2011 Vol. 6 No. 5
2011, 6(5): 1-6.
DOI: 10.3969/j.issn.16733185.2011.05.001
Abstract：
为探寻美国航母的防护结构设计思路,对比分析了美国典型航母的防护结构设计型式和特点,结合武器装备的技术发展,分析了美国航母防护结构设计发展趋势。在此基础上,根据现代反舰武器的攻击特性和部分公开的美国核动力航母设计信息,推测了美国现代航母防护结构设计思想和基本结构型式。
Abstract：
The single and double hull are main types of submarine structure.In order to compare the residual strength characteristic of two type structures after impacted,the two type structure modes have been designed and used with same initial static strength.First,the dynamical response of this two structure modes under the same impact load was calculated based on FE codeMSC/Dytran,then the residual displacement field was picked out,the static strength analysis was carried out based on FE codeMSC/Marc.The comparison analysis results show that the double hull structure have higher residual strength,when the collision load is low.However,with the impact load increased,the residual strength of this two types structure will correspond with each other.
The single and double hull are main types of submarine structure.In order to compare the residual strength characteristic of two type structures after impacted,the two type structure modes have been designed and used with same initial static strength.First,the dynamical response of this two structure modes under the same impact load was calculated based on FE codeMSC/Dytran,then the residual displacement field was picked out,the static strength analysis was carried out based on FE codeMSC/Marc.The comparison analysis results show that the double hull structure have higher residual strength,when the collision load is low.However,with the impact load increased,the residual strength of this two types structure will correspond with each other.
2011, 6(5): 11-15.
DOI: 10.3969/j.issn.16733185.2011.05.003
Abstract：
在对纵筋环肋圆柱壳结构进行理论分析的基础上,建立了该结构的力学和数学模型,得出计算公式。采用理论设计公式和有限元仿真计算设计一个大比例的舱段模型,并对该模型进行外压试验。通过对理论计算结果、有限元仿真计算结果和试验数据进行对比分析,认为环肋纵筋结构能显著提高结构的承载能力。
2011, 6(5): 16-22.
DOI: 10.3969/j.issn.16733185.2011.05.004
Abstract：
Mechanical properties of cracked stiffened plates under uniaxial compression loads were studied.The ultimate strength reduction of stiffened plates due to different sizes and locations of the cracks were investigated.A series of nonlinear finite element analyses for cracked stiffened plates under uniaxial compression loads were carried out by software Abaqus.Then the mechanical characteristics and failure modes are presented.It is shown that the ultimate strength of stiffened plates can be reduced due to the cracks,and the ultimate strength will be sharply decreased when crack sizes exceed critical values.
Mechanical properties of cracked stiffened plates under uniaxial compression loads were studied.The ultimate strength reduction of stiffened plates due to different sizes and locations of the cracks were investigated.A series of nonlinear finite element analyses for cracked stiffened plates under uniaxial compression loads were carried out by software Abaqus.Then the mechanical characteristics and failure modes are presented.It is shown that the ultimate strength of stiffened plates can be reduced due to the cracks,and the ultimate strength will be sharply decreased when crack sizes exceed critical values.
Abstract：
Based on the theory of structural dynamic optimization,the design method for ship pedestal with rigid vibration isolation mass was studied.Within the total weight limits of pressure hull section,two kinds of structural dynamic optimization design models were established with regard to the sectional dimensions and the layout of isolation mass respectively.The target function is average vibration acceleration of pressure hull section.The sectional dimensions and layout of the rigid vibration isolation mass with optimal vibration reduction performance were obtained.The results indicate that the greater the height of isolation mass becomes,the smaller the average vibration acceleration will be.With this model,the optimal design solution satisfied the structural requirement is found and the feasibility of design method is verified.
Based on the theory of structural dynamic optimization,the design method for ship pedestal with rigid vibration isolation mass was studied.Within the total weight limits of pressure hull section,two kinds of structural dynamic optimization design models were established with regard to the sectional dimensions and the layout of isolation mass respectively.The target function is average vibration acceleration of pressure hull section.The sectional dimensions and layout of the rigid vibration isolation mass with optimal vibration reduction performance were obtained.The results indicate that the greater the height of isolation mass becomes,the smaller the average vibration acceleration will be.With this model,the optimal design solution satisfied the structural requirement is found and the feasibility of design method is verified.
