126 results about "Linear elasticity" patented technology

The invention discloses a method for simulating offshore oilfield micro fracturing injection increase crack propagation on the basis of fluid-solid-heat coupling theory. The method comprises the following steps that geological characteristic parameters are obtained on the basis of offshore micro fracturing well geological data; a hydraulic crack propagation model is built, and fluid pressure and filter loss in a crack are obtained; on the basis of a reservoir matrix model, dynamically changing pore pressure in a reservoir is worked out; on the basis of elastic mechanics and permeation fluid mechanics, a pore elastic deformation relation between fluid and rock is built, that is to say, a fluid-solid coupling model is built, and by means of the calculated pore pressure, rock strain caused bythe fluid can be obtained; a heat effect relation between the temperature and the rock is built, a strain, porosity, permeability and temperature fluid-solid-heat coupling model is built, the permeability and porosity after coupling change are obtained, the pore pressure after three-field coupling change is obtained, the changed pore pressure reacts on a Darcy filtration model, and the crack extension dynamic of the next moment is obtained. According to construction and geological parameters, the dynamic extension situation of the hydraulic crack and real-time change situation of the reservoir parameters in the offshore micro fracturing well long-term injection increase process can be predicted according to the construction and geological parameters.

The invention discloses a design method for property parameters of anti-collapse drilling fluid for fractured formations. According to sequence, the design method includes the following steps: core samples are prepared; four of the core samples are chosen for a triaxial compression test and an acoustic emission test, and the crustal stress of a formation owning the core samples is determined; two of the core samples are chosen for the triaxial compression test, and the cohesion and internal friction angle of the weak planes of the rocks are tested; eight of the core samples are chosen to be put into the drilling fluid, the triaxial compression test is carried out after the core samples are soaked for different times, and the cohesion and internal friction angle of the weak planes of the rocks are tested; the cohesion and internal friction angle of the weak planes of the rocks are respectively linearly fitted to soaking times; the fluid-solid coupling theory is utilized to create a fractured formation well surrounding rock stress distribution model; the elastic mechanics coordinate transformation theory is utilized to create a fractured formation weak plane destruction model; a relation chart between the property parameters of the drilling fluid is determined. The design method disclosed by the invention can quantitatively optimize the key property parameters of the drilling fluid according the requirement of a site for well wall stability.

The invention belongs to the technical field of detection and discloses a load measurement-based residual stress detection method. The method comprises the following steps: establishing a computer geometric model of a to-be-detected member, applying restrictions to the model by a finite element method, performing linear elasticity finite element static analysis after a load is applied to a loading point, reading stress value sigma'<b1> of an experimental measuring point, and adjusting the position of the loading point or increasing the load so as to enable the maximum value of the component of the stress value sigma'<b1> to be larger than 0.1MPa if the maximum value of the component of the stress value sigma'<b1> is less than 0.1MPa; applying restrictions and a load same as those of the computer geometric model to the to-be-detected member, and performing a strain experiment to obtain a stress value sigma<c1> of the experimental measuring point; and transforming the sigma'<b1> under local coordinates of the experimental measuring point to obtain sigma<b1>, and subtracting sigma<b1> from sigma<c1> to obtain residual stress value sigma<a1> of the member at the experimental measuring point. According to the method disclosed by the invention, the surface of the member is not damaged in the detection process, and the problem that a member is damaged due to a conventional mechanical residual stress method is solved. In addition, the method is convenient, simple and flexible to apply.

The invention discloses a method for measuring static elasticity modulus of a porous metal material. The method comprises the following steps of: measuring the flexibility of a simply supported beam span in different loads by utilizing a simply supported beam four-point bending testing device and adopting static step-by-step loading; subsequently establishing a relationship curve between the flexibility in the span and the loads, and calculating according to a curve slope in equations so as to obtain a single time measurement value of the static elasticity modulus of the porous metal material; and measuring for multiple times within a linear elasticity range, and taking the average value so as to obtain the static elasticity modulus of the porous metal material. The method not only has the advantages of measurement result accuracy, good repeatability, high reliability, simple equipment, low testing cost, simpleness in sample preparation and the like, but also can realize repeated loading (unloading) and multiple measurements within the linear elasticity range; the method can be carried out on a conventional material mechanics pure bending testing table, no strain gages are necessary to be adhered, and only a dialgauge (micrometer gauge) is additionally arranged; and the method is simple and easy to operate and is applicable to popularization and application.

The invention provides a major diameter pile longitudinal vibration analysis method in axisymmetric radial inhomogeneous medium soil. The method comprises the following steps that soil body around pile adopts a three-dimensional axisymmetric model to consider a vertical fluctuation effect; the soil body around pile is divided into an internal disturbance area and an external area, the internal disturbance area is divided into random layers, each layer of the soil body is a respective homogeneous isotropy linear viscoelastic body, the soil body of the outer area infinitely extends in the axialdirection, and soil body material damping adopts viscous damping; constant displacement and balanced stress are achieved on pile-soil interfaces and two sides of each layer of soil interface and pile-soil interfaces, and pile-soil system vibration is small in deformation; pile body concretes are linear elasticity, and stress wave propagation in the pile body meets plane cross-section assumption; asoil body around pile and pile body longitudinal vibration function is constructed under the condition of constructing three-dimensional axial symmetry; Laplace conversion and a variable separation method are used for solving the vibration function, and a time domain speed responding function that any exciting force is applied to a pile top. The method is closer to a realistic model and can provide theoretical guidance and reference for pile foundation dynamic detection.

