1049 results about "Finite elemente analyse" patented technology

A method and apparatus for determining the fluid permeability of an earth formation is described. An instrument comprising an acoustic source and acoustic and electrokinetic sensors is located in a borehole at a site of interest. The acoustic source is fired and the resulting variations in pressure and electric field generated are measured and recorded. The Biot equation, and an equation for the streaming potential coupled to fluid displacement terms, is solved using finite element analysis to give an expected pressure waveform and electrokinetic waveform based on estimated earth formation properties. By comparison of the measured waveforms and those calculated from the equations, the actual permeability of the earth formation can be deduced.

A materials characterization method models dynamic, non-linear, temperature-dependent stress, strain, hysteresis, creep, and loss of elasticity at high strain, both in test samples and in Finite Element Analysis (FEA). Incorporating universal properties of statistical mechanics and adapting domain models from ferromagnetics to the higher-dimensional realm of stress tensors, the model is applicable to polymers, rubbers, liquids, and metals in elastic and plastic deformation. The model quantifies the dynamics of both plastic and brittle failure. Apparatus and methods are shown for testing material samples and matching the computational model to sample characteristics, leading to a set of characterizing parameters and predictive simulations using those parameters. Though apparatus and testing protocols of the invention yield optimum characterizations, pre-existing data from conventional testing yield useful results.

The invention discloses a method for controlling the machining accuracy of large integrated thin-walled parts based on finite element analysis. The method comprises the following steps of: 1, extracting local structural features of the large integrated thin-walled part; 2, performing finite element simulative analysis on local structural features to obtain an optimized cutting technology; 3, numerically modeling a large integrated workblank, and loading an initial internal stress; 4, protocoling a tool path, namely protocoling the machining sequence of the feature structures; 5, performing simulative analysis on the integrated structure to obtain a predicted deformation result under the condition of process technology; 6, regulating and optimizing a clamp scheme to control machining deformation. The method adopts finite element simulation, can analyze and predict in advance before the actual machining of the parts, and thereby corresponding machining strategy is adjusted, machining deformation is effectively controlled, production cycle of the parts is shortened, and production cost is reduced.

The invention discloses a material tensile real constitutive curve testing technology for obtaining an engineering stress-engineering strain curve and a load-displacement curve. The technology comprises the following steps of: obtaining a necking distortion profile curve and a stress strain field by non-contact optical measurement, establishing a finite element analytical model of a funnel round bar sample, stimulating the whole process that the sample is stretched until the necking is broken, and demarcating the real constitutive curve in an iteration solution mode. The technology disclosed by the invention overcomes the defects that the construction defect mode cannot precisely simulate a necking phenomenon of all metal material, the iteration times in the finite element iteration computation are more, and the computation cost is high; and the technology is combined with a non-contact optical distortion measurement system to monitor the tensile so as to obtain the load-displacement curve of the full-course sample tensile and the distortion field.

The invention discloses an online thermal distribution image predicting method, and belongs to the technical field of fault detection and diagnosis. The online thermal distribution image predicting method is characterized by being a method for performing thermodynamic analysis on changes in heat distribution, giving a prediction and synthesizing a vivid heat distribution image through finite element analysis measures, digital image processing, thermodynamic theories and thermal imaging simulation based on an infrared imaging technology under the condition that heat source parameters are uncertain. According to the method, the thermal dynamic features within the heat distribution image are widely applied to the infrared imaging technology; and in the field of temperature monitoring and temperature prewarning, a temperature change trend is predicted, and even through dynamic numerical features in the heat distribution image, a temperature change characteristic in a future time domain is quantitatively given, so that the temperature prewarning time is further advanced, precious time is saved for equipment repair, the production safety is further ensured, considerable economic benefits are brought to an enterprise, and a certain contribution is made to the state development.

The invention relates to a finite element method and a strength evaluation method for a bolt and belongs to the technical field of bolt strength evaluation. The finite element method and the strength evaluation method for the bolt can be applied to rapid modeling and strength evaluation of a large number of bolts under the condition of complicated structures and complicated loads. The strength evaluation method comprises the steps that a bolt stress finite element analysis result is read; a cross section parallel to a nut is established in the middle of a screw, and the tension and bending moment on the cross section under different load steps are extracted; a curve chart is made with the tension of the screw as the horizontal coordinate and the bending moment of the screw as the longitudinal coordinate; the bending moment of the bolt reaches a peak value along with the increase of the tension of the bolt; the bending moment of the bolt starts to be reduced along with the continuous increase of the tension of the bolt, and it is indicated that the bolt enters the yield stage; it is indicated that the bolt reaches the ultimate strength when the bending moment of the bolt reduces to half of the peak value along with further increase of the tension of the bolt. Bolt stress is calculated with the finite element method, a bolt strength criterion is established, and the precision of bolt strength calculation is improved.

