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1.
In combat operations, a warship can be subjected to air blast and underwater shock loading, which if detonated close to the ship can damage the vessel form a dished for hull plating or more serious holing of the hull. This investigation develops a procedure which couples the nonlinear finite element method with doubly asymptotic approximation method, and which considers the effects of transient dynamic, geometrical nonlinear, elastoplastic material behavior and fluid–structure interaction. This work addresses the problem of transient responses of a 2000-ton patrol-boat subjected to an underwater explosion. The KSF=0.8 is adopted to describe the shock severity. Additionally, the shock loading history along keel, the acceleration, velocity and displacement time histories are presented. Furthermore, the study elucidates the plastic zone spread phenomena and deformed diagram of the ship. Information on transient responses of the ship to underwater shock is useful in designing ship hulls so as to enhance their resistance to underwater shock damage. 相似文献
2.
Sandwich panel is commonly used in ship and marine engineering equipment, such as side structure and superstructure deck of a ship, which is of good anti-explosion performance. This paper addresses a study on the dynamic response of the U-typed sandwich panel under explosion load through the numerical simulation and theoretical methods. Based on the orthotropic plate theory, the U-typed sandwich panel is simplified and transformed into a single degree of freedom (SDOF) spring system, the equivalent motion equation of the SDOF system and the expression of triangular explosion load function are established based on the SDOF theory, and the maximum response spectrum of the SDOF system is obtained. Then, the response of the equivalent SDOF system of the U-typed sandwich panel under explosion load is analyzed, and the theoretical results match well with the numerical simulation results, which verifies the accuracy of the theoretical method proposed in this paper. The theoretical method proposed in this paper could have good engineering applications for the structural anti-explosion design, and provide a reference for the evaluation of the anti-explosion performance of ship and offshore platform structures.
相似文献3.
Application of the ALE technique for underwater explosion analysis of a submarine liquefied oxygen tank 总被引：1，自引：0，他引：1
The design of submarines has continually evolved to improve survivability. Explosions may induce local damage as well as global collapse to a submarine. Therefore, it is important to realistically estimate the possible damage conditions due to underwater explosions in the design stage. The present study applied the Arbitrary Lagrangian–Eulerian (ALE) technique, a fluid–structure interaction approach, to simulate an underwater explosion and investigate the survival capability of a damaged submarine liquefied oxygen tank. The Lagrangian–Eulerian coupling algorithm, the equations of state for explosives and seawater, and the simple calculation method for explosive loading were also reviewed. It is shown that underwater explosion analysis using the ALE technique can accurately evaluate structural damage after attack. This procedure could be applied quantitatively to real structural design. 相似文献
4.
采用LS-DYNA软件,对装药半径为0.15m、0.42m、0.55m的战斗部有、无壳体的爆炸特性进行数值模拟研究,分析了炸药在有无壳体的水下爆炸时的冲击波压力、气泡脉动压力等特性参数,对比总结了不同当量、不同装药半径及有无壳体的数值计算结果。结果表明:壳体对水下爆炸气泡脉动的影响是较为显著的。壳体厚度对气泡形成时间没有太多影响,但对气泡压力峰值影响较大。因此,研究战斗部水下爆炸威力时必须考虑壳体因素,不能简化。 相似文献
5.
大型集装箱船（LCS）具有较大的甲板开口，抗扭刚度非常低。在恶劣海况下航行时，大型集装箱船可能会遭遇斜浪的作用，此时船体将受到三向载荷的联合作用，水平波浪弯矩和扭转波浪弯矩可能会接近甚至超过垂向波浪弯矩，船体可能因发生组合变形而破坏。因此有必要研究大型集装箱船在三向载荷联合作用下的结构可靠性。在研究三向载荷联合作用下各维度极限强度的相互关系的基础上，提出了大型集装箱船的极限承载能力的可靠性评估方法，并对目标船在各浪向角下的结构可靠性进行评估。结果表明：目标船在0°浪向角下的失效概率最高；考虑水平波浪弯矩影响后目标船的结构可靠性有所降低；扭转波浪弯矩对目标船船中剖面的结构可靠性影响较小。 相似文献
6.