Abstract：
Bending vibration is an ordinary modal of the cylindrical shell.Based on the theory of sound radiation of oscillating cylinder,the acoustic radiation of finite cylindrical shell was transformed from infinite cylinder by introducing a modifying factor,an approximate analytical method for solving bending vibration and acoustic radiation of cylindrical shell was proposed.Taking a special long power cabin as an example,the characteristic of far filed acoustic pressure was calculated by the proposed method and boundary element method.The results show the two methods agree well.The proposed method has the advantages of convenient and fast,and it is suitable for engineering evaluation.
Bending vibration is an ordinary modal of the cylindrical shell.Based on the theory of sound radiation of oscillating cylinder,the acoustic radiation of finite cylindrical shell was transformed from infinite cylinder by introducing a modifying factor,an approximate analytical method for solving bending vibration and acoustic radiation of cylindrical shell was proposed.Taking a special long power cabin as an example,the characteristic of far filed acoustic pressure was calculated by the proposed method and boundary element method.The results show the two methods agree well.The proposed method has the advantages of convenient and fast,and it is suitable for engineering evaluation.
Abstract：
A dynamic optimization method based on admittance method and genetic algorithm was presented to optimize grillage structures considering their sound radiation characteristics.In the analysis,the grillage system was first separated into a plate and some discrete beams and then the admittance method was employed to calculate the dynamic response of the grillage system with vibration isolators,which was more efficient than one using the finite element method.And together with the boundary element method,the acoustic radiation power could be computed easily.The inertia moments of the beams were selected to be design variables in the study to reduce the number of optimal variables and the computational burden was greatly reduced accordingly.In order to obtain discrete optimal results a scheme database was constructed and from which the possible design scheme was selected based on the inertia moments of the beams that were determined by genetic algorithm.A numerical example showes that the dynamic response from the admittance method is well agreed with one obtained from the finite element method.A dynamic optimization example is also provided to demonstrate the validity and effectiveness of the proposed optimal method.
A dynamic optimization method based on admittance method and genetic algorithm was presented to optimize grillage structures considering their sound radiation characteristics.In the analysis,the grillage system was first separated into a plate and some discrete beams and then the admittance method was employed to calculate the dynamic response of the grillage system with vibration isolators,which was more efficient than one using the finite element method.And together with the boundary element method,the acoustic radiation power could be computed easily.The inertia moments of the beams were selected to be design variables in the study to reduce the number of optimal variables and the computational burden was greatly reduced accordingly.In order to obtain discrete optimal results a scheme database was constructed and from which the possible design scheme was selected based on the inertia moments of the beams that were determined by genetic algorithm.A numerical example showes that the dynamic response from the admittance method is well agreed with one obtained from the finite element method.A dynamic optimization example is also provided to demonstrate the validity and effectiveness of the proposed optimal method.
2011, 6(5): 37-40,45.
DOI: 10.3969/j.issn.16733185.2011.05.008
Abstract：
In order to find the weak links of the ship equipment suffered attack and ensure its fighting strength,it is necessary to analyze the shock resistance of marine turbine.The threedimensional geometrical model of the turbine was built by the ProE and the finite element（FE） mesh was built by the HyperMesh.Then the FE model is imported in the ABAQUS software and the shock resistance of the turbine was calculated in time domain baseed on the explicit solution.The results show that the shock responses of the bear at typical parts of the turbine are intense,and the response of the spindle of compressor is relatively complex,which should be protected.The turbine has enough security in shock assessment condition,and weak links of the shock resistance are found out mainly at lapped joint of frame,chassis under frame,the joints among the shaft bearing,gear mate and bolt.
In order to find the weak links of the ship equipment suffered attack and ensure its fighting strength,it is necessary to analyze the shock resistance of marine turbine.The threedimensional geometrical model of the turbine was built by the ProE and the finite element（FE） mesh was built by the HyperMesh.Then the FE model is imported in the ABAQUS software and the shock resistance of the turbine was calculated in time domain baseed on the explicit solution.The results show that the shock responses of the bear at typical parts of the turbine are intense,and the response of the spindle of compressor is relatively complex,which should be protected.The turbine has enough security in shock assessment condition,and weak links of the shock resistance are found out mainly at lapped joint of frame,chassis under frame,the joints among the shaft bearing,gear mate and bolt.
