FEM modeling for 3D dynamic analysis of deep-ocean mining pipeline and its experimental verification

3D dynamic analysis models of 1000 m deep-ocean mining pipeline, including steel lift pipe, pump, buffer and flexible hose, were established by finite element method (FEM). The coupling effect of steel lift pipe and flexible hose, and main external loads of pipeline were considered in the models, such as gravity, buoyancy, hydrodynamic forces, internal and external fluid pressures, concentrated suspension buoyancy on the flexible hose, torsional moment and axial force induced by pump working. Some relevant FEM models and solution techniques were developed, according to various 3D transient behaviors of integrated deep-ocean mining pipeline, including towing motions of track-keeping operation and launch process of pipeline. Meanwhile, an experimental verification system in towing water tank that had similar characteristics of designed mining pipeline was developed to verify the accuracy of the FEM models and dynamic simulation. The experiment results show that the experimental records and simulation results of stress of pipe are coincided. Based on the further simulations of 1 000 m deep-ocean mining pipeline, the simulation results show that, to form configuration of a saddle shape, the total concentrated suspension buoyancy of flexible hose should be 95%?105% of the gravity of flexible hose in water, the first suspension point occupies 1/3 of the total buoyancy, and the second suspension point occupies 2/3 of the total buoyancy. When towing velocity of mining system is less than 0.5 m/s, the towing track of buffer is coincided with the setting route of ship on the whole and the configuration of flexible hose is also kept well.     

Suspension principle of deep-ocean nodule collector简

To make sure that the nodule collector can walk on the soft sediments of seafloor effectively, suspension principle of deep-ocean nodule collector is proposed. The supporting and driving mechanisms are separated to avoid collector sinking. The supporting mechanism is a streamlined body with large and smooth supporting area. The grounding pressure is reduced to 0.5-1 N/cm^2 to make sure that the sinkage is limited. The impellers serve as the driving mechanism to supply enough driving power. The position between the supporting mechanism and the driving mechanism can be adjusted according to the operating condition to decrease the walking resistance and to increase driving efficiency. The test results indicate that the collector can walk on the surface of the soft sediments with the limited sinkage. The traction forces were up to 800 kg and the sinkage of the impeller was under the limitation.     

轮胎受力分析

轮胎力学是计算力学领域中比较复杂而新兴的一个分支。它伴随着非线性有限元法发展而产生。本文着重介绍重直载荷作用下充气轮胎的两种计算方法。一种是傅氏级数解法,把非对称的垂直载荷展成傅氏级数,从而将它简化为轴对称问题求解;另一种是几何非线性接触问题解法,把轮胎看作与地面接触的离散了的物体,采用接触体有限元法解得变形。有关算例已列于文中。结果表明,上述分析方法可行而正确,不仅可供轮胎设计工作者应用而且为类似结构分析提供了有力工具。     

输电自立塔多塔腿有限元分析

对输电自立塔建立桁架有限元模型进行几何非线性的分析.针对输电自立塔自身结构的特点,在进行多塔腿分析时,对总刚度矩阵的集成提出了一种全新的方法:保留总刚度矩阵中相同的部分,将不同的部分进行替换,并应用VB与Fortran语言编制了一个分析软件.通过算例表明,在进行多塔腿计算时,计算速度大为加快,计算结果能满足设计分析要求.     

水管冷却等效热传导方程中混凝土初温的研究

针对进行水管冷却的混凝土浇筑仓温度场仿真计算时,水管冷却等效热传导方程中的混凝土初温的计算存在不同的算法,采用水管冷却精细有限元法和水管冷却等效热传导法,对含冷却水管的混凝土棱柱体进行温度场对比分析,研究了水管冷却等效热传导法中混凝土初始温度的计算方法.分析认为水管冷却等效热传导方程中的混凝土初温应是含冷却水管的混凝土棱柱体在通水开始时刻的混凝土平均温度,该平均温度可由混凝土棱柱体单元高斯点温度与高斯点所占体积的乘积除于混凝土棱柱体单元体积获得.     

有限元动态方程差分解法的研究

构造了一种求解有限元动态方程的稳定的差分格式,并将其成功地应用于求解结构振动问题,这种差分方法对求解有限元动态方程是有效的。     

低温推进剂弹状汽泡形成过程的数值模拟研究

弹状汽泡形成过程的准确预测对于分析和预防低温推进剂的间歇泉现象具有重要意义.分析了竖直推进剂管内汽泡的碰撞及聚合机理, 建立了描述这一过程的MUSIG模型并进行了数值计算.与实验结果对比表明, 建立的模型能够有效预测竖直低温推进剂输送管内的汽泡起始聚合高度、弹状汽泡形成高度以及汽泡尺寸分布等重要参数, 为间歇泉现象的研究和抑制提供了理论依据.     

