Journal articles on the topic 'Moment scheme of the finite element'
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Zhao, Wei, Li Bin Zhao, Jian Yu Zhang, and Bang Cheng Han. "Modal Analysis of Magnetic Suspended Control Moment Gyroscope." Applied Mechanics and Materials 50-51 (February 2011): 59–62. http://dx.doi.org/10.4028/www.scientific.net/amm.50-51.59.
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3D finite element models of magnetic suspended control moment gyroscope structure are established by general finite element analysis software. Initial modal analysis scheme of the MS-CMG structure, in which the frame and gyro-chamber are analyzed separately, is described. A new modal analysis scheme that the MS-CMG is analyzed as a whole structure is presented. The connection between the gyro-chamber and frame is realized by defining a revolution pairs. The numerical predictions from two modal analysis schemes show obvious difference. The new scheme is more reliable since it simulates the real wok status of MS-CMG.
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Jiang, Wei Guo. "The Finite-Element Simulation for Reinforced Concrete Frames Including the Softening Behaviour." Advanced Materials Research 243-249 (May 2011): 204–8. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.204.
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In performance-based seismic design method, it is very important to have a good command of the nonlinear performance of a structural system, including in the collapse stage. In this paper, a nonlinear finite-element analysis on reinforced concrete moment frames is carried out. After studying the forces and deformations behavior in beam-column elements, the element stiffness matrix of distributed plasticity beam-column element is deduced using the Cotes scheme with 5 integration points. During the occurrence and development of plastic hinges, sections at some integration points will experience loading, unloading and reverse loading and the stiffness of these sections will experience various status. A quadrilinear form moment-curvature relationships with curvature- softening behavior and the hysteretic modes are used in the nonlinear static analysis program. The numerical analysis is carried out and the numerical results validate the load-displacement relationships and the yield mechanism of experiment frames.
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Ju, Shen Haw, and Hsin Hsiang Hsu. "Beam moment and shear force calculations using digital-camera experiments." Advances in Mechanical Engineering 11, no. 6 (June 2019): 168781401986067. http://dx.doi.org/10.1177/1687814019860675.
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This article presents an image-based method to find the beam moment and shear force using the measured beam displacements. A least-squares method is first developed to find the rotations and lateral displacements at beam ends using the measured displacements along the beam. Then, the moments and shear forces of this beam segment are obtained using the matrix formulation including shear deformation and large displacement effects. Two experimental schemes, image symbol dot and image-correlation methods, were used to validate the accuracy of the proposed scheme. The comparison of the results between the finite element analysis and the two methods shows acceptable accuracy. Although this method is mainly applied to the elastic region, one can still find the moment and shear force at the inelastic region using the equilibrium equation.
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Su, Wen Zheng. "Finite Element Formulation for the Vibration Analysis of Couple-Stress Continuum." Applied Mechanics and Materials 367 (August 2013): 156–60. http://dx.doi.org/10.4028/www.scientific.net/amm.367.156.
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This paper proposed a finite element formulation to analysis the vibration of couple-stress continuum. A four-node discrete couple-stress element relaxed the requirement of C1 continuity is developed. This element is modified by a bubble function, based on the classical four-ode Lagrange element. The element includes the internal bending constants and the internal initial moment of rotation. Numerical examples show that the present FE scheme is accurate for the eigenvalue analysis of couple-stress continuum structures, especially for the low order frequency analysis.
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Sun, Xue Xian, Yong Wang, and Feng Chen. "Design Application in Suspender Tensile Force of Tied-Arch Bridges Based on Inversion Optimization Method." Applied Mechanics and Materials 226-228 (November 2012): 1586–90. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.1586.
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Taking an actual tied-arch bridge project as the background, this thesis has a system static analysis by building up the finite element analysis model with Midas/civil, a large-scale FEM software, then establishes a mathematical optimization model for the back analysis to suspender tensile forces through two optimization schemes. Scheme one takes the reasonable bending moment distribution and minimum moment stain energy as the optimal control objective function to inverse analysis. Scheme two takes the bending moment distribution of dead load as the control objective of inversion optimization analysis, when the difference of the positive and negative absolute value is the minimum in the moment envelope under the load combination, which thinks about live load on the finished state. Through comparing the analysis results, the thesis demonstrates that the inversion optimization method could fulfill the requirement of factual project and be widely used for determining suspender tensile forces of tie-arch bridges.
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Ivanchenko, Grigory, Yurii Maksimyuk, Andriy Kozak, and Ivan Martyniuk. "CONSTRUCTION OF SOLVING EQUATIONS OF SEMI-ANALYTICAL METHOD OF FINISHED ELEMENTS FOR PRISMATIC BODIES OF COMPLEX SHAPE." Management of Development of Complex Systems, no. 46 (June 24, 2021): 55–62. http://dx.doi.org/10.32347/2412-9933.2021.46.55-62.
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The article presents an effective numerical approach to the study of arbitrarily loaded massive and thin-walled prismatic bodies of complex shape, the deformation of which can take place beyond the elasticity of the material. The equations of the semi-analytical finite element method (SAFEM) when used to decompose the displacements of Fourier series. The main relations between the spatial problem of the theory of elasticity in a curvilinear coordinate system and the theory of plastic flow for an isotropically reinforcing material under the Mises fluidity condition are presented. In accordance with the method of the moment scheme of finite elements (MSFE), the expressions of deformations of the prismatic finite element due to the nodal values of amplitude displacements are obtained. Formulas for calculating the stiffness matrix coefficients of a finite element (FE) with variable and averaged in the cross-sectional plane mechanical and geometric parameters are derived.
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Kibets, A. I., and M. V. Bezhentseva. "ANALYSIS OF FINITE ELEMENT SOLUTION CONSERVATIVE SMOOTHING INFLUENCE ON THE ZERO ENERGY MODES SUPPRESSION." Problems of strenght and plasticity 83, no. 1 (2021): 101–10. http://dx.doi.org/10.32326/1814-9146-2021-83-1-101-110.
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The problem of high-speed penetration of a non-deformable cylinder into a steel plate is considered. The defining system of equations is formulated in Lagrange variables in a three-dimensional formulation. The equation of motion is derived from virtual work capacities balance. Kinematic relations are recorded in the metric of the current state. The relations of the flow theory with kinematic and isotropic hardening are used as equations of state. The contact interaction of the cylinder and the plate is modeled by non-penetration conditions. The numerical solution of the problem under given boundary and initial conditions is based on the moment scheme of the finite element method and “cross” type explicit time integration scheme. To discretize the defining system of equations with respect to spatial variables, 8-node isoparametric finite elements with multilinear form functions are used. To suppress the high-frequency oscillations of the numerical solution, the procedure of nodal displacement velocities conservative smoothing is used. The smoothing algorithm is based on the momentum conservation law, focused on finite element grids consisting of blocks that are mutually unambiguously mapped to a unit cube. To analyze the nodal displacement velocities monotonicity, the numerical solution splitting in the directions of the finite element grid lines is used. As the results of computer modeling have shown, the finite elements of the plate are exposed large deformations and rotation angles as a rigid whole during local intense dynamic loading. The conservative smoothing procedure influence on the numerical solution stability is analyzed. It is shown that in the problem under consideration, without applying the conservative smoothing procedure, zero-energy modes develop in the contact zone in the finite-element grid of the plate (an hourglass-type instability) and the collision process cannot be modeled before the cylinder rebounds.
