41 results about "Geometrical nonlinearity" patented technology

The invention discloses a real-time compensation control method and system for thrust fluctuation of a linear motor, and belongs to the technical field of linear motors, and the method comprises the steps: collecting a hybrid fluctuation source in the operation process of the linear motor, splitting the hybrid fluctuation source, and generating independent geometric nonlinear fluctuation signals; further screening the mixed fluctuation source, screening out a non-geometric nonlinear fluctuation signal, and preprocessing the non-geometric nonlinear fluctuation signal; establishing an independent compensation strategy, and respectively performing targeted compensation on geometric nonlinear fluctuation and non-geometric nonlinear fluctuation; and establishing a feed-forward compensation network, inputting the compensation strategy into the feed-forward compensation network, predicting a fluctuation component, and performing pre-compensation processing in advance. In the implementation process of the technical scheme provided by the invention, the pertinence and effectiveness of a compensation strategy are ensured through precise splitting and preprocessing of the hybrid fluctuation source, and meanwhile, the compensation amount is adjusted in real time by using the prediction function of the feedforward compensation network, the thrust fluctuation is remarkably reduced, and the operation stability of the linear motor is improved.

The invention provides a high aspect ratio wing topological optimization method considering pneumatic-structure coupling. The method comprises the following steps: establishing a pneumatic-structure strong coupling topological optimization model; performing finite element analysis to obtain an original variable field of the high aspect ratio wing; generating a filtering variable field and a projection variable field; deformation displacement of each finite element unit is obtained based on a UMMI material interpolation model; establishing information transmission, structure displacement response, aerodynamic load transmission and aerodynamic load updating strategies under pneumatic-structure coupling, and analyzing and updating the aerodynamic load; according to the method, manufacturing constraints such as geometric nonlinearity, multi-material layout and wing rib orientation size are comprehensively considered, design variables in an original variable field are subjected to iterative optimization solution, a wing optimization configuration is obtained, the three core problems of calculation distortion, performance deviation and manufacturing difficulty in lightweight design of the high aspect ratio wing are successfully solved, and the method is suitable for the lightweight design of the high aspect ratio wing. And the comprehensive performance and economical efficiency of the aircraft are remarkably improved.

The invention discloses a rapid deformation reconstruction method for a large-displacement flexible beam structure, and belongs to the field of structural health monitoring. On the basis of a co-rotation coordinate method, the local displacement is obtained after rigid body displacement is removed from the total displacement of the flexible beam structure. Local displacement obtained through a co-rotation coordinate method is substituted into an iFEM formula based on a small deformation hypothesis, and the deformation reconstruction problem under the geometric nonlinear condition is converted into the problem that the mean square error sum of theoretical strain and actually measured strain is minimum by searching an optimal node displacement parameter to achieve square functional optimization. And solving the optimal solution of the functional by adopting an optimization algorithm. In addition, a simplification strategy which ignores a high-order small quantity is adopted, so that the whole nonlinear deformation reconstruction method remarkably improves the calculation efficiency on the premise that the calculation precision is not sacrificed. According to the method, the node displacement parameter enabling the functional to be minimum can be rapidly solved, and rapid and high-precision deformation reconstruction of the large-displacement flexible beam structure is achieved.

The invention discloses a visual sparse observation and physical model fused flexible body deformation tracking method, which comprises the following steps of: firstly, constructing a flexible body co-rotation finite element model considering geometric nonlinearity, and establishing a low-dimensional flexibility coupling model for describing a mechanical transfer relationship between a virtual actuating source and a characteristic observation point by utilizing a static condensation technology; in the real-time tracking process, a binocular vision system is used for collecting images and resolving three-dimensional coordinates of sparse feature points in a real physical world; constructing and solving a reverse optimization problem based on the low-dimensional flexibility coupling model, and calculating a virtual correction force vector capable of minimizing an observation error; and applying the virtual correction force vector to the finite element model to drive the finite element model to deform, and updating a full-field geometric node position and a tangent stiffness matrix in real time. Through deep fusion of a physical model and sparse visual observation, the problems of visual occlusion and virtual-real model deviation in flexible body assembly are effectively solved, and online real-time full-field high-precision deformation state estimation is realized.