The invention relates to a static microrelay based on a bistable compliant mechanism, belonging to static relays used in a micro-electro mechanical system (MEMS). Bistable fully-compliant beams of the static microrelay adopt two compliant beams, wherein one end of the left compliant beam is fixed on a left insulated anchor point, and the other end of the left compliant beam is fixed on a member; one end of the right compliant beam is fixed on a right insulated anchor point, and the other end of the right compliant beam is also fixed on the member; under the voltage drive, a movable comb tooth drives the bistable fully-compliant beams to transversely move and rapidly overturn to a second stable position; a movable contact is in bridging connection with a left fixed contact and a right fixed contact which are fixed on a lower insulated anchor point so as to switch a circuit on; and the relay is rapidly skipped to return to a first stable position when an aelotropic driving voltage is applied. The static microrelay substitutes a traditional linear elasticity structure by adopting the bistable compliant mechanism so as to improve the response speed and the stable holding capacity and has the characteristics of simple mechanism, short-distance drive, low energy consumption and strong anti-jamming capacity.

The invention provides a correcting method for a layer-peeling-method residual stress measurement value based on the plate and shell theory. For increasing the measurement accuracy of the residual stress inside a material of the layer peeling method, based on the elastic mechanics and the plate and shell theory, a calculating method for releasing of the residual stress inside the material in the material removing process is deduced, and therefore the conversion relationship between surface residual stress peeled layer by layer and initial residual stress of a layer is established; under the condition that all kinds of surface residual stress after layer peeling are known, the initial residual stress of the layer can be reversely calculated and obtained.

The invention relates to a parallel type flexible wrist mechanism. The parallel type flexible wrist mechanism comprises a fixed platform, a moving platform and three branched chains between the fixedplatform and the moving platform. The fixed platform comprises an upper sub-platform, a lower sub-platform and three sets of guide rails fixedly connected between the two sub-platforms. The upper sub-platform and the lower sub-platform are parallel to each other and the central axes of the upper sub-platform and the lower sub-platform coincide. The three sets of guide rails are distributed in an axial symmetry mode about the central axis of the upper sub-platform. The three branched chains are identical in structure, include linear elasticity bodies, sliding blocks, middle rod pieces and motion pairs, and are correspondingly connected with the fixed platform and the moving platform to form a spatial parallel closed-loop mechanism. The sliding blocks are mounted on the guide rails between the two fixed sub-platforms, and can only move along the guide rails. The linear elastic bodies are installed between the sliding blocks and the fixed platform. The three branched chains of the parallel mechanism are matched with each other to realize the error compensation of a position or an angle of an end effector.

The invention discloses a complex foundation extra-high arch dam overall crack resistance design method, relates to the technical field of hydropower station arch dam design, and provides the complex foundation extra-high arch dam overall crack resistance design method. The method comprises the following steps that A, arch dam body shape design is conducted; B, the arch dam is analyzed by adopting an arch beam method, a linear elasticity finite element method, a nonlinear finite element method and a geomechanical model test method; numerical calculation and physical test results are comprehensively compared, and arch dam deformation, stress characteristics and the overall damage process are analyzed, judged and grasped, so that crack initiation points, crack weak links and reinforcement key objects and parts of arch dam damage are found out; the comprehensive influence of various factors influencing arch dam cracking on arch dam cracking is systematically analyzed; C, arch dam anti-cracking measures are designed in a targeted manner according to different cracking mechanisms of the anti-cracking weak area and the controllable cracking influence factors of the anti-cracking weak area; and D, the effect of the anti-cracking measure is evaluated by adopting a three-dimensional finite element equal numerical analysis method.

The invention discloses an elastic-plastic buckling bearing capacity calculation method which comprises the following steps: S1, carrying out linear elasticity analysis on a truss structure under a stress load condition, and determining the most unfavorable rod piece of the truss structure under the load condition; S2, calculating and acquiring the linear elastic buckling bearing capacity and the elastic-plastic buckling bearing capacity of the most unfavorable rod piece of the truss structure; S3, calculating the elastic-plastic buckling bearing capacity of the truss structure according to the elastic-plastic buckling bearing capacity of the most unfavorable rod piece of the truss structure; S4, respectively calculating the elastic-plastic buckling bearing capacity of the truss structure by adopting a characteristic value buckling analysis method and a riks analysis method in finite element software Abaqus, comparing and analyzing the obtained elastic-plastic buckling bearing capacity result of the truss structure and the calculated elastic-plastic buckling bearing capacity result of the truss structure so as to verify the correctness and feasibility of the elastic-plastic buckling bearing capacity of the truss structure.

The invention discloses a monocular video high precision measuring method for wing wind tunnel test model elastic deformation. Based on a fact that relative deformation of two adjacent cross sections of a wing wind tunnel test model is small linear elasticity deformation, coordinate figures of corners and deformation mark points Y of all cross sections are orderly calculated from a wing root according to a superposition principle; a conventional monocular video measuring method is adopted, the coordinate figures of the deformation mark points Y are brought in a collinearity equation, and deformation data of the mark points on all the cross sections can be orderly obtained. Via the monocular video high precision measuring method, monocular video measurement errors of wing wind tunnel test model elastic deformation can be greatly reduced, only one camera needs to be used, multi-view video measurement precision can be obtained, hardware cost of a measurement device can be lowered, tedious homonymous point matching work of multi-view video measurement can be prevented, the monocular video high precision measuring method is particularly suitable for an environment where camera installation positions are limited, and the monocular video high precision measuring method has great engineering application prospects.

The present invention discloses a three-dimensional side slope model establishing method for study on an anti-slide pile position. The method comprises: arranging two anti-slide piles symmetrically; arranging a row of prestressed anchor cables in the top center of each anti-slide pile; arranging four rows of anchor cables on a middle-layer slide surface, wherein a short edge is a force-receiving surface; implanting a two-dimensional massless and zero-thickness beam unit coupled with the entity anti-slide pile, and arranging three-dimensional Goