Determining the fiber/matrix interfacial shear strength under cryogenic conditions by statistical inversion

Abstract The fiber/matrix interfacial shear strength (IFSS) in fiber‐reinforced plastics (FRP) under cryogenic condition is critical to the strength of FRP vessels while used in liquid fuel tanks. However, a direct in situ characterization of IFSS in FRPs under cryogenic condition is difficult to be achieved by combining mechanical testing facility and cryogenic oven at microscale. In this article, a new approach is proposed to identify the cryogenic IFSS of FRPs by statistical inversion by using the results of tensile experiments at cryogenic temperatures and morphological characterization of FRPs at room temperature. The failure of unidirectional FRPs is characterized by cryogenic mechanical testing at macroscale, and microscopic morphological analysis is conducted to summarize the statistical characterization of material failures. Based on the mechanical behavior and the statistical distribution of failure modes in the FRPs, statistical inversion technique is employed to estimate the cryogenic IFSS. This method can avoid the difficulties in conducting in situ cryogenic mechanical tests at microscale and achieve a reliable evaluation of cryogenic interfacial properties in FRPs, which improving the evaluation ability of the mechanical performance of FRPs under cryogenic conditions.