The invention relates to the technical field of ocean resource development, in particular to a method for calculating vortex-induced vibration of a deep-sea mining riser under the action of internal waves. According to the method, velocity and acceleration distribution characteristics of a flow field are determined according to wave parameters such as amplitude and wavelength of ocean internal waves, and load input is provided for calculation of vortex-induced vibration of the deep-sea mining riser; the ocean internal wave flow field has remarkable particularity, is different from uniform flow and typical shear flow, and is unsteady non-uniform shear flow; based on the particularity of an ocean internal wave flow field, vortex-induced load distribution on a deep-sea mining riser under the action of a traditional wake flow vibrator model is obtained by improving the traditional wake flow vibrator model; according to the geometric nonlinear problem caused by the large slenderness ratio of the deep-sea mining super-long riser and the weak constraint characteristic of the deep-sea mining riser, the rigid body displacement and the elastic deformation of the riser are separately calculated by adopting a co-rotation coordinate method, so that the calculation efficiency is improved to meet the actual engineering requirements; the invention discloses a calculation method for vortex-induced vibration of a deep-sea mining riser under the action of ocean internal waves.

The invention provides a long-term deformation prediction method and system for a large-span rigid frame bridge, and relates to the technical field of bridge deformation prediction. The method aims at solving the problems that in the prior art, a prediction method insufficiently considers the coupling effect of geometric nonlinearity and the concrete shrinkage and creep effect and lacks the dynamic response capacity to damage events in the operation period, and consequently the deviation between a prediction result and the reality is large. According to the method, synchronous coupling analysis of the two effects is realized by establishing a space finite element model and constructing a structure balance equation which simultaneously considers the geometric nonlinearity and the shrinkage and creep effect; through reference simulation and damage event identification based on a probability distribution model, dynamic damage correction and simulation restart are carried out on the model in combination with monitoring data, a closed-loop prediction mechanism for identification, correction and restart is constructed, the precision and accuracy of long-term deformation and internal force prediction are effectively improved, and the adaptability in a complex scene is improved.

The invention provides a geometric nonlinear multi-material topological optimization method based on a hyperelastic material model, and the method comprises the steps: building a topological optimization framework which takes the minimum end point type flexibility of a structure as an optimization target and takes the ratio of the overall mass of the structure to a single material body as an optimization constraint condition; according to the method, a projection variable field of a to-be-optimized engineering structure is obtained based on finite element analysis, a Neo-Yeoh hyperelastic material model is designed and established, in the topological optimization process of a structural material, screening of units with different projection variable values is achieved based on a set of original grids, and the optimal structure material is obtained. According to the geometric nonlinear topological optimization method based on the Neo-Hookean hyperelastic material, the entity unit is endowed with the Neo-Hookean hyperelastic material, and the hole or the low-density unit is endowed with the second-order Yeoh hyperelastic material, so that the problem of numerical instability caused by distortion of the low-density unit in geometric nonlinear topological optimization is solved, the designed model can be solved by utilizing a traditional commercial solver, and the universality is high.

The application discloses an adjustable nonlinear dynamic vibration absorber and system, and has the technical scheme that a tuning mass block is slidably connected to the surface of a support plate, and first scissor structures are rotatably connected between the tuning mass block and the two ends of the support plate; the first scissor structures are provided with second scissor structures and dampers, the second scissor structures and the dampers can drive the first scissor structures to stretch and contract through elastic belts, the second scissor structures are provided with elastic elements for driving the second scissor structures to stretch and contract; the stretching direction of the elastic elements is parallel to the sliding direction of the tuning mass block, and is perpendicular to the damping direction of the dampers, so that the first scissor structures and the second scissor structures can realize vibration absorption through geometric nonlinearity when moving. The stiffness and damping characteristics of the application can be adjusted, and the linear elements can be used to realize nonlinear stiffness, damping and super-low natural frequency, and the problem of Duffing system instability that cannot be eliminated by traditional nonlinear vibration absorbers is solved.

