复合材料螺栓连接预紧力松弛的温度-时间依存行为

针对碳纤维增强环氧基复合材料机械连接结构耐久性设计中的2个关键问题:黏弹性预紧力松弛的温度-时间依赖行为及其长期性能预测方法进行研究。建立了以蠕变全应变理论为基础的预紧力松弛预测模型。36 h的恒温耐久试验表明:初始预紧力越大,温度越高,连接件预紧力松弛速率越快;复合材料连接件的松弛速率远大于金属连接件;预紧力松弛主要表现为材料蠕变过程。对比短期试验结果表明:本模型能较好地实现对不同温度、预紧力和连接材料的松弛预测,为确立试验数据的外推方法提供了依据。 

Temperature-time dependent behavior for preload relaxation in bolted composite joints

Two key problems in structural durability design for mechanically fastened carbon fiber reinforced epoxy composite joints:temperature-time dependent behavior for viscoelastic preload relaxation and prediction method for its long time performance were investigated. Preload relaxation prediction model was developed on basis of the creep total-strain theory. 36 h constant temperature durability tests show that the relaxation rate of preload for joints is faster with the greater initial preload and higher temperature; relaxation rate of composite joints is much greater than that of metallic joints; preload relaxation mainly behaves as the material creep process. Compared to the short-term test results, it shows that the model can well predict the relaxation for different temperatures, preloads and joint materials, which also provides a basis for extrapolation method of determining test data.