International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 11 Issue: 12 | Dec 2024
p-ISSN: 2395-0072
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Fracture Characteristic of Natural Fiber Metal Laminates Hitesh Raiyani 1, H. S. Patil 2, C. K. Desai 3 1Ph.D. Research Scholar, Gujrat Technological University. Assistant Professor, Mechanical Engineering Department
L J Institute of Engineering and Technology, L J University, Ahmedabad, India
2 Professor and Head, Mechanical Engineering Department, GIDC Degree Engineering College, Abrama, Navsari,
India
3Associate Professor and Head, Mechanical Engineering Department, C.K. Pithawala College of Engineering and
Technology, Surat, India ---------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - Fiber metal laminates (FMLs) are innovative
these needs, hybrid FML structures have been created by alternating metal and composite layers [1, 2, 3]. Materials like aluminum alloys (e.g., Al-2024-T3, [3,4,5] Al-7475-T6 [6,7,8]), titanium [2,9,10,11], magnesium [12,13], and reinforced fibers (such as glass, aramid, and carbon) are commonly used to fabricate FMLs. Recently, there has been a shift towards the development of eco-friendly FMLs by substituting natural fibers for traditional glass or carbon fibers. Epoxy resins, typically mixed with hardeners at a 10:1 ratio, are employed to form composite layers and as adhesives to bond metal and composite layers together [13,14].
hybrid composite materials formed by laminating metal alloy sheets with composite layers, aimed at improving mechanical properties and fracture resistance. This study focuses on the development of FMLs, specifically exploring the influence of thickness variations on their mechanical properties and fracture behavior. The research examines the impact of size effects on the nominal strength and fracture characteristics of Natural Bamboo Fiber Metal Laminates (NB-FMLs). FMLs were initially fabricated with a thickness of 1.8 mm to assess their mechanical properties, and then a reduced thickness of 1.5 mm was used to analyze the effect on strength. 2D scaled specimens were prepared with size ratios of 1:1, 1:2, and 1:4, with rectangular samples of 25 mm, 13 mm, and 6 mm in width, and corresponding lengths of 178 mm, 127 mm, and 101 mm, respectively, for the different scale ratios. A double notch was introduced at the center of each specimen to study the fracture characteristics in relation to size effects. The nominal tensile strength of the Natural Bamboo reinforced Fiber Metal Laminates, created by alternating layers of Al2024-T3 and bamboo-epoxy composite, was evaluated for each scaled model. The size effect parameter was determined by comparing the nominal strength across specimens. The tensile strength of the NB-FMLs was obtained using a Universal Testing Machine, following ASTM D 3039 standards. This paper provides an analysis of the tensile test results to determine the nominal strength of FMLs and evaluates the size effect parameters, including the length of the fracture process zone (FPZ) and fracture energy, to predict the material's fracture behavior.
The hybrid structure of FMLs is formed through adhesive bonding of metal alloy sheets and composite layers [3,15,16], making the surface treatment of aluminum sheets crucial to improving FML strength. Surface preparation techniques, such as mechanical abrasion, alkaline treatment, anodizing, and etching, are commonly employed to enhance the bonding properties between layers [3, 13, 16]. In addition, alternative manufacturing methods, such as autoclave processing and resin transfer molding, have been adopted over traditional hand-layup techniques for FML production. The mechanical properties of FMLs depend on factors such as the thickness of the aluminum sheets, composite layers, resin-to-fiber ratio, and overall laminate thickness. The overall mechanical properties of FMLs can be predicted using two methods: Metal Volume Fraction (MVF) [9,11,17] and Classical Laminate Theory (CLT) [8,18]. While CLT provides more detailed predictions, MVF is a simpler method for estimating properties like tensile strength and modulus of elasticity.
Key Words: Fiber Metal Laminates, Mechanical Properties, Nominal Tensile Strength, Effect of changing Thickness Size Effect Law, Fracture Characteristics
Standard FMLs typically consist of thin metal alloy sheets (0.2 to 0.5 mm) and thin composite layers (0.2 to 0.3 mm) with various fiber orientations. However, a significant challenge in FML development is the lengthy resin curing process. Additionally, during the cutting of FMLs, the possibility of delamination between layers can occur. Cutting methods such as water jet cutting, wire cutting, and laser machining are commonly used. Water jet cutting is particularly effective for FMLs containing non-conducting materials, as laser and wire cutting methods may struggle with such materials. However, water jet cutting can cause
1.INTRODUCTION Fiber metal laminates (FMLs) have been recently developed using diverse materials and fibers to enhance mechanical properties, such as high strength, superior fatigue resistance, and improved fracture characteristics, to meet the demands of the automation and aerospace industries, which require lightweight structures with enhanced mechanical and fracture properties [1]. To address
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