The invention discloses a zero-dispersion nonlinear MEMS accelerometer for monitoring construction stress of a floating fan platform, and belongs to the technical field of ocean engineering structure monitoring. The zero-frequency-dispersion nonlinear MEMS accelerometer comprises a mass block, an amplification beam pair assembly, an electrode system and resonant beams arranged on the two sides of the mass block in a bilateral symmetry mode, and the mass block is connected with the resonant beams through the amplification beam pair assembly. According to the invention, adjustable static nonlinearity is introduced in the capacitance excitation process of the double-end clamped resonant beam, and the adjustable static nonlinearity is matched and counteracted with the geometric nonlinearity of the resonant beam, so that the resonator enters a zero-frequency dispersion working area within a preset excitation range, and therefore, under the working conditions of construction load disturbance, structural vibration amplitude fluctuation and the like, the resonance efficiency of the resonator is improved. Frequency response information related to structural dynamic characteristics can still be stably output, and a high-stability perception basis is provided for inversion analysis of welding residual stress and structural health states.

The application relates to a structure lightweight design method based on a modified equivalent static load method, which comprises the following steps: step 1, establishing a finite element model of an initial structure to be optimized, and calculating linear equivalent static loads; step 2, calculating modulus proportionality coefficients of a plastic deformation stage of the structure to be optimized; step 3, modifying the equivalent static loads of the structure according to the calculated modulus proportionality coefficients; and step 4, carrying out nonlinear topology optimization according to the modified equivalent static loads to obtain an energy-absorbing point lattice cell configuration, and realizing structure lightweight design. The application is based on a material and geometric nonlinear numerical modified equivalent static load method, the equivalent static load method is modified through modulus proportionality coefficients and strain matrix correction coefficients, nonlinear topology optimization of the structure is realized, a three-dimensional model of the point lattice cell configuration is reconstructed according to an optimization result, a geometric parameterized model of the energy-absorbing point lattice cell configuration is obtained, and the model is used for lightweight design of the point lattice structure under a compression load working condition.

The invention relates to the technical field of solid mechanical modeling, and solves the technical problem that an existing unified mechanism modeling strategy neglects geometric nonlinear characteristics of local weak-rigidity parts of an assembly, so that the static response prediction precision of the assembly is not high. The assembly deformation stress cooperative control-oriented aircraft rigid-flexible hybrid structure multi-level analysis method comprises the following steps: carrying out linear and nonlinear response analysis on finite element models of rigid framework parts and weakly rigid thin-wall parts, and establishing a linear mapping model and a nonlinear explicit mapping model; combining the two models to obtain a deformation stress analysis model; and obtaining a clamp holding force-displacement stress mapping model for representing the mapping relationship between the multi-point holding force of the assembly and the node displacement and the node stress based on the deformation stress analysis model. According to the method, the problems of lack of explanation and few mechanisms of a variable stiffness structure model are solved, and efficient prediction and damage early warning of the internal stress of the component are realized.

The invention discloses a dynamic modeling and performance analysis method for a quartz double-end tuning fork resonator, and the method comprises the steps: constructing a high-order displacement field which meets the condition that the free boundary stress is zero in prior to describe the deformation of a mass block, and employing a coupling scheme based on a virtual work principle; the tuning fork arms and the mass block are integrated into an energy conservation dynamic self-consistent system. According to the method, the linear characteristic frequency and modal of the system are solved, then geometric nonlinearity is introduced, and the amplitude-dependent nonlinear frequency response is accurately calculated through an iterative algorithm. According to the dynamic modeling and performance analysis method for the quartz double-end tuning fork resonator, the fundamental frequency prediction error is reduced to 0.34% from 1.6% of a traditional model, and the relative precision is improved by 79%; meanwhile, the non-physical residual stress at the free boundary is restrained to the magnitude of the maximum stress in the domain, the boundary stress distortion is fundamentally eliminated, and a reliable theoretical tool is provided for accurate design and optimization of the high-performance MEMS resonator.

