Investigation On Damage And Failure Of Three-Span Continuous Pressure Pipelines Under Lateral Impact

It is urgently necessary to conduct investigation on the crashworthiness of pressure pipelines in that network of pipeline transporting a wide variety of potentially hazard fluid with high energy and high temperature and high pressure that may be released into environment by an impact event that is sufficiently severe to cause material failure.First of all, the dissertation investigated experimentally on damage and failure of three-span continuous pipelines (OMPa, 5MPa, 10MPa, 15MPa and 20MPa) under lateral impact using drop hammer with various shape indenters of flat-nose, spherical-nose and conical-nose. The diameter (D) of pressure pipeline is 45mm, the thickness(H) is 3mm, the total length(27I) is 1900mm andper-span(2L)is 597mm.The experimental investigation demonstratesthat (1) the critical perforation energy of pressure pipelines (D/H=15) with pressure OMPa under lateral impact of flat-nose and spherical-nose indenters ranges from 2~3%,the critical perforation energy of empty pipelines is higher 1 ~2% than pipelines filled in water without pressure. (2) The critical perforation energy reduce limitedly with pressure increasing, the critical perforation energy of pressure pipelines (D/H= 15) reduces no more than 8% when the pre-pressure of pipeline is filled in pressure 15MPa, the effect of pressure on the critical perforation energy is little while the pressure reaches a given magnitude. (3) The critical perforation energy of the pipelines under lateral impact of spherical-nose indenters is little higher than conical-nose indenters on same condition of pressure, the critical perforation energy of the pipeline under lateral impact of flat-nose indenters is much lower than conical-nose indenters, this shows the flat-nose indenters is destructive. (4) The failure modes of pressure pipelines under lateral impact of flat-nose and spherical-nose indenters are plugging and disking, the failure modes of pressure pipelines under lateral impact of indenters conical-noseindenters change with different ratios of diameter to thickness (D/H), the failure modes of thick pipelines (D/H= 15) is plugging, but the failure modes of thin pipelines (D/H=44) is petalling.Secondly, a theoretical dual rigid-plastic modal under lateral impact of blunt indenters is firstly developed in order to predict damage pipeline which is fully clamped across a span based on rigid-plastic beam on a perfectly plastic foundation, which is made up of a rigid-plastic sub-beam and a rigid-plastic basic-beam, the rigid-plastic sub-beam is used to predict denting deformation, the rigid-plastic basic-beam is used to predict global deformation, the sub-beam and the basic-beam interact by a perfectly plastic foundation. The whole dynamic response motion of dual rigid-plastic beam is divided into two phases and deduced. This theoretical study allows the denting deformation to continue during the global deformation phase, and large deflection effects are incorporated in this analysis by considering interaction between bending and stretching in deforming regions, the 'membrane factors' of sub-beam and basic-beam are used to amend the effect ofmembrane on final displacement.Finally, the numerical examples demonstrate that the impact kinetic energy of indenters is dissipated by plastic work of denting deformation and global deformation, the coupling extent of denting deformation and global deformation relatives with ratios of span to diameter(2L/D) and diameter to thickness(D/H).