442 results about "Stiffness matrix" patented technology

The invention relates to the field of thighbone modeling software development, discloses a thighbone biomechanics finite element analysis system based on force feedback, and aims to solve the problems that the conventional thighbone modeling analysis software is very complicated to operate, and has lower success rate to guide an external operation. A thighbone CT image gray value extraction module is used for leading various-format CT images; a thighbone elasticity modulus assignment module is used for acquiring inner coordinates of corpus femoris grid cells; a thighbone biomechanics finite element analysis module is used for calculating the stiffness matrix of each corpus femoris grid cell through the elasticity modulus of each corpus femoris grid cell; a force feedback module is used for simulating the mechanical properties, including size and direction, of test points according to the strain data and stress data and also for transmitting the size and direction of a force to a control handle of an external force sensing device; a force feedback device after data conversion can output the force generated when the thighbone actually deforms, and truly percept the biomechanical characteristic of a thighbone model.

The invention relates to a multi-support shafting finite element method with bearing stiffness coupling nonlinearity considered. The method comprises the steps of (1) establishing a local coordinate system of each bearing and obtaining a six-freedom-degree bearing stiffness matrix of each bearing under the corresponding local coordinate systems through calculating by means of the difference method with a corresponding bearing load calculation formula; (2) dividing a shaft into different shaft sections according to the difference of diameters, establishing nodes at the positions of bearing section starting positions, the bearing installation position and load action positions, then establishing finite element models of the shaft between the nodes, and obtaining a stiffness matrix of the whole shaft; (3) establishing a global coordinate system of a shafting, establishing another node at the bearing installation position to be used for simulating a fixed end, integrating the bearing stiffness matrix onto the installation node and the corresponding fixed end node on the shaft to obtain the overall stiffness matrix of the shafting, and establishing the stiffness equation of the shafting; (4) restraining the freedom degrees in six directions of the fixed end node, restraining the freedom degree, of rotating around the axis, of the node at the position of origin of the global coordinate system of the shafting, reducing the stiffness equation of the shafting according to restraining conditions, and solving the reduced stiffness equation of the shafting with the Newton-Raphson method in an iterative mode to obtain the displacement and load of each node.

A finite element method of forecasting slab band temperature field during a hot rolling process belongs to the rolling technique field, and comprises the following steps: (1) collecting rolling process data; (2) carrying out unit division to cross section, establishing finite element analysis model, coding a unit node, and calculating a node coordinate; (3) ensuring border heat transfer coefficient and internal heat source intensity according to different rolling processes; (4) calculating the type-function of quadrangle isoparametric unit, B matrix, Jacobian matrix J and Jacobian matrix determinant |J| by using the finite element basic principle; (5) assembling the temperature rigidity matrix and dynamic heating matrix of the finite unit; (6) solving linear system of equations by adopting unidimensional variable bandwidth storage to obtain transient temperature field. The invention has the advantages that: the invention can obtain very high temperature forecasting precision and detailed information of the entire hot rolling slab band temperature distribution, which provides set and optimized parameter for rolling process, moreover, the invention has strong adaptability, reduces calculating time and improving calculating efficiency.

The invention discloses a topological optimization method based on a meshfree RKPM (reproducing kernel particle method) for a thermal structure of an anisotropic material. The method comprises a step of establishing a meshfree RKPM thermal stiffness matrix of the structure of the anisotropic material with a transformation matrix method, and the step comprises the following sub-steps: (1) solving dynamic influence domain radius of each calculation point according to coordinate information of input nodes and Gaussian points; (2) solving relative density of each RKPM node according to an RAMP (rational approximation of material properties) material interpolation model; (3) searching Gaussian points in a design domain, and establishing thermal conductivity tensor of each node according to the thermal conductivity of the anisotropic material, an orthotropic factor and a material direction angle; (4) taking a dot product of a thermal conductivity coefficient matrix and a geometric matrix of each node as an RKPM thermal stiffness matrix of the node; (5) forming the integral RKPM thermal stiffness matrix in the design domain. According to the method, topological optimization of the thermal structure of the anisotropic material is performed on the basis of the meshfree RKPM, the transformation matrix method and the RAMP material interpolation model, and the numerical stability is high.

The purpose of this invention is to reduce the calculation time in the numerical structure analysis system based on load-transfer-path method.