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Siekierski, Wojciech. "Analysis of Deck Slab of Reinforced Concrete Gerber-Girder Bridge Widened by Addition of Continuous Steel-Concrete Composite Girders." Baltic Journal of Road and Bridge Engineering 14, no. 2 (June 27, 2019): 271–84. http://dx.doi.org/10.7250/bjrbe.2019-14.443.
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Many Gerber-girder bridges have become obsolete in terms of deck width and load carrying capacity. If bridge replacement is not necessary, additional girders are installed. Sometimes, due to erection convenience, the added girders do not replicate the static scheme of the refurbished structure. Such an arrangement requires special attention to preserve structural durability. An example of the inappropriate arrangement of the widening of a Reinforced Concrete Gerber-girder road bridge is presented together with an alternative concept of refurbishment based on the addition of the continuous steel-concrete girders as the outermost ones. The added deck slab connects the added and the existing parts of the structure. Attention is drawn the static analysis of the added deck slab and the influence of the added outermost girders that do not replicate the static scheme of the existing ones. Due to different static schemes of the existing and the added girders, the traditional method of the deck slab analysis is inappropriate. The Finite Element 3D model is to be applied to access bending moments in the deck slab spans correctly. It is shown that: a) the analysis of the distribution of the bending moments in the existing and the added slab spans, especially near Gerber-hinges, should be based on the Finite Element 3D modelling; b) the analysis should consider live loads acting on the whole width of the Gerber-hinge span; c) the bending moment distribution in the widened deck slab is sensitive to the distance to the Gerber hinge.
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Chen, Guang Hua, De Tian, and Ying Deng. "Main Beam Optimization of Wind Turbine Blade Base on Multi-Objective Genetic Algorithm." Advanced Materials Research 655-657 (January 2013): 496–501. http://dx.doi.org/10.4028/www.scientific.net/amr.655-657.496.
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Take s814 airfoil as an example, established the multi-objective optimization model of moment of inertia and the weight for wind turbine blade main beam,Using the genetic algorithm global optimization algorithm, and given the Pareto solution set of optimal with the form of Pareto front. Select four kinds of optimization results scheme to do finite element calculation. The results shows that the magnitude of moment of inertia accordance with the change trend of main beam deflection, the width and thick of beam cap have great affect on moment of inertia and weight, the nearer aerodynamic center of leading edge, the greater moment of inertia, the thick of web almost no influence on moment of inertia.
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Quintana-Rodríguez, J. A., J. F. Doyle, F. J. Carrión-Viramontes, Didier Samayoa-Ochoa, and J. Alfredo López-López. "Material Characterization for Dynamic Simulation of Non-Homogeneous Structural Members." Key Engineering Materials 449 (September 2010): 46–53. http://dx.doi.org/10.4028/www.scientific.net/kem.449.46.
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Generally, simulation of non-homogeneous materials requires a homogeneous representation with equivalent properties different from the constitutive elements. Determination of the equivalent properties for dynamic simulation is not always a direct and straightforward calculation, as they have to represent, not only the static reactions, but also the dynamic behavior, which depends on a more complex relation of the geometrical (area, inertia moment), mechanical (elastic modulus) and physical (density) properties. In this context, the Direct Sensitivity Method (DSM) is developed to calibrate structural parameters of a finite element model using a priori information with an inverse parameter identification scheme, where parameters are optimized through an error sensitivity function using experimental data with the dynamic responses of the model. Results demonstrate that parameters of materials can be calibrated efficiently from the DSM and that key aspects for this calibration are noise, sensitivity (structural and sensor), and the finite element model representation.
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Dan, Danhui, Yanyang Chen, and Bin Xu. "A PSO Driven Intelligent Model Updating and Parameter Identification Scheme for Cable-Damper System." Shock and Vibration 2015 (2015): 1–14. http://dx.doi.org/10.1155/2015/423898.
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The precise measurement of the cable force is very important for monitoring and evaluating the operation status of cable structures such as cable-stayed bridges. The cable system should be installed with lateral dampers to reduce the vibration, which affects the precise measurement of the cable force and other cable parameters. This paper suggests a cable model updating calculation scheme driven by the particle swarm optimization (PSO) algorithm. By establishing a finite element model considering the static geometric nonlinearity and stress-stiffening effect firstly, an automatically finite element method model updating powered by PSO algorithm is proposed, with the aims to identify the cable force and relevant parameters of cable-damper system precisely. Both numerical case studies and full-scale cable tests indicated that, after two rounds of updating process, the algorithm can accurately identify the cable force, moment of inertia, and damping coefficient of the cable-damper system.
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Bazhenov, Viktor, Olga Krivenko, and Andrii Kozak. "Modal analysis of a complex shell structure under operational loads." Strength of Materials and Theory of Structures, no. 106 (May 24, 2021): 5–13. http://dx.doi.org/10.32347/2410-2547.2021.106.5-13.
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The results of calculation of a complex shell structure under the action of operational loads are presented. A three-section cooling tower, called a three-petal cooling tower, is regarded as a complex-shaped structure. Three variants of loads on the shell are considered: wind pressure, heating and load combination. The design model of a shell of a complex shape is based on the developed universal spatial finite element. The universal spatial finite element allows one to take into account the geometric features of structural elements for a thin shell (constant or varying thickness, knees, ribs, cover plates, holes, cavities, channels, inserts, facets) and multilayer structure of the material. According to the method, thin and medium thickness shells of various shapes and structures are considered. The shells are under the action of static mechanical and temperature loads. The finite element method is based on the unified positions of the three-dimensional geometrically nonlinear theory of thermoelasticity and the moment finite element scheme. The method for determining the natural vibrations of thin-walled shell structures is based on an integrated approach. Modal analysis is carried out taking into account the prestressed and deformed states of the shell at each step of thermomechanical loading. Thus, the problem of determining the natural frequencies and vibration modes of the shell is solved by the step method in two stages.
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Kamiński, M., and Ł. Supeł. "Elastic critical moment for bisymmetric steel profiles and its sensitivity by the finite difference method." International Journal of Applied Mechanics and Engineering 21, no. 1 (February 1, 2016): 37–59. http://dx.doi.org/10.1515/ijame-2016-0003.
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Abstract It is widely known that lateral-torsional buckling of a member under bending and warping restraints of its cross-sections in the steel structures are crucial for estimation of their safety and durability. Although engineering codes for steel and aluminum structures support the designer with the additional analytical expressions depending even on the boundary conditions and internal forces diagrams, one may apply alternatively the traditional Finite Element or Finite Difference Methods (FEM, FDM) to determine the so-called critical moment representing this phenomenon. The principal purpose of this work is to compare three different ways of determination of critical moment, also in the context of structural sensitivity analysis with respect to the structural element length. Sensitivity gradients are determined by the use of both analytical and the central finite difference scheme here and contrasted also for analytical, FEM as well as FDM approaches. Computational study is provided for the entire family of the steel I- and H - beams available for the practitioners in this area, and is a basis for further stochastic reliability analysis as well as durability prediction including possible corrosion progress.
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Liu, Zhi Hui, Liang De He, Ying Fa He, and Yuan Yuan Lu. "On Dredging Renovation of High-Piled Wharf by FEA." Advanced Materials Research 1065-1069 (December 2014): 613–18. http://dx.doi.org/10.4028/www.scientific.net/amr.1065-1069.613.
