Journal of Material Sciences & Engineering

Strain-Based Fatigue Damage Modeling of Plain Woven Glass/Epoxy Fabric Composites

Abstract

Indra Narayan Yadav and Kamal Bahadur Thapa

Strain-Based Fatigue Damage Modeling of Plain Woven Glass/Epoxy fabric Composites is well developed by utilizing Helmholtz Free Energy Model, S-N Model and Strain-Life Model. Due to repeated cyclic loading at a defined number of cycles to the failure, Glass Fiber experienced disturbance in their intermolecular bonding structures and finally development of microcracks, macrocracks, cracks and fatigue fracture at final stage. For, validation of Model, Strain Based constant amplitude of fatigue loading is achieved through Fatigue Testing which was performed by adopting the positive load method for evaluation of any potential crack propagation, fiber fractures, de-laminations, etc. With the application of continuous stressing in the material, evaluation of life cycle capabilities of glass fiber composites are essential for Research Development, Structural Design, Quality assurance, Modeling and finally the preparation of Specifications for the product of said Material. By using an epoxy resin system with glass fiber at a mandrel diameters 140 mm and the winding angle of 15° and 90° were selected in four lay-up i.e. 15°, 90°, 15°, 90° had fabricated according to filament winding process. The Specimen is cut into 20 pieces each of width 50 mm, thickness 3.3 mm was fixed in 809 MTS Axial/Torsional Test Machine with constant frequency 1 HZ and the test result was recorded in the Computer connected to that Machine. From the fatigue test, it is observed that final reading at the time of fracture i.e. in terms of running time, axial force, axial displacement, and axial integral count cycle was recorded as 72801.390625 Sec, 0.121522857666016 KN, 4.7763674519961 mm and 72737.50 Cycles. The maximum number of cycle to failure obtained from the fatigue testing is Nf=72737.50 interfere cycles at 1.00 fatigue damage factor, initial strain at 0.00 cycle at 63.57617 sec time was recorded as 0.0244, final strain at 72735.50 cycle at 72801.40 sec was recorded as 0.0659. Initial, at middle and final stress was recorded as 0.329183 GPA initial, varying to 0.58809 GPA at middle point and 0.002202 GPA to 0.00 at failure state. Minimum and Maximum Strain Measurement corresponding to 0001 Cycle were -0.00045313 and 0.0075, at 30000 Cycle -0.00050313 and 0.00995, at 50000 Cycle -0.00075 and 0.0115, at 70000 Cycle (Final Cycle for fracture) was -0.010234375 and 0.515625 which validates the required Strain-based fatigue model achieved through theoretically.