The failure properties of trouser-shaped tests on flexible composite called Uretek-3216LV were studied by experiment and theory. Based on the failure mechanical behavior of the trouser-type tests, theoretical model of the three stages (displacement, fiber stretching, and fiber breaking) were established. In the model, a spring system including the tail, tear del, and the fiber elongation is introduced to characterize the mechanical behavior of the displacement stage and the fiber stretching stages. Based on the strain wave model, the failure model of fiber breaking stage is established. Based on the trouser tearing tests and failure model, the trouser-shaped failure performance of flexible composites was analyzed in detail.

This paper presents a transversely hyperelastic constitutive model for predicting mechanical properties of flexible composites under unidirectional tension. A strain energy function which reflects the behavior of anisotropic elastic material is decomposed into three parts: matrix, fiber and fiber-matrix interaction. The fiber-matrix interaction was decomposed into in-plane shear stresses and out-of-plane shear stress, the in-plane shear stresses were related to the fiber elongation invariants, and the out-of-plane shear stress was related to the fiber elongation invariants and the matrix invariants. The fiber-matrix interaction considering shear factor was established. Based on fiber reinforced continuum mechanics, a transverse hyperelastic constitutive model including fiber, matrix and their interaction is developed. The transversely hyperelastic constitutive model is verified by the uniaxial tension tests. The constitutive model can be used to design the flexible structure of stratospheric airship.