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In this paper, high-piled wharf is reinforced with a view to studying how the wharf dredging renovation affects its structure. As regarding the problem that the original balance of the bank slope is destroyed after upgrading, two retrofit schemes that set sheet pile wall at anterior wharf and low-piled caps at surcharge area are conducted to analyze the bank slope deformation and the inter force before and after wharf retrofit by means of three-dimensional finite element models. The analysis shows that for the scheme of setting sheet pile wall at front wharf, the inter force of the anterior pile station reduced while that of the post pile station near the stack area remains large. For the other scheme, the bending moment of the pile that closes to stack area significantly decreases after setting low pile caps. If both schemes are adopted coherently, the reinforcement effects to the anterior and post pile stations would be improved greatly.
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Li, Penglin, Yuquan Lu, Jinxing Lai, Houquan Liu, and Ke Wang. "A Comparative Study of Protective Schemes for Shield Tunneling Adjacent to Pile Groups." Advances in Civil Engineering 2020 (January 21, 2020): 1–16. http://dx.doi.org/10.1155/2020/6964314.
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Shield tunneling adjacent to pile groups is always an unavoidable problem in urban metro construction. A case was found in the project of Tianjin Metro Line 7, where a shield tunnel would be constructed near the existing pile groups of Shiyou Bridge. The whole shield tunnel is close to pile groups, and the minimum distance is only 0.8 m. Therefore, four kinds of protective schemes are proposed in this paper. It is vital to select an appropriate protective scheme to guarantee the safety during the tunnel construction. In this study, the main mechanical characteristic and physical parameters of site soil were obtained through laboratory tests. Besides, the three-dimensional finite element method was carried out to compare and analyze the effectiveness of the protective schemes in mitigating the effects of tunneling on adjacent pile groups. The results show that the deep-hole grouting scheme has better control effect on the lateral deformation and bending moment of piles, while the pile foundation underpinning scheme has better effectiveness on reducing the settlement of bridge structure and ground deformation. Finally, the deep-hole grouting reinforcement scheme will be adopted to ensure the shield passing through the pile groups smoothly.
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Pegg, N. G. "An Investigation of Dynamic Pulse Buckling of Thick Rings." Journal of Applied Mechanics 59, no. 3 (September 1, 1992): 615–21. http://dx.doi.org/10.1115/1.2893767.
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The occurrence of dynamic buckling of thick rings responding to an impulse load is investigated by analytical and numerical solutions to the equation of motion and by nonlinear finite element analyses. An extension to the linearized analytical solution is made using a finite difference scheme which incorporates a nonlinear moment-curvature relationship to model the effects of elastoplastic behavior and strain-rate reversal on the buckle formation. The finite element solution to the problem is formulated with the nonlinear code, ADINA. A comparison of the results shows that the numerical solutions (and, in particular, the ADINA solution) predict a significant reduction in the amplitude of buckling response and an increase in the predominant wavelength of response with time, in comparison to the linear analytical solution. A limited comparison to published experimental results of dynamic pulse buckling of thick rings is also given.
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Choporov, Serhii, Nataliia Manko, Oksana Spytsia, and Sergii Grebenyuk. "Stifness matrix of a “semi-infinite” finite element for a weakly compressible material based on the moment scheme." Visnyk of Zaporizhzhya National University. Physical and Mathematical Sciences, no. 1 (2019): 98–106. http://dx.doi.org/10.26661/2413-6549-2019-1-13.
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LIU, G. R., G. Y. ZHANG, K. Y. DAI, Y. Y. WANG, Z. H. ZHONG, G. Y. LI, and X. HAN. "A LINEARLY CONFORMING POINT INTERPOLATION METHOD (LC-PIM) FOR 2D SOLID MECHANICS PROBLEMS." International Journal of Computational Methods 02, no. 04 (December 2005): 645–65. http://dx.doi.org/10.1142/s0219876205000661.
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A linearly conforming point interpolation method (LC-PIM) is developed for 2D solid problems. In this method, shape functions are generated using the polynomial basis functions and a scheme for the selection of local supporting nodes based on background cells is suggested, which can always ensure the moment matrix is invertible as long as there are no coincide nodes. Galerkin weak form is adopted for creating discretized system equations, and a nodal integration scheme with strain smoothing operation is used to perform the numerical integration. The present LC-PIM can guarantee linear exactness and monotonic convergence for the numerical results. Numerical examples are used to examine the present method in terms of accuracy, convergence, and efficiency. Compared with the finite element method (FEM) using linear triangle elements and the radial point interpolation method (RPIM) using Gauss integration, the LC-PIM can achieve higher convergence rate and better efficiency.
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Demareva, A. V. "ANALYSIS OF THE CONSERVATIVE SMOOTHING EFFECT ON THE ACCURACY OF DYNAMIC ELASTIC-PLASTIC SPHERICAL SHELLS BUCKLING NUMERICAL SIMULATION." Problems of strenght and plasticity 81, no. 4 (2019): 474–87. http://dx.doi.org/10.32326/1814-9146-2019-81-4-474-487.
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Large changes of a lead spherical shell enclosed in an aluminum spacesuit under the action of an overload pulse are considered. The defining system of equations is formulated in Lagrange variables in a two-dimensional (axisymmetric) formulation. Strain and stress rates are determined in the local coordinate system. Kinematic relations are recorded in the metric of the current state. The relations of the flow theory with isotropic hardening are used as state equations. The contact interaction of the shell and the spacesuit is modeled by non-penetration conditions taking into account friction. The numerical solution of the problem under given boundary and initial conditions is based on the finite element method moment scheme and the explicit time integration “cross” type scheme. 4-node isoparametric finite elements with bilinear form functions are used to discretize the defining system of equations for spatial variables. To suppress the numerical solution high-frequency oscillations, the procedure of nodal displacements rates conservative smoothing is used. As shown by the results of numerical research spherical shell in the process of intensive dynamic loading undergoes large deformation and rotation angles as a rigid whole. The calculation results reliability is confirmed by a good correspondence to the experimental data. The influence of conservative smoothing procedure and moment components of deformations and stresses on the solution accuracy is analyzed. It is shown that without conservative smoothing procedure using, the shape of the spherical shell buckling obtained in the calculation does not correspond to the experimental data. Neglect of the moment components of strains and stresses leads to the development of instability of the “hourglass” type.
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Demareva, A. V. "ANALYSIS OF THE CONSERVATIVE SMOOTHING EFFECT ON THE ACCURACY OF DYNAMIC ELASTIC-PLASTIC SPHERICAL SHELLS BUCKLING NUMERICAL SIMULATION." Problems of strenght and plasticity 81, no. 4 (2019): 475–88. http://dx.doi.org/10.32326/1814-9146-2019-81-4-475-488.
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Large changes of a lead spherical shell enclosed in an aluminum spacesuit under the action of an overload pulse are considered. The defining system of equations is formulated in Lagrange variables in a two-dimensional (axisymmetric) formulation. Strain and stress rates are determined in the local coordinate system. Kinematic relations are recorded in the metric of the current state. The relations of the flow theory with isotropic hardening are used as state equations. The contact interaction of the shell and the spacesuit is modeled by non-penetration conditions taking into account friction. The numerical solution of the problem under given boundary and initial conditions is based on the finite element method moment scheme and the explicit time integration “cross” type scheme. 4-node isoparametric finite elements with bilinear form functions are used to discretize the defining system of equations for spatial variables. To suppress the numerical solution high-frequency oscillations, the procedure of nodal displacements rates conservative smoothing is used. As shown by the results of numerical research spherical shell in the process of intensive dynamic loading undergoes large deformation and rotation angles as a rigid whole. The calculation results reliability is confirmed by a good correspondence to the experimental data. The influence of conservative smoothing procedure and moment components of deformations and stresses on the solution accuracy is analyzed. It is shown that without conservative smoothing procedure using, the shape of the spherical shell buckling obtained in the calculation does not correspond to the experimental data. Neglect of the moment components of strains and stresses leads to the development of instability of the “hourglass” type.
