13 results about "Plane stress" patented technology

The invention belongs to the technical field of aircraft thin-wall structure design, and particularly relates to a method for correcting a quadrilateral shell unit in aircraft thin-wall structure finite element analysis, which comprises the following steps of: 1, establishing a unit coordinate system for the quadrilateral shell unit; step 2, under the unit coordinate system, establishing an equilibrium equation of a plane stress unit related to in-plane deformation, and calculating a rigidity matrix of the plane stress unit; step 3, under the unit coordinate system, establishing a balance equation of a bending plate unit related to out-of-plane deformation, and calculating a rigidity matrix of the bending plate unit; 4, applying an in-plane rotation penalty term on the rotational stiffness of the quadrilateral shell unit, and calculating the influence of the in-plane rotation penalty term on the strain energy function of the quadrilateral shell unit under the unit coordinate system to obtain an in-plane rotation stiffness matrix; 5, calculating a stiffness matrix of the quadrilateral shell unit under the unit coordinate system; and step 6, coordinate transformation is carried out to obtain a stiffness matrix of the quadrilateral shell unit under the overall coordinate system.

The invention relates to the technical field of steel rail damage, and provides a near-field dynamics simulation method for steel rail head multi-crack competitive propagation, which comprises the following steps: establishing a near-field dynamics plane stress model of a steel rail head and dispersing the near-field dynamics plane stress model into particles; defining a particle interaction domain by adopting a double-vision-field key-based near-field dynamics method; setting boundary conditions and introducing a plurality of initial cracks on the surface of the rail head; applying a load to simulate a wheel-rail rolling contact process; simulating a multi-crack competitive expansion behavior based on the fracture state and fatigue life evolution of the key; and the interaction between the cracks is quantified by calculating the opening displacement and the sliding displacement of the crack tip. According to the method, the limitation that only a single crack can be simulated in the prior art is overcome, competitive expansion high-precision simulation of multiple cracks under the dynamic load is realized, the experiment cost is remarkably reduced, and a scientific basis is provided for steel rail fatigue damage assessment and maintenance decision making.

The application discloses a test system and a test method for simulating the stress wave action of a columnar charge blast hole, and relates to the technical field of rock dynamics and blasting engineering. The test system comprises a dynamic loading system, an incidence system, a stress wave conversion body and a sample model. The dynamic loading system generates a plane stress wave. The plane stress wave is conducted to the stress wave conversion body through the incidence system. The stress wave conversion body is attached to the sample model half-cylindrical channel through a semi-cylindrical pressure-arc surface, and the plane stress wave is converted into a cylindrical stress wave acting on the sample. The application generates controllable plane stress waves through the dynamic loading system, and the plane stress waves are shaped and directed through the incidence system, so that the waveform is stable, the energy loss is low, and the input conditions are consistent. The stress wave conversion body converts the plane stress wave into a cylindrical stress wave attached to the columnar blast hole through a plane-arc structure, highly simulates the radial diffusion characteristics of the real blasting stress wave, and realizes the simulation of the columnar charge blast hole blasting stress wave loading in the laboratory.

This invention relates to a method for testing the fracture toughness of anisotropic eccentrically loaded single-sided notched tensile specimens, comprising: S1, establishing a two-dimensional plane stress model of anisotropic material ESET specimens; S2, mesh generation; S3, calculating displacement, strain, and stress field to obtain the stress intensity factor K and compliance C under different initial crack lengths and anisotropic material parameters; S4, establishing crack length calculation formulas and stress intensity factor calculation formulas based on compliance under different eccentric loading rates, initial crack lengths, and anisotropic material parameters. This invention allows for rapid and accurate measurement of crack length simply by measuring the deformation of the material under external force; it reliably extends the application range of standardized eccentrically loaded single-sided notched tensile specimens from traditional isotropic metals to modern advanced materials such as composite materials, additive manufacturing alloys, and rolled plates, while ensuring the calculation accuracy under anisotropic conditions.