2011, 6(5): 41-45.
DOI: 10.3969/j.issn.16733185.2011.05.009
Abstract：
The research on hydrodynamics of ship maneuverability based on the potential flow theory was presented.The velocity of flow field near the Wigly ship and the yawing moment of the ship when sailing with drift angle were calculated using boundary element method.The distributing of flow field near the sailing ship with drift angle was analyzed and variation of the yawing moment with the drift angle was studied.The results show that these researches adapt to prediction of ship movement with drift angle.
The research on hydrodynamics of ship maneuverability based on the potential flow theory was presented.The velocity of flow field near the Wigly ship and the yawing moment of the ship when sailing with drift angle were calculated using boundary element method.The distributing of flow field near the sailing ship with drift angle was analyzed and variation of the yawing moment with the drift angle was studied.The results show that these researches adapt to prediction of ship movement with drift angle.
2011, 6(5): 46-49,77.
DOI: 10.3969/j.issn.16733185.2011.05.010
Abstract：
For modeling the optimum propulsion system of glidinghydrofoil craft,a mathematic model was established in the software MATLAB by applying the weighting factors of rapidity and economical efficiency.And corresponding simulation analysis was performed on SIMULINK.The improved chaos optimum algorithm was adopted to optimize the fuzzy control system for obtaining minimum desired value.The rotate speed of prime（RMP） engine and pitcch of APP propeller were optimized,realizing optimum control of fuzzy controller over the RMP of prime engine and the pitch of APP propeller at various operating conditions.The optimized controller via an improved algorithm is compared with conventional controller.The results show that the optimized controller of propulsion system is valid,which allows small overshoots in speed control and also presents a good stability.
For modeling the optimum propulsion system of glidinghydrofoil craft,a mathematic model was established in the software MATLAB by applying the weighting factors of rapidity and economical efficiency.And corresponding simulation analysis was performed on SIMULINK.The improved chaos optimum algorithm was adopted to optimize the fuzzy control system for obtaining minimum desired value.The rotate speed of prime（RMP） engine and pitcch of APP propeller were optimized,realizing optimum control of fuzzy controller over the RMP of prime engine and the pitch of APP propeller at various operating conditions.The optimized controller via an improved algorithm is compared with conventional controller.The results show that the optimized controller of propulsion system is valid,which allows small overshoots in speed control and also presents a good stability.
2011, 6(5): 50-54.
DOI: 10.3969/J.issn.16733185.2011.05.011
Abstract：
在海洋工程水池试验中,造波机与模型之间的二次波浪反射严重影响试验结果的准确性和可靠性。在势流理论的基础上,采用边界元法建立了二维线性数值波浪水池。通过数值模拟结果与解析解的比较,证实该数值波浪水池的适用性。采用全相位频谱分析方法作为水动力反馈,对入射和反射波进行分离,以分离的反射波信号控制摇板运动以达到吸收二次反射波浪的目的。在此基础上,对摇板式造波机在数值波浪水池中进行了无反射造波仿真试验。仿真结果表明,采用无反射造波后,能有效减弱波浪的二次反射。
2011, 6(5): 55-62.
DOI: 10.3969/J.issn.16733185.2011.05.012
Abstract：
Based on Arbitrary LagrangeEuler（ALE） method,the Finite Element model of the fluidpropeller interaction was built using LSDYNA software.The hydrodynamic characters and mechanical performance of structure（fluid resultant velocity and structure internal stress of blade） were studied under the incoming flow of fixed blade of propeller,analyzing the internal varying stress of blade and vortex motion behind the propeller.The ressults show that irregular surface of blade result in vortex shedding phenomenon behind the propeller.And the element stress of blade was determined by its′ thickness and the distance to the constraint location.
