摘要
金属薄壁结构在热声载荷作用下会发生复杂的大挠度非线性响应，结构内部快速变化的复杂应力严重降低了结构的疲劳寿命。在结构热声激振非线性响应分析基础上，采用雨流循环计数法对应力响应时间历程进行疲劳循环计数，通过Morrow TFS，SWT平均应力模型将疲劳循环进行零均值等效处理，结合Miner线性损伤累积理论，计算结构的热声疲劳寿命。以2024-T3型铝合金薄板为研究对象，计算得到了屈曲前后四种温度条件有限带宽高斯白噪声载荷作用下的非线性动态响应，并估算了疲劳寿命。分析结果表明，屈曲前结构的疲劳寿命随着温度升高下降，屈曲后结构持续跳变时的疲劳寿命持续下降直至最低，结构进入间歇跳变区域后疲劳寿命上升，结构热声疲劳寿命与非线性响应特征具有特定的对应关系。
Abstract
Metallic thin-walled structures subjected to thermal-acoustic loadings will exhibit complex nonlinear response. Fast alternating complex stresses in structures can decrease the fatigue life seriously. Based on the nonlinear thermal-acoustic response analysis, the rain flow cycle counting (RFC) method is used to calculate the number of fatigue cycles. Then the Miner accumulative damage model is employed in conjunction with various mean stress models, including Morrow TFS with true fracture strength, SWT, to predict the high cycle fatigue life. The nonlinear responses of 2024-T3 aluminum plate are obtained under band-limited Gaussian white noise loadings with pre/post-buckled temperature loadings, and the fatigue life is estimated. Analytical results show that the fatigue life of pre-buckled plate decreases with the increase of temperature, keeps going down to the lowest undergoing persistent snap-through at the post-buckled region, and then goes up after entering intermittent snap-through region, which indicate that there exists a specific relationship between the thermal-acoustic fatigue life and nonlinear response behaviors.
关键词
薄壁结构 /
热声疲劳 /
热屈曲 /
跳变响应 /
平均应力模型
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Key words
Thin-walled structure /
Thermo-acoustic fatigue /
Thermal buckling /
Snap-through /
Mean stress models
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沙云东;魏静;高志军;钟皓杰.
热声激励下金属薄壁结构的随机疲劳寿命估算[J]. 振动与冲击, 2013, 32(10): 162-166
SHA Yun-dong;WEI Jing;GAO Zhi-jun;ZHONG Hao-jie.
Random Fatigue Life Prediction of Metallic Thin-walled Structuresunder Thermo-acoustic Excitation[J]. Journal of Vibration and Shock, 2013, 32(10): 162-166
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