Failure analysis GRP pipes and crack inlet opening with J-Integral criteria under internal pressure

Today, because of widespread faults in metallic pipes such as internal and external corrosion, hard deformability, abundant deposition arising from much roughness on internal parietal and profuse salt absorption and high pressure drop because of internal surface roughness, weightiness and installation difficulties and low lifetime etc. the tendency to use polymer pipes in transfer pipelines, industrial, marine, drilling and agricultural zones has increased. Examine the rate of damage the plastic tubes reinforced with the glass fiber under internal pressure from different angles, which might be defeated under creep phenomenon in long term, has not receive the attention to a large extend. Therefore, in the present research, it has been tried to simulate the fracture by Tsai-Wu, Hashin criterions and also the crack inlet opening with J-integral criterion in this pipes with different layering at internal pressure using finite element method and ABAQUS software. This research results show that the fibers under compressive and tensile stress and the resin of tube has not fractured by tensile stress, but the fracture has occurred in the resin of composite tubes that were under pressure. According to the yielded results, the fracture index is less than one for each of ten layers, when layering angle varies from [(30)] to[(60)], but the fracture index is more than one, layering decoration for[(70)], [(80)] and [(90)] of composite tubes has been fractured. However, the value of stress intensity factor was immediately decreased for layering decoration angle of [(55)], but this factor has improved when layering angle increased.