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1.
This paper describes a soil‐structure coupling method to simulate blast loading in soil and structure response. For the last decade, simulation of soil behavior under blast loading and its interaction with semi buried structure in soil becomes the focus of computational engineering in civil and mechanical engineering communities. In current design practice, soil‐structure interaction analysis often assumes linear elastic properties of the soil and uses small displacement theory. However, there are numerous problems, which require a more advanced approach that account for soil‐structure interaction and appropriate constitutive models for soil. In simplified approaches, the effect of soil on structure is considered using spring‐dashpot‐mass system, and the blast loading is modeled using linearly decaying pressure–time history based on equivalent trinitrotoluene and standoff distance, using ConWep, a computer program based on semi‐empirical equations. This strategy is very efficient from a CPU time computing point of view but may not provide accurate results for the dynamic response of the structure, because of its significant limitations, mainly when soil behavior is strongly nonlinear and when the buried charge is close to the structure. In this paper, both soil and explosive are modeled using solid elements with a constitutive material law for soil, and a Jones–Wilkins–Lee equation of state for explosive. One of the problems we have encountered when solving fluid structure interaction problems is the high mesh distortion at the contact interface because of high fluid nodal displacements and velocities. Similar problems have been encountered in soil structure interaction problems. To prevent high mesh distortion for soil, a new coupling algorithm is performed at the soil structure interface for structure loading. The coupling method is commonly used for fluid structure interaction problems in automotive and aerospace industry for fuel sloshing tank, and bird impact problems, but rarely used for soil structure interaction problems, where Lagrangian contact type algorithms are still dominant. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
2.
This paper outlines the development as well as implementation of a numerical procedure for coupled finite element analysis of dynamic problems in geomechanics, particularly those involving large deformations and soil-structure interaction. The procedure is based on Biot’s theory for the dynamic behaviour of saturated porous media. The nonlinear behaviour of the solid phase of the soil is represented by either the Mohr Coulomb or Modified Cam Clay material model. The interface between soil and structure is modelled by the so-called node-to-segment contact method. The contact algorithm uses a penalty approach to enforce constraints and to prevent rigid body interpenetration. Moreover, the contact algorithm utilises a smooth discretisation of the contact surfaces to decrease numerical oscillations. An Arbitrary Lagrangian–Eulerian (ALE) scheme preserves the quality and topology of the finite element mesh throughout the numerical simulation. The generalised-α method is used to integrate the governing equations of motion in the time domain. Some aspects of the numerical procedure are validated by solving two benchmark problems. Subsequently, dynamic soil behaviour including the development of excess pore-water pressure due to the fast installation of a single pile and the penetration of a free falling torpedo anchor are studied. The numerical results indicate the robustness and applicability of the proposed method. Typical distributions of the predicted excess pore-water pressures generated due to the dynamic penetration of an object into a saturated soil are presented, revealing higher magnitudes of pore pressure at the face of the penetrometer and lower values along the shaft. A smooth discretisation of the contact interface between soil and structure is found to be a crucial factor to avoid severe oscillations in the predicted dynamic response of the soil. 相似文献
3.
为研究浅埋输水隧道内部流体对隧道地震响应的影响,考虑黏弹性人工边界、土壤的非线性、隧道结构刚度有效率及流-固耦合作用,建立了双线隧道-土体-流体相互耦合作用的力学模型。通过刚度折减试验得到衬砌环环向、径向、轴向刚度,进而引入正交各向异性连续材料作为衬砌材料模型。采用基于任意拉格朗日-欧拉（ALE）描述法的流-固耦合方法,对上海某大直径双线输水隧道在流体作用下的地震响应进行了分析。通过与等效密度法对比,验证耦合模型对于处理输水隧道多物质非线性耦合抗震问题的可行性。计算结果表明,在水平方向地震激励下,无论一致激励或是非一致激励流体对隧道地震变形和内力都有较大影响,但对位移影响较小;对于不同隧道内水量,隧道弯矩均集中于衬砌隧道45°交叉斜线位置;相比于一致激励,非一致激励增强隧道地震位移和变形响应是明显的。 相似文献
4.
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
5.