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Bezhentseva, M. V., L. I. Vutsin, A. I. Kibets, and L. Kruszka. "FINITE ELEMENT METHOD FOR NUMERICAL MODELING OF ELASTIC-PLASTIC DEFORMATION OF WOOD UNDER SHOCK LOADING." Problems of strenght and plasticity 82, no. 4 (2020): 428–41. http://dx.doi.org/10.32326/1814-9146-2020-82-4-428-441.
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The 3D problem of wood deformation under shock loading is considered. The governing system of equations is formulated in Lagrange variables. A defining system of equations in a three-dimensional formulation is presented. The equation of motion is derived from the balance of the virtual powers of work. Wood is modeled as a unidirectionally reinforced material with a description of the descending branch of the deformation diagram. Deformations and stresses are determined in a local basis, the position of which in space is related to the direction of the wood grain. Wood material is represented as a combination of reinforcing fibers and a matrix, the elastoplastic deformation of which is described by the relations of the theory of flow with combined kinematic and isotropic strengthening. The deformation characteristics of the matrix and fibers are determined on the basis of a computational and experimental study of the mechanical properties of wood along and across the fibers. In numerical simulation, the moment scheme of the finite element method and an explicit time integration scheme of the “cross” type are used. Discretization of the computational domain is based on an eight-node isoparametric finite element adapted to the specifics of the problem under consideration. Software realization of the developed mathematical model and numerical methodology is implemented within the computing complex “Dynamics-3”. Computer simulation of compression of an experimental specimen of spruce along and across the fibers has been performed. The reliability of the calculation results is confirmed by good agreement with the experimental data.
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Belevičius, Rimantas, Saulius Valentinavičius, and Edvard Michnevič. "MULTILEVEL OPTIMIZATION OF GRILLAGES." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 8, no. 2 (June 30, 2002): 98–103. http://dx.doi.org/10.3846/13923730.2002.10531259.
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The mathematical models and solution algorithms for optimization of grillage-type foundations are presented. Optimization of grillage is based on optimization of separate beams comprising grillage. Minimising of maximum in absolute value vertical reactive force, bending moment, and reaction-bending moment together is sought in a separate beam. All these problems are non-linear, therefore are solved iteratively changing in each iteration the structure shape to a better neighbouring shape. Solution of this requires three steps: finite element analysis, analytical sensitivity analysis, and optimal re-design via linear mathematical programming. The main problem related to the proposed technique is to guarantee the global minimum solution. Engineering algorithm is suggested for avoidance of local minimum solutions: optimization procedure starts from quasi-optimal initial pile placement scheme, which is designed by a special expert system.
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Rylski, Adam, and Krzysztof Siczek. "Study on the Operating Conditions of Micropump Components." Advanced Materials Research 1051 (October 2014): 813–18. http://dx.doi.org/10.4028/www.scientific.net/amr.1051.813.
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The micropumps driven by AC, DC brush, DC brushless or stepper motors can be used in pharmaceutical industry. The particular property of such pumps is magnet coupling between motor and pump. The aim of the analysis has been to investigate the operating conditions for bearing in such pump during flow of water, oil and glycerin – water solution and to investigate the dependency of the glycerin – water solution flow upon the outlet – inlet pressure difference and upon the speed of motor driving pump. It has been also investigated the possibility of application for NdFeB – NdFeB magnet assembly in the magnet coupling. The loading of pump are connected of flow resistance determined by outlet and inlet pressure difference, speed and temperature of pumped liquid, geometry and material properties of pump elements. The driving motor is loaded by mechanical resistance of pump element motion either. The moment – pressure difference relationship and flow – pressure difference – speed relationship have been made for water and oil and then approximated equation for them have been elaborated. With help of such equation scheme of moment – pressure difference relationship and flow – pressure difference – speed relationship for glycerin – water solution have been made for various values of glycerin strength. The model of pump bearing has been elaborated using Finite Element Method. Auxiliary mathematical equations have been utilized for calculating sliding velocity in bearing and loading force. The obtained contact pressure in bearing has been presented in the article. The model of magnet coupling has been elaborated with use of Finite Element Method and presented in the paper. Dimensions of model are closed to the one used in original pump. It has been observed that for up to 50% glycerin - water solution the moment – pressure difference relationship and flow – pressure difference – rotational speed relationship are very similar to these in the water case. With increasing of solution strength above 50% they start to be more different. Values of contact pressure nonlinearly increase with driving moment value increasing. Calculated values of torque excited values given out by manufacturer with about 20%. Calculated value of decoupling torque for NdFeB – NdFeB magnet assemblies is greater more than 50 % comparing SmCo – NdFeB case.
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Huang, Jun, and Lian Shui Guo. "The Research on the Torque-Tension Relationship for Bolted Joints." Key Engineering Materials 486 (July 2011): 242–45. http://dx.doi.org/10.4028/www.scientific.net/kem.486.242.
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This paper has proposed an improved formula for the torque-tension relationship of bolted joints with consideration of all forces and moments acting on fasteners. Finite element analysis (FEA) is used to analyze and evaluate the relationship. An effective finite element (FE) modeling scheme which considers the helical geometry is developed. Effects of contact radii ratios of the nut bearing surface on the percentages of component torques are investigated. Percentages of component torques are calculated according to present and conventional formula, to compare with FEA results.
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Kashani, Mir Tahmaseb, and Seyed M. Hashemi. "A Finite Element Formulation for Bending-Torsion Coupled Vibration Analysis of Delaminated Beams under Combined Axial Load and End Moment." Shock and Vibration 2018 (September 25, 2018): 1–12. http://dx.doi.org/10.1155/2018/1348970.
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Free vibration analysis of beams with single delamination undergoing bending-torsion coupling is made, using traditional finite element technique. The Galerkin weighted residual method is applied to convert the coupled differential equations of motion into to a discrete problem, where, in addition to the conventional mass and stiffness matrices, a delamination stiffness matrix, representing the extra stiffening effects at the delamination tips, is introduced. The linear eigenvalue problem resulting from the discretization along the length of the beam is solved to determine the frequencies and modes of free vibration. Both “free mode” and “constrained mode” delamination models are considered in formulation, and it is shown that the continuity (both kinematic and force) conditions at the beam span-wise locations corresponding to the extremities of the delaminated region, in particular, play a great role in “free mode” model formulation. Current trends in the literature are examined, and insight into different types of modeling techniques and constraint types are introduced. In addition, the data previously available in the literature and those obtained from a finite element-based commercial software are utilized to validate the presented modeling scheme and to verify the correctness of natural frequencies of the systems analyzed here. The paper ends with general discussions and conclusions on the presented theories and modeling approaches.
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Belevičius, Rimantas, Darius Mačiūnas, and Dmitrij Šešok. "THE MINIMIZATION OF MOMENTS AND REACTIVE FORCES IN GRILLAGES WITH A GENETIC ALGORITHM." Engineering Structures and Technologies 3, no. 2 (June 30, 2011): 56–63. http://dx.doi.org/10.3846/skt.2011.07.