A continuous extrusion process is provided capable of producing graded index plastic optical fiber at commercially useful speeds, e.g., at least 1 m/sec for 250 mum outer diameter fiber. Moreover, it is possible to predict the refractive index profile of the fiber, prior to actual fabrication, by performing a finite element analysis using various parameters of the extrusion process. Such prediction allows one to tune the parameters of the process to obtain a desirable outcome, while avoiding the need for substantial trial and error with the extrusion equipment.

The invention discloses a method for predicting electrical properties of deformed log-periodic antennae based on an electromechanical coupling model, aiming to mainly solve the problem of electromechanical separation in the log-periodic antennae. The method comprises the following steps: building a finite element model based on the structural design parameters of the log-periodic antennae, loading dead load, random wind and other environmental loads and carrying out finite element analysis to obtain the structure displacement field of the log-periodic antennae; utilizing the analysis results to obtain current distribution of oscillator units in the log-periodic antennae and phase difference caused by the positions and deflection of the oscillator units and computing the far field patternsof the log-periodic antennae according to the superposition theorem; and obtaining the electrical property parameters of the log-periodic antennae to realize electromechanical coupling analysis of the log-periodic antennae. The method can help the log-periodic antenna structural design personnel improve the antenna design and manufacturing quality.

The invention relates to a safety assessment method for a pressure-bearing structure with creep damages and volume defects. The safety assessment method comprises the following steps of (1) establishing an elastoplastic constitutive model for the pressure-bearing structure working for a long time in order to predicate elastoplastic response of the pressure-bearing structure and make a preparation to estimate bearing limit of the pressure-bearing structure; (2) doing research on an expansion process and a failure mode of a plastic range of the pressure-bearing structure with various pits and local thinning defects under loading action of internal pressure or bending moment through a finite element method, doing research on influence of different creep damages caused by various pits and local thinning defects on bearing limit of the pressure-bearing structure and calculating out a bearing limit value of the pressure-bearing structure quantificationally; (3) determining safety assessment steps and performing safety assessment on the pressure-bearing structure with the creep damages and/ or the volume defects. By means of the safety assessment method, effects of the creep damages and the volume defect dimensions are tightly combined for the first time to work out a safety assessment standard suitable for the pressure-bearing structure working for a long time under high temperature and high pressure. Therefore, the safety assessment method for the pressure-bearing structure with creep damages and volume defects has a clear physical meaning and is adaptive to projects.

The invention provides an assessment method for building damage after fire, and the assessment method for the building damage after the fire includes the following steps: 1. collecting data of a scene of the fire, 2. modeling the scene of the fire according to the data of the scene of the fire and carrying out fire simulation in the scene of the fire for achieving fire simulation results, 3. analyzing the fire simulation results, 4. establishing a finite element model, and adding second data to the finite element model for finite element analysis so as to obtain finite element analysis results, 5. carrying out safety assessment for the finite element results. Provided is a corresponding system. The assessment method for the building damage after the fire can be widely used for the fire reappearance and the practice of the safety design of the building structure after the fire, not only can improve the accuracy and reliability of the reappearance of the building fire, but also can greatly save time and cost for the reappearance of the building fire and the safety design of the structure. Therefore, the assessment method for the building damage after the fire has an important theoretical guiding significance and a practical value.

The invention discloses an axial layered cutting method for turning coarse-pitch threads, a tool wear testing method and a force-heat load calculating method of tool wear for eliminating principle errors caused by radial layered cutting of the coarse-pitch threads. The axial layered cutting method for turning the coarse-pitch threads, the tool wear testing method and the force-heat load calculating method of tool wear are technically characterized in that through the cutting method, a testing tool with a left cutting edge and a right cutting edge is used for axially turning a left thread surface and a right thread surface of a coarse-pitch test piece in a layered mode, wear tests of the tool turning the coarse-pitch threads are conducted through the cutting method, the wear pattern of the tool turning the coarse-pitch threads is obtained, the influence of tool wear on thread machining surfaces is revealed, then a finite element analytical model of the tool is reconstructed according to the flank wear data of the tool and the blunt round radius measurement data of the cutting edges, analysis and calculation of the temperature field and the stress field of the tool are carried out, and the force-heat load change characteristic on the tool wear condition is obtained.

