Fracture failure behavior of Al2O3 fabric under the combined interaction of high-temperature heat flow and tensile load

Abstract

The aircraft will be subjected to severe aerodynamic and thermal effects during the reentry of the spacecraft into the earth’s atmosphere. Flexible woven structure plays an important role in thermal protection of aircraft surface, and Al₂O₃ fiber fabric is an important candidate material in weaponry, aerospace and other fields, which puts forward higher requirements for the prediction of mechanical properties at high temperature. In this paper, the extreme environment faced by the thermal protection structure during the high-speed entry/reentry of spacecraft is simulated by using the self-built loading and testing system of oxygen–methane high-temperature heat flow and mechanical stretching. Based on the experimental data, the finite element model of Al₂O₃ fabric was constructed. Combined with the stress–strain relationship and physical parameters of the material, the fracture process of Al₂O₃ fiber fabric under the combined action of high-temperature heat flow and tensile load was simulated. The results show that due to the poor high-temperature stability of amorphous SiO₂ phase in Al₂O₃ fiber under high-temperature heat flow, the surface defects of the fiber surface increase due to hot corrosion, which reduces the mechanical properties of the fabric. The breaking strength, elongation at break, elastic modulus and strength limit of Al₂O₃ fabric at 1300 °C were 0.318 kN/cm, 9.108%, 319 MPa, 51.1 MPa (plain) and 0.412 kN/cm, 3.356%, 720 MPa, 58.44 MPa (twill), respectively. Due to the different forms of fabric structure, warp yarns exhibit varying degrees of buckling. Under the action of tensile load, the warp yarn is from buckling to straightening, so that the stress–strain relationship of Al₂O₃ fabric has nonlinear characteristics. The nonlinear Ogden model can well simulate the deformation process of Al₂O₃ fabric under high-temperature heat flow.