Investigation of the Mechanical Behavior of Novel Fiber Metal Laminates

Transcription

1 International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:15 No: Investigation of the Mechanical Behavior of Novel Fiber Metal Laminates Mohamed K. Hassan 1, Mohammed Y. Abdellah 2, S. K. Azabi 1, W.W. Marzouk 1 1 Production Engineering and Design Department, Faculty of Engineering, Minia Universities, Minia, Egypt, Mechanical Engineering Department, Faculty of Engineering, South Valley University, Qena, Abstract-- Fiber metal laminates is newly fabricated composite material. Glass fiber reinforced aluminum epoxy laminates (GLARE) is common type of such fiber metal laminates. Hand layup technique is used to make the GLARE composite with help of advanced new methodology for achieve the good adhesion with each components of sandwich. The layup contains specimens with 1, 2, 4, 6, and 8 layers of woven fiber sandwiched between two thin sheets of aluminum. Tension and bending tests are carried out to measure both tensile and flexural strength for different layup specimens. Moreover, the effect of composite laminate with the linear behavior on the plasticity of aluminum has been investigated. The results illustrate that as the number of woven layer increase as both strengths increase. The failure modes for tension specimen are observed and showed a behavior of net tension mode without any delamination between aluminum layers and glass fiber composite laminates. Delamination appears in the failure modes of bending. Also it is illustrated that plasticity region degrease with increasing number of linear elastic behavior composite laminated sandwiched between the two aluminum plates. Index Term-- GLARE, delamination, layup, sandwiched material, composite material. INTRODUCTION A hybrids composite Fiber metal laminates (FML s) is manufactured based on glass fiber reinforced epoxy and aluminum alloy (GLARE). This composite laminates used in manufacturing of aircraft structures such as the upper fuselage of Airbus A380 [1, 2, 3]. FML s are distinguished by their relatively very low fatigue crack propagation rates and their high damage tolerance [3, 4]. Laminates system have given distinguished durability and machinability related to many metal of superior fatigue properties [4, 5, 6]. Corte s and Cantwell [7] manufactured and tested fiber metal laminates (FML) based on a lightweight magnesium alloy. Two types of composite reinforcement have been investigated, a woven carbon fiber reinforced epoxy and a unidirectional glass fiber reinforced polypropylene. Both tensile and fatigue properties are investigated showing that little or no surface treatment is required to achieve a relatively strong bond between the composite plies and the magnesium alloy. The impact behavior of FMLs had been investigated in many works [8, 9, 10]. Castrodeza et al. [11] studied the applicability of the elastic compliance technique for crack resistance curves evaluation of a bidirectional GLARE laminate using small C(T) specimens. According to the results, the elastic compliance technique seemed to be applicable to bidirectional GLARE laminates, and this technique was accurately predicting stable crack Growth during the tests. Carrillo and Cantwell [12] characterized the mechanical properties of a new type of thermoplastic-matrix FML based on a self-reinforced polypropylene (SRPP) composite and an aluminum alloy by investigating their properties in flexure, tension and impact tests. Many investigations [13, 14, 15] investigated mechanical properties of FMLs in fatigue and tensile strength and they compared the obtained results with the monolithic aluminum alloy. The novelty of the present paper is to describe completely the manufacturing procedures for GLARE composite sandwich. In addition to study mechanical behaviors and debonding efficiency and durability, the plasticity of these materials under static loading is investigated. MATERIAL AND FABRICATION The material used in the manufacturing GLARE are woven E- glass fiber, epoxy resin and aluminum alloys sheet of 0.5 mm thickness. The mechanical properties of these components are listed in table 1. The GLARE composites are fabricated using hand layup technique according to reference [16]. Mainly, the treatment of aluminum surface should be taken into consideration upon fabrication procedure because it is a dominant factor to increase debonding between aluminum and other component of the composite material. The treatment of GLARE aluminum surface consists of 7 steps as follows: 1. Immersing Al sheets in Methyl Ethyl Ketone (MEK) for degreasing, 2. water break test for inspection of cleaning procedure, 3. hand abrasion with 400 and 200 grit aluminum-oxide paper on rolling and its cross direction, respectively, to create macro roughness followed by tissue wiping to remove contaminates, 4. etching in alkaline by immersion in a 5% NaOH solution for 10 min at room temperature, 5. rinsing in hot water and then etching Al sheets in sulfo-chromic solution (FPL-Etch) for 12 min based on ASTM D2674 [17] and D2651 [18] standards, 6. putting aluminum sheets in a boiling water bath for 60s to produce a porous pseudoboehmite aluminum oxyhydroxide layer (ALOOH) on Al surface (see Fig. 2), then 7. Coating aluminum surfaces with an organosilane adhesion promoter, γ- Glycidoxypropyltrimethoxysilane (γ-gps) to improve the strength and durability of adhesion followed by drying process in an oven at