Investigation of hydroelastic ship responses has been brought to the attention of the scientific and engineering world for several decades. There are two kinds of high-frequency vibrations in general ship responses to a large ocean-going ship in its shipping line, so-called springing and whipping, which are important for the determination of design wave load and fatigue damage as well. Because of the huge scale of an ultra large ore carrier (ULOC), it will suffer seldom slamming events in the ocean. The resonance vibration with high frequency is springing, which is caused by continuous wave excitation. In this paper, the wave-induced vibrations of the ULOC are addressed by experimental and numerical methods according to 2D and 3D hydroelasticity theories and an elastic model under full-load and ballast conditions. The influence of loading conditions on high-frequency vibration is studied both by numerical and experimental results. Wave-induced vibrations are higher under ballast condition including the wave frequency part, the multiple frequencies part, the 2-node and the 3-node vertical bending parts of the hydroelastic responses. The predicted results from the 2D method have less accuracy than the 3D method especially under ballast condition because of the slender-body assumption in the former method. The applicability of the 2D method and the further development of nonlinear effects to 3D method in the prediction of hydroelastic responses of the ULOC are discussed. 相似文献
7.
The longitudinal strength of turret mooring productive/storage tanker is studied.A numeri-cal example has been implemented according to the method presented in this paper to give practical il-lustration.From the results of the numerical example,it is concluded that the turret hole located near theforward of the amidships has small effect on the longitudinal strength of the ship hull.As for design ex-treme value of wave bending moment of storage tanker,statistic method is a more reasonablemethodology,especially with the consideration of the servere environmental conditions.The primary esti-mation of design section modulus of turret storage tanker can be determined by this design bending mo-ment. 相似文献
8.
水下井口的疲劳完整性是海洋油气田长期安全开采的前提。工业界往往采用贴应变片直接测量水下井口应变来计算弯矩和疲劳损伤，但水下井口应变片粘贴困难且不能长时间连续工作。采用对水下井口监测方法，基于隔水管—防喷器组—水下井口的运动和力学特性，考虑防喷器组惯性力矩建立系统耦合动力学方程，最终形成基于监测数据的水下井口循环弯矩计算方法。以南海某深水水下井口为例，建立隔水管—防喷器组—水下井口系统有限元模型并进行动态分析，提取隔水管底部张力、转角、防喷器组加速度及转角等参数，代入所建立的系统耦合动力学模型，得到水下井口弯矩与有限元计算结果吻合良好。研究表明只需通过在线监测获得所需的输入数据，无需监测水下井口应变即可获取水下井口循环弯矩。建立的系统耦合动力学模型可为水下井口疲劳完整性评估提供理论依据。 相似文献
9.
Parametric roll of a containership in head sea condition has been studied in the paper. A time domain routine for GZ righting arm calculation based on exact underwater hull geometry has been implemented into a two-degree-of-freedom procedure for roll response calculation. The speed variation due to e.g. added resistance has been accounted for in the model by the surge velocity. The ship roll motion due to a regular wave critical for parametric roll occurrence has been simulated, as well as the ship roll response in a severe stochastic sea. The present method has been compared with other existing methods for parametric roll prediction. 相似文献
10.
An assessment is made of the maximum wave induced bending moment expected to occur during the operational lifetime of a fast monohull, based on long term distribution calculations of the non-linear vertical bending moment at mid-ship. The ship is assumed to operate in the Northern North Sea, with an operational life of 25 years. A succession of short-term stationary ship responses represented by Rayleigh distributions of peaks results in the long-term distribution of the structural loads. Non-linear pseudo transfer functions are used in the procedure to calculate the variances of the short-term responses. The amplitudes of these transfer functions are calculated by a non-linear time domain seakeeping program. The results are compared with rules minimum required values and also with results from simpler calculation procedures such as adopting design sea states. 相似文献
11.
