In order to study interface tightness characteristics of bimetal clad pipes widely used in the fields such as oil and gas gathering transportation,and ocean engineering,a mechanical model of bimetallic mechanical clad pipes under hydraulic forming and axial loading was established.The influences of trapezoidal loading,incremental loading and pulsating loading hydraulic forming process on the interfacial tightness of clad pipes were compared.The influences of forming pressure and structural parameters on the interfacial tightness of clad pipes under axial loading were investigated.The results show that compared with trapezoidal loading and incremental loading processes,the pulsating loading hydraulic forming process increases the contact pressure between pipes by 45%,which can better ensure the stability of bimetallic composite pipe forming.Increasing the residual contact pressure after forming is helpful to enhancing load resistance of the clad pipes.The wall thickness of the outer pipe has the greatest impact on the bearing capacity of the clad pipe;The interface separation phenomenon is most obvious when the inner liner pipe is subjected to tensile load alone,and increasing the wall thickness of the liner pipe can delay the interface separation.
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