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The aim of the article is to report a technology for the optimization of grillage-type foundations seeking for the least possible reactive forces in the piles for a given number of piles and in the absolute value of the bending moments when connecting beams of the grillage. Mathematically, this seems to be the global optimization problem possessing a large number of local minima points. Both goals can be achieved choosing appropriate pile positions under connecting beams; however, these two problems contradict to each other and lead to diff erent schemes for pile placement. Therefore, we suggest using a compromise objective function (to be minimized) that consists of the largest reactive force arising in all piles and that occurring in the absolute value of the bending moment when connecting beams, both with the given weights. Bending moments are calculated at three points of each beam. The design parameters of the problem are positions of the piles. The feasible space of design parameters is determined by two constraints. First, during the optimization process, piles can move only along connecting beams. Therefore, the two-dimensional grillage is “unfolded” to the one-dimensional construct, and supports are allowed to range through this space freely. Second, the minimum allowable distance between two adjacent piles is introduced due to the specific capacities of a pile driver. Also, due to some considerations into the scheme of pile placement, the designer sometimes may introduce immovable supports (usually at the corners of the grillage) that do not participate in the optimization process and always retain their positions. However, such supports hinder to achieve a global solution to a problem and are not treated in this paper. The initial data for the problem are as follows: a geometrical scheme of the grillage, the given number of piles, a cross-section and material data on connecting beams, the minimum possible distance between adjacent supports and loading data given in the form of concentrated loads or trapezoidal distributed loadings. The results of the solution are the required positions of piles. This solution can serve as a pilot project for more detailed design. The entire optimization problem is solved in two steps. First, the grillage is transformed into the one-dimensional construct and the optimizer decides about a routine solution (i.e. the positions of piles in this construct). Second, backward transformation returns pile positions into the two-dimensional grillage and the “black-box” finite element program returns the corresponding objective function value. On the basis of this value, the optimizer predicts new positions of piles etc. The finite element program idealizes connecting beams as beam elements and piles – as mesh nodes of the finite element with a given boundary conditions in the form of vertical and rotational stiff ness. Since the problem may have several tens of design parameters, the only choice for optimization algorithms is using stochastic optimization algorithms. In our case, we use the original elitist real-number genetic algorithm and launch the program sufficient number of times in order to exclude large scattering of results. Three numerical examples are presented for the optimization of 10-pile grillage: when optimizing purely the largest reactive force, purely the largest in the absolute value of the bending moment and both parameters with equal weights.
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Miao, Feng, Guan Ping, and Wang Bo. "Vertical Seismic Response of Self-Anchored Cable-Stayed Suspension Bridge under Pile-Soil-Structure Interaction." Advanced Materials Research 243-249 (May 2011): 1798–802. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.1798.
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Based on scheme of Dalian gulf cross-sea bridge, in this paper, a 3-dimensional FE model for Self-anchored cable-stayed suspension bridge is established with finite element program and pile-soil-structure interaction is simulated by use of the equivalent embed fixation model. Based on the FE model, model analysis is carried out and the effects of pile-soil-structure interaction on dynamic behavior of long-span self-anchored cable-stayed suspension bridge are specially studied. Under vertical excitation, the seismic response analysis result considering that pile-soil-structure interaction was compared with that of without considering such interaction. The analysis result show that interaction reduced longitudinal displacement of stiffening beam in middle of main span and tower at bottom, moment at bottom of tower and auxiliary pier pile, but enlarged the moment of conjoining section between steel and steel beam. The research results provide some theoretical foundation to composite structure system.
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Miao, Feng, Wang Bo, and Guan Ping. "Research of Longitudinal Seismic Response of Self-Anchored Cable-Stayed Suspension Bridge under Pile-Soil-Structure Interaction." Advanced Materials Research 255-260 (May 2011): 1167–70. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.1167.
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Based on scheme of Dalian gulf cross-sea bridge, in this paper, a 3-dimensional FE model for Self-anchored cable-stayed suspension bridge is established with finite element program and pile-soil-structure interaction is simulated by use of the equivalent embed fixation model. Based on the FE model, model analysis is carried out and the effects of pile-soil-structure interaction on dynamic behavior of long-span self-anchored cable-stayed suspension bridge are specially studied. The seismic response analysis result considering that pile-soil-structure interaction was compared with that of without considering such interaction. The analysis result show that interaction extend the nature period of structure, has the greatest impact to the first vibration mode; meanwhile, enlarged longitudinal displacement and moment of stiffening beam in middle of main span, longitudinal displacement on top of tower and axial force at bottom, but reduced the moment of tower at bottom. The research results provide some theoretical foundation to composite structure system.
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Chen, Daihai, Yinxin Li, Zheng Li, Yilin Fang, Laijing Ma, and Fengrui Ma. "Reaction Spectrum Comparative Analysis of Seismic Performance of 62 m CFST Bridge with Curved-String Truss before and after Reinforcement." Advances in Civil Engineering 2020 (July 14, 2020): 1–13. http://dx.doi.org/10.1155/2020/4536365.
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Taking a 62 m CFST bridge with a curved-string truss as the research object, according to its reinforcement scheme, the spatial finite element models of the bridge before and after reinforcement were established by using the general finite element software ANSYS. The natural frequencies of the bridge before and after reinforcement were calculated, and the seismic performance of the bridge was analyzed by using the response spectrum method. The results show that the frequencies of the reinforced bridges increase in varying degrees, especially the vertical and torsional frequencies. Before and after reinforcement, the maximum axial force in the upper chord of the bridge is the largest, and the shear force and bending moment are small. The maximum internal force appears at the two ends of the upper chord. This position should be regarded as the weak link of the bridge seismic resistance. Under the same conditions, the axial force of the bridge after reinforcement is reduced by about 30% compared with that before reinforcement, and the displacement of the bridge after reinforcement is reduced in varying degrees. The reinforcement measures can improve the lateral and vertical stiffness of the bridge, especially the stiffness of the deck system.
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Dokhnyak, B. M., V. V. Kirichevskii, and M. I. Ishchenko. "Application of the moment scheme of the finite element method to the solution of problems with initial stresses in the incremental elasticity theory." Strength of Materials 38, no. 3 (May 2006): 313–23. http://dx.doi.org/10.1007/s11223-006-0045-2.
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Riemer, M., R. Taschner, and V. Pavelic. "Analysis of a Bolted Flange With Eccentric Loading." Journal of Vibration and Acoustics 108, no. 3 (July 1, 1986): 369–76. http://dx.doi.org/10.1115/1.3269352.
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A new method is presented for the analysis of a bolted flange subjected to bending moments. Bolt axial cyclic loads are calculated using the force ratio method. Bolt bending moments are found with the new analysis scheme presented. A key factor in the analysis is the area in compression of the flange. Experimental results are used to substantiate the theoretical methods. A finite element analysis was also conducted to support the theory.
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Antonopoulou, Dimitra, Ĺubomír Baňas, Robert Nürnberg, and Andreas Prohl. "Numerical approximation of the stochastic Cahn–Hilliard equation near the sharp interface limit." Numerische Mathematik 147, no. 3 (February 17, 2021): 505–51. http://dx.doi.org/10.1007/s00211-021-01179-7.
