水下耐压壳体结构可靠性的设计方法

在水下耐压壳体的环肋圆柱壳结构设计中,为了保证结构的强度和稳定性,几何参数的确定必须要满足规范所要求的五个约束条件.完工后的几何尺度与设计几何尺度存在着一定的误差,可将这些误差分布密度函数认为服从正态分布,利用其约束条件结合可靠性理论建立环肋圆柱壳耐压壳体可靠性分析方法,以实际测量中统计得到的数据为已知条件给出了可靠度计算方法.     

电动汽车轴向轮毂电机的工作特性

本文针对轴向永磁轮毂电机变负载调速时的传动性能,分析了启动过程中的转矩和转速等启动性能以及启动完成后的磁密、涡流损耗、传动效率等工作性能。首先运用矢量磁位法建立了数学模型,得到气隙磁密、转矩、轴向力和传动效率等工作参数的数学表达式,并运用Matlab软件进行了系统气隙磁密的数值计算;然后利用Magnet软件模拟得到了不同输入转速和不同变负载系数下启动过程的转矩和转速的变化规律,接着分析启动完成后稳定运行时的磁密、涡流损耗和传动效率;最后搭建模拟的轴向磁通轮毂电机实验平台,测量得到了不同输入转速下的转速、转矩和传动效率,验证了理论分析和模拟的正确性。本文研究成果有利于轴向永磁磁通轮毂电机传动性能的研究,对提高轮毂电机工作效率的提高具有重要意义。     

Dynamic response analysis of load transfer of topsides from T-barge onto twin-barge in floatover installation

The twin-barge floatover method is a promising approach in the topsides installation of the offshore platform. However, the topsides transfer onto the twin-barge is a challenging task and is seldom investigated. This study focuses on the floatover load transfer operation of the topsides onto the twin-barge by a T-shaped barge and investigates the dynamic responses of the three proximate barges in the operation. The floatover mating process was experimentally simulated by three representative intermediate stages, including 0%, 50%, and 100% stages. The barge and topsides motions, the relative motions of mating points, the contact loads on mating units, tether forces, and mooring forces at various environmental conditions were analyzed. The three floating barges experienced large surge drift motions as well as the sway and yaw drift motions in head seas because of the unsymmetrical configurations. Although a relative radial distance between mating points occurred and exceeded the capture radius of the mating unit at limited instants, the relative motions were to a great extent within the capture radius, indicating the feasibility of the twin-barge floatover method. Comparisons of the loads at the three stages show that the mating units and the tether lines were subjected to larger impact impulse loads at the 0% stage than the 100% stage.     

Analysis on maneuvering motion characteristics of submarine under static moment in vertical plane北大核心CSCD

[Objectives]Aiming at the problem of poor depth-changing ability of the stern rudder of submarine at low speed, and the problem of reversing the movement trend is difficult when the stern rudder is stuck and encountering abrupt changes of seawater density in the vertical steering maneuver. This paper conducts the mechanism research of static moment maneuver. [Methods]First, it is proved through theoretical analysis that the static moment maneuver can eliminate the reversed velocity phenomenon of the stern rudder. Then, the surfacing process under the static moment maneuver and the rudder hydrodynamic control is numerically simulated. [Results]The simulation results show that the static moment maneuver can make the submarine maintain good vertical plane maneuverability at low speed, eliminate the reversed velocity phenomenon of the stern rudder, and avoid excessive trim angle of the submarine at high speed. At the same time, the recovery effect of the two emergency situations of rudder jamming and falling deep has been improved. [Conclusions]The static moment maneuver is beneficial to the maneuverability and safety of the submarine. The research in this article can provide a reference for the maneuverability design of submarine. © 2023 The Author(s).     

面向刚度设计的 GFRP 和 VRB/GFRP 混合层合板应变能密度分布研究

针对 VRB/GFRP混合结构刚度优化设计复杂而耗时这一问题，利用有限元法分析了 GFRP铺层角度和铺层数量、VRB厚度分布形式对两种层合板刚度特性及各组分应变能密度分布的影响规律。研究结果表明，应变能密度越小能表征更好的刚度性能；抗弯与抗凹工况下，采用# （0/90） 铺层角度、增加 GFRP铺层数量以及 VRB采用 0.9-1.8-0.9 mm 的厚度分布形式时，VRB/GFRP层合板各组分的应变能密度分布更加均匀，从而获得更好的刚度性能。