Performance Research Of CFRP Reinforced Pipes Subjected To Low-velocity Transverse Impact Loads

As a common method of transportation, steel pipes are widely used in petroleum, natural gas, etc. During the period of service, they will inevitably suffer from corrosion, impact, explosion and damage, causing serious safety accident, property damage and loss of lives. In order to avoid the accidents and ensure the safe operation of the pipelines, and steel tubes strengthened by FRP as a new technology has been paid more attention by domestic and foreign experts or scholars. In this paper, experiments and numerical simulations were carried out to investigate the interfacial bonding properties of FRP reinforced steel structure, and the damage of the FRP bonded steel tubes which subjected to the hammer impact with low velocity. Specific contents of this study are summarized as follows:(1) Numerical simulation validations of single shear tests were carried out, and the bilinear model was used to simulate the interface between steel and CFRP. Interfacial shear stress-slip curves and load-displacement curves were obtained. The FE results are in good agreement with the experimental ones. And the influence of the FRP length, thickness and interfacial fracture energy of adhesive are also taken in consideration.(2) Numerical simulations of the CFRP reinforced defect steel tubes were conducted in static tension and in bend. The reinforcement were evaluated by the comparison of stress variation of steel pipes before and after strengthened. The internal pressure, external load and the thickness of reinforcement have also been analyzed.(3) Experiments of round steel pipes bonded with CFRP subjected to drop hammer impacts in low-velocity were carried out, and the whole processes of impact loads and damages were obtained. The dynamic responses and failure modes of CFRP reinforced circular pipes were numerically simulated. The deformations of the pipes under the impact load were acquired. The influences of CFRP layers, impact velocity and minor defects upon impact resistance were discussed.