Method for testing interlayer I-type fracture toughness of composite material without tracking cracks

Abstract

The invention belongs to the technical field of composite material mechanical property testing. The invention relates to a method for testing interlayer I-type fracture toughness of a composite material without tracking cracks. According to the test method, based on a correction beam theory of I-type interlayer fracture toughness calculation, a layering length expression and a fracture toughness expression about the real-time flexibility of a DCB test piece are established by utilizing an internal mechanical relationship between a layering length and the flexibility of the DCB test piece; theproblems that interlayer cracks need to be tracked in a layering test and the layering length under the current load needs to be recorded in real time are solved; the method is suitable for testing the I-type interlayer fracture toughness of the continuous fiber reinforced polymer matrix composite laminate, the operation process is simple, and engineering application is convenient to achieved; andmoreover, the method is particularly suitable for continuous fiber reinforced polymer matrix composite laminates, such as continuous fiber reinforced polymer matrix composites of carbon fibers, glassfibers, aramid fibers and the like.

Description

technical field [0001] The invention belongs to the technical field of mechanical performance testing of composite materials, and relates to a method for testing interlayer I-mode fracture toughness of composite materials without tracking cracks, and is especially suitable for continuous fiber reinforced polymer-based composite material laminates, such as carbon fiber, glass fiber, aromatic Polymer matrix composites reinforced with continuous fibers such as nylon fibers. Background technique [0002] Continuous fiber reinforced composites have high specific strength and specific stiffness, which can achieve significant weight reduction of structures, and have been widely used in the main load-bearing structures of aerospace vehicles. In aircraft structures, composite materials mostly exist in the form of laminates, and the laminate structure has the disadvantage of being prone to interlaminar cracks, that is, delamination. Once delamination occurs, the integrity of the comp...

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Problems solved by technology

[0003] The purpose of the present invention is to provide a method for testing interlayer I fracture toughness of composite materials that does not need to track cracks, so as to solve the technical problems of time-consuming and labor-intensive real-time observation of delamination extension length in DCB tests, and difficult observation at low temperatures

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