The present application relates to the field of gyroscopic load calculation, and discloses a gyroscopic load calculation method and system based on 2D finite elements, which comprises the following steps: establishing a ring element model for the axisymmetric structure in an aero-engine rotor, and using integration and isoparametric transformation to calculate the gyroscopic load expression of all ring elements in the ring element model; establishing a plane stress element model for the non-axisymmetric structure in the aero-engine rotor, and calculating the gyroscopic load expression of all plane stress elements according to the element thickness of the plane stress elements in the plane stress element model; generating a system total load equation according to the gyroscopic load expression of the ring elements and the gyroscopic load expression of the plane stress elements, and solving the system total load equation to obtain the gyroscopic load of the aero-engine rotor; and the system comprises a data acquisition module, a modeling module and a calculation module. The present application can improve the accuracy of the calculation results, simplify the calculation process, improve the calculation efficiency, and save a large amount of manpower.

The invention provides a method and a system for carrying out steel plate plane stress ultrasonic detection by utilizing multiple holes, belongs to the technical field of ultrasonic detection, and aims to solve the technical problems of how to accurately measure the wave velocity of ultrasonic waves in a steel plate and how to obtain stress-strain parameters of the steel plate by utilizing the wave velocity. Comprising the following steps: establishing a rectangular coordinate system I, an original point O, a transverse axis X1 and a longitudinal axis Y1, located on the plane of a measured steel plate; a second rectangular coordinate system located on the plane of the measured steel plate is established, the second rectangular coordinate system is obtained by rotating the first rectangular coordinate system around an original point O by theta, and the original point is O, the transverse axis is X2, and the longitudinal axis is Y2; acquiring the propagation speed of the ultrasonic wave in each axial direction; obtaining positive strain in each axial direction based on the first equation and the propagation speed; obtaining the positive stress in each axial direction based on the second equation and the positive strain; and obtaining the shear stress of each coordinate system based on the third equation and the normal stress. The method has the technical effects of improving the wave velocity detection accuracy and further improving the stress strain detection accuracy.

This invention discloses an experimental system and method for simulating the stress wave effect of a cylindrical charge blast hole, relating to the fields of rock dynamics and blasting engineering. The system includes a dynamic loading system, an incident system, a stress wave converter, and a sample model. The dynamic loading system generates a plane stress wave, which is transmitted through the incident system to the stress wave converter. The converter, through a semi-cylindrical pressure arc surface, conforms to the semi-cylindrical channel of the sample model, converting the plane stress wave into a cylindrical stress wave that acts on the sample. This invention generates a controllable plane stress wave through the dynamic loading system, which is shaped and directionally transmitted by the incident system, ensuring waveform stability, low energy loss, and consistent input conditions. The stress wave converter, with its flat-arc structure, converts the plane stress wave into a cylindrical stress wave conforming to the cylindrical blast hole, highly simulating the radial diffusion characteristics of real blasting stress waves. This allows for the simulation of stress wave loading during a cylindrical charge blast hole blast in a mine within the laboratory.

The invention discloses a drill hole plane stress measurement method based on hole circumference relative displacement change. The method comprises the following steps: step 1, drilling a to-be-measured drill hole at a preset position to a preset measurement depth; 2, a mounting hole is concentrically drilled in the bottom of the drill hole, and a plurality of deformation meters used for measuring the relative displacement of the hole periphery are mounted on the hole periphery of the mounting hole; and step 3, the sleeve core is adopted to remove the to-be-measured drill hole, the relative displacement change of the periphery of the deformation meter mounting hole is obtained through the deformation meter in the removing process, and the plane stress state of the rock around the to-be-measured drill hole is obtained through relative displacement calculation. The method is simple in measurement and high in anti-interference capability, and the stress state of the drill hole can be calculated only by testing the relative displacement of three points around the hole.

The application belongs to the technical field of aircraft thin-walled structure design, and particularly relates to a correction method of quadrilateral shell element in finite element analysis of aircraft thin-walled structure, which comprises the following steps: step one, establishing an element coordinate system for the quadrilateral shell element; step two, establishing a balance equation of a plane stress element related to in-plane deformation under the element coordinate system, and calculating a plane stress element stiffness matrix; step three, establishing a balance equation of a bending plate element related to out-of-plane deformation under the element coordinate system, and calculating a bending plate element stiffness matrix; step four, applying an in-plane rotation penalty term to the rotational stiffness of the quadrilateral shell element, calculating the influence of the in-plane rotation penalty term on the strain energy function of the quadrilateral shell element under the element coordinate system, and obtaining an in-plane rotation stiffness matrix; step five, calculating the stiffness matrix of the quadrilateral shell element under the element coordinate system; and step six, performing coordinate transformation to obtain the stiffness matrix of the quadrilateral shell element under the overall coordinate system.

