汽车车身模态分析实例研究

建立了某车型车身总成的有限元模型,基于线形广义特征值问题的矩阵摄动重分析公式, 得到了系统各阶固有频率及固有振型随结构质量和刚度的修改而变化的情况, 找到了对结构进行摄动修改的最灵敏位置。以频率及其振型为校正依据, 兼顾其他频率特征, 对车身有限元模型进行了修正。     

某类雷达车车身地板附加结构阻尼层布置优化技术

车辆的振动舒适性不仅影响乘客的乘坐体验，对于雷达车等装载精密设备的特种车辆而言，车辆的振动噪声还会影响雷达的正常工作或降低指挥官间的沟通质量。车身附加结构阻尼是改善车辆乘坐舒适性的一种有效措施，以某类雷达车车身地板为研究对象，详细研究了附加结构阻尼层的布置优化方法，认为拓扑优化设计方法是附加结构阻尼层优化布置的有效方法。在此基础上进一步研究了附加自由阻尼层的局部约束化优化方法，探讨了局部约束化对自由阻尼层性能的影响。     

Support condition monitoring of monopile-supported offshore wind turbines in layered soil based on model updating

Monopile-supported offshore wind turbines (OWTs) are dynamically sensitive structures whose fundamental frequencies may be close to those of environmental and turbine-related excitations. The changes in fundamental frequencies caused by pile-soil interaction (PSI) may result in unwanted resonance and serious O&M (Operation and Maintenance) issues, which have been identified as major challenges in the research field. Therefore, a novel model updating framework with an implicit objective function is proposed to monitor both the stiffness and damping variation of the OWT system based on the measured vibration characteristics, which is further verified by laboratory tests. In particular, layered soil was considered in the tests to simulate the practical soil conditions of Chinese seas. Different pile lengths were introduced to consider the long-term PSI effects for rigid piles and slender piles. The results showed that the variation in the fundamental frequency is significantly reduced in layered soil compared with the pure sand scenario. For the OWT systems in layered soil, the variation in foundation stiffness is negatively related to the burial depth under cyclic loading. The proposed model updating framework is proven reliable for support condition monitoring of OWT systems in complicated soil conditions.     

Modeling and calculation of acoustic radiation of underwater stiffened cylindrical shells treated with local damping

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.     

大体积混凝土止浆垫块及拉杆装置在龙溪口航电枢纽中的应用

在船闸工程大体积混凝土施工过程中，常使用高大模板，为保证模板的稳固，增加其安全性，现场施工中往往采用斜拉杆对模板加固，并使用发泡剂或者缠绕胶带等进行止浆，然而这种传统的方法往往存在工序复杂、止浆效果不佳、拆模后混凝土外观质量差等缺点。为解决该问题，采用一种基于大体积混凝土高大模板施工的弹性材质止浆垫块，并辅以端头带螺纹的拉杆装置，可有效防止混凝土浆液渗漏，还可为拉杆预留保护层以防止锈蚀。该止浆垫块在现场施工的应用取得了较好成效，在提升施工质量及效率的同时，较大程度改善了混凝土表面外观，可为类似工程的大体积混凝土施工止浆提供参考。     

沥青船独立液货舱垫块布置设计优化与选取

以17 000 t沥青船为例，研究沥青船独立液货舱垫块的布置设计优化与选取。针对当前沥青船市场两种主要的垫块ULEPSI和FEROFORM，基于法国船级社（BV）的舱段有限元分析方法进行垫块的受力分析，对两种垫块的布置设计进行优化，并对两种垫块的选取进行分析。该研究可为其他沥青船独立液货舱垫块的布置设计提供参考。     

Fluid-structure-material coupling analysis for a floating laminated structure consisting of high-stiffness panels and a soft core

This paper presents a fluid-structure-material coupling analysis for the interaction between water waves and a very large floating laminated structure (VLFLS), which is consisted of two enhanced ultrahigh-performance concrete (UHPC) panels and a middle lightweight foamed rubber core. The representative volume element (RVE) method is used to design the mechanical properties of enhanced UHPC and foamed rubber, and the parameterized formulas are presented to reveal the dependency between macroscale mechanical properties and mesoscale hierarchical characteristics. By idealizing the rubber core as a uniformly distributed spring layer, an eighth-order differential equation of motion of the laminated structure is derived. In the context of linear potential flow theory, a hydroelastic analytical model is developed for the floating laminated structure with finite length under wave action. In the process of solving velocity potentials, a complicated dispersion equation for the wave motion below the laminated structure is derived, and this equation contains two pairs of conjugate complex roots with positive real parts. The various hydrodynamic quantities, including reflection coefficient, transmission coefficient, deflection, shear force, and bending moment, are calculated. The hydroelastic model is confirmed by considering the convergence of calculation results and the energy conservation of wave propagation. The coupled effects of wave action, material characteristics, structural parameters, and edge conditions on the hydroelastic and mechanical response of the floating laminated structure are clarified to provide important information regarding the optimal design of such structures.     

减振垫刚度变化对U型梁桥系统振动及结构噪声的影响研究

为了研究隔离式减振垫垂向刚度对U型梁桥结构振动及噪声的影响,采用多体动力学和有限元联合仿真的方法建立基于Timoshenko梁模型的车辆-轨道-桥梁刚柔耦合动力学模型,并将理论计算结果与以往文献对比,验证了模型的有效性.基于该模型计算了减振垫垂向刚度不同情况下的桥梁系统振动及噪声响应.结果表明:随着隔离式减振垫垂向刚度...