Method for distinguishing damage degree of C/C (Carbon-carbon) composite material structure based on acoustic emission technique

Abstract

The invention belongs to the technical field of aerospace nondestructive testing and in particular relates to a method for distinguishing damage degree of a C / C (Carbon-carbon) composite material structure based on an acoustic emission technique. When the damage degree of the C / C woven composite material structure is slight, the generation of tiny damage sources and the characteristics of generation of stress waves comply with stable probability distribution, and acoustic emission event counts, ringing counts, and energy counts grow in equal proportion; when the damage degree is serious, a group of impact chains comprising a large number of ringing counts and high energy counts appears, namely, inflection points appear in a curve on a correlation diagram of the ringing counts and the high energy counts, and the envelope line slope is obviously increased; for a C / C woven composite material in a specific structure, acoustic emission events comprising a large number of ringing counts and high energy counts appear, and the specific value of loads at the inflection points obviously appearing in impact counts, the ringing counts and the relevant curves and a final load is within a certain scope; a bearing load of the structure when an inflection point generates is recorded, and therefore, a damage load of a structure can be predicted.

Description

technical field [0001] The invention belongs to the technical field of aerospace nondestructive testing, and in particular relates to a method for judging the damage degree of a C / C composite material structure based on acoustic emission technology. Background technique [0002] In the field of aerospace, especially the high-temperature resistant structure of high-speed aircraft, a large number of C / C composite materials are used to design its load-bearing structure. Unlike traditional metal materials, which usually undergo plastic deformation and crack propagation before failure, composite materials, especially new materials such as C / C braided composite materials, have relatively insufficient research on early warning before failure. [0003] Acoustic emission is an effective non-destructive testing technology that can detect damage sources online in real time. It can monitor the stress waves released by the structure during the loading process due to stress concentration ...

AI Technical Summary

Problems solved by technology

Unlike traditional metal materials, which usually undergo plastic deformation and crack propagation before failure, composite materials, especially new materials such as C / C braided composite materials, have relatively insufficient research on early warning before failure

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