Stability and reliability of pit slopes in surface mining combined with underground mining in Tonglushan mine

Slope stability is of critical importance in the process of surface-underground mining combination. The influence of underground mining on pit slope stability was mainly discussed, and the self-stabilization of underground stopes was also studied. The random finite element method was used to analyze the probability of the rock mass stability degree of both pit slopes and underground stopes. Meanwhile, 3D elasto-plastic finite element method was used to research into the stress, strain and rock mass failure resulting from mining. The results of numerical simulation indicate that the mining of the underground test stope has certain influence on the stability of the pit slope, but the influence is not great. The safety factor of pit slope is decreased by 0.06, and the failure probability of the pit slope is increased by 1.84%. In addition, the strata yielding zone exists around the underground test stope. The results basically conform to the information coming from the field monitoring.     

Nonlinear static response of piezoelectric plates considering electro-mechanical coupling

Nonlinear static analysis of piezoelectric plates has been carried out using nonlinear finite element method considering electro-mechanical coupling. The geometrical nonlinearity has been taken into account and electric potential is assumed to be quadratic across the plate thickness. The governing equations are obtained using potential energy and Hamilton’s principle that includes elastic and piezoelectric effects. The finite element model is derived based on constitutive equation of piezoelectric material accounting for coupling between elasticity and electric effect using higher order plate elements. Results are presented for piezoelectric plate under different mechanical boundary conditions. Numerical results for the plate are given in dimensionless graphical forms. Effects of boundary conditions on linear and nonlinear response of the plate are also studied. The numerical results obtained by the present model are in good agreement with the available solutions reported in the literature.     

Critical velocity and dynamic respondency of pipe conveying fluid

0　ＩＮＴＲＯＤＵＣＴＩＯＮＩｔｉｓｓｈｏｗｎｉｎＦｉｇ .1ｔｈａｔｔｈｅｎａｔｕｒｅｆｒｅｑｕｅｎｃｙｏｆｆｌｕ ｉｄ ｃｏｎｖｅｙｉｎｇｐｉｐｅｓｒｅｄｕｃｅｗｈｅｎｔｈｅｆｌｏｗｖｅｌｏｃｉｔｙｉｎｃｒｅａｓｅ .Ｉｆｆｌｏｗｖｅｌｏｃｉｔｙｉｎｃｒｅａｓｅｓｔｏｔｈｅｃｒｉｔｉｃａｌｖａｌｕｅ ,ｐｉｐｅｓｗｉｌｌｂｅｕｎｓｔａｂｌｅ .Ｆｏｒｔｈｉｓｐｒｏｂｌｅｍ ,ｕｓｉｎｇｆｉｎｉｔｅｅｌｅｍｅｎｔｍｅｔｈｏｄ ,ｔｈｅｃｕｒｖｅｓｏｆｆｕｎｄａｍｅｎｔａｌｆｒｅｑｕｅｎｃｙ ｆｌｏｗｉｎｇｖｅ …     

预应力钢筒混凝土管(PCCP)的数值仿真分析

根据预应力钢筒混凝土管的结构型式及特点,分析国内外有关PCCP数值研究现状.采用大型有限元分析软件ANSYS研究PCCP从制造、施工到运行的各个阶段的力学特性,采取依次施加预应力、管自重、回填土压、流体自重及内水压力等荷载方法研究PCCP的结构受力特性,得出PCCP的变形、应力、裂缝在不同荷载作用下的变化规律,以及裂缝出现后PCCP的应力重分布方式,为PCCP的设计制造和运行管理提供数值仿真分析方法和路线.     

板壳非线性分析的三维退化壳条

将三维退化壳条应用到板壳结构的几何和材料非线性分析,几何非线性是通过Von Karman假定考虑的．利用作者提出的“拟刚度矩阵法”,消除了有限条法在非线性分析时刚度矩阵与级数项的耦合,大大简化了有限条在处理非线性问题时的数值计算．两个钢筋混凝土板壳算例的结果验证这种理论方法的有效性和准确度。     

