聚酯缆动力学行为计算方法研究

The dynamic stiffness of polyester rope presents a complex mechanical performance,and the search for an appropriate calculation method to simulate this property is important.Distorted simulation results eventually yield inaccurate line tension and vessel offset predictions,with the inaccuracy of vessel offset being particularly large.This paper proposes a flexible calculation method for the dynamic behavior of polyester rope based on the dynamic stiffness model.A real-time varying stiffness model of polyester rope is employed to simulate tension response through rope strain monitoring.Consequently,a simulation program is developed,and related case studies are conducted to explore the differences between the proposed method and analytical procedure of the DNV standard.Orcaflex is used to simulate the results of the latter procedure for comparison.Results show the convenience and straightforwardness of the procedure in the selection of an approximate dynamic stiffness model for polyester rope,which leads to an engineering-oriented approach.However,the proposed method is related to line property,which can directly reflect the dynamic behavior of polyester rope.Thus,a flexible calculation method may provide a reference for the simulation of the dynamic response of polyester mooring systems.

Research on the Viscoelasticity of Polyester Mooring Lines Using the Absolute Nodal Coordinate Formulation

The taut mooring system using synthetic fiber ropes has overcome the shortcomings such as the large self-weight of the mooring lines and provides better mooring performance for the floating structures.The polyester rope has attracted much attention among numerous synthetic fiber rope materials due to its lightweight,low price,corrosion resistance,and high strength.Thus,the mooring characteristics of it are worth studying.Polyester mooring lines are flexible in deep water,when a marine structure is moored by them,the geometric nonlinearity such as large displacement,large stretch,and large bending deformation,and the material nonlinearity like viscoelastic of the polyester ropes become complex integrated problems to be studied.Considering the nonlinear phenomenon,the simulation and calculation of a polyester line were carried out by the absolute nodal coordinate formulation(ANCF)in this paper since the ANCF method has advantages in dealing with the significant deformation problems of the flexible structures.In addition,a chain mooring line was also simulated for comparison,and the results show that the polyester ropes reduce the self-weight of the mooring lines and provide sufficient mooring strength at the same time,and the nonlinear phenomenon of the polyester ropes is different from that of the chain mooring lines.

Numerical and Experimental Study on the Dynamics of the Tendon/Top Tension Riser System of a Tension-Leg Platform

In this study,the dynamics of the tendon/top tension riser(TTR)system of a tension-leg platform(TLP)are investigated through an experiment and by using absolute nodal coordinate formulation(ANCF).First,the model test of the TLP system is conducted in the water tank of Harbin Engineering University to examine the motion response of the TLP and the dynamic response characteristics of the tendon and TTR.The test scale ratio is set to 1:66.3.Then,on the basis of the ANCF,the stiffness,external load,and mass matrices of the element are deduced to establish the motion equation of the tendon/riser.Finally,the static and dynamic characteristics of the tendon/TTR system of TLP are analyzed systematically by using the ANCF method.The results are compared with commercial software and test results.The motion response of tendon/TTR is affected by the TLP movement and environmental load simultaneously.The analysis proves the effectiveness and accuracy of the ANCF method despite the low number of riser units,suggesting the superiority of the ANCF method for calculating the dynamics of tendon/riser in the field of ocean engineering.

岩溶地下水系统冷泉和热泉的形成机制:以趵突泉群为例

岩溶地下水和地热水分别是中国北方重要的供水水源和供暖热源,但二者水力联系尚缺乏系统研究;为实现保泉、供水和地热清洁能源开发的三赢,通过含水层/热储层空间分布、同位素测年、水文地球化学场、水动力场、温度场特征及规律分析等方法,揭示了趵突泉泉域岩溶地下水流系统从浅、中循环子系统至深循环子系统,即岩溶地下水至冷泉和热泉的演变过程、驱动机制与响应机理.在地下水位高程差引起的重力势能差驱动下,岩溶地下水沿济南含水层系统从上游浅循环—开放式地下水动力系统,向中游中循环—半开放式地下水动力系统径流,径流途中在济南市区遇不透水的辉长岩体或石炭纪二叠纪砂岩页岩地层阻截,大部分地下水沿垂向强裂隙岩溶发育通道上涌、穿透第四纪砾岩或辉长岩体裂隙发育带喷出地表形成17~18℃的承压上升冷泉.一小部分地下水从深部穿过或从侧面绕过辉长岩体,沿裂隙岩溶通道继续向下游深循环运移,形成弱开放地热水动力系统;高大地热流传导聚热、深大断裂带/侵入岩体—灰岩接触带带状对流聚热、凸起区高热导率分流聚热、盖层低热导率保温聚热、地下水深循环运移传导—对流聚热等五元聚热驱动14~18℃的常温地下水演变为33~95℃的承压热泉(自流地热水).