Study on the Damage Evolution Mechanism of Fiber‐Reinforced Composite Pipe Under Tensile Load

ABSTRACT Fiber‐reinforced composite pipe has gained significant attention due to its high specific strength, high specific modulus, and corrosion resistance, gradually becoming an alternative substitute to traditional metal pipes. However, mechanical behavior and failure mechanisms remain insufficiently understood due to material property heterogeneity and anisotropy. This article independently researches and manufactures UV‐resistant and low‐temperature‐resistant aramid/nylon 12 composite pipes. Full‐scale tensile tests were combined with multi‐scale modeling to develop both macroscopic and mesoscopic mechanical three‐dimensional anisotropic elastoplastic models. The mechanical response and damage mechanism of composite pipes under tensile loads are investigated at both macroscopic and microscopic levels. Three full‐scale tensile tests of the composite pipe (with a maximum ultimate tensile load of 192.177 kN and a maximum tensile elongation at break of 5.22%) demonstrated strong agreement with the finite element analysis results. Building on this, stress analysis and investigation of the damage mechanisms of composite pipes under tensile loads are conducted. The finite element results indicate that, upon reaching the elongation at break, the stress distribution in the reinforcing layer shows a significant disparity. The axial stress (S33 = 597 MPa) carried by the axial reinforcing layer is approximately 5.4 times greater than that of the circumferential reinforcing layer (S33 = 110 MPa). Additionally, the contribution of the inner and outer linings to the tensile bearing energy of the composite pipe is relatively small, with the axial stress being approximately 30 MPa. Fiber fracture and fiber/matrix debonding are the primary failure modes affecting the performance of composite pipes.