The invention relates to a method for improving finite element analysis accuracy of a transmission case. The method comprises the steps of establishing a finite element model of an assembly consisting of major parts such as a clutch case, the transmission case, an upper cover and gears, applying gear engagement force to gear engagement nodes, fixing bolt holes of the clutch case connected with a flywheel case, applying rotation freedom degree constraints of gear shafts between all gears and corresponding supporting bearings on two sides and fully cutting off paths of transmission of torque from gear shafts to case bearing holes. The method for improving finite element analysis accuracy of the transmission case has the advantages that since the rotation freedom degree constraints of gear shafts are applied between all gears and corresponding supporting bearings on two sides, relative rotation or relative rotation trend between bearings and bearing holes is prevented, the problem that the stress of the bearing holes in the case is relatively large is solved, the finite element simulation of the transmission case is more compliant with the actual situation, the finite element analysis accuracy of the case is effectively improved, and further the goals of improving the product design accuracy, reducing the product test frequency and decreasing the product development cost are achieved.

The invention relates to an asphalt mixture viscoelastic property test method based on a wheel load instrument. In the method, the wheel load instrument, a test piece, a dynamic modulus test and a creep test are provided. The method comprises the following steps: a, before the test, assembling a strain sensor at the bottom of an asphalt mixture test piece and calculating by a mechanical method or a finite element analysis method to obtain the stress distribution condition of the test piece under the action of moveable load according to moving wheel load features and the test piece size; b, during the test, employing the modulus test and the creep test: measuring the tensile deformation strain capacity of the test piece by using the strain sensor, and measuring the tensile deformation strain capacity of the test piece through the strain sensor; and c, after the test, obtaining the stress and the strain capacity of the test piece and the action time of the wheel load by the wheel load instrument and the strain sensor. The method has the characteristics of simplicity, practicability, high operability and high applicability. According to the method, the stress characteristic of the test piece during the test is similar to the actual asphalt concrete road surface, and the viscoelastic property obtained by the test is accurate and reliable.

The invention discloses a bidirectional evolutionary structure topological optimization based disk type flywheel optimized design method. The disk type flywheel is made of a homogeneous material. The design method comprises the following steps: performing finite element grid division on an initial design domain of the disk type flywheel and giving a target volume, a volume evolution rate and a filtering radius of a structure; performing finite element analysis on the flywheel structure and calculating a stress sensitivity number of each unit; obtaining the sensitivity number of the current iteration and the structure target volume of the next iteration; and deleting and adding units until the target volume and the condition of convergence are satisfied at the same time. Through the bidirectional evolutionary structure topological optimization based disk type flywheel optimized design method, disclosed by the invention, practical flywheel optimized design can be guided rationally, and therefore, mass of the flywheel can be reduced on the basis of a certain intensity.

The invention relates to a real-time temperature rise measurement method of an electromagnetic system of a low-voltage apparatus based on finite element analysis. The real-time temperature rise measurement method comprises the following steps that a temperature field distribution diagram of the electromagnetic system is obtained through finite element simulated analysis software, and a steady-state average value of the highest temperature inside a coil and the temperature on the surface of the coil is obtained under the different control voltages by calculation; the steady-state average value is compared with a steady-state value, measured in the given control voltage test, of the temperature on the surface of the coil, and correctness of a model is verified; a mathematical model of the highest temperature inside the coil and the temperature on the surface of the coil of the electromagnetic system of the low-voltage apparatus under the different control voltages is built, and the corresponding relation is found; the control voltage of the electromagnetic system of one low-voltage apparatus is measured, the temperature on the surface of the coil of the electromagnetic system is measured, the corresponding relation between the highest temperature inside the coil and the temperature on the surface of the coil under the control voltage is taken out, and the highest temperature inside the coil is calculated out. The real-time temperature rise measurement method can obtain the highest temperature rise of the coil of the electromagnetic system, directly judge the running state of products and break through the limitation that an existing measurement method only can measure the surface temperature and the average temperature.

A computational optimization process uses the variable stiffness performance of composite laminates attributed to steered fiber to guide the design of stream functions describing the fibers to build it. This design process combines a finite element-based analysis tool, failure criteria and geometry optimization to determine steered angles associated with stream functions by an optimization program to meet target performance requirements, e.g., load condition(s), and failure criteria for quasi-static or dynamic events. The fiber angle distribution and thickness buildup are computed based on the stream function. The simulated structure is analyzed using finite element analysis. The disclosed process allows the designer to impose manufacturing constraints such as fiber steering radius.

The invention provides a noninvasive portal vein hemodynamic parameter measuring method which includes the steps of firstly, using a thin-section CT image to build a three-dimensional geometric model of a liver portal vein; secondly, using the finite element analyzing method of hydromechanics calculating software ANSYS to perform meshing on the geometric model and build a three-dimensional mathematic model; thirdly, calculating the hemodynamic parameter of the portal vein in an analog manner to obtain a speed and pressure distribution effect picture. The method is safe, noninvasive, simple to operate, visualized, quantized and high in accuracy, and the effective model is built for scientific researches and clinic services.