The parameters are set in the condition that the supporting point B in the objective structure is fixed and the load is applied to the specific loading point A. The FEM calculation means 2 calculates the deformation of the objective structure according to the structural stiffness matrix in the stiffness matrix holding means 1 to find the basic data such as the displacement of each point and so on. The FEM calculation means calculates each deformation to find the displacement under the condition that the specific loading point A and the supporting point B are fixed and three inspection loadings are applied to the variable loading point C. The partial stiffness matrix calculation means 3 solves the multidimensional simultaneous linear equation based upon the internal stiffness matrix of the objective structure, the load value and the displacement to find the partial stiffness matrix K_AC. The stiffness parameter calculation means 8 calculates the value of the stiffness parameter U* according to the partial stiffness matrix K_AC and the displacement in the basic data and so on. The value of U* of each point is calculated with changing the variable loading point C as to follow sequentially all the necessary points in the objective structure.

The invention discloses a continuous rigid frame bridge prestress damage identification method based on deflection monitoring. The continuous rigid frame bridge prestress damage identification method comprises the following steps: I, establishing a bridge deflection monitoring system, that is, the bridge deflection monitoring system comprises n deflection monitoring devices and one data acquisition device, and the n deflection monitoring devices are respectively arranged on n deflection monitoring points; II, monitoring deflection of a bridge, namely, respectively monitoring deflection data of n deflection monitoring points on a main beam by using the bridge deflection monitoring system in real time, and synchronously transmitting the monitored deflection monitoring data to data processing equipment; III, identifying prestress damage, namely, establishing a finite element model of the bridge, processing the bridge deflection monitoring data, acquiring deflection data caused by prestress damage, establishing a damage identification rigidity matrix and identifying prestress damage. The continuous rigid frame bridge prestress damage identification method is simple in step, reasonable in design, convenient to realize, good in use effect, capable of easily and conveniently completing the prestress damage identification process of a continuous rigid frame bridge, and relatively high in identification result reliability.

The invention provides a statistical energy analysis parameter acquisition method based on a finite element method and a power input method. A finite element model of a structure is established according to a geometric model of the structure, boundary conditions are applied, the finite element model of the structure is subjected to mode analysis, a mode of a system and a rigidity matrix and a mass matrix of a subsystem are obtained, vibration energy of the subsystem and input power of the system are obtained through a power flow model, and statistical energy analysis parameters are obtained through calculation through the power input method. The finite element method and the power input method are combined to obtain the statistical energy analysis parameters of the structure, the calculated rigidity matrix, mass matrix, mode shape and inherent frequency are obtained through the finite element method, the input power and the vibration energy are obtained through calculation through the power flow model, and the input power and the vibration energy are substituted into the power input method for calculation to obtain the statistical energy analysis parameters. According to the method, statistical energy analysis can be carried out aiming at the problem of strong coupling between structures, the limitation about weak coupling assumption between the structures in existing statistical energy analysis is solved, and the method can be popularized to complex structures.

The invention relates to a modal synthesis dynamic modeling and analysis method for an automobile driving axle system. The method is characterized by comprising the steps that 1, a finite element model of all components of a driving axle is established, boundary nodes are defined according to the connecting relation between the components, a modal synthesis model of all the components is established, and a modal synthesis rigidity matrix and a mass matrix of all the components are obtained; 2, a connecting relation model of all the components is established; 3, the modal synthesis rigidity matrix and the mass matrix of all the components are assembled according to the connecting relation, a complete modal synthesis dynamic model of the driving axle system is established, and a rigidity matrix and a mass matrix of the driving axle system are obtained; 4, natural vibration frequency and a regular vibration mode of the dynamic model of the driving axle system are calculated, and a mode superposition method is adopted to calculate the dynamic response of the driving axle system under excitation of dynamic engaging force of gears of a main reducing gear. In the whole modeling process, high universality and calculating efficiency are achieved, and the method can be widely applied to dynamic analysis of a gear transmission system.

The invention relates to a multiscale prediction method for the mechanical property of a woven composite material. The method comprises the following steps that 1), an initial parameter is input; 2), elastic stiffness matrixes of a fiber/basal body scale, a fiber bundle scale and a unit cell scale are computed sequentially according to a bottom-to-top homogenization process; 3), a multiscale incidence matrix is constructed; 4), stress-strain analysis is performed on unit cell entirety, stress is decomposed by the multiscale incidence matrix from top to bottom, and stress-strain fields under all the scales are obtained synchronously; 5), whether an ingredient material is in a failure is judged according to respective failure criteria of a fiber and a basal body; if so, the corresponding ingredient material is subjected to stiffness reduction; 6), whether the unit cell entirety is in a failure is judged, and if so, Step 7) is executed, or else, a next displacement increment is added and Step 2) is returned; and 7), stiffness and strength computation results of the woven composite material are output. Compared with the prior art, the method has the advantages of high computation efficiency, high precision, high universality and the like.