浮体运动是引起钢悬链式立管(steel catenary riser,简称SCR)动态响应和疲劳损伤的关键因素,目前研究SCR问题时,为简化计算往往仅考虑平台一阶运动,忽略二阶运动影响。而实际上不同浮体结构的二阶运动响应特征明显,拟以SCR服役张力腿平台(tension leg platform,简称TLP)为例,探讨浮体二阶运动对SCR触地区动态响应的影响。建立考虑海床刚度退化的管土作用模型以改进现有的CABLE3D RSI程序,通过编写程序接口,将有限元分析得到的平台实际运动响应导入,研究平台不同运动作用下SCR触地区的位移、动力响应及疲劳分布情况。根据波流作用方向将TLP二阶慢漂运动分为近端和远端漂移两种工况,发现二阶运动下立管与海床的作用范围会增大,且触地区不仅发生高频小幅振荡运动,同时伴随低频大幅运动响应;平台远端漂移时,管内张力敏感程度高,而近端漂移时触地区的弯矩显著增大,都会不同程度提高触地区的疲劳损伤率。研究可为服役不同浮体的SCR响应预测与疲劳分析提供参考和借鉴。 相似文献
12.
13.
The shock wave and cavitation are main effects in the far-field underwater explosion, which could cause serious damage to marine structures. In this paper, the fluid mechanical behavior of blast load is described by the propagation of pressure wave. The acoustic pressure caused by far-field explosion is determined by solving the wave equation, where a strongly discontinuous axisymmetric numerical model is established with the local discontinuous Galerkin (LDG) method. The model can calculate the dynamic pressure in the fluid field and capture the high-resolution shock wave. The pressure cutoff model is employed to deal with the cavitation effect due to the reflection of the shock wave. The numerical model is verified by comparing with the analytical solution of the cavitation effect near the structure in one dimension. With the same mesh discretization, the present model shows higher precision than the results calculated by the acoustic finite element method. In addition, the propagation of shock wave in the cylindrical water column is studied. Finally, the formation, growth and collapse of the cavitation region near the free surface are simulated. The LDG model can remove the spurious oscillations behind the shock front and it’s more accurate than the results of the acoustic finite element method, in terms of capturing the sharpness of shock wave and calculating the shock and cavitation loading. And the present model can be applied to calculate the structural damage caused by shock wave in three dimensions. 相似文献
14.
常规耐压结构拓扑优化设计研究主要集中于静水压条件下的设计相关载荷拓扑优化理论及方法。但是,在深海环境下,耐压结构可能面临内爆所产生的冲击载荷,其载荷呈现高频率的周期性变化。为研究载荷变化对耐压结构优化设计的影响,在BILE模型的基础上,结合修正的SIMP插值模型,开展不同频率、设计相关动载荷作用下的水下耐压结构拓扑优化理论及方法研究。设计相关动载荷的难点在于不仅载荷的作用位置和方向在优化过程中发生变化,且其大小也随优化过程进行而发生变化,这是与常规设计相关静载荷本质的不同。通过经典的拱形结构优化算例验证BILE模型在动力学拓扑优化中的可行性,进而研究设计相关动载荷作用下的水下耐压结构的最佳拓扑形式。研究表明,在低频时,圆环型耐压结构无明显变化,但多球交接耐压结构在交接处会出现明显材料聚集;高频时,两者均发生明显变化,得到耐压结构新形式。关于设计相关动载荷作用下的水下耐压结构拓扑优化研究,将对新型水下耐压结构的探索具有一定的工程应用价值。 相似文献
15.
Coupled Dynamic Response Analysis of A Multi-Column Tension-Leg-Type Floating Wind Turbine 总被引：4，自引：3，他引：1
This paper presents a coupled dynamic response analysis of a multi-column tension-leg-type floating wind turbine (WindStar TLP system) under normal operation and parked conditions. Wind-only load cases, wave-only load cases and combined wind and wave load cases were analyzed separately for the WindStar TLP system to identify the dominant excitation loads. Comparisons between an NREL offshore 5-MW baseline wind turbine installed on land and the WindStar TLP system were performed. Statistics of selected response variables in specified design load cases (DLCs) were obtained and analyzed. It is found that the proposed WindStar TLP system has small dynamic responses to environmental loads and it thus has almost the same mean generator power output under operating conditions as the land-based system. The tension mooring system has a sufficient safety factor, and the minimum tendon tension is always positive in all selected DLCs. The ratio of ultimate load of the tower base fore-aft bending moment for the WindStar TLP system versus the land-based system can be as high as 1.9 in all of the DLCs considered. These results will help elucidate the dynamic characteristics of the proposed WindStar TLP system, identify the difference in load effect between it and land-based systems, and thus make relevant modifications to the initial design for the WindStar TLP system. 相似文献
16.