Based on Arbitrary LagrangeEuler（ALE） method,the Finite Element model of the fluidpropeller interaction was built using LSDYNA software.The hydrodynamic characters and mechanical performance of structure（fluid resultant velocity and structure internal stress of blade） were studied under the incoming flow of fixed blade of propeller,analyzing the internal varying stress of blade and vortex motion behind the propeller.The ressults show that irregular surface of blade result in vortex shedding phenomenon behind the propeller.And the element stress of blade was determined by its′ thickness and the distance to the constraint location.
2011, 6(5): 63-68.
DOI: 10.3969/j.issn.16733185.2011.05.013
Abstract：
According to projection theory and curvedsurface offsets,a 3D geometry model of propeller was built.Based on computational fluid dynamics（CFD） method,the subdomains hybrid meshes method,the dynamic meshes method and the moving reference frame（MRF） method were adopted to simulate the hydrodynamic performance of propeller in openwater by using the ReynoldsAveraged NavierStokes（RANS） equation and RNG turbulence models.Thruust and torque of the propeller in open water were obtained and compared with experimental results.The results show the proposed method can achieve the numerical prediction of hydrodynamic performance for propeller in open water.
According to projection theory and curvedsurface offsets,a 3D geometry model of propeller was built.Based on computational fluid dynamics（CFD） method,the subdomains hybrid meshes method,the dynamic meshes method and the moving reference frame（MRF） method were adopted to simulate the hydrodynamic performance of propeller in openwater by using the ReynoldsAveraged NavierStokes（RANS） equation and RNG turbulence models.Thruust and torque of the propeller in open water were obtained and compared with experimental results.The results show the proposed method can achieve the numerical prediction of hydrodynamic performance for propeller in open water.
2011, 6(5): 69-72,88.
DOI: 10.3969/j.issn.16733185.2011.05.014
Abstract：
The research and application of trimaran push on the development of high speed ship.Seakeeping property plays an important role in the performance of the trimaran sailing at sea,while the roll radius of inertia is a basic property that will have impacts on the rolling natural period and ship stability.Because of the trimaran＇s special structure,assessment of radius of inertia is a little bit different from single hull ship.Througgh a threebody beam model and its numeration results,this paper found the key parameters,proposed an estimated formula for the radius of inertia of trimaran,and validated the feasibility of the assessment method.
The research and application of trimaran push on the development of high speed ship.Seakeeping property plays an important role in the performance of the trimaran sailing at sea,while the roll radius of inertia is a basic property that will have impacts on the rolling natural period and ship stability.Because of the trimaran＇s special structure,assessment of radius of inertia is a little bit different from single hull ship.Througgh a threebody beam model and its numeration results,this paper found the key parameters,proposed an estimated formula for the radius of inertia of trimaran,and validated the feasibility of the assessment method.
2011, 6(5): 73-77.
DOI: 10.3969/j.issn.16733185.2011.05.015
Abstract：
采用CFD软件Fluent对二维矩形液舱不同舱内水深、不同激振频率时的横荡进行数值计算,并将数值结果与实验结果进行比较。结果表明,Fluent可以模拟自由面的翻卷和破碎运动现象,其对于距自由面较深点处流体载荷的计算结果与实验值相符合,但对于自由面附近点,尤其是舱顶上点处的砰击载荷,其计算结果与实验值差别较大。因此,对大幅晃荡的数值模拟仍需进一步研究。
2011, 6(5): 78-82.
DOI: 10.3969/j.issn.16733185.2011.05.016
Abstract：
对船用升降机动态特性的研究一直以来都是升降机研究领域的一个薄弱环节。针对船用升降机的特殊性,根据曳引式升降机的物理模型建立升降机垂直方向上的动力学模型,并结合模态分析法研究该模型,得出升降机位置对其固有频率的影响。以船体振动中螺旋桨和主机振动频率为激励频率,将理想电气速度曲线引入系统中,运用Matlab软件模拟系统响应的全过程,得出船用升降机的一些基本运行特性。
2011, 6(5): 83-88.
DOI: 10.3969/j.issn.16733185.2011.05.017
Abstract：
Based on the laminate equivalent stiffness model,the laminates of composite ship hull were simplified as orthotropic lamina,and using degenerated 3D single lamina a whole ship finite element（FE） model was established.With this model,stiffness of equivalent lamina and grid refinement was adjusted to precisely reflect mechanical properties of laps with local reinforcement.The results from the FE calculations on the modals,stiffness and local stress of whole ship under different load conditions were compared with the experimental results.It shows that using this method not only consume less working load but also can meet the requirement of engineering application.
