13 results about "Finite element program" patented technology

The invention discloses a crack stress intensity factor calculation method based on a three-dimensional weight function method, and belongs to the technical field of reliability. Based on a complex variable function Taylor series expansion method, a complex variable finite element program is operated to obtain a weight function of given crack geometry, and then a stress intensity factor of the crack is obtained through stress on a crack surface and weight function integration. Specifically, the method comprises the following steps: establishing a crack-containing finite element model and dividing grids; carrying out perturbation on a crack tip unit node on an imaginary axis; running a complex variable finite element program to obtain an imaginary part of a node crack opening direction on the crack surface so as to obtain a weight function on the crack surface; and solving the stress intensity factor of the corner of the connecting pipe by integrating the weight function of the crack surface and the stress of the crack surface. Compared with a two-dimensional weight function, the method is expanded to three-dimensional elliptical cracks, and the application range is wider; by adopting the method, the calculation result of solving the stress intensity factor of the corner of the connecting pipe under the action of complex load is accurate, and the use is simple and effective.

The application discloses a preprocessing method for a finite element program generator, which is used for automatically translating and converting a high-level XML format physical problem description file, i.e., an.flc file, written by a user into underlying C language source code and a series of input scripts required by a finite element program generator (FEPG) solver, and specifically includes a parsing mode and a modification mode; and the application can automatically translate a high-level physical problem description into underlying source code and input scripts.

The invention relates to the technical field of logging while drilling, and discloses a stratum simulation box for a lateral resistivity logging while drilling tool and a design method of the stratum simulation box. The design method comprises the following steps: determining an electrode structure of an azimuth electrode system of the lateral resistivity logging-while-drilling tool; determining a resistance network of the stratum simulation box based on an electrode structure and a working principle of the azimuth electrode system; according to the resistance network of the stratum simulation box and a working principle, determining a calculation scheme of each resistance parameter in the resistance network of the stratum simulation box; and determining each resistance value of the stratum simulation box resistance network under the typical stratum condition by utilizing a three-dimensional finite element program. The formation simulation box for the while-drilling lateral resistivity logging instrument is designed and generated through the method, various formations simulated by the formation simulation box can be measured by the while-drilling lateral resistivity logging instrument indoors, the working state of the instrument can be checked conveniently, and the instrument can be debugged, maintained and calibrated conveniently; and the time for repeatedly testing and verifying the performance of the instrument is greatly saved.

This invention discloses a method for calculating crack stress intensity factor based on a three-dimensional weighted function method, belonging to the field of reliability technology. Based on the Taylor series expansion method of complex functions, a complex variable finite element program is run to obtain the weighting function for a given crack geometry. Then, the stress intensity factor of the crack is obtained by integrating the stress on the crack surface with the weighting function. Specifically, a finite element model containing the crack is established and meshed; the nodes of the crack tip are perturbed on the imaginary axis; the imaginary part of the crack opening direction at the nodes on the crack surface is obtained by running the complex variable finite element program, thus obtaining the weighting function on the crack surface; the stress intensity factor at the nozzle corner is solved by integrating the weighting function and the stress on the crack surface. Compared to two-dimensional weighting functions, this method extends to three-dimensional elliptical cracks, broadening its application range; the method provides accurate calculation results for the stress intensity factor at the nozzle corner under complex loads, and is simple and effective to use.

A damage assessment method for a ship impacting a reinforced concrete structure. The method includes the following steps: obtaining residual displacements detected on-site for the damaged reinforced concrete structure; a finite element numerical model; obtaining a maximum impact force-impact duration curve; calculating numerical simulation residual displacements of the damaged reinforced concrete structure; comparing the degree of fit; and extracting damage indexes of hidden parts of the damaged reinforced concrete structure. The present invention uses a simplified ship impact force-time curve to input into a finite element program to simulate the dynamic response of a ship impacting a reinforced concrete structure, which has high computational efficiency and low computational cost. The correctness of the numerical calculation is ensured by comparing and verifying with the residual displacements detected on-site. Based on the correct numerical model, quantitative damage values ​​are obtained, and the damage state of the damaged reinforced concrete structure can be accurately assessed. Therefore, the damage state of the damaged reinforced concrete structure can be efficiently and accurately assessed, providing a basis for the repair, reinforcement and safe use of the structure.

The invention relates to a discrete interpolation-based composite material structure optimization method with continuous fiber angle change. The method comprises the following steps: 1, inputting structure parameters and material parameters in a structure finite element program, and calculating an original elastic modulus of a structure; 2, calculating a transformation matrix and an elastic modulus of a fiber candidate angle; 3, calculating a weighting function and a weight value of discrete fiber angle optimization; 4, calculating an equivalent elastic modulus of discrete fiber angle optimization; 5, performing finite element analysis; 6, updating a fiber candidate angle selection variable; step 7, outputting an optimal candidate angle; 8, calculating a transformation matrix and an equivalent elastic modulus of continuous fiber angle optimization; 9, performing finite element analysis; 10, updating a fiber angle design variable; and step 11, outputting the optimized fiber continuous angle variable. According to the method, the risk that the continuous angle falls into the local minimum value is reduced, and the complex or rapid local change of the fiber angle is met.