Analysis of large deformation of geomaterials subjected to time‐varying load poses a very difficult problem for the geotechnical profession. Conventional finite element schemes using the updated Lagrangian formulation may suffer from serious numerical difficulties when the deformation of geomaterials is significantly large such that the discretized elements are severely distorted. In this paper, an operator‐split arbitrary Lagrangian–Eulerian (ALE) finite element model is proposed for large deformation analysis of a soil mass subjected to either static or dynamic loading, where the soil is modelled as a saturated porous material with solid–fluid coupling and strong material non‐linearity. Each time step of the operator‐split ALE algorithm consists of a Lagrangian step and an Eulerian step. In the Lagrangian step, the equilibrium equation and continuity equation of the saturated soil are solved by the updated Lagrangian method. In the Eulerian step, mesh smoothing is performed for the deformed body and the state variables obtained in the updated Lagrangian step are then transferred to the new mesh system. The accuracy and efficiency of the proposed ALE method are verified by comparison of its results with the results produced by an analytical solution for one‐dimensional finite elastic consolidation of a soil column and with the results from the small strain finite element analysis and the updated Lagrangian analysis. Its performance is further illustrated by simulation of a complex problem involving the transient response of an embankment subjected to earthquake loading. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
6.
In this paper, an arbitrary Lagrangian–Eulerian (ALE) method is generalized to solve consolidation problems involving large deformation. Special issues such as pore‐water pressure convection, permeability and void ratio updates due to rotation and convection, mesh refinement and equilibrium checks are discussed. A simple and effective mesh refinement scheme is presented for the ALE method. The ALE method as well as an updated‐Lagrangian method is then used to solve some classical consolidation problems involving large deformations with different constitutive laws. The results clearly show the advantage and efficiency of the ALE method for these examples. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
7.
利用有限元流固耦合理论来模拟二维、三维海啸触发阶段的动态过程,将海啸可能的触发类型分离出来独自模拟分析,并解决了触发过程中,流固计算可能失效而面临的问题,从形变图,压强图以及能量图多侧面地表达出流固耦合在海啸触发模拟中的可行性.由于不需要进行浅水波近似,因此所使用的计算方法和结果可推到较广的使用范围. 相似文献
8.
吸力式筒形基础在海洋工程中已获得越来越广泛地应用,其安装过程的数值模拟对指导工程实践具有重要意义。在大型通用有限元软件ABAQUS平台上建立了二维轴对称模型,基于ALE（任意拉格朗日-欧拉法）技术模拟了黏土中吸力筒的大变形沉贯过程。模拟过程利用了子程序VUFIELD控制土体的不排水抗剪强度和弹性模量随土体深度变化。参照离心机试验及理论计算,对模型进行验证。利用已验证模型分析不同吸力下沉贯阻力、土塞高度,并讨论了筒壁摩擦特性。数值计算结果表明,ALE技术能有效地模拟吸力筒贯入过程,避免网格畸变。贯入方式对贯入阻力影响很大,吸力式贯入阻力明显低于压力式贯入阻力。进一步研究发现,随着最终吸力值的增大,沉贯阻力会显著降低,土塞高度会显著提高。对内壁摩擦特性的研究表明,内壁摩擦阻力是导致沉贯阻力改变的主要因素,并且相比吸力式贯入方式,筒壁摩擦特性会对压力式贯入造成更大的影响。 相似文献
9.
The high-speed water entry process of an autonomous underwater vehicle (AUV) has a strong impact nonlinearity, and a cavity formed by air and water will often be generated as part of the entry process. The shape of the water-entry cavity plays an important role in the load characteristics and stability of the water-entry trajectory. In this paper, a numerical model for describing the cavity and impact load characteristics of a high-speed water-entry AUV is established. The simulation results such as cavity shape and impact load are compared with experimental data. The good agreement between the numerical results and those of the experiments reveals the accuracy and capability of the numerical algorithm. Subsequently, the arbitrary Lagrange-Euler (ALE) numerical algorithm is used to simulate and analyse the variation laws of the cavity characteristics and impact loads with different head shapes, water-entry velocities, water-entry angles and angles of attack. The results obtained in this study can provide a good reference for the trajectory control and structural design of the AUV. 相似文献
10.
有限元法被广泛用于解决几何和材料非线性的问题,但标准的有限元方法难以有效解决某些材料的大变形问题和计算中的网格扭曲问题。任意拉格朗日-欧拉法（ALE法）吸取了拉格朗日和欧拉法的优点,并克服了两者的缺点,可用于解决仅用拉格朗日或欧拉有限元法所难以解决的问题。基于ALE有限元方法和弹塑性大变形基本原理,研究了岩土工程中土质边坡在自重作用下的稳定问题;计算结果不仅能直观地显示失稳时的大变形状态,并能确定较符合实际的临界滑移面形状;同时分析了含软弱夹层复杂土质边坡的稳定性。结果表明,ALE方法能有效分析土质边坡的稳定性问题,适用于岩土工程的弹塑性分析。 相似文献