Based on the laminate equivalent stiffness model,the laminates of composite ship hull were simplified as orthotropic lamina,and using degenerated 3D single lamina a whole ship finite element（FE） model was established.With this model,stiffness of equivalent lamina and grid refinement was adjusted to precisely reflect mechanical properties of laps with local reinforcement.The results from the FE calculations on the modals,stiffness and local stress of whole ship under different load conditions were compared with the experimental results.It shows that using this method not only consume less working load but also can meet the requirement of engineering application.
2011, 6(5): 89-93.
DOI: 10.3969/j.issn.16733185.2011.05.018
Abstract：
为解决多波束扫描天线阵中多接收通道的一致性问题,并简化多波束形成所需的复杂波束形成网络,采用电抗加载方法设计了仅需一个输出通道的五元多波束扫描天线阵。仿真结果表明,该天线阵采用MUSIC算法,能实现最多4个信号到达方向（DOA）的较精确估计。另外,对信噪比、采样点数、信号角间距对信号到达方向估计效果的影响进行了定量分析。该天线阵的设计方法与计算结果对电抗加载高频地波雷达（HFSWR）天线阵的优化设计与工程应用具有一定的指导意义。
2011, 6(5): 94-97.
DOI: 10.3969/j.issn.16733185.2011.05.019
Abstract：
针对舰艇、轮船等经常处于低频圆锥运动、角机动等恶劣工作环境,传统姿态更新的误差补偿方法在多子样更新中补偿效果较差的问题,提出了一种改进方法。通过建立角增量的2N2阶近似模型并利用其各阶导数之间的解析关系,实现了对等效旋转矢量的进一步修正。使用参数解析法与改进算法分别推导研究了四子样情况下的优化结果,并分析研究了改进算法在四子样以上情况下的适用性。研究表明,与参数解析法相比,改进算法可以在四子样及四子样以上的情况下简单直观地得到更加精准的优化系数,且与四子样参数解析法相比,其误差缩小了2个数量级,同时也比五子样参数解析法更精确。
2011, 6(5): 98-102.
DOI: 10.3969/j.issn.16733185.2011.05.020
Abstract：
The slave station of ship energy management system（SEMS） transmitting data to master station places significant demands on the abilities of realtime and reliability.On the one hand,it requires the realtime transmission of general data frames with largecapacity,on the other hand,it must be reliable while receiving dynamic configuration frames and command frames from master station,and in turn transmitting fault record frame back to the master station.For this purpose,we proposed an Ethernet structure that could satisfy the requirements of realtime data transmission with high reliability.The structure was established by using ARM processor of CortexM3 kernel as the hardware platform,while μCOSII realtime operating system（LwIP protocol stack was transplanted） was adopted as the software platform.From communication experiments,the proposed scheme proovides good realtime and reliability,and achieves different requirements for transmitting different data frames in SEMS.
The slave station of ship energy management system（SEMS） transmitting data to master station places significant demands on the abilities of realtime and reliability.On the one hand,it requires the realtime transmission of general data frames with largecapacity,on the other hand,it must be reliable while receiving dynamic configuration frames and command frames from master station,and in turn transmitting fault record frame back to the master station.For this purpose,we proposed an Ethernet structure that could satisfy the requirements of realtime data transmission with high reliability.The structure was established by using ARM processor of CortexM3 kernel as the hardware platform,while μCOSII realtime operating system（LwIP protocol stack was transplanted） was adopted as the software platform.From communication experiments,the proposed scheme proovides good realtime and reliability,and achieves different requirements for transmitting different data frames in SEMS.
2011, 6(5): 103-107.
DOI: 10.3969/j.issn.16733185.2011.05.021
Abstract：
Ship deployment and repair activities should be managed in accordance with its own periodical repair structure throughout the life span of ship,however,for the fleetwide repair activities,it must be carried out under the guidance of the periodical repair structure of other ships in the fleet,that is to say,the repair should proceeds in concert with the other ship repair schedule,so as to expand the deployment period of fleet by obtaining optimal periodical repair structures of all ships.Quantitatively modeling the periodical structure for ship repair,a repair scheduling model was established to optimize the deployment capability of fleet by the use of genetic algorithm.The analyses of examples show that the deployment period of fleet will be expanded up to 110 months based on the optimal periodical repair structure,50 months longer than that without optimization.
