilkumar S, Stress Analysis and Weight Optimization of a Wing Box Structure Subjected To Flight Loads The International Journal Of Engineering And Science (IJES), Volume 3, Issue 1, Pages 33-40, 2014, ISSN(e): ISSN(p): [4] NurainHashim, Dayang Laila Abdul Majid, Rizal Zahari and NoorfaizalYidris, Tensile Property of Woven / Kevlar Reinforced Epoxy Hybrid Composite, Mater. Sci. Forum Vol. 890 (2016), p [5] Keshavamurthy Y C, Chetan H S, Dhanush C and NithishPrabhu T, Design and Finite Element Analysis of Hybrid Composites Mono Leaf Spring International Journal of Mechanical and Production Engineering Research and Development, ISSN , Vol-3, Issue 3, 2013, p editor@iaeme.com