The application discloses a large wind power blade fatigue test load calculation method considering pre-bending and geometric nonlinearity, and aims at solving the problem of significant deviation between calculation results and actual test data in traditional large wind power blade fatigue test load calculation. The method comprises the following steps: step 1, a wind power blade discretization model considering pre-bending is established, and sectional data is optimized through a piecewise cubic Hermite interpolation method; step 2, the rotation angle of a pre-bending curve and the deflection of the pre-bending curve of each discretization section of the blade are calculated based on the optimized sectional data, and a geometric nonlinearity corrected stiffness matrix is used to calculate the static equilibrium position and the average bending moment of each discretization section of the blade under the action of a static load; and step 3, based on the static equilibrium position of the blade, a multi-degree-of-freedom system dynamics method is used to solve the bending moment amplitude of each discretization section of the blade in a steady state operation of a blade fatigue test system.

The invention discloses a truss structure nonlinear buckling stability optimization design method based on a finite mass point method and automatic differentiation, and the method comprises the steps: constructing a parameterized truss model, and taking the cross-sectional area and / or node coordinates of a rod piece in the parameterized truss model as design variables; constructing an optimization objective function for determining the nonlinear buckling stability performance of the structure as an objective; and on the basis of the parameterized truss model, constructing a corresponding finite mass point method analysis model, and performing iterative optimization on the optimization objective function in the process of simulating nonlinear static response to buckling in the finite mass point method analysis model in combination with automatic differential software, so as to output a final design variable as the optimal truss structure design. The method provided by the invention can effectively solve the problem of buckling stability optimization of the truss structure which becomes abnormally complex due to geometric nonlinearity and path dependence characteristics.

The invention relates to a nonlinear structure reduced-order model construction method based on sparse recognition and a mixed mode, belongs to the technical field of structural dynamics analysis and aeroelastic mechanics analysis, and solves the problem that complex motion caused by geometric nonlinearity under large deformation cannot be accurately described in the prior art. Comprising the following steps: S1, establishing a nonlinear finite element model of a target large flexible wing to obtain a training data set; s2, solving a mixed modal basis based on the displacement residual error and SVD (Singular Value Decomposition); s3, establishing a nonlinear stiffness coefficient solving problem model, introducing LASSO regression to establish an LASSO regression optimization objective function, and solving to obtain a sparse nonlinear stiffness coefficient; s4, based on the sparse nonlinear stiffness coefficient and the structural kinetic equation, establishing a nonlinear structure reduced-order model; and S5, applying the nonlinear structure reduced-order model to statics response solution and dynamics response solution of the large flexible wing to obtain statics response and dynamics response results.

The application belongs to the technical field of marine resource development, and is a calculation method for vortex-induced vibration of a deep-sea mining riser under the action of internal waves. According to wave parameters such as the wave amplitude and wavelength of the marine internal waves, the velocity and acceleration distribution characteristics of the flow field are determined to provide load input for the calculation of vortex-induced vibration of the deep-sea mining riser. The marine internal wave flow field has significant particularity, which is different from uniform flow and typical shear flow, and is a kind of non-uniform shear flow. Based on the particularity of the marine internal wave flow field, the vortex-induced load distribution on the deep-sea mining riser under the action of the improved traditional wake oscillator model is obtained. In view of the geometric nonlinearity problem caused by the large slenderness ratio of the deep-sea mining super-long riser and the weak constraint characteristics of the deep-sea mining riser, the rigid body displacement and elastic deformation of the riser are separated and calculated by using the co-rotational coordinate method, so as to improve the calculation efficiency to meet the actual engineering requirements, and form the calculation method for vortex-induced vibration of the deep-sea mining riser under the action of the marine internal waves.