Ship deployment and repair activities should be managed in accordance with its own periodical repair structure throughout the life span of ship,however,for the fleetwide repair activities,it must be carried out under the guidance of the periodical repair structure of other ships in the fleet,that is to say,the repair should proceeds in concert with the other ship repair schedule,so as to expand the deployment period of fleet by obtaining optimal periodical repair structures of all ships.Quantitatively modeling the periodical structure for ship repair,a repair scheduling model was established to optimize the deployment capability of fleet by the use of genetic algorithm.The analyses of examples show that the deployment period of fleet will be expanded up to 110 months based on the optimal periodical repair structure,50 months longer than that without optimization.
2011, 6(5): 108-112.
DOI: 10.3969/j.issn.16733185.2011.05.022
Abstract：
The parts need to be moved in/out from the equipment in ship cabins with a proper and feasible path when the Assembly/Disassembly is implemented.Usually,motion planning is used to find the Assembly/Disassembly path.Among the existing motion planning algorithms,RRTConCon algorithm has higher efficiency than that of other algorithms and is suitable for the motion planning of ship parts＇ Assembly/Disassembly,but it has low efficienccy with motion planning for narrow passages in ship cabins because of the random adding of free configurations.So,we proposed one kind of RRTGaussion algorithm with Gaussion sampling based on RRTConCon algorithm.The algorithm used the Gaussian sampling strategy that sampled less in large open regions while more in complex regions and narrow passages,and then based on this the local planner was used to try to connect these samples with a path.The proposed algorithm was validated in virtual environment.The experiments show that in solving the motion planning problems for narrow passages in ship cabins,the proposed RRTGaussion algorithm has higher efficiency than RRTConCon algorithm.
The parts need to be moved in/out from the equipment in ship cabins with a proper and feasible path when the Assembly/Disassembly is implemented.Usually,motion planning is used to find the Assembly/Disassembly path.Among the existing motion planning algorithms,RRTConCon algorithm has higher efficiency than that of other algorithms and is suitable for the motion planning of ship parts＇ Assembly/Disassembly,but it has low efficienccy with motion planning for narrow passages in ship cabins because of the random adding of free configurations.So,we proposed one kind of RRTGaussion algorithm with Gaussion sampling based on RRTConCon algorithm.The algorithm used the Gaussian sampling strategy that sampled less in large open regions while more in complex regions and narrow passages,and then based on this the local planner was used to try to connect these samples with a path.The proposed algorithm was validated in virtual environment.The experiments show that in solving the motion planning problems for narrow passages in ship cabins,the proposed RRTGaussion algorithm has higher efficiency than RRTConCon algorithm.
2011, 6(5): 113-116.
DOI: 10.3969/j.issn.16733185.2011.05.023
Abstract：
In order to enhance the quality and the cost effectiveness of ship maintenance,the requirement as to applying a sound set of rationales and scientific reasoning on the individual tendering project of maintenance is of significance to the ship operators.As this assessment is more likely to focus on overall planning and sustainable maintenance,so a series of indices for the assessment model were put forward,and the weight of each index was determined by the Analytical Hierarchy Process（AHP）.Base on this,fuzzy comprehensive assessment method was used to minimize the impact of subjective factors,resulting in a more accurate and definite outcome.TThis model was validated by an actual assessment.
In order to enhance the quality and the cost effectiveness of ship maintenance,the requirement as to applying a sound set of rationales and scientific reasoning on the individual tendering project of maintenance is of significance to the ship operators.As this assessment is more likely to focus on overall planning and sustainable maintenance,so a series of indices for the assessment model were put forward,and the weight of each index was determined by the Analytical Hierarchy Process（AHP）.Base on this,fuzzy comprehensive assessment method was used to minimize the impact of subjective factors,resulting in a more accurate and definite outcome.TThis model was validated by an actual assessment.
