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研究了Johnson提出的倾转旋翼不平衡载荷前飞动力学模型,将其桨叶分析方法应用于直升机旋翼系统模态分析。在刚性条件假设下推导了直升机旋翼弹性阻尼和惯性力综合作用时桨叶的挥舞和摆振运动方程,给出了固定和旋转坐标系下对应的运动方程。通过引入均匀入流和线性扭转假设,获得了运动方程的理论解析解。利用叠加原理,得到了桨毂轴心运动方程;采用Newmark法进行振动微分方程求解,最终得到了直升机旋翼的轴心运动轨迹。以某型直升机旋翼系统为例,验证了本研究所提出旋翼桨叶模态分析方法的准确性,给出了兼顾计算精度和效率的最佳求解步长选取方法;预测了典型飞行状态下的桨毂轴心运动轨迹,为直升机旋翼系统设计提供了基础方法和技术参考。 相似文献
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A Comparative Study on the Self Diffusion of N-Octadecane with Crystal and Amorphous Structure by Molecular Dynamics Simulation 下载免费PDF全文
The straight chain n-Mkanes and their mixture, which can be used as phase change materials (PCM) for ther- mal energy storage, have attracted much attention in recent years. We employ the molecular dynamics (MD) simulation to investigate their thermophysical properties, including self diffusion and melting of n-octadecane with crystal and amorphous structures. Our results show that, although the initial and melted structures of n-octadecane with crystal and amorphous are different, the melting behaviors of n-octadeeane judged by the self diffusion behavior are consistent. The MD simulation indicates that both the crystal and amorphous structures are effective for the property investigation of n-octadecane and the simulated conclusion can be used as reference for modeling the alkanes-based PCM system. 相似文献
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为了获得高分辨率和耐侧蚀性能优异的阻焊油墨,本文利用叔碳酸缩水甘油酯(E10p)对碱溶性酚醛环氧丙烯酸酯进行改性,并将其应用到阻焊油墨体系。实验结果表明,该改性树脂具有优异的感光性,同时涂层性能测试表明该树脂具有优异的耐热性及柔韧性。与未改性树脂相比,该树脂所制备的阻焊油墨分辨率由75 μm线距提高到50 μm,侧蚀由37.5 μm降低到24.5 μm,表现出了更高的分辨率及更优的耐侧蚀性。 相似文献
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Recently, magnetism in two-dimensional(2 D) van der Waals(vd W) materials has attracted wide interests. It is anticipated that these materials will stimulate discovery of new physical phenomena and novel applications. The capability to quantitatively measure the magnetism of 2 D magnetic vd W materials is essential to understand these materials. Here we report on quantitative measurements of ferromagnetic-to-paramagnetic phase transition of an atomically thin(down to 11 nm) vd W magnet, namely C... 相似文献
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