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AbstractWe consider the stochastic Cahn–Hilliard equation with additive noise term $$\varepsilon ^\gamma g\, {\dot{W}}$$ ε γ g W ˙ ($$\gamma >0$$ γ > 0 ) that scales with the interfacial width parameter $$\varepsilon $$ ε . We verify strong error estimates for a gradient flow structure-inheriting time-implicit discretization, where $$\varepsilon ^{-1}$$ ε - 1 only enters polynomially; the proof is based on higher-moment estimates for iterates, and a (discrete) spectral estimate for its deterministic counterpart. For $$\gamma $$ γ sufficiently large, convergence in probability of iterates towards the deterministic Hele–Shaw/Mullins–Sekerka problem in the sharp-interface limit $$\varepsilon \rightarrow 0$$ ε → 0 is shown. These convergence results are partly generalized to a fully discrete finite element based discretization. We complement the theoretical results by computational studies to provide practical evidence concerning the effect of noise (depending on its ’strength’ $$\gamma $$ γ ) on the geometric evolution in the sharp-interface limit. For this purpose we compare the simulations with those from a fully discrete finite element numerical scheme for the (stochastic) Mullins–Sekerka problem. The computational results indicate that the limit for $$\gamma \ge 1$$ γ ≥ 1 is the deterministic problem, and for $$\gamma =0$$ γ = 0 we obtain agreement with a (new) stochastic version of the Mullins–Sekerka problem.
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Stegemiller, M. E., and D. R. Houser. "A Three-Dimensional Analysis of the Base Flexibility of Gear Teeth." Journal of Mechanical Design 115, no. 1 (March 1, 1993): 186–92. http://dx.doi.org/10.1115/1.2919317.
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This paper presents the development of a simple model which computes the deflection of the base of wide face width gear teeth. The model was developed using the results of numerous finite element analyses of gear teeth and a nondimensional analysis of the results. Tooth end effects are considered through the application of the moment image method. The method is very simple and allows easy implementation in three-dimensional gear tooth deflection analysis schemes.
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Luo, Bin, Benchun Duan, and Dunyu Liu. "3D Finite-Element Modeling of Dynamic Rupture and Aseismic Slip over Earthquake Cycles on Geometrically Complex Faults." Bulletin of the Seismological Society of America 110, no. 6 (September 1, 2020): 2619–37. http://dx.doi.org/10.1785/0120200047.
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ABSTRACT We develop a new dynamic earthquake simulator to numerically simulate both spontaneous rupture and aseismic slip over earthquake cycles on geometrically complex fault systems governed by rate- and state-dependent friction. The method is based on the dynamic finite-element method (FEM) EQdyna, which is directly used in the simulator for modeling 3D spontaneous rupture. We apply an adaptive dynamic relaxation technique and a variable time stepping scheme to EQdyna to model the quasi-static processes of an earthquake cycle, including the postseismic, interseismic, and nucleation processes. Therefore, the dynamic and quasi-static processes of an earthquake cycle are modeled in one FEM framework. Tests on a vertical strike-slip fault verify the correctness of the dynamic simulator. We apply the simulator to thrust faults with various dipping angles, which can be considered as the simplest case of geometrically complex faults by breaking symmetry, compared with vertical faults, to examine effects of dipping fault geometry on earthquake cycle behaviors. We find that shallower dipping thrust faults produce larger seismic slip and longer recurrence time over earthquake cycles with the same rupture area. In addition, we find an empirically linear scaling relation between the recurrence interval (and the seismic moment) and the sinusoidal function of the dip angle. The dip-angle dependence is likely due to the free-surface effect, because of broken symmetry. These results suggest dynamic earthquake simulators that can handle nonvertical dipping fault geometry are needed for subduction-zone earthquake studies.
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BANNIKOV, D. O., V. P. KUPRII, and D. YU VOTCHENKO. "REGULARITIES OF THE LINING STRESS-STRAIN STATE DURING OF THE PYLON METRO STATION CONSTRUCTION." Bridges and tunnels: Theory, Research, Practice, no. 19 (July 27, 2021): 19–27. http://dx.doi.org/10.15802/bttrp2021/233871.
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Purpose. Perform numerical analysis of the station structure. Take into account in the process of mathematical modeling the process of construction of station tunnels of a three-vaulted station. Obtain the regularities of the stress-strain state of the linings, which is influenced by the processes of soil excavation and lining construction. Methodology. To achieve this goal, a series of numerical calculations of models of the deep contour interval metro pylon station was performed. Three finite-element models have been developed, which reflect the stages of construction of a three-vaulted pylon station. Numerical analysis was performed on the basis of the finite element method, implemented in the calculation complex Lira for Windows. Modeling of the stress-strain state of the station tunnel linings and the soil massif was performed using rectangular, universal quadrangular and triangular finite elements, which take into account the special properties of the soil massif. Station tunnel linings are modeled by means of rod finite elements. Findings. Isofields of the stress-strain state in finite-element models reflecting the stages of construction are obtained. The vertical displacements and horizontal stresses that are characteristic of a three-vaulted pylon station are analyzed. The analysis of horizontal stresses proved that at the stage of opening of the middle tunnel the scheme of pylon operation is rather disadvantageous. The analysis of bending moments and normal forces was also carried out and the asymmetry of their distribution was noted. Originality. Based on the obtained patterns of distribution of stress-strain state and force factors, it is proved that numerical analysis of the station structure during construction is necessary to take measures to prevent or reduce deformation of frames that are in unfavorable conditions. Practical value. In the course of research, the regularities of changes in stresses, displacements, bending moments and normal forces in the models of the pylon station, which reflect the sequence of its construction, were obtained.
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Feng, Miao, Guan Ping, and Wang Bo. "Horizontal Seismic Response of Self-Anchored Cable-Stayed Suspension Bridge under Pile-Soil-Structure Interaction." Applied Mechanics and Materials 63-64 (June 2011): 421–24. http://dx.doi.org/10.4028/www.scientific.net/amm.63-64.421.
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Based on scheme of Dalian gulf cross-sea bridge, in this paper, a 3-dimensional FE model for Self-anchored cable-stayed suspension bridge is established with finite element program and pile-soil-structure interaction is simulated by use of the equivalent embed fixation model. Based on the FE model, model analysis is carried out and the effects of pile-soil-structure interaction on dynamic behavior of long-span self-anchored cable-stayed suspension bridge are specially studied. The seismic response analysis result considering that pile-soil-structure interaction was compared with that of without considering such interaction. The analysis result show that interaction reduced horizontal displacement in middle span of stiffening beam and top of tower, horizontal moment not only at bottom of tower, but also assistant piers. The research results provide some theoretical foundation to composite structure system.
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van Wees, Jan-Diederik, Maarten Pluymaekers, Sander Osinga, Peter Fokker, Karin Van Thienen-Visser, Bogdan Orlic, Brecht Wassing, Dries Hegen, and Thibault Candela. "3-D mechanical analysis of complex reservoirs: a novel mesh-free approach." Geophysical Journal International 219, no. 2 (August 30, 2019): 1118–30. http://dx.doi.org/10.1093/gji/ggz352.
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SUMMARY Building geomechanical models for induced seismicity in complex reservoirs poses a major challenge, in particular if many faults need to be included. We developed a novel way of calculating induced stress changes and associated seismic moment response for structurally complex reservoirs with tens to hundreds of faults. Our specific target was to improve the predictive capability of stress evolution along multiple faults, and to use the calculations to enhance physics-based understanding of the reservoir seismicity. Our methodology deploys a mesh-free numerical and analytical approach for both the stress calculation and the seismic moment calculation. We introduce a high-performance computational method for high-resolution induced Coulomb stress changes along faults, based on a Green's function for the stress response to a nucleus of strain. One key ingredient is the deployment of an octree representation and calculation scheme for the nuclei of strain, based on the topology and spatial variability of the mesh of the reservoir flow model. Once the induced stress changes are evaluated along multiple faults, we calculate potential seismic moment release in a fault system supposing an initial stress field. The capability of the approach, dubbed as MACRIS (Mechanical Analysis of Complex Reservoirs for Induced Seismicity) is proven through comparisons with finite element models. Computational performance and suitability for probabilistic assessment of seismic hazards are demonstrated though the use of the complex, heavily faulted Gullfaks field.
