Experimental study on the deformation of fully clamped pipes under lateral impact

Accidental loads often cause failure to tubular structures on offshore platforms and subsea pipelines due to, for instance, dropped objects and collisions. Thus, the dynamic behavior of pipes subjected to lateral impact loadings should be investigated in order to ensure safe operations. An experimental programme is used in this paper to study the deformation mode since it is an important characteristic of the behavior. About 70 pipes are tested using a drop hammer rig under various impact energies and are categorized into five groups according to the outside diameters of 25 mm, 42 mm, 60 mm, 89 mm and 114 mm, respectively. The impact acceleration and deformation of pipes are measured, and a method to determine global and local deformations is proposed. The characteristics of the permanent upper and lower surface deformations of a pipe are investigated as well as the relative magnitude of those two values. With upper and lower surface information, the deformation process of the impacted section and deformation modes along the axial direction can be precisely portrayed which are helpful for establishing an integrated system to evaluate the dynamic response of pipes under impact loads. Other parameters, such as the dent length, are also measured in this paper for a better understanding of denting changes and can be a basis for further theoretical study. Overall, a method to describe the deformation profile is proposed in this paper according to the impact experiments which gives a clear explanation of the phenomenon observed in the tests. The mechanism of dynamic behavior of pipes under lateral impact can be established in an integrated way based on the deformation mode in this paper.