The invention discloses a method for the layout optimal design of a multi-assembly structure system, which is used for solving semi-analytical sensitivity of geometric parameters in the layout optimal design of a multi-assembly structure system. The method comprises the following steps of: dividing a finite element model of the multi-assembly structure system into three parts: structure lattice, assembly lattice and transition lattice; respectively evaluating influences of different geometric parameter perturbations on the three parts of lattices as well as a rigidity matrix and a quality matrix thereof to obtain the semi-analytical sensitivity of the rigidity matrix and the quality matrix; and further obtaining the sensitivity of various design indexes by derivation. Compared with the finite differential method for the traditional layout optimal design, the semi-analytical method of the invention effectively avoids the finite element solving process after the geometric parameter perturbations are updated, saves the time for sensitivity analysis and optimal design, shortens the cycle of the layout optimal design of the multi-assembly structure system, and enhances design efficiency.

The invention provides a curvature fairing method for a high-speed numerical control processing track. The curvature fairing method comprises the steps of: inputting tool location points of an initial processing track; interpolating the initial tool location points by utilizing B-spline curve repeatedly to obtain a tool processing track line, and representing the tool processing track line by using the B-spline curve; calculating a stiffness matrix of a track curve according to node vectors of the B-spline curve; calculating a closest point from each initial tool location point to the B-spline curve and curve parameters corresponding to the closet points, and calculating a first-order derivative of a distance (from the initial tool location points to the closest points of the B-spline curve) to control points of the B-spline curve; solving a tool processing track curvature derivative fairing model by adopting a sequence linear method to obtain a processing track after fairing optimization; and outputting tool locating points of the tool processing track after fairing optimization. The curvature fairing method solves the problem of generating the high-speed numerical control processing tool track with fair curvature, and is suitable for generating a 2.5-axis cavity high-speed processing track.

The invention relates to a meshless cloth-based simulation method. The method comprises the following steps of: (a) parameterizing a given cloth model omega onto a middle surface lambda and determining a configuration before deformation and a reference configuration when calculation is started; (b) selecting a limited number of nodes in the parameterized middle surface lambda and determining a local subdomain omega s of each node; (c) calculating a shape function phi I in a definition domain of each node and calculating a derivative of the shape function; (d) determining Gauss integral points of all nodes, calculating a numerical integral and assembling a stiffness matrix; (e) assembling a node mass matrix and a viscosity matrix; and (f) determining the number of cycles according to the simulation time t and the set time step interval delta t to cycle the following steps for t/delta t times: calculating a rotated global stiffness matrix, implementing constraints on the global stiffness matrix, the node mass matrix and the viscosity matrix, obtaining and solving a system linear equation set according to time integral to obtain nodal displacement, implementing meshless collision detection and a response algorithm to modify the nodal displacement, and generating the displacement of all sampling points of each time step after re-sampling.

The invention discloses a meshless RKPM-based two-dimensional thermal deformation and stress analysis method for an anisotropic material structure. The method mainly comprises the following steps of (1) performing RKPM node discrete preprocessing on a calculation model; (2) solving an RKPM thermal deformation displacement value: assembling RKPM overall force stiffness matrix and overall thermal load column vector; applying a boundary, and processing a first boundary condition by adopting a penalty function method; establishing a meshless RKPM thermal stress discrete control equation of the anisotropic material structure, and solving the RKPM thermal deformation displacement parameter value of a node; (3) solving an RKPM thermal stress value: performing approximation on the obtained thermaldeformation displacement parameter value by adopting reproducing kernel approximation to calculate out a thermal stress of a Gaussian point, thereby obtaining the RKPM thermal stress value of the node; and (4) post-processing a calculation result. The two-dimensional thermal deformation and stress analysis of the anisotropic material structure is performed based on a meshless RKPM; and a numerical method is stable and high in precision.

The invention discloses a Yeh-multi-scale finite element method for simulating water flow Darcy velocity of a porous medium, comprising the steps of: performing variation on the problem which needs resolution by a Galerkin method; subdividing a research area into coarse grid cells and subdividing all the coarse grid cells into fine grid units; resolving a degradation elliptic equation on each coarse grid cell to construct a basis function; resolving variational form by applying the basis function to obtain a total rigidity matrix; obtaining a right-hand term according to the source sink term and the boundary condition of the research area; performing simultaneous operation to obtain a waterhead equation set; resolving the equation set by an effective numerical method to obtain the node waterhead of the research area; and resolving a Darcy equation directly in the research area by combining a Galerkin finite element model of Yeh and applying the constructed basis function and the waterhead value of the research area to obtain continuous Darcy permeating velocity on the coarse-scale node, and linearly expressing the fine-scale Darcy permeating velocity by the basis function. Compared with the prior art, the method has similar precision and higher efficiency.

