Interlaminar Fracture Major Failure in Polymer Composites

Interlaminar pass Major Failure in Polymer CompositesComposites considered new class of materials produced that argon strong, non well corroded, and have low densities. Polymer matrix composites can further be developed to get better mechanical strength and other necessary properties. Polymer Composite materials are heterogeneous in content and an-isotropic in their mechanical behavior. If compared to metallic material, whirl toughness characterization of polymer composite are new and in the process of development.Fracture may be describe as the mechanical split of a solid owing to the function of tune. Fractures of engineering material are classify as brittle or ductile fractures 18. Brittle fractures absorb small amount of energy, while ductile fractures absorb high amount of energy, and are generally categorised by fracture which the surface is flat. Fracture toughness is associated with the sum of the energy needed to create fracture on the surfaces. For material which is b rittle, such as scum the energy needed for fracture is earthyly the elemental surface energy of the material 18. For structural alloys materials at room temperature more energy is needed for fracture because plastic deformation exist in the fracture process. The function of fracture mechanics concepts has classify and quantified the main parameters that influence structural integrity 18. These parameters comprise the wheel and magnitude of the stresses applied, the shape, size, and crack orientation, fracture toughness of the material and the propagation rate of the existing cracks 18. The fracture rampart is expressed in terms of the stress rapture factor, K and strain energy release rate is expressed in term of, G. The energy released during speedy crack propagation is an elemental material properties which not influenced by size of the part 18. According to ASTM standard, stress intensity factor, K can be expressed as (1)Where KI, the panache I crucial stress intensity fac tor, f (g) is the dimensionless specimen geometry and loading condition factor, and the a is the preliminary crack length. The chosen size of the specimen must have small scurf plasticity around the dot of the crack. One of the basic principles of fracture mechanics, the unstable fracture exist when the stress intensity factor, K at the crack tip achieve a critical value, KC 18. The Higher the amount of fracture toughness, the greater the intensity of stress needed to develop crack propagation and the resistance of material also become greater to brittle fracture. unfavorable stress intensity factor can be determined by using a laboratory experiment, the limiting value being KIC / KIIC / KIIIC 18.Fracture not only applied in metallic materials it can also applied brittle materials such as ceramics, glass and polymers. Polymer composite materials usually indicate a mixture of brittle and ductile failure processes. There a few fracture modes in polymer composites failure such as p art breaking, intralaminar fracture or matrix cracking, matrix-fiber debonding, fiber pullout, interlaminar fracture or delamination, and etc 19. In the polymer composite system, the matrix or resin absorbs energy in tearing, on the other hand the fibers break or damaged by brittle cleavage 20. Factors that control the toughness in fiber reinforced composites are, the cracks deflection due to twisting or tilting movement near the fiber and debonding between fibers and matrix.Interlaminar fracture major failure in polymer composites. Its development enormously weaken the stiffness of a composite structure, which can lead to the failure during service 21 and also it hugely affected the performance of laminated composite. The interlaminar performance is determined by weakness under both shear and tensile stresses. If discontinuities exist in the material the effect of the interlaminar stress to the overall performance become more significant. This delamination and their addition can be classified by the way load is applied and the strain energy release rate, G. Delamination can be categorized in Mode I tensile, Mode II shear, Mode III tearing and shear, or it also can be loaded in combination of between these modes. Critical strain energy release rate, GC at which the delamination started to begins to extend vary significantly depending on the mode of loading 22. Classification of delamination resistance has attract the liaison researchers, hence, it result in the development of many different test orders. According to ASTM D 5528 standard which equivalent to ISO 15024 recommends using Double Cantilever Beam (DCB) method for measuring the Mode I fracture toughness GIC of polymer composites. Next, the usage of End Notch Flexure (ENF) test for Mode II fracture toughness GIIC common method used among researchers. For Mode III fracture toughness GIIIC, Ratcliffe J 23, suggested using the Edge Crack Torsion Test (ECT). However, for Mixed-Mode bending (MMB) will k eep abreast the ASTM D6671 standard which can measure fracture toughness across a wide range of combinations of Mode I and Mode II loading.