面对通航区很可能发生的船舶抛锚、落物以及沉船等事故造成的危险,使用新型沉箱防护设施对水下生产系统进行安全防护,但目前撞击载荷下沉箱防护设施的安全评估标准并无明确界定。采用有限元方法对水下生产系统沉箱安全防护设施的撞击损伤进行了深入研究,考虑不同落物形状、下落速度、落物质量、碰撞位置对沉箱防护设施撞击损伤的影响。结果表明,锚、长方体落物对沉箱撞击最严重;撞击速度和落物质量与撞击应力成正比;对于非对称开孔的沉箱顶盖,距离开孔较近区域为应力敏感区,受到撞击时撞击应力较大。 相似文献
17.
The current scenario of oil production in ultra deep waters challenges the design of flexible pipes since they have to withstand high pressures, temperatures and dynamic loads during operation. Amongst the known failure mechanisms in flexible pipes, armor wire lateral buckling is of uttermost importance as there is no undisputable model for its prediction. In this work, compressive failure load for tensile armor lateral buckling is calculated for a sample of 29 flexible pipes based on the resolution of a numerical model that considers force and moment equilibrium conditions and geometric compatibility relations from differential geometry concepts. The obtained results are fitted on an equation via symbolic regression. Thus, a simple empirical model to predict compressive failure load is proposed as a function of the radius of tensile armor, wire lay angle and torsional, normal and binormal bending stiffness of the wire cross section. The model assumes the absence of frictional distributed forces in the wire and curvature of the flexible pipe, therefore it provides conservative results. For the 29 flexible pipe sample, the mean absolute percentage error of the empirical results in view of the numerical results was 0.6%. 相似文献
18.
Highly dependent on boundary conditions, the behaviors of underwater explosion (UNDEX) bubbles would be quite unusual near boundaries that are discontinuous with abrupt changes in shape, e.g. ship structures that have already been deformed by previous attacks. The oscillation features of the UNDEX bubble near the bilge with a circular opening representing previous deformation are studied experimentally with electric-spark-generated bubbles and high-speed photographing. The bubble behaviors are found highly dependent on two non-dimensional variables, D and Φ, representing the opening-bubble distance and the opening diameter, respectively. Seven distinctive oscillation scenarios are summarized from 180 experiments, namely the ‘rim-constrained oscillation’, the ‘inward jet’, the ‘outward jet’, the ‘bump and dimple’, the ‘quasi-spherical oscillation’, the ‘spherical oscillation with jet’ and the ‘spherical oscillation without jet’. The occurrence domains of the scenarios are identified as functions of D and Φ. Significantly affected by the opening, the bubble behaviors are quite different from that near a non-opening bilge; the bubble jet might not be formed, or even develop from inside the bilge, which indicates that the bubble load on the bilge should be re-evaluated. Finally the speeds, initiation time and displacements of the jets in different scenarios are measured and noticeable variation trends are found. 相似文献
19.
A new hybrid method for the time-domain nonlinear simulation of the hydroelastic load effects and the peak over threshold (POT) method for the calculation of the short-term extreme responses are briefly described and applied to a flexible SL-7 class containership and a flexible liquefied natural gas (LNG) ship. Three stiffness levels, three stiffness distributions and three modal damping ratios are used to study the influence of the hull flexibility and structural damping on the short-term prediction of extreme vertical hydroelastic load effects. The results give justification for some simplified treatment of the first vertical flexible mode in early design stage when structural details are not available. 相似文献
20.
A new hybrid method for the time-domain nonlinear simulation of the hydroelastic load effects and the peak-over-threshold (POT) method for the calculation of the short-term extreme responses are briefly described and applied to a flexible containership of the latest design. Statistical analysis has been carried out to study the sensitivity of the predicted extreme vertical bending moments and vertical shear forces to the changes in the threshold of the POT method, as well as the statistical uncertainty in the prediction due to the limited duration of the nonlinear simulation. It is recommended that 90%–95% quantile should be used as the threshold in the POT method and more than 100 h of time-domain simulation should be carried out in order to obtain satisfactory predictions of the short-term extreme nonlinear load effects. 相似文献