The application provides a vertical multi-plate wave making system with linkage of a rod system and high-precision control and a control method thereof. A computer control system generates a nonlinear wave control signal, and a controller and a driving device are used to independently drive the hinged points on each wave making plate, so that fine adjustment of local movement of the wave making plate is realized, and the vertical velocity and displacement profile of a target wave are highly accurately reproduced by precisely controlling the displacement of each hinged point. Specifically, a transfer function of the swing amplitude of each plate of the vertical multi-plate wave making machine and the wave height is derived by using the ideal fluid potential flow theory of hydrodynamics, the consistent relationship between the swing amplitude of each plate and the ratio of the displacement or velocity of the nonlinear wave vertical distribution, and the geometric invariable characteristics of each wave making plate are combined, and the specific displacement of each hinged point is solved, and then the motion law of the servo motor is obtained according to the geometric nonlinear relationship between the hinged points of the wave making plate and the linkage motion of the servo sliding block, so that the high-precision reproduction of the target wave by the vertical multi-plate wave making system is realized.

The invention discloses a spanning frame structure size optimization method and system based on a firefly algorithm, and relates to the technical field of electric power engineering construction, and the method comprises the steps: firstly building a parameterized finite element model, implementing normalized hierarchical loading, obtaining a tangent stiffness matrix evolved along with a load, calculating the modal participation degree of a component, and constructing a dynamic participation degree track; and according to the quantitative trajectory smoothing index, the modal dominance and the key component suppression index, constructing a brightness function with coupled rigidity and trajectory features. The firefly attraction degree is corrected by means of trajectory similarity based on modal energy fingerprints, and nonlinear search is executed through a characteristic resonance mechanism. The method solves the problem that traditional static optimization neglects geometric nonlinear evolution to cause modal abrupt change, and the dynamic stability and evolution robustness of the spanning frame in the full stress process are remarkably improved while the structural light weight is achieved.

This invention relates to the field of structural impact dynamics and numerical calculation technology, specifically disclosing a numerical prediction method for the nonlinear response of a variable cross-section beam under multi-point time-series strong impact. The method includes: S1, determining the parameters of the variable cross-section beam and establishing an equivalent multi-degree-of-freedom model; S2, determining the multiple loading conditions for the multi-point time-series strong impact; S3, calculating the stiffness changes of each element under large deformation effects; S4, calculating the initial plastic limit displacement difference at both ends of each element; S5, calculating the stiffness matrix affected by geometric nonlinearity at the current moment; S6, calculating the stiffness matrix affected by material nonlinearity at the current moment; S7, calculating the total internal force at the current moment; S8, calculating the acceleration at the current moment; and S9, calculating the velocity and displacement at the current moment. This invention achieves numerical prediction of the nonlinear response of a variable cross-section beam under multi-point time-series strong impact by establishing an equivalent multi-degree-of-freedom model, combining geometric and material nonlinearity to correct the stiffness matrix, and solving the equations of motion.

The application discloses a kind of geometric nonlinear equivalent plate dynamics modeling and response analysis method of truss structure, its implementation steps are: for the truss structure containing geometric nonlinearity, first, construct linear equivalent Mindlin plate dynamics model;Then describe the geometric constraint relationship of Mindlin plate, carry out displacement and angle approximation and simulate general elastic boundary condition;Finally, according to the extended Hamilton principle, establish the equivalent plate dynamics model containing geometric nonlinearity, and carry out nonlinear dynamic response analysis.The application overcomes the defect that the installation position characteristics of distribution hinge in the width direction of cross section is not considered in the traditional equivalent beam model, and is suitable for geometric nonlinear large deformation analysis;It is suitable for truss structure with general boundary conditions, and has strong engineering applicability;The equivalent nonlinear model established by semi-analytical method is more efficient than traditional finite element numerical algorithm, and is more suitable for dynamic analysis and control law design.

The invention discloses a large-span arch bridge live load bending stress active control method based on an influence matrix, and relates to the technical field of bridge engineering, and the method comprises the steps: constructing a refined finite element model containing material and geometric nonlinearity; a dead load-long-term effect influence matrix is constructed, and the initial adjustment amount of the closure gap enabling the total bending moment decreasing amplitude to be larger than or equal to 30% is solved; a typical live load working condition and a control target are determined; constructing a live load bending stress control influence matrix, solving the additional adjustment amount, and superposing the initial adjustment amount to obtain the optimal adjustment amount of the closure gap; in the construction stage, the optimal adjustment amount of the closure gap is achieved by adjusting the cable force of the buckle cable, and the actual bending stress of the control section under each typical live load working condition is monitored and verified on site after the bridge is formed. According to the method, full-load collaborative optimization can be achieved, the consumption of main arch materials is reduced, the method is suitable for multiple types of arch bridges, and control precision, engineering practicability and economical efficiency are considered.

