Effect of residual stress on impact damage in a dissimilar laminated plate at a biaxial bending mode

Systematic investigations have been performed on the mechanisms that lead to impact damage in a dissimilar laminated plate with a thermal residual stress at a biaxial bending mode. Glass/polymer laminated plates are often used as blast-proof safety screens, and bullet-proof windows, and in windshields in the automotive and the aerospace and aeronautical fields. Their many advantages, the development of new materials, and the need for high-performance, low-weight structures ensure that laminated plate construction will continue to be in demand. In this work, the impact damage in glass/Al alloy laminated circular plates cured at RT and 80°C was investigated using an instrumented long bar impact tester at a biaxial bending mode. A circular plate was cured at different curing temperatures to form a thermally induced residual stress at the bonding interface. To improve the damage tolerance of laminated circular plates, various geometric (thickness ratio of the inner to outer layer) and material parameters are considered by determining their effects of maximizing impact absorbed energy. The measured impact force profiles and the impulse of the force explained the impact damage behaviors induced in the laminated circular plates. We show that a compressive residual stress could reduce the initiation of radial cracks and the impact damaged area of the laminated plate in the outer layer. Greater an inner layer thickness results in smaller a damaged area. A design guideline for effective dissimilar laminated plate construction is proposed.     

Three-dimensional numerical analysis of shipping water onto a moving ship using a particle method

The objective of this study was to develop a numerical analysis method based on the moving particle semi-implicit method for simulating shipping water on a moving ship. Towing tests of a very large crude carrier were numerically analyzed for three typical wavelengths. The ship was forced to move in order to express previously measured ship oscillations, and the calculated fluid behavior and the impact pressure on the deck were compared with the experimental results.     

商用车正面碰撞模拟仿真及其结构优化

应用LS-DYNA软件对某商用车整车进行了正面碰撞模拟仿真试验。结果表明,实车碰撞试验与模拟仿真的车辆变形趋势一致。在此基础上,提出了减小车身地板纵梁变形的有效措施,改进后可使纵向变形减小20%,为提高汽车碰撞安全性能提供了参考依据。     

海上风电环境影响评估及对策研究

本文通过对国内外已建、在建和拟建海上风电项目在建设和运行过程中出现的各类环境问题进行深入的分析、研究,提出了符合当地实际情况,经济、技术可行的监测、预防和治理措施。并以东台海上风电场项目的环境影响评估为例进行了实例的研究。     

新型汽车碰撞能量吸收器

提出一种新型汽车碰撞吸收器,该装置具有机械的、剪切型的吸能方式。文中给出了该吸收器的结构和工作原理,对吸收器特性进行了台架与台车碰撞试验。试验结果表明:该吸收器能分解一次性碰撞的巨大能量,逐渐减小碰撞力并逐渐吸收其能量;降低人体所承受的减速度值及减少发生二次碰撞的概率。     

Comparative assessment of liquid sloshing in dry and wet storage tank of floating offshore platform

In order to explore the characteristics of the single-layer liquid sloshing in offshore dry oil storage tank and the two-layer liquid sloshing in offshore wet oil storage tank, two series of experiments were carried out: one was free surface sloshing in a closed rectangular tank partially filled with colored water, and the other was interfacial sloshing in the identical tank but completely filled with white oil and colored water. The tank was mounted on a shake table and was subjected to harmonic horizontal excitation with different excitation amplitudes and a wide range of excitation frequencies, including the first seven natural modes of single-layer or two-layer liquid system. The present study find that the frequency responses of interfacial sloshing wave are analogous to those of the free surface sloshing wave, but smaller in amplitudes. The experiments also produce results that are unique to the two-layer liquid sloshing. For example, when the external excitation frequency is equal to or close to the odd mode natural frequency of two-layer liquid system, a complicated three-dimensional (3D) gravity-capillary wave might be generated at the oil-water interface. Finally, the comparisons of free surface and interfacial sloshing in the viscous damping ratio, higher sloshing modes, impact pressure amplitude and mass center displacement were conducted, which revealed the superiority of wet storage technology in structural safety and dynamic stability.     

Time-domain strip method with memory-effect function considering the body nonlinearity of ships in large waves (second report)

In the previous paper, one of the authors proposed a new time-domain nonlinear strip method for a rigid body, in which hydrodynamic forces are evaluated by a convolution integral with the memory function computed for the instantaneous submerged part of the transverse sections, and the Froude–Krylov and hydrostatic forces are evaluated on the instantaneous wetted hull surface. In this paper, first, that nonlinear strip method is extended for an elastic body using a method of superposition of elastic mode functions, which enabled us to investigate whipping phenomena due to impulsive large waves. Second, the influence of different approximations of the pressure above the still-water surface is investigated, and then the results calculated by the proposed nonlinear strip method are compared with the experimental ones. Third, whipping phenomena observed for an elastic body at higher Froude numbers are studied through a comparison between computed and measured results. Higher-frequency vibrations in the vertical bending moment due to slamming are discussed. Furthermore, the wave load due to green water on deck is calculated by introducing a practical model, and the effects of the green water on responses of both rigid and elastic bodies are investigated.     

区域性交通影响评价阈值的确定方法

新改扩建项目交通影响评价协调了交通需求与交通供给之间的关系,但单体建设项目的交通影响评价方法对于协调城市中某一区域的交通往往带来诸多利益主体平衡的困难,导致交通影响评价的效果不理想.为此,在城市快速发展时期,需要建立侧重于较大范围的区域性交通影响评价方法.针对区域性交通影响评价中范围阈值的确定,提出了标准区域类比法,研究了标准区域的确定方法和阈值确定的过程,并结合北京某区域实际,进行了区域确定方法的案例研究.     

Impact of climate change on pavement structural performance in the United States

This study uses climate projections from multiple models and for different climate regions to investigate how climate change may impact the transportation infrastructure in the United States. Climate data from both an ensemble of 19 different climate models at both RCP8.5 and RCP4.5 as well as three individual prediction models at the same Representative Concentration Pathways (RCP) levels is used. These models are integrated into the AASHTOWare Pavement ME software to predict the pavement performance. Comparisons are made between the predicted performance with respect to typical pavement distresses using both historical climate data as well as climate projection data. Though there is substantial variation for different prediction models in terms of the magnitude of the impact, the consistency in results suggest that projected climate changes are highly likely to result in greater distresses and/or earlier failure of the pavement. This finding is consistent across all the climate zones studied, but varies in magnitude of 2–9% for fatigue cracking and 9–40% for AC rutting at the end of 20 years depending on the climate region of the pavement section and prediction model used. This study also compares the impacts incorporating temperature only projections with temperature and precipitation projections. In this respect, the sections considered in this study do not show any substantial difference in the pavement performance when the precipitation data from the climate predictions are also considered in the climate inputs into AASHTOWare Pavement ME software.     

关于加强公路施工企业负债管理的探讨

资金是公路施工企业生存和发展的瓶颈,解决这个难题,除了挖潜之外,积极吸收、利用债务资金也可以满足生产经营需要,为企业发展作动力,但是负债失控,就会给企业和社会造成损失。加强公路施工企业负债管理,是企业会计诚信建设的具体体现之一。