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711.
This paper presents a benchmark study on the slamming responses of offshore structures’ flat-stiffened plates. The objective was to compare the fluid-structure interaction (FSI) simulation methodologies, modeling techniques, and established researchers' experiences in predicting slamming pressure. Three research groups employing the most common commercial software packages for numerical FSI simulations (i.e. LS-Dyna ALE, LS-Dyna ICFD, ANSYS CFX, and Star-CCM+/ABAQUS) participated in this study. Wet drop test data on flat-stiffened aluminum plates of light-ship-like bottom structures available in the open literature was utilized for validation of the FSI modeling. A summary of the experimental conditions including the geometry model and material properties, was distributed to the participants prior to their simulations. A parametric study on flat-stiffened steel plates having actual scantlings used in marine installations was performed to investigate the effect of impact velocity and plate rigidity on slamming response. The FE simulation results for the total vertical forces acting on the stiffened plates and their structural responses to those forces, as obtained from the participants, were analyzed and compared. The reliable and accurate predictions of slamming loads using the aforementioned commercial FSI software packages were evaluated. Additionally, equivalent static slamming pressures resulting in the same permanent deflections, as observed from the FSI simulations, were reported and compared with analytical models proposed by the Classification Standards DNV and existing experimental data for calculation of the slamming pressure. The study results showed that the equivalent load model depends on the water impact velocity and plate rigidity; that is, the equivalent static pressure coefficient decreases with an increase in impact velocity, and increases when impacting structures become stiffer. 相似文献
712.
在航道疏浚、港口设计、环保清淤工程中,往往需要高精度的水深测量成果,水深测量的质量直接影响最终的测量成果,因此对水深测量的质量控制尤为重要。水深测量模式分为传统水深测量和RTK三维水深测量模式,其中后者是水运工程测量规范中推广的新技术。针对RTK三维水深测量这种新的作业模式,结合航道测量工程实例,从软硬件设置、外业测量过程、内业数据处理、成果质量检查4个方面,对数据的规范性、合理性、完整性进行控制,保障最终成果满足要求。 相似文献
713.
The hull excitation generated by marine propellers constitutes one of the most significant vibration sources affecting comfort on passenger ships. Consequently, the evaluation of the propeller-generated excitation through reliable numerical tools during the preliminary stage of ship design is fundamental. The Holden Method (HM) is an empirical tool utilized to calculate the propeller-induced pressure distribution on a ship hull. The present paper validates the HM, which is applied to a twin-screw, 54-m super-yacht. Finite Element Analysis (FEA) is used to benchmark the HM numerical predictions against a set of full-scale vibration measures. The outcomes show that the magnitude of the propeller-induced dynamic excitation predicted by the HM is overestimated. Thereafter, the calibrated propeller-induced forces and the diesel engine excitation are applied to the FE model to perform a series of forced vibration analyses and estimate the global structural damping coefficient of the super-yacht. The study highlights the necessity of developing new empirical methodologies, analogous to the HM, to be applied to modern small luxury vessels. 相似文献
714.
Stress evaluation of a submerged floating tunnel (SFT) is an issue important for determining the section dimensions required to resist environmental loads. However, the complex interaction between an SFT and surrounding fluid has confined most research on SFTs to longitudinal global time-history analyses based on Morison's equation [1]. Even though these analyses give sufficient information in the longitudinal direction, too little information about the circumferential direction compels an SFT section to be designed conservatively. This means that SFT design requires additional information on the structural behavior of the tunnel in the circumferential direction for efficient design. Accordingly, a supplementary approach by which to obtain structural responses in the circumferential direction is introduced in this paper. Upon consideration of the static responses equivalent to the dynamic behavior, three-dimensional (3-D) finite-element analyses of an SFT were performed by application of static loads corresponding to dynamic loads equivalent to those of wave, current and earthquake. The validation of each equivalent static load was supported by the results from comparison of the tension forces in mooring lines obtained using OrcaFlex [2] and ABAQUS [3]. These were used mainly for longitudinal dynamic analysis and 3-D stress evaluation, respectively, of an SFT. Based on the stresses obtained in the longitudinal and circumferential directions, the selection of suitable section dimensions for an SFT is considered. 相似文献
715.
费书香 《铁道劳动安全卫生与环保》1993,(4):297-298
报道了利用微波消化检验样品的基本原理,并介绍了利用民用微波炉,聚四氟乙烯高压罐消化样品的操作方法及最佳消化条件。经微波消化的消化液。应用原子吸收法测定其中的铅和铜,并做了回收率实验。测定结果变异系数铜:2.0%-4.5%,铅:2.5%-3.8%。回收率铜98.0%-99.0%,铅:96.0%-99.5%。 相似文献
716.
717.
本机器采用多层水平圆式输送料槽,并首次集振动输送与内热干煤为一体,结构紧凑新颖,干燥充分均匀,是较理想的颗粒原料干燥和热清洗设备. 相似文献
718.
根据现行给水排水设计规范、海港工程设计手册,对港口码头给水系统设计、系统用水贮水量、水压、水质提出自己的浅见,希望能对港口码头给水系统设计以及系统优化设计起到积极的作用。 相似文献
719.
铁路框架地道桥受下穿隧道施工影响的研究 总被引:1,自引:0,他引:1
采用荷载结构模型及连续介质力学模型分别对铁路顶桥受下穿地铁区间隧道施工影响所产生的沉降及内力变化进行计算分析 ,并据此提出下穿框架式地道桥的地铁区间的设计及施工的有关技术要求。 相似文献
720.
压力容器爆炸事故的事故树分析 总被引:1,自引:0,他引:1
王小群 《铁道劳动安全卫生与环保》2004,31(2):78-80
压力容器事故隐患较多 ,危害亦较严重 ,运用事故树方法可以分析出事故发生的各种途径 ,并依据最小径集的分析 ,制定出合理的预防措施 相似文献