2 International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:15 No: C o for 60 min. This coating was done by 15 min brushing of a 1% aqueous solution of γ- GPS that had been hydrolyzed for 60 min to reach full hydrolysis in reverse osmosis deionized and carbon filtered water. GLARE specimen with 1, 2, 4, 6 and 8 layers of composite laminates are sandwiched between the two aluminum sheets. The volume fraction of glass fiber composite laminate sandwiched between the two aluminum plates is determined using ignition removal technique according to ASTM D standard [19]. It is found that glass fiber volume fraction 45% and 55% epoxy resin volume fraction. MECHANICAL TESTING The fabricated specimens are tested in tension and bending according to ASTM D3039 and ASTM D test standard [20, 21], respectively. The tensile specimen is of dimension as shown in Fig. 1, whereas bending specimen is of dimension as shown in Fig. 2. All testing are carried out at universal testing machine (Model MachineWDW-100) of load capacity 200 KN and at a controlled speed of 2 mm/min. Fig. 1. Tension Test specimen geometry Fig. 2. Bending test specimen geometry RESULTS AND DISCUSSION The important goal of this work is to study the mechanical behaviors of the newly composite hybrid material and to investigate the debonding, performance and durability. Moreover, effect of stacking sequence and number of glass fiber composite layers on pervious characteristic properties are studied. Fig. 3 shows relation between stress and strain for all fabricated specimens. It is clearly observed that increasing number of composite glass fiber layers in the laminates increase the composite strength (see Fig. 4), however this trend is changed for specimen having eight layers. This can be attributed to delamination creation through the thickness between aluminum sheets and glass fiber composite laminate layer (see Fig. 5). The delamination failure is common failure mode in laminated material, but in case of GLARE the delamination occurs at the interface between isotropic aluminum thin sheet and the glass fiber composite laminates. Therefore, the debonding strength is reduced and less efficient with increasing thickness of laminates material. Plasticity is observed in the flow behaviors and plastic deformation zone is created. This plasticity is created respect to aluminum plasticity. However, the curve plateau in the plasticity region has increasing slop with increasing orthotropic composite linear elastic material until it is vanished for six and eight layers; this can be attributed to the high strength obtained for elastic composite laminates at increasing glass fiber layers (see Fig. 6). Modes of failure for specimen are net tension for aluminum sheet with shear planes, fiber bridging and fiber breakage through composite laminate. Clearly, the strain to failure of the FML is similar to that of the plain composite and greater than that of the plain aluminum alloy. This is a result of the high degree of bonding between the components,

3 International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:15 No: allowing the aluminum on the FML to deform by up to 25% more than its plain counterpart [12]. Fig. 3. Stress Strain relation for effect of stacking sequences Fig. 4. Effect of GRP on nominal strength of GALRE

4 International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:15 No: Fig. 5. Failure Modes in tensile specimens Fig. 6. Plastic stress strain relation for GLARE Three point bending test is commonly used to measure stiffness of material and determine flexural young modulus. Fig. 7 shows flexural strength deflection curves for GLARE material, it is clear that as number of glass fiber increase the flexural strength and flexural young (see Fig. 9 and 10) modulus increase. This due to high stiffness of glass fiber combined with aluminum plates. The flexural strength of a material is higher than its tensile strength, because during a tensile test, the whole specimen is subjected to a constant stress whilst in flexure; a relatively small region of the specimen is subjected to the maximum stress. This difference in loading volume reduces the likelihood of failure in the sample [22]. The specimens have not failed after reaching the maximum load. A closer examination shows that the constituents in the FML (i.e., the aluminum and the SRPP) remained well bonded. Considerable out-of-plane deformation was in evidence without apparent damage as shown in Fig. 8. Delamination through interface between aluminum and glass fiber reinforced polymer is appeared in Fig. 8. This can be attributed to local compressive stress induced in the upper surface of specimen.