The invention discloses a high-pile wharf foundation pile damage diagnosis method based on structural residual modal force. The method includes the steps that a finite element model of a high-pile wharf foundation pile structure is established, the structure is divided into a plurality of units, and each unit comprises two nodes; an acceleration sensor is arranged on each unit, and modal test data detected under natural environment excitation are recorded and saved; modal parameter recognition is performed on the modal test data, and a low-order modal frequency and a vibration mode of previous orders are recognized; model correction is performed, and a reference finite element model is obtained; under the non-damage and damage condition, a rigidity matrix and a mass matrix of each unit are extracted; and each freedom-degree residual modal force vector in each unit is calculated, when the absolute value of each freedom-degree residual modal force vector in each unit is larger than a set value, it is judged that damage exists, and the position where structural damage is located is positioned according to the nodes corresponding to freedom degrees. Only through low-order modal information generated before and after structural damage, damage diagnosis can be performed under the condition that the structure has single damage and multi-site damage.

The invention aims at providing a structural vibration analysis method based on a finite element method and a generalized Fourier series method, which comprises the following steps of: dividing a structure region to be subjected to vibration analysis to respectively and correspondingly form a finite element expression region and a generalized Fourier series expression region; dividing the finite element grids of the finite element expression region to form a corresponding quality stiffness matrix, and selecting a corresponding assumption displacement form according to the characteristics of the generalized Fourier series expression region to form a quality stiffness matrix; subsequently, establishing a virtual spring between the two regions, and converting the potential energy of the virtual spring into an overall coupling stiffness matrix by using an energy variation method; then, arranging the formed quality stiffness matrices according to displacement to form an overall structure quality stiffness matrix; and solving linear equations to obtain an unknown coefficient in corresponding node displacement and series expansion. When applied to a large complex structure, the method not only can obtain precision higher than the finite element method, but also can save a large amount of calculation cost.

The invention discloses a determination method for mechanical parameters of transverse isotropy shale reservoir rocks. The determination method comprises the following steps: carrying out an X-ray diffraction experiment to determine rock mineral constituents of a certain well depth; inverting rock porosity of the certain well depth by utilizing acoustic logging information; determining the stacking density of clay by utilizing the determined rock mineral constituents and the porosity; determining rigidity matrixes of transverse isotropy rocks of shale under a scale 0 by using a closed cycle-correction-identification method; determining the rigidity matrixes of the transverse isotropy rocks of the shale under a scale 1 and a scale 2 by utilizing a pore elastic theory; and substituting the rigidity matrixes into inversion models of Young modulus, poisson ratio and shear modulus and determining the mechanical parameters of the rocks. According to the determination method, the mechanical strength parameters of the rocks are inverted by using the X-ray diffraction experiment, so that the inversion result is accurate on the basis of establishing the experiment; field rock fragments are easy to obtain so that the determination method has the characteristics of time conservation, labor conservation and money conservation in the aspect of experiment operation.

The invention provides a novel lining design method of shield tunnel, comprising: respectively establishing stress calculating models of shell unit, tube piece joint unit, and inter-ring joint unit, and considering the soil spring unit to form joint displacement unknown quantity number by the information of tube piece and load and to form structure rigidity matrix and structure load matrix by considering the shell unit and joint unit respectively, solving displacement and joint force of the shell unit by dividing the structure rigidity matrix, and checking whether the result satisfies the iteration condition, if not, returning to reestablish the structure rigidity matrix and structure load matrix, if so, carrying out relative structure design based on the calculation result.

The invention provides a method for measuring towercrane crane jib structural distortion and stress of a trolley-jib amplitude type tower crane, which is based on the finite element method. The measuring method comprises the following steps: firstly, determining main parameters of the tower crane steel structure in the form of man-machine interaction, then calculating the nodes, the coordinates of finite element joints, the number of the finite elements, space direction cosine, and the dead weight of the finite element, determining the weight of a luffing mechanism, determining the equivalent joint load, generating the equation to form a total stiffness matrix, accurately calculating the element stress of spacetruss based on the finite element method, considering the effect of the deformation and stress of truss due to temperature change and reaching the aim of computer-aided tower crane design, thus greatly reducing the design cost.

