排序方式: 共有8条查询结果,搜索用时 15 毫秒
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The application of displacement and energy approaches to the determination of stress intensity factors in ultrasonic fatigue crack growth (fcg) studies is discussed.The particular advantages as well as the limitations of the two approaches are evaluated.Two types of ultrasonic fatigue loading with different stress ratios are exerted on the specimen respectively: the ultrasonic fatigue loading with a stress ratio R=-1 and the ultrasonic fatigue excitations superposed upon a static mean stress with R>-1 From comparison the conclusion is formed that the energy approach developed in the investigation is more accurate,concise and suitable than commonly adopted approaches and/or formulas proposed.Experimental fcg data on a titanium alloy Ti-6Al-4V and the characteristic mechanism of the ultrasonic fcg are investigated. 相似文献
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Stress and modal analyses are performed on an ultrasonic vibration system by means of a 3-dimensional finite element computation and dynamic modal analysis code "Algor" The system consists of an edge-cracked specimen linked elastically with one or two amplifying horns which come into resonant longitudinal vibration at 20kHz.Operating principle of the ultrasonic fatigue machines and experimental procedures for ultrasonic fatigue crack growth studies are briefly presented. 相似文献
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双质量磁吸振器理论与试验研究 总被引:2,自引:0,他引:2
在单质量磁吸振器的基础上提出了双质量磁吸振器的设计方案,并对其减振性能进行了理论和试验研究。正弦扫描和窄带随机振动试验结果表明,平板小阻尼系统在添加双质量磁吸振器后,比单质量磁吸振器振动水平明显减小。 相似文献
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针对传统方法的不足,提出将一种模拟退火组合算法用于支持向量机的参数选择,将优化指标设定为最大化SVM的泛化能力,并据此确立适当的目标函数;同时借鉴交叉检验的思想,建立以训练集和测试集中的数据分别选择模型和搜索最优参数组合的研究手段。最后,在仿真实验的基础上同基于遗传算法和精化网格法的选取方法进行了对比分析,结果表明该组合算法具有更好的全局搜索性能和收敛速度,是SVM参数选取的一种有效方法,具有较强的实用价值。 相似文献
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形状记忆合金在“智能性材料结构”中的应用研究 总被引:7,自引:0,他引:7
介绍了“智能性材料结构”的应用研究情况,包括其定义、实现方案和意义。认为把形状记忆合金NiTi丝埋在复合材料中(或金属材料中)或将其复合在构件上,是工程上应用前景最大的方案之一。作者对该方案的如下内容,即构件外形的改变以自动适应机器工作状态的变化、构件振动的主动控制、裂纹的探测和主动控制等进行了研究。经试验和计算分析,其效果是显著的。 相似文献
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