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排序方式: 共有409条查询结果,搜索用时 46 毫秒
401.
402.
研究了含有环向表面裂纹损伤的无限长圆柱壳中的波传播和振动功率流特性.用Flügge方程来描述圆柱壳的振动.对于裂纹损伤圆柱壳,运用断裂力学的理论,考虑到裂纹的张开、滑移和剪切三种状态建立了裂纹区域的局部柔度矩阵,得到由此引起的附加广义位移和壳体中内力之间的关系.根据裂纹两侧区域的位移和内力的连续性条件得到了四支反射波和四支透射波的幅值,继而求得壳体中各内力传播的功率流.分析了透射功率流、反射功率流与激励频率和裂纹尺寸之间的联系.文中的研究为基于振动功率流方法识别圆柱壳表面损伤提供了理论基础. 相似文献
403.
球壳开孔应力分析的一种解析方法 总被引:2,自引:0,他引:2
圆柱形围壁加强的球壳开孔是一种组合回转壳结构.该文采用与回转壳相对应的弹性基础梁理论方法进行求解.该方法较壳体理论(或扁壳理论)求解更方便,并能适应较复杂的加强结构和受力状态,同时获得较多的计算结果,该方法计算结果与有限元方法计算结果基本吻合. 相似文献
404.
In various engineering fields like aerospace and aircraft structures or marine and offshore platforms, constitutive material of critical components should be made of specific materials that can work properly in the required workspace. Such materials must have excellent properties such as high mechanical strength as well as great resistance to corrosion, oxidation, and creep. Inconel 625 is a superalloy that is chosen as constitutive material of critical components due to its great abilities. On the other hand, since investigating Inconel 625 pipe has not been done yet, different mechanical characteristics of using structures made of Inconel 625 should be assessed. Additionally, doing so would be necessary to gather information for current industrial affairs and also future investigations. Therefore, the nonlinear dynamic instability response of axially loaded Inconel 625 pipes is investigated in the current article. The pipe structure is modeled via the Donnell shell theory and nonlinear von Kármán theory. The motion equations of pipes are established by applying the Hamiltonian approach. Then, in order to alter the nonlinear derived partial differential equations into the Mathieu-Hill equation, both Navier's solution and Airy stress function are implemented. Additionally, the amplitudes of steady-state oscillation of the Inconel 625 pipe are determined by employing Bolotin's method. Eventually, the impacts of various effective parameters on the nonlinear dynamic behaviors of Inconel 625 pipes are evaluated. The results indicate static and dynamic load factors possess a remarkable effect on instability exciting areas and steady-state vibration amplitudes of pipe. Moreover, the dynamic instability response of the pipe is dependent on the radius-to-thickness and length-to-radius ratios, and also how the ratios are affected depends on the wave number. 相似文献
405.
The present study investigates the collapse performance of composite-repaired cylinders with internal metal loss subjected to external pressure. Three groups of intact, thinned, and repaired cylinders were designed, analytically verified, fabricated, geometrically measured, externally tested, and numerically modeled. Each group had three nominally identical cylinders to ensure the repeatability of experiments. The cylinders had the same end closure, effective length, total length, external radius, and intact thickness for an equivalent comparison. The thinned cylinder was considered as the intact cylinder with internal metal loss, whereas the repaired cylinder was considered as the thinned cylinder with composite reinforcement. The results indicated that the external loading capacity of cylinders with internal metal loss could be fully restored and even enhanced by composite reinforcement. Composite-repaired cylinders are much less sensitive to initial geometrical imperfections than intact cylinders. 相似文献
406.
Damping materials are widely used and playing an essential role in reducing the vibration and noise of various ships and underwater vehicles. In practical engineering, damping materials are often applied over the structural surface of ships and underwater vehicles. They are generally distributed not evenly in the whole area, but locally in some vital regions. The stiffened cylindrical shell is the most representative configuration for the main structure of underwater vehicles. Therefore, research on modeling and calculation of underwater acoustic radiation from stiffened cylindrical shells locally treated with damping has high practical value. This paper introduces a mixed analytical-numerical acoustic-vibration interaction method to achieve efficient calculation of the vibration and acoustic radiation from a locally damped cylindrical shell immersed in water. Two kinds of vibration and noise reduction measures are proposed for the damping treatment of a large-scale stiffened cylindrical shell structure. Calculation and analysis are carried out for both measures. The results can provide reference for developing the technology of reducing vibration and noise from ships and underwater vehicles via damping treatment. 相似文献
407.
408.
[目的]旨在利用解析法求解环肋圆锥壳的振动方程,对环肋圆锥壳的振动特性进行理论研究。[方法]首先,对圆锥壳分段处理,将圆锥壳沿母线方向、环向和法向的位移分别写成幂级数解的形式,并推导出幂级数项前系数的递推关系式;然后,采用梁模型模拟不同环肋数对圆锥壳振动响应特性的影响;接着,将圆锥壳分段及其环肋边界条件、位移和内力矩阵进行组装求解,得到在外部简谐力激励下圆锥壳的振动响应特性,并将所得结果与ANSYS有限元数值方法的计算结果进行对比,验证所提计算方法的有效性。最后,运用所提理论方法进行环肋圆锥壳的振动特性分析。[结果]结果显示,圆锥壳安装的环肋可明显抑制圆锥壳的振动,具体表现为响应幅值降低、固有频率升高,且在相同频段内共振峰数量减小;增大壳体厚度会引起壳体振动响应幅值降低以及固有频率升高;此外,增大半锥角、轴线长度和环肋数均可降低环肋圆锥壳的振动响应幅值。[结论]研究表明,所用方法对环肋圆锥壳振动的理论研究具有一定意义。 相似文献
409.
随着经济建设的发展,桥梁宽度日益增加,宽幅钢箱梁被广泛的应用于各类工程实践,为探究此类结构的受力模式,以2×40 m跨径的宽幅钢箱梁为研究对象,建立三维数值分析模型。以典型工况为荷载条件,验证单梁法、梁格法及板壳单元法的设计精度,在此基础上,分析、归纳及总结了宽幅钢箱梁的受力特性,结合有限元分析成果及中外规范着重论述了宽幅钢箱梁横梁的受力模式及简化计算方法,提出了宽幅钢箱梁的设计建议,以期为类似结构的设计提供参考。 相似文献