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杆件在偏心压(拉)力作用下的正应力及其强度计算问题在一般材料力学教科书中都有过专门的介绍,然而在这些介绍当中均没有考虑作用在杆件上的轴向外力在杆件弯曲变形中所引起的附加弯矩对正应力的影响贡献,本文在考虑这一影响贡献的基础上,推导出了计算杆件最大正应力的表达式,并与材料力学教科书中的未考虑上述影响的对应公式进行了比较,给出了二者之间的相对误差随载荷的变化规律,并说明了这种误差的影响范围。 相似文献
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随着压电晶体材料的迅速发展, 基于压电效应的能量采集系统是俘获环境中的宽带随机振动能量的一种有效途径. 研究了有限宽带随机激励作用下, 磁斥力双稳态压电俘能系统的相干共振俘能机理, 并进行了实验验证. 运用Euler-Maruyama方法求解了随机非线性压电振动耦合方程, 比较分析了相干共振发生前后系统的动力学特性和俘能效率, 然后基于Kramers逃逸速率解释了相干共振. 最后的随机振动实验结果验证了双稳态压电俘能系统的相干共振俘能机理. 并且观察到: 当相干共振发生时, 系统会在两个势能阱之间剧烈运动, 此时宽带随机振动能量会被转化为大幅值窄带低频振动响应, 从而极大地提高了宽带随机振动能量的俘获效率. 相似文献
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Prompt efficiency of energy harvesting by magnetic coupling of an improved bi-stable system 下载免费PDF全文
In order to improve the transform efficiency of bi-stable energy harvester(BEH),this paper proposes an advanced bi-stable energy harvester(ABEH),which is composed of two bi-stable beams coupling through their magnets.Theoretical analyzes and simulations for the ABEH are carried out.First,the mathematical model is established and its dynamical equations are derived.The formulas of magnetic force in two directions are given.The potential energy barrier of ABEH is reduced and the snap-through is liable to occur between potential wells.To demonstrate the ABEH's advantage in harvesting energy,comparisons between the ABEH and the BEH are carried out for both harmonic and stochastic excitations.Our results reveal that the ABEH's inter-well response can be elicited by a low-frequency excitation and the harvester can attain frequent jumping between potential wells at fairly weak random excitations.Thus,it can generate a higher output power.The present findings prove that the ABEH is preferable in harvesting energy and can be optimally designed such that it attains the best harvesting performance. 相似文献
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