The application discloses a method for determining key parameters of a cable structure and relates to the technical field of bridge construction. The method comprises the following steps: obtaining the position information of two end points and a lowest point of a catenary of the cable structure, the cross-sectional area of the cable structure, the gravity per unit length and the elastic modulus; establishing a functional relationship about the position information of the cable structure and the cross-sectional area of the cable structure, the gravity per unit length and the elastic modulus based on the balance of cable element force and Hooke's law; and determining the key parameters of the cable structure according to the functional relationship about the position information of the two end points and the lowest point of the catenary of the cable structure and the cross-sectional area of the cable structure, the gravity per unit length and the elastic modulus. The method solves the problems that the calculation of a suspension cable in the prior art usually adopts a finite element program simulation analysis, the model is complex to establish, the calculation amount is large, and the correctness of the calculation result cannot be determined.

The invention discloses a preprocessing method for a finite element program generator, which is used for automatically translating and converting an advanced XML (Extensible Markup Language) format physical problem description file written by a user into a bottom layer C language source code and a series of input scripts required by a finite element program generator FEPG solver, and specifically comprises an analysis mode and a modification mode; according to the method, advanced physical problem description can be automatically translated into bottom layer source codes and input scripts.

The application discloses a simulation method for wave-absorbing performance of fabric composite material covered with carbon nanotubes, which comprises carbon nanotube microstructure homogenization analysis, carbon nanotube-glass fiber mesostructure homogenization analysis and macrostructure homogenization analysis of the fabric composite material covered with carbon nanotubes. The carbon nanotube microstructure homogenization analysis comprises the following steps: a Monte-Carlo method is used to establish a carbon nanotube composite material microstructure model; the carbon nanotube composite material microstructure model is divided into tetrahedral grids; a self-programmed finite element program is used to calculate the conductivity of the carbon nanotube composite material under different filling densities; a numerical simulation method is used to calculate the electromagnetic shielding performance of the fabric composite material covered with carbon nanotubes under different carbon nanotube lengths, densities and weaving modes; the physical mechanism behind the wave-absorbing performance is understood in depth through the numerical simulation result, the structure design of the wave-absorbing composite material of the structure can be better guided, and the design scheme can be efficiently guided.

The invention discloses an energy and environmental rock-soil multiphase flow multi-field coupling finite element automatic modeling method. The method comprises the steps that a universal control equation for describing multiphase substance mass conservation, momentum conservation and energy conservation in energy and environmental engineering is deduced based on porous medium mechanics and unsaturated rock-soil mechanics; constructing a weak general format of an energy and environmental geotechnical engineering multiphase multi-field coupling control equation based on a Galerkin method and a Petroleum-Galerkin method; constructing a stiffness matrix of a control equation after multiphase multi-field coupling discretization of the energy and environmental geotechnical engineering; generating an input file of a finite element program automatic generation system FEPG; according to the method, numerical modeling is carried out on energy and environmental rock and soil problems through a unified method.

The invention relates to the technical field of civil engineering and artificial intelligence, in particular to an automatic modeling method and system for a bridge finite element model. Comprising an interaction module, a large model cascade engine, a compiler and a modeling program language grammar error debugging module. The large model cascade engine comprises a natural language pseudo code generation and check module, a modeling program language cue word generation module and a bridge structure parameter generation module; the technical threshold of finite element modeling in the field of civil engineering is greatly reduced, modeling personnel do not need to have a firm computer programming capability, an operable finite element program and a calculation result can be quickly obtained only through input requirements, and the bridge finite element modeling efficiency is remarkably improved.

The application discloses a metamaterial sound barrier modular reverse design method based on targeted noise attenuation, comprising the following steps: carrying out noise measurement on a target noise source; collecting, classifying and exporting the measured noise; filtering and Fourier transforming the collected noise to export an explicit target image and a target function, and importing the target function into a conditional function; controlling a wave finite element program through a particle algorithm to iteratively optimize and solve a band gap range; at the beginning of iteration, N-dimensional position variable initial values and N-speed variable initial values are randomly generated, wherein each position variable corresponds to a current structure evolution result and an evolution direction, the wave finite element method is combined to evaluate the wave dispersion characteristics of each candidate structure, the optimal position of each individual is discriminated through the conditional function, and the optimal position of the population in the optimal individual is discriminated through the target function; and the application has significant advantages in design efficiency, equivalent volume, attenuation frequency band and attenuation amount.

The invention discloses a double-gap test piece capable of quantifying the influence of stress gradient on life, which comprises the following steps of: firstly, determining a stress concentration coefficient required by the test piece, and determining the geometric dimension of a gap according to a related manual; then, single-notch test pieces are machined respectively, fatigue tests are completed, and parameters of the life prediction model are fitted according to test results; further arranging the two notches on one test piece, calculating the stress distribution of the double-notch test piece by using a finite element program, finely adjusting the geometric dimensions of the notches to meet the requirement that the stress and strain of the roots of the two notches are the same, and calculating the stress gradient influence factors of the two notches at the same time; further completing a double-notch fatigue test, recording experimental data, and determining a minimum observation number by adopting a variable coefficient method until the number meets a confidence coefficient requirement; and finally detecting the prediction precision by using the service life prediction model. According to the method, data errors caused by machining and casting of the test piece are eliminated, the test precision is improved, and the influence of the stress gradient on the fatigue life can be visually and quantitatively detected.