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115 results about "Virtual work" patented technology

Virtual work arises in the application of the principle of least action to the study of forces and movement of a mechanical system. The work of a force acting on a particle as it moves along a displacement is different for different displacements. Among all the possible displacements that a particle may follow, called virtual displacements, one will minimize the action. This displacement is therefore the displacement followed by the particle according to the principle of least action. The work of a force on a particle along a virtual displacement is known as the virtual work.

Method for computing electromagnetic force of transformer iron core based on finite element method

The invention discloses a method for computing electromagnetic force of a transformer iron core based on a finite element method. The method comprises the steps that structural parameters of a winding, the iron core and a fuel tank of a transformer are collected, and then a three-dimensional geometric grid model of the transformer is established; the three-dimensional geometric grid model is input into software, sinusoidal currents with a phase different of 120 DEG are applied to the cross section of the three-phase low voltage winding respectively, and Dirichlet boundary conditions are applied to the outer side of the structural grid model; and an instant electromagnetic field is solved by a virtual displacement method, magnetic field energy is computed, a virtual work method is used to compute instant electromagnetic force borne by the transformer iron core and the winding, FFT is conducted to the instant electromagnetic force, and frequency domain distribution of the electromagnetic force of the iron core can be obtained. The computation method disclosed by the invention is direct and convenient; electromagnetic vibration and force bearing situations of the transformer iron core can be analyzed from the perspective of energy; each influential factor on force bearing of the iron core is considered comprehensively; and computation results are accurate and reliable.
Owner:CHINA ELECTRIC POWER RES INST +1

Upper-bound limit analysis method of ultimate bearing capacity of jointed rock slope considering translation and rotation effects at the same time

The invention relates to an upper-bound limit analysis method of ultimate bearing capacity of rock slope considering rock translation and rotation effects at the same time, and belongs to the technical field of rock slope bearing capacity analysis. According to the method, based on a plastic upper-bound limit analysis theory, by means of multiple freedom degree rigid block unit discrete jointed rock slope, the translational speed and rotational speed of the rigid block unit centroid are used as unknown quantities, the translation and rotation mechanical effects of rocks are considered at the same time, the overload coefficient of the slope is used as a target function, and plastic flowing conditions satisfying shear failure, tensile failure and rotational failure of a structural plane are constructed; then combined with a virtual work principle and speed boundary conditions, a linear mathematic programming model for working out the ultimate bearing capacity of the jointed rock slope is built, the linear mathematic programming model is solved by means of a simplex method, a strength reserve coefficient is solved by means of an iterative method at the same time, and finally the upper-bound solution and corresponding failure mechanism of the ultimate bearing capacity of the jointed rock slope are acquired. The method has the advantages that the concept is clear and the computational accuracy is high.
Owner:KUNMING UNIV OF SCI & TECH

First-order perturbation expansion progressive homogenization method for statistical prediction of elastic constitutive matrix of random distributed composite materials

InactiveCN108153962APrediction Method of Reliable Material Structure Equivalent Elasticity MatrixAvoid repeating the tedious trial calculation processDesign optimisation/simulationComplex mathematical operationsVirtual workScale effects
The invention discloses a first-order perturbation expansion progressive homogenization method for statistical prediction of an elastic constitutive matrix of random distributed composite materials. The method comprises the steps that (1), according to an actual material domain, the source and range of random variables are determined, and a probability model is established; (2), the random variables are introduced by a material elastic constitutive flexibility matrix based on a first-order perturbation hypothesis, and a stiffness matrix is obtained by inversion; (3), a microscopic representative unit subdomain is intercepted in a macroscopic material structure system, and a functional scale effect relationship on a microscopic representative volume unit is hypothesized based on a progressive homogenization method to derive a virtual work principle equation and establish the equivalence relation between a macro elastic matrix and a finite element equation of a representative volume unitmaterial domain; (4), the equivalence relation between probability and statistical characteristics of the macroscopic elastic matrix and the finite element equation of the representative volume unitmaterial domain is solved; (5), probability and statistical characteristics of elastic engineering constanTS are derived from the macroscopic elastic matrix.
Owner:BEIJING UNIV OF TECH

Nuclear/thermal power turbine set fluid excitation numerical calculation method and system based on flow field simulation

The invention provides a nuclear/thermal power turbine set fluid excitation numerical calculation method and system based on flow field simulation. The method comprises: according to set structure andoperation conditions, simplifying fluid computational domain, creating a flow channel geometric model comprising two stator blades and three rotor blades; discretizing the surface of the blade by utilizing a structured grid, introducing a discretized fluid calculation domain, setting a phase change model, a turbulence model, a boundary condition and a numerical solution parameter according to different flow working conditions, and solving transient distribution pressure of the surface of the blade under different working conditions through flow field simulation; for the blades adopting three-dimensional hexahedron unit discretization, the transient distribution pressure on the surfaces of the blades is equivalent to fluid excitation suitable for different blade structure units by utilizing an inverse distance weighted interpolation method and an equivalent method based on a virtual work principle; and for the blades adopting the spatial twisted beam units for dispersion, transient distribution pressure on the surfaces of the blades is converted into equivalent fluid excitation of the spatial twisted beam units by utilizing a virtual work principle.
Owner:SHANDONG UNIV

Hybrid type automobile electrophoresis coating conveying mechanism dynamics modeling method

ActiveCN105159137AHas coordinate invarianceNeat and concise expressionProgramme controlSimulator controlHybrid typeDynamic models
The invention discloses a hybrid type automobile electrophoresis coating conveying mechanism dynamics modeling method. First of all, the symmetrical structure characteristic of a mechanism is fully utilized, the speed and the accelerated speed of each passive joint in the mechanism are analyzed through an analytical geometry method, and then the speed and the accelerated speed of each active joint of the mechanism are obtained by introducing a screw theory; secondly, based on this, a kinetic equation in a mechanism spinor form is established by use of virtual work principle; and finally, axial driving power of each active joint of the conveying mechanism capable of directly realizing control is obtained through calculation so that construction of a dynamics model capable of realizing high-performance control is completed. According to the invention, the analytical geometry method, the screw theory and the virtual work principle are combined together, so that the problem of coordinate transformation due to lack of coordinate invariance during dynamics modeling of a complex special mechanism is solved, the calculation complexity is reduced, and at the same time, the dynamics modeling method brought forward by the invention is quite simple, is tidy in form and is easy in programmed realization.
Owner:JIANGSU UNIV

Creep constitutive model parameter identification method for creep test

ActiveCN108009311APredicting Creep Deformation BehaviorSatisfied with the optimal solutionDesign optimisation/simulationSpecial data processing applicationsStress conditionsMeasurement point
The invention discloses a creep constitutive model parameter identification method for creep test. The method includes the steps: extracting a strained measuring value epsilon y (xi, yi and tk) of ani measuring point of a sample analysis surface at a k strained measuring moment tk by a creep load F in a y direction to obtain a creep strain of the i measuring point of the sample analysis surface at the moment tk as shown in the specification; determining a grid area Ai taking the i measuring point as a center; selecting a creep constitutive model, and enabling the creep strainepsilon <cr> to express a function of stress level sigma and creep time t; acquiring virtual work under the action of the creep load F; acquiring an objective function phi (p) for identifying creep constitutive model parameters, and solving a value popt and a parameter popt of a corresponding p of a minimal value of the objective function. The corresponding parameter popt is an identified creep constitutive model parameter. The method has the advantages that sample material creep deformation behaviors can be forecasted according to stress conditions without change of materials and environmental conditions.
Owner:HEFEI GENERAL MACHINERY RES INST +1
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