The invention relates to the technical field of wind turbine modeling, in particular to a dynamic integrated wind turbine structure modeling method, which comprises the following steps of: establishing a platform, a tower drum, a cabin and a rotor of a wind turbine in LS-DYNA, and transmitting force and motion response data between associated structures in the LS-DYNA; the geometric nonlinearity, the material nonlinearity and the contact nonlinearity of the wind turbine can be simulated, interaction keywords for data interaction with the Simulink are established in the LS-DYNA, and an aerodynamic module, a servo dynamics module and an FMU module for data interaction with the LS-DYNA are established in the Simulink. According to the method, the interaction keywords of the LS-DYNA and the FMU module of the Simulink can perform bidirectional data interaction, so that the Simulink and the LS-DYNA are combined to perform analogue simulation on the wind turbine, the dynamic integrated simulation of the wind turbine can be performed, the analysis accuracy can be ensured, and the simulation process is simpler and more controllable.

The application discloses a kind of flexible mechanics metamaterial and preparation method and application thereof, belong to the technical field of metamaterial, the present application is combined with negative stiffness theory to carry out crystal structure beam design and insert thin-walled support structure in inside, the geometric model of the metamaterial constructed has excellent geometric nonlinear characteristics, is manufactured using silicone mold method, can guarantee that the metamaterial is in or close to low stiffness state under specific load condition, to realize the purpose of low-frequency vibration isolation. Compared with the traditional parallel vibration isolator through positive and negative stiffness unit, the structure is more simple, compact, more easily realizes low-frequency vibration isolation under specific load conditions in limited space by the method designed by the present application.

This invention discloses a nonlinear compensation method, apparatus, computer program product, and storage medium for frequency fragmentation in a hemispherical resonator gyroscope. The method includes obtaining the frequency fragmentation amount of the hemispherical resonator under different polarization voltages in amplitude conditions capable of exciting the geometric nonlinear effect of the resonator, generating a frequency fragmentation-voltage evolution trajectory; identifying the error coupling type based on the morphological characteristics of the frequency fragmentation-voltage evolution trajectory relative to a static reference state, where the static reference state is the initial frequency fragmentation value when the polarization voltage is zero; determining the corresponding optimal compensation voltage based on the identified error coupling type, and configuring the optimal compensation voltage as the operating polarization voltage of the hemispherical resonator gyroscope. This invention solves the problem of difficult nonlinear error compensation in high-precision gyroscopes under large amplitude conditions, reduces the complexity and power consumption of the control system, and improves the signal-to-noise ratio and long-term stability of the gyroscope.

This invention relates to the field of cable-stayed bridge technology and discloses a wind-resistant catwalk system for a spatial cable suspension bridge. The system module assembly includes a wind tunnel module, a static wind analysis module, and an optimization design module. The wind tunnel module analyzes the aerodynamic parameters of the catwalk through a scaled-down model wind tunnel three-force experiment, analyzing the influence of different permeability rates on these parameters, providing support for static wind stability analysis and buffeting response calculation. The static wind analysis module, based on wind tunnel test data and combined with a finite element model, calculates the critical wind speed for static wind instability of the catwalk, and analyzes the displacement and internal force distribution of the catwalk under different wind speed gradients based on the influence of geometric nonlinear effects on stability. Based on the analysis results of the static wind analysis module, this invention adjusts structural parameters, optimizes the permeability rates of the side and bottom netting, reduces the span, and adds horizontal and inclined stay cables or external cables to improve structural stiffness and reduce vibration amplitude, proposing a reliable wind-resistant system design.

