Experimental investigations of thermal modal parameters for a C/SiC structure under 1600 °C high temperature environment

Abstract

This work aims to investigate the thermal–mechanical behavior of a carbon fiber reinforced silicon carbide (C/SiC) structure under 1600 °C high temperature environment. In this test, both the contact and non-contact measurement are used. Four laser vibrometers were used for non-contact measurement. The laser reflection characteristics of C/SiC surface under high temperature were tested. The fiber Bragg grating sensor (FBG) sensor network measures both strain and temperature of the test piece, by means of wavelength shifts due to the tensile stress on a Bragg grating. The energy spectrum of the signal is obtained by the time–frequency analysis method, and the peak value is extracted by an algorithm to obtain the time–frequency characteristic of different modes. The result shows that the modal frequencies of C/SiC structure under time-varying thermal loads change with the temperature of the structure, which has a great influence on the modal characteristics of the structure. Besides, this study indicates that the FBG sensor is suitable for structural health monitoring of C/SiC structure under 1600 °C high temperature environment. The results provide an important basis for the dynamic performance analysis and safety design of structure under high-temperature thermal-vibration conditions.