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Principal parametric and three-to-one internal resonances of flexible beams undergoing a large linear motion 总被引:7,自引:0,他引:7
A set of nonlinear differential equations is established by using Kane‘s method for the planar oscillation of flexible beams undergoing a large linear motion. In the case of a simply supported slender beam under certain average acceleration of base, the second natural frequency of the beam may approximate the tripled first one so that the condition of 3 : 1 internal resonance of the beam holds true. The method of multiple scales is used to solve directly the nonlinear differential equations and to derive a set of nonlinear modulation equations for the principal parametric resonance of the first mode combined with 3 : 1 internal resonance between the first two modes. Then, the modulation equations are numerically solved to obtain the steady-state response and the stability condition of the beam. The abundant nonlinear dynamic behaviors, such as various types of local bifurcations and chaos that do not appear for linear models, can be observed in the case studies. For a Hopf bifurcation,the 4-dimensional modulation equations are reduced onto the central manifold and the type of Hopf bifurcation is determined. As usual, a limit cycle may undergo a series of period-doubling bifurcations and become a chaotic oscillation at last. 相似文献
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并联压电电机采用多个压电致动器提高电机输出功率,但由于驱动器间相互干扰,导致输出效率下降。该文提出了一种由簧片和质量块组成的柔性驱动足定子结构,可降低并联直线电机中致动器间的相互干扰。建立驱动足的接触振动模型,并分析各参数对输出性能的影响。设计并制作电机样机,实验结果表明,电机的输出力随着预紧力增大而增大,激励电压峰-峰值为30 V时电机的最大输出力可达1.8 N。激励电压越大,电机的最大输出力越大。通过六足和四足电机的负载特性测试对比,证明了每个驱动足都可有效作用于滑轨上,驱动足间的相互干扰降低,输出效率提高,且电机的输出力可随着驱动足数量的增大而线性增大。 相似文献
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研究了PZT5软陶瓷压电叠堆在100 MPa高压应力下、PZT4硬陶瓷压电叠堆在300 MPa高压应力下的位移输出特性变化,分析了应力对它们压电性能的影响,并对软陶瓷压电叠堆的重新极化问题和硬陶瓷压电叠堆的做功能力进行了讨论.实验结果表明,软陶瓷压电叠堆在适当的低压应力下,压电性能显著提高,较高的压应力下则出现退极化,卸载后重新极化可以恢复大部分性能.硬陶瓷压电叠堆在高压应力下压电性能有所提高,做功能力远高于低应力时,高压应力可更有利于发挥硬陶瓷的做功优势. 相似文献
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重点介绍PtSi肖脱基势垒红外焦平面光腔的介质生长技术及介质的折射率和介质层厚度对PtSi肖脱基势垒探测器性能的影响,发现适当的合金条件和减薄PtSi层厚度有利于提高探测器的量子效率,背面增加抗反射层能减少红外辐射在入射界面的能量损失. 相似文献
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