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Chen, Chungang, Juzhong Bin, and Feng Xiao. "A Global Multimoment Constrained Finite-Volume Scheme for Advection Transport on the Hexagonal Geodesic Grid." Monthly Weather Review 140, no. 3 (February 1, 2011): 941–55. http://dx.doi.org/10.1175/mwr-d-11-00095.1.
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Abstract A third-order numerical model is developed for global advection transport computation. The multimoment constrained finite-volume scheme has been implemented to the hexagonal geodesic grid for spherical geometry. Two kinds of moments (i.e., point value and volume-integrated average) are used as the constraint conditions to derive the time evolution equations to update the computational variables, which are the values defined at the specified points over each mesh element in the present model. The numerical model has rigorous numerical conservation and third-order accuracy. One of the major merits of the present method is that it does not explicitly involve numerical quadrature, which leads to great convenience in accurately computing curved geometry and source terms. The present paper provides an accurate and practical formulation for advection calculation in the hexagonal-type geodesic grid.
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DU, HEJUN, and YAN LIU. "INVESTIGATION OF HEAD-DISK INTERFACE AND UNLOADING PROCESS IN HDD WITH AN EFFICIENT SCHEME." International Journal of Modern Physics: Conference Series 19 (January 2012): 311–19. http://dx.doi.org/10.1142/s2010194512008902.
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An efficient scheme was developed to analyze head-disk interfaces (HDIs) in hard disk drives. HDIs were studied by decoupling the nanometer scale variations of the air bearings and the micrometer scale changes of the suspensions. The nonlinear variations of the air bearing forces and moments were described with analytical expressions obtained from a surface fitting scheme. Combined with a 3 degree of freedom (DOF) suspension model whose parameters were estimated from a comprehensive finite element model, the historical behaviors of a subambient slider during an unloading process can be obtained in a very short computation period, thus providing a way of exploring a large number of parameter values of the suspension stiffness matrix.
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Bazhenov, B. A., A. S. Sakharov, N. A. Solovei, O. P. Krivenko, and N. Ayat. "Moment scheme of the finite-element method in problems of the strength and stability of flexible shells subjected to the action of forces and thermal factors." Strength of Materials 31, no. 5 (September 1999): 499–504. http://dx.doi.org/10.1007/bf02511170.
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Shan, De Shan, Yuan He, and Li Qiao. "Longitudinal Vibration Control of Long-Span Railway Cable-Stayed Bridge." Advanced Materials Research 255-260 (May 2011): 1795–99. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.1795.
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As the floating type cable-stayed bridge has no longitudinal constraint between the main girder and the pylon, it may cause the main girder a large longitudinal displacement and the root of tower a large longitudinal bending moment, and affect the normal use and safety of the bridge under the earthquake or the train braking. It is an important part of the design to select an appropriate vibration control scheme. Taking a long-span railway bridge for example, this paper build the finite element model and analyses the damping effect in the view of train braking, moreover, the present study also examines the dynamic behavior with focus on two parameters of damping coefficient C and damping exponent αof the viscous dampers through dynamic time-history analysis. The results show that setting viscous dampers with the reasonable parameters can reduce the vibration and the response of the bridge by train braking and have a good energy dissipation effect.
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Tan, Hongmei, Zhujian Hou, Zhou Qiu, Junlin Ji, and Dahan Chen. "The USGT Method for Suspender Tensioning of Self-Anchored Suspension Bridges." Advances in Civil Engineering 2021 (May 24, 2021): 1–10. http://dx.doi.org/10.1155/2021/6619924.
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Unlike earth-anchored suspension bridges, self-anchored suspension bridges (SASBs) involve a special construction stage, namely, suspender tensioning, in which the tensioning force and sequence are crucial and complicated. Against this background, an example bridge A, a SASB with a steel-concrete composite beam, is introduced in detail. Using MIDAS finite element software, a suspender tensioning scheme is formulated based on a combination method of the unstrained state method and graded tension method (the USGT method), in which a suspender is tensioned according to its unstrained length. By analyzing the bending moment change of the beam and deflection of the main cable throughout the entire construction process, a “high-to-low” suspender tensioning sequence is proposed that also involves symmetrical tensioning from the main towers to the midspan or the anchor positions. In the optimized construction process, the deviation and stress of the main towers are controlled well, thereby ensuring the safety of the main beam and main towers in the construction process.
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Hua, Shun Gang, Li Na Zhang, and Jun Hua Zeng. "Beam Layout Optimization for Vehicle Body Stiffness." Advanced Materials Research 548 (July 2012): 667–71. http://dx.doi.org/10.4028/www.scientific.net/amr.548.667.
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In this paper we research the beam layout optimization to strengthen the stiffness of a tracked vehicle’ body. Based on CAD models of vehicle parts, a rigid-flexible coupling virtual prototype of the vehicle is constructed through body finite element meshing and modal analysis. The multi-body system dynamics simulation is conducted under several typical driving conditions. Loads acting on the vehicle body at several typical moments are exported and then imposed on the body finite element model to carry out the static analysis, such that the multi-load steps topology optimization for the hull is achieved. On the basis of the optimization results the local beam layout is modified and the vehicle virtual prototype is reconstructed. By re-executing the dynamics simulation, the change of the stress and deformation are compared. The simulation result shows the strength and stiffness of the body are improved. So the proposed scheme is effective for the body stiffness and could provide references for similar structural optimization problems.
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Khulief, Y. A., and A. A. Shabana. "Dynamics of Multibody Systems With Variable Kinematic Structure." Journal of Mechanisms, Transmissions, and Automation in Design 108, no. 2 (June 1, 1986): 167–75. http://dx.doi.org/10.1115/1.3260798.
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The problem of predicting the dynamic behavior of a general multibody system subject to kinematic structure changes is addressed using a mixed set of Lagrangian coordinates. Changes in the kinematic structure may occur smoothly or accompanied by a change in the system momenta. The finite element method is employed to estimate the modal characteristics of flexible bodies. An automated pieced-interval computational scheme that accounts for the change in the dynamic characteristics due to the imposition of new sets of constraints on the boundaries of flexible components is developed. The resulting change in the deformation modes and the associated change in basis of the configuration space requires a new set of generalized coordinates for each subinterval of the analysis. A numerical example is used to demonstrate the analysis scheme developed in this paper.
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Zhou, Wei. "Inner Force Analysis of Two Typical Frames with Vertical Displacement." Key Engineering Materials 400-402 (October 2008): 341–46. http://dx.doi.org/10.4028/www.scientific.net/kem.400-402.341.
