损伤对平纹编织陶瓷基复合材料梁振动特性影响的试验研究

为研究平纹编织陶瓷基复合材料(CMCs)梁受损伤影响的非线性振动特性,分别开展了拉伸试验和振动试验.拉伸试验用于获得平纹编织CMCs受损伤影响的变刚度行为,多次正弦扫频试验用于获得振动载荷下平纹编织CMCs梁受损伤影响的非线性行为.拉伸试验得到的非线性应力-应变曲线表明材料受损伤影响变刚度行为明显.梁初始固有频率的试验...

Experimental Study on Effects of Damage on Vibration Characteristics of a Plain Woven Ceramic Matrix Composites Beam

In order to study the nonlinear vibration characteristics of the plain woven ceramic matrix composites(CMCs) beam affected by damage, the tensile test and vibration tests were carried out in this paper. The tensile test was used to obtain the variable stiffness behavior of plain woven CMCs affected by damage, and the multiple sine sweep tests were used to obtain the nonlinear behavior of the plain woven CMCs beam affected by damage under vibration load. The nonlinear stress-strain curve obtained from the tensile test indicated that the material had an obvious behavior of variable stiffness due to damage. The relative error of initial natural frequency of the beam between the results of test and theory was less than 1%. The results of the vibration tests showed the effects of damage on vibration characteristics of the beam from two aspects. The first was the change of modal parameters. The natural frequency decreased from the initial value(256.44Hz) and the damping ratio increased. The resonance displacement amplitude was nonlinear and non-monotone due to the coupling of natural frequency and damping ratio. The change of the natural frequency caused the left shift phenomenon of displacement amplitude-frequency curves. The second was the multi-peak phenomenon of displacement amplitude-frequency curves. Displacement peak points were generated under multiple load frequencies. The experimental results in this paper can be used to guide the establishment of a dynamic calculation theoretical model for the structures of plain woven CMCs.