The invention relates to an in-plane internal stress driven fatigue crack area expansion rate model, the specific model is a formula (1), the in-plane internal stress driven fatigue crack expansion rate can be determined by using the model, and the crack expansion area and form are obtained; the model construction method comprises the following steps: establishing a global digital twinning model, introducing an initial crack and a welding residual stress field at typical details, loading by utilizing a fatigue load model, simulating fatigue crack propagation by adopting a digital twinning method, and constructing the model. Counting fatigue crack area increments corresponding to different loading times in the crack propagation process and I-type fatigue crack strain energy release rates, obtaining an in-plane internal stress driven fatigue crack area propagation rate / -delta GI curve by using a difference algorithm, and establishing an in-plane internal stress driven fatigue crack area propagation rate model by using a least square method in a fitting manner; the model can represent the surface internal stress driven crack three-dimensional expansion behavior, and can provide a basis for detail surface internal stress driven fatigue mechanism research and damage evaluation.

An ultrasonic measurement method for plane stress on the basis of a multi-wafer air-coupled transducer relates to the technical field of ultrasonic testing. The method solves problems that a traditional measurement method for plane stress generally computes the plane stress by changing at least 3 different measurement directions and obtaining information such as an acoustic time difference in the 3 measurement directions by using a pair of contact ultrasonic transducers, which is too complicated in operation, and a coupling agent can influence measurement accuracy of the plane stress. The method includes: emitting, by an excitation signal transmission end, an ultrasonic wave passing a wafer of the multi-wafer air-coupled transducer to a member to be measured; receiving, by an excitation signal reception end, an echo returned from the member to be measured through a corresponding wafer of the multi-wafer air-coupled transducer; obtaining an acoustic time difference of lamb waves through data processing according to the ultrasonic wave and the echo; and obtaining first principal stress, second principal stress and an included angle between the first principal stress and a fiber direction of an orthotropic composite material according to the acoustic time difference of the lamb waves. The method is suitable for the field of plane stress testing.

The application provides a method and system for steel plate plane stress ultrasonic detection by using a plurality of holes, belongs to the technical field of ultrasonic detection, and is used for solving the technical problems of how to accurately measure the wave speed of ultrasonic waves in a steel plate and how to obtain the stress and strain parameters of the steel plate by using the wave speed. The method comprises the following steps: establishing a rectangular coordinate system I located on the plane of the measured steel plate, wherein the origin is O, the horizontal axis is X1, and the vertical axis is Y1; establishing a rectangular coordinate system II located on the plane of the measured steel plate, wherein the rectangular coordinate system II is obtained by rotating the rectangular coordinate system I around the origin O by an angle of θ, the origin is O, the horizontal axis is X2, and the vertical axis is Y2; obtaining the propagation speed of ultrasonic waves in each axial direction; obtaining normal strain in each axial direction based on a first equation and the propagation speed; obtaining normal stress in each axial direction based on a second equation and the normal strain; and obtaining shear stress of each coordinate system based on a third equation and the normal stress. The application has the technical effect of improving the accuracy of wave speed detection and then improving the accuracy of stress and strain detection.

The invention provides a parallel inclined rock stratum deep-buried support tunnel mechanical response analysis method and system, and the method comprises the steps: obtaining mechanical parameters of a parallel inclined rock stratum deep-buried support tunnel, and constructing a plane stress mechanical model according to the mechanical parameters; constructing corresponding conformal mapping functions for all independent boundaries in the plane stress mechanical model; deducing an undetermined complex coefficient vector based on the plane stress mechanical model and the conformal mapping function; selecting a plurality of calculation boundary points on the independent boundary by using a point matching method, and constructing a corresponding condition constraint equation according to the boundary condition of the independent boundary where each calculation boundary point is located; and assembling all the condition constraint equations to obtain an integral linear equation set, and then resolving the undetermined complex coefficient vector by using the integral linear equation set to obtain a mechanical property solution. The problems that in the prior art, the analysis difficulty of the mechanical response of the deep-buried supporting tunnel in the parallel inclined rock stratum is high, and the accuracy of the analysis result is difficult to control are solved.