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Finite element method is often used to obtain exact solution in the course of internal force calculation of some complex frames which contain nodal vertical displacement such as frames with transferring layer and mega-frames with sub-structure. In the phase of scheme comparison and schematic design, methods which can quickly produce calculation results of the above said frameworks are necessary. Based on the basic principle of displacement method, this paper proposes a simple analytical method for frameworks that contain nodal vertical displacement. According to the proposal, the basic structure for calculation is the framework in which is added vertical chain-pole at relevant node; the basic unknown quantities are the nodal vertical displacement of the basic structure; the basic equation is fixed according to the equilibrium of node forces; unit vertical displacement as well as bending moment and shear diagram of the basic structure under external load are respectively obtained by using moment redistribution method; nodal vertical displacement is determined through substitution of shear force of relevant rod into the equilibrium equation of the chain-pole node; the actual internal force is determined through superposition of actual vertical displacement and internal force diagram algebra of the basic structure under vertical external load. An engineering example is introduced, which is intended to provide reference for the simple calculation for the above said complex frameworks.
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Ma, Teng, Jingkai Zhao, and Dafang Mei. "Research on the Arrangement Form of Net Suspenders with Constant Inclination Angle for Steel Box Tied Arch Bridge." E3S Web of Conferences 165 (2020): 04039. http://dx.doi.org/10.1051/e3sconf/202016504039.
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In order to explore the rational suspender layout of reticulated suspender steel box tied arch bridge, eight different suspender layout schemes were established by using finite element software Midas civil, taking a real bridge as the background and the constant inclination angle of suspender as the research variable. The structural stress characteristics of vertical suspender and reticulated suspender layout were analyzed and compared. The results show that the bending moment of arch rib and tied beam of reticulated suspender system is smaller, and the stress of arch beam is closer to the ideal state of “arch rib is compressed, tied beam is pulled”. The results show that in the range of 60 ~90, the smaller the inclination angle is, the more favorable the stress of the structure is, but the lower the moment reduction efficiency is when the inclination angle of the suspender is less than 60.
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Lien, F. S., and M. A. Leschziner. "A Pressure-Velocity Solution Strategy for Compressible Flow and Its Application to Shock/Boundary-Layer Interaction Using Second-Moment Turbulence Closure." Journal of Fluids Engineering 115, no. 4 (December 1, 1993): 717–25. http://dx.doi.org/10.1115/1.2910204.
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A nonorthogonal, collocated finite-volume scheme, based on a pressure-correction strategy and originally devised for general-geometry incompressible turbulent recirculating flow, has been extended to compressible transonic conditions. The key elements of the extension are a solution for flux variables and the introduction of streamwise-directed density-retardation which is controlled by Mach-number-dependent monitor functions, and which is applied to all transported flow properties. Advective fluxes are approximated using the quadratic scheme QUICK or the second-order TVD scheme MUSCL, the latter applied to all transport equations, including those for turbulence properties. The procedure incorporates a number of turbulence models including a new low-Re k–ε eddy-viscosity variant and a Reynolds-stress-transport closure. The predictive capabilities of the algorithm are illustrated by reference to a number of inviscid and turbulent transonic applications, among them a normal shock in a Laval nozzle, combined oblique-shock reflection and shock-shock interaction over a bump in a channel and shock-induced boundary-layer separation over channel bumps. The last-named application was computed both with eddy-viscosity models and Reynolds-stress closure, leading to the conclusion that the latter yields a much greater sensitivity of the boundary layer to the shock and, arising therefrom, a more pronounced λ-shock structure, earlier separation and more extensive recirculation. On the other hand, the stress closure is found to return an insufficient rate of wake recovery following reattachment.
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Bulat, A. F., A. S. Kobets, V. I. Dyrda, V. A. Lapin, S. M. Grebenyuk, M. I. Lysytsia, M. H. Marienkov, H. M. Ahaltsov, and Ye V. Kalhankov. "VIBROSEISMIC PROTECTION OF BUILDINGS AND STRUCTURES AGAINST NATURAL AND TECHNOGENEOUS DYNAMIC IMPACTS." Series of Geology and Technical Sciences 445, no. 1 (February 1, 2021): 58–65. http://dx.doi.org/10.32014/2021.2518-170x.9.
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In this article, the authors analyze results of their long-term researches on protection of buildings and structures against dynamic loads caused by the nature and/or human activities. They also give the grounds for necessity to provide vibration insulation of buildings, and show how to choose and calculate proper parameters for rubber vibroseismic insulators. Specifics of finite element method applied for static calculating the vibroseismic insulators is also described. In order to take into account weak compressibility of rubber, a moment finite element scheme was used, which assumes a triple approximation of the displacement vector components consisting of strain tensor and volume change function. Stress-strain state of the shock absorbers was determined for different standard sizes and diameters. The authors also describe two variants of calculation depending on the method of fixing the insulator’s ends. In the first case, the ends are vulcanized to the metal plates. In the second variant, the ends are free and can move in a horizontal plane. Influence of ratio of the shock absorber height and radius to the strain state of a structure was also analyzed. In order to determine factual levels of the soil and pile vibration (in two horizontal and one vertical directions), vibrodynamic studies were carried out. The obtained vibration signals were registered by the one-component vibration transducers 731A (vibration sensors) produced by the Wilcoxon Research company (the USA). Then, the vibration records were processed by the specialized program “Seismic Monitoring”. Based on the results of these studies, numerical calculations were performed in order to determine whether the predicted levels of the residential building vibrations are in compliance with the existing sanitary standards when exposed to real technogeneous loads. Vibrodynamic tests on vibration acceleration levels of the vibration-insulated reinforced concrete slabs and floors in residential building confirmed high effectiveness of the used vibroseismic insulation system with the rubber elements: the registered vibration acceleration levels in the residential building on all floors did not exceed acceptable levels set by the sanitary standards, and ensured comfortable living conditions under different dynamic impacts. The results of this work make it possible to design buildings with anti-seismic protection by using the designed rubber elements in accordance with the local conditions of the city of Almaty.
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Mudrov, Andrej, Antanas Šapalas, Gintas Šaučiuvėnas, and Kęstutis Urbonas. "Moment Resisting Connection with Curved Endplates: Behaviour Study." Applied Sciences 11, no. 4 (February 8, 2021): 1520. http://dx.doi.org/10.3390/app11041520.
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This article provides a behaviour analysis of moment resisting joints with curved endplates. This is a new type of connection that can be used for joining steel beams to the circular hollow section (CHS) columns by means of bolts. Some researchers apply the Eurocode model without considering the differences in calculation schemes and assumptions, such as by using the general model of an equivalent T-stub in tension. Consequently, many of the existing behaviour studies are somewhat misleading, thus there is a need for further research. Apart from the absence of analytical methods that are devoted to predicting the initial stiffness and strength of the curved T-stub, other technical difficulties were encountered, such as gaps between the endplate and the column, as well as the initial pre-loading force of the bolts. In the previous studies, endplates were manufactured by rolling flat plates to the precise curvature which resulted in firm contact. In contrast, in this study, endplates were manufactured from a standard CHS tube, which led to significant initial gaps. Meanwhile, in terms of preloading force, it was found that it affected the moment resistance of the joint. This paper discusses problems associated with ongoing researches and presents experimental tests of the two connections. The obtained results were further used in the parametric finite element analysis (FEA) to determine the effect of the gaps and preloading force of the bolts on the moment resistance and initial rotational stiffness of the joint. The results indicate that the behaviour of curved plated connections is exceedingly complex and that the preloading force is the key factor, therefore, it should be controlled.
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Tang, Wenwu, Yaoguo Li, Andrei Swidinsky, and Jianxin Liu. "Three-dimensional controlled-source electromagnetic modelling with a well casing as a grounded source: a hybrid method of moments and finite element scheme." Geophysical Prospecting 63, no. 6 (October 29, 2015): 1491–507. http://dx.doi.org/10.1111/1365-2478.12330.
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