径向非均质黏性阻尼土中管桩纵向振动特性

为分析施工扰动对管桩纵向振动特性的影响,发展建立了基于复刚度传递径向多圈层平面应变模型黏性阻尼土中管桩-土体纵向耦合振动模型.利用拉普拉斯变换和径向复刚度传递,得到桩芯土与桩身界面处的复刚度,并利用桩土界面上位移连续、力平衡条件推导得出桩顶动力阻抗的解析解,通过进一步参数化分析分别探讨桩长径比、桩内外径比、桩身弹性模量、土体黏性阻尼系数、桩周土施工扰动程度和扰动范围对桩顶纵向振动特性的影响规律.结果表明:管桩桩长增加使得桩顶动力阻抗曲线振幅和共振频率降低;桩芯土体对桩体可以起到减震作用;桩顶动刚度和动阻尼曲线振幅随施工引起桩周土软(硬)化程度增加而减小(增大);管桩桩顶动力阻抗振幅水平随施工扰动引起桩周土体软(硬)范围增加而增大(减小),此种影响仅在近桩小范围内较为明显,超出该范围即大幅衰减至稳定;当施工扰动较明显时,在管桩纵向振动特性分析中宜考虑此种桩周土体径向非均质性的影响.     

多柔体系统刚柔耦合动力学有限单元法

传统的多柔体系统动力学建模理论 ,往往基于小变形线性动力学的基本假定 ,采用线性的Cauchy应变理论描述应变—位移关系。但是 ,对于具有刚性旋转的位移场来说 ,Cauchy应变理论并不适用。本文采用Green Lagrange应变理论 ,描述有大位移运动的梁单元的非线性位移—应变关系 ,通过对应变能的分析和线性化处理 ,建立起相对变形坐标一阶精确的一致线性化的多柔体系统有限元模型 ,仿真算例的结果验证了该方法的有效性和结构中的几何非线性对系统动力学响应的重要作用。     

载流管道固液耦合振动计算

根据Hamilton原理,用有限元法推导载流管道的固液耦合振动方程,用QR法计算不同边界条件下管道的临界速度和固有的频率,用Newmanrk计算了管道对阶跃载载荷的响应,所得结果可用于火箭发动机燃料馈给管道,水轮机供水管道和其他管道的设计与研究。     

深厚粘土层冻结管受力机理模拟分析

针对杨村煤矿副井407．3m～445．35m段特厚砂质粘土层冻结管断裂情况,本文利用有限元软件ABAQUS进行受力机理模拟分析,得到冻结管应力、位移分布规律,从而判断出冻结管断裂位置在砂质粘土与砂土交界处,通过与现场监测情况进行对比,分析出冻结管受力断裂主要原因在于两种土层冻胀不同造成的,并提出相关施工建议为后期矿井建设提供参考。     

舰船管路冲击响应的离散时间传递矩阵法

为求解舰船管路在冲击载荷作用下的响应,应用离散时间精细传递矩阵法,编制计算程序,对管路冲击响应进行模拟,形成了一套管路冲击响应计算方法.设计管路冲击试验,对方法进行验证,结果表明,基于离散时间精细传递矩阵法的管路冲击响应计算方法精度较高;同时,建立弯头管路和三通管路有限元模型,与离散时间传递矩阵方法计算结果进行对比,提出的方法既保证了较高的计算精度,同时计算时间大为降低,效率明显提高,可以为管路冲击响应预报和抗冲击设计校核计算提供指导和参考.     

Mechanical performance of a double-face reinforced retaining wall in an area disturbed by mining

The application of a double-face reinforced retaining wall during road construction can reduce engineering costs, speed road paving and have a good influence on environment. An ABAQUS numerical model of a double-face reinforced retaining wall was built. The influence of surface subsidence induced by mining was considered. A physical model test was also performed in the laboratory on a reinforced retaining wall. The influence of subsidence induced by mining was observed. The numerical results match measurements in the laboratory very well. The vertical pressure on the base of the retaining wall, the horizontal displacement of the wall and the horizontal soil pressure acting on the wall were analyzed. The differential settlement of the reinforced belt and axial forces in the wall were also studied.     

Influence of wave and current on deep-sea mining transporting system

As a solution to the breaking of pipeline under high axial force, carbon fiber composite pipe with low density and high intensity is applied to deep-sea mining transporting system. Based on the fact that the transporting pipe is under the forces of gravity, inner liquid, buoyancy as well as hydrodynamic force, geometric nonlinear finite element theory has been applied to analyzing the transporting system. Conclusions can be drawn as follows. Under the interaction of waves and currents, node forces F _X and F _Z acted by the transporting pipe on the mining vehicle are less than 2 kN, which indicates that waves and currents have little influence on the spatial shape of the transporting pipe and the mining vehicle movement. On the other hand, the horizontal force acting on the mining ship could be as large as 106 830 N, which has great influence on the mining system.