5 International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:15 No: Fig. 7. Flexural stress vs. deflection curve Fig. 8. Modes of failure for specimen subject to bending

6 International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:15 No: Fig. 9. Effect of stacking sequence on flexural strength of GLARE Fig. 10. Effect of stacking sequence on GLARE stiffness

7 International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:15 No: Specimen layup Table I Mechanical Properties of GLARE Averge Tensile strength MPa Averge Flexural strength MPa Flexural young modulus (Mpa) 1 Layer Layers Layers Layers Layer CONCLUSION GLARE is a hybrid composite material; it has a competitive role in aerospace industry. The proposed procedures for manufacturing the GLARE material is an effective and having good durability. Increasing the number of glass fiber composite laminates gives good strengths but increases the thickness of the whole specimen, results in weakening the specimen in form of delamination failures. Plasticity regions are affected with increasing number of glass fiber composite laminates. REFERENCES [1] V. A. Glare, " History of the Development of a New Aircraft Material," Dordrecht: Kluwer Academic Publishers, [2] S. Krishnakumar, " Fiber metal laminates: the synthesis of metals and composites," Materials and Manufacturing Processes, vol. 9, p , [3] L. Vogelesang and A. Vlot, "Development of fibre metal laminates for advanced aerospace struc-tures," J. Mater. Process. Technol., vol. 103, no. 1, pp. 1-5, [4] R. Van Rooijen, J. Sinke, T. De Vries and S. Van Der Zwaag, "Property optimization in fibre metal laminates," Appl. Compos. Mater., vol. 11, no. 2, pp , [5] E. Botelho, L. Pardini and M. Rezende, "Hygrothermal effects on damping behavior of met-al/glass fiber/epoxy hybrid composites," Materials Sci-ence and Engineering A, vol. 399, pp , [6] K. M. O. R. S. C. Soltani P, "Studying the tensile behaviour of GLARE laminates: a finite element modelling approach," Applied Composite Material, vol. 18, no. 4, p , [7] W. C. P. Corte s, "The fracture properties of a fiber metal laminate based on magnesium alloy," Composites: Part B, vol. 37, p , [8] A. E. K. a. G. L. R. Vlot, "Impact response of fiber metal laminates," Key Engineering Materials, vol. 141, pp , [9] H. M., "Chapter 27 in fibre metal laminates; an introduction," Dordrecht: Kluwer Academic Publishers, [10] A. G. J. Vlot, "Fiber Metal Laminates," Kluwer Academic, [11] L. S. F. B. E.M. Castrodeza, "CRACK RESISTANCE CURVES OF GLARE LAMINATES BY ELASTIC COMPLIANCE," in 17º CBECIMat - Congresso Brasileiro de Engenharia e Ciência dos Materiais, Foz do Iguaçu, PR, Brasil, 15 a 19 de Novembro de [12] *. W. C. J.G. Carrillo a, "Mechanical properties of a novel fiber metal laminate based on a polypropylene composite," Mechanics of Materials, vol. 41, p , [13] P. I. J. B. F. Castrodeza EM, "Experimental Techniques for Fracture Instability Toughness Determination of Unidirectional Fibre Metal Laminates," Fatigue & Fracture of Engineering Materials & Structures, vol. 25, no. 11, pp , [14] P. I. J. B. F. Castrodeza EM, "Fracture toughness evaluation of unidirectional fibre metal laminates using traditional CTOD (δ) and Schwalbe (δ5) methodologies," Engineering fracturew mechanics, vol. 71, no. 7-8, pp , [15] G. Reyes and H. Kang, "Mechanical behavior of lightweight thermoplastic fiber-metal laminates," Journal of Materials Processing Technology, vol. 186, no. 1-3, pp , [16] A. A. K. S. A. G. Mohammad Alemi Ardakani, "A study on the manufacturing of Glass-Fiber-Reinforced," in Proceedings of the XIth International Congress and Exposition, Orlando, Florida USA, [17] A. D , Standard Methods of Analysis of Sulfochromate Etch Solution Used in Surface Preparation of Aluminum, West Conshohocken, PA: ASTM International, [18] D.-0. ASTM standard, tandard Guide for Preparation of Metal Surfaces for Adhesive Bonding, West Conshohocken, PA: ASTM International, [19] A. D , Stander Test method constituent content of composite materials, American Society of testing and materials, [20] A. S. T. M. D3039, Standard test method for tensile properties of polymer matrix composite materials, West Conshohocken (PA) : ASTM International, [21] A. D790-10, Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials,, West Conshohocken, PA: American Society for Testing Material, [22] M. Wisnom, "The relationship between tensile and flexural," Journal of Composite, vol. 26, p , 1992.