This invention provides a method and system for monitoring the deformation of slender marine structures, belonging to the field of marine engineering structure monitoring technology based on computer data processing. The invention first acquires measured strain using sparsely arranged sensors, and then generates a continuous curvature vector field that allows for stiffness steps through cross-sectional equivalent mapping and physical piecewise interpolation. Subsequently, based on the piecewise constant curvature theory, the structure is discretized, and the local geometric features of the infinitesimal elements are extracted and analyzed using a three-dimensional special Euclidean group. SE (3) Construct a local homogeneous transformation matrix in space; finally, combine the chain rule to recursively deduce the global pose and reconstruct the three-dimensional large deformation curve. This invention avoids the cumbersome modal parameter identification, strictly decouples spatial bending deformation, eliminates the geometric nonlinearity accumulation error caused by plane integration from the bottom layer, and breaks through the high-fidelity monitoring limitation of complex and slender marine structures such as variable cross-section towers and irregular blades with extremely low sensing cost.

The invention belongs to the technical field of aerodynamic performance characteristic analysis of aircrafts, and particularly relates to a geometric nonlinear flutter boundary prediction method based on a chaos phase space principal component. According to the method, nonlinear flutter characteristics are analyzed and flutter boundaries are predicted by analyzing attractor characteristics of system response signals, and planarity of attractors is represented by analyzing variance contribution rates EVR of first two dimensions of a phase space matrix by utilizing characteristics of pie-shaped attractors of the response signals in a phase space when flutter occurs in a geometric nonlinear structure. The flutter characteristics of a wing with geometric nonlinear characteristics are quantitatively analyzed and described, a brand-new extrapolation prediction method of the flutter critical speed is provided based on the rule that the index changes along with the wind speed, and accurate prediction of the nonlinear flutter boundary can be achieved.

This invention relates to the fields of computer-aided engineering and computational fluid dynamics, and particularly to a computer-implemented dynamic mesh generation method, computing device, and storage medium. The invention provides a computer-implemented dynamic mesh generation method for updating the mesh within a computational domain based on the motion of a moving boundary in numerical simulations. The method includes: acquiring initial mesh data of the computational domain and motion information of the moving boundary; constructing a topological hierarchy of all internal nodes within the computational domain, starting from the moving boundary nodes, based on the connection relationships of the mesh nodes in the initial mesh data; decomposing the total displacement of the moving boundary into multiple displacement increment steps; and performing an iterative processing step for each displacement increment step. This invention aims to overcome the mesh quality deterioration and computational failure problems caused by geometric nonlinear effects in the traditional linear spring analogy method under large deformation boundary motion conditions.

The invention belongs to the technical field of large-span space structure design, and provides a non-linear form optimization method and system for a free-form surface single-layer latticed shell structure, which takes the minimum overall strain energy of the structure as an optimization target and coordinates of latticed shell nodes as optimization variables to construct a non-linear optimization equation of a single-layer latticed shell form and convert the non-linear optimization equation into an unconstrained optimization equation. Solving an optimization problem by adopting a conjugate gradient method; based on solution of a conjugate gradient method, the sensitivity of strain energy to optimization variables is determined; obtaining a nonlinear strain energy gradient based on the sensitivity so as to determine a conjugate gradient direction; based on the conjugate gradient direction, carrying out line search according to a preset load and a step length until the line search in the conjugate gradient direction meets a convergence condition; the overall strain energy minimization, obtained based on nonlinear calculation, of the structure serves as an optimization target, coordinates of latticed shell nodes serve as optimization variables, a conjugate gradient method serves as an optimization algorithm, and the influence of geometric nonlinearity of the structure under the load effect is fully considered.

The invention relates to a rigid constant force device based on a parallel mechanism. The rigid constant force device comprises an elastic paper folding mechanism and a torsion mechanism. Wherein the elastic paper folding mechanism comprises an upper platform and a lower platform; the three groups of paper folding units are the same in structure; the three groups of paper folding units are uniformly distributed in the circumferential direction and are connected between the upper platform and the lower platform in parallel; according to the constant force device, the specific geometric nonlinear characteristic of a paper folding structure is utilized, the torsion spring serves as an energy storage element to provide constant output force, and the defects that a traditional constant force device is small in constant force range and limited in output force are overcome. The device has the advantages of being large in constant force range, large in output force, high in structural rigidity and adjustable in performance.