The invention discloses a rolling bearing-rotor system damage vibration response quantitative calculation method. The method comprises the steps that the structure parameter and the initial parameter of a bearing-rotor system are acquired; according to the bearing parameters, a five freedom degree bearing model is established, and a bearing stiffness matrix of the bearing-rotor system is acquired; according to the geometric size and the material characteristic parameter of a subcomponent, a finite element model is established, and a rotor stiffness matrix, a rotor gyroscopic matrix, and an equivalent mass matrix caused by a centrifugal force are acquired; a dynamics model of the bearing-rotor system is established; a time-domain integral method is used to solve the bearing-rotor dynamics model, so as to acquire the displacement vibration response of the bearing-rotor system. According to the invention, based on the finite element dynamics model, quantitative calculation can be carried out on vibration response generated by single point or multi-point damage of inner and outer rings of a bearing, and a basis is provided for the analysis and the diagnosis of a fault mechanism of the rotor-bearing system.

The invention provides a vibration analysis method for a uniform section beam structure. The method comprises the steps that geometric size characteristics of the beam structure are extracted, a displacement field of the beam structure is separated to be in-section displacement and axial displacement; fitting is performed on the in-section displacement of the beam structure; extension is performedon the axial displacement of the beam structure; the in-section displacement and the axial displacement of the beam structure are combined to calculate integral displacement of the beam structure; strain vectors and stress vectors of an elastic plate structure are calculated; strain energy, a kinetic energy equation and boundary energy of the beam structure are calculated; a structural Lagrange energy function is established to obtain a core mass matrix and a stiffness matrix of the beam structure; an integral mass matrix, an integral stiffness matrix and an overall mass matrix are solved through iterative looping of the core matrix, and then a characteristic equation of the structure is obtained; and a characteristic equation matrix of the beam structure is solved, and inherent frequencyand a vibration mode are obtained through calculation. The method is suitable for the beam structure with multiple boundary conditions and multiple section shapes and is high in precision, fast in convergence, low in calculation cost and simple in calculation method.

A variable stiffness segmented composite material including reinforcements embedded in a variable stiffness matrix and having a structure for precisely controlling the three-dimensional (3D) distribution and connectivity of the reinforcements in the variable stiffness matrix. The composite material includes a variable stiffness matrix and a plurality of rigidly interconnected reinforcements embedded within the variable stiffness matrix, the interconnected reinforcements being for mitigating a deformation of the composite material along a first direction by blocking a rigid body motion of the reinforcements with respect to one another in the first direction while allowing a deformation in a second direction differing from the first direction. That is, in one embodiment, the interconnected reinforcements are configured to move with respect to one another to allow for an in-plane deformation of the composite material while mitigating an out-of-plane deformation of the composite material.

The invention provides a soft tissue deformation method based on a finite element model of an octree mesh. The method comprises: drawing a three-dimensional model of soft tissue, constructing a plurality of uniform hexahedral meshes based on the AABB method, and generating an octree mesh based on the mesh generation algorithm of an octree based on the hexahedral mesh, modeling the hexahedron meshby the finite element method, solving the deformation process of the soft tissue, assembling the element stiffness matrixes on adjacent element nodes into the total stiffness matrix of the discrete domain, solving the dynamic equilibrium differential equation for each matrix by time integral under dynamic equilibrium, to obtain the displacement of the nodes with time, and displaying the stress deformation of the soft tissue by the rendering of the displacement of the nodes. The method realistically simulates the process of tension deformation of the soft tissue epidermis of any shape in virtual surgery, has high real-time performance, reduces the calculation amount, and solves the problem that the number of finite element meshes is complicated and the soft tissue deformation process cannotbe simulated in real time.

The invention provides a multi-robot synergistic system static stiffness real-time performance evaluation method without additional devices. The method comprises the steps that based on a robot kinematics transfer matrix and a robot end operation stiffness matrix, a robot joint stiffness identification scheme is established and implemented, and accurate robot practical joint stiffness is acquired; by employing robot system software to feed back real-time joint angles, a robot jacobian matrix is established, and a multi-robot synergistic system overall stiffness matrix is formed through the robot jacobian matrix and joint stiffness parameters identified by a robot; robot real-time stiffness is subjected to visual characterization through robot stiffness matrix ellipsoids, and the maximum value of system stiffness matrix characteristic values is selected as an evaluation index for carrying out robot stiffness evaluation; finally, through a GUI design interface, a stiffness performance evaluation visual interface is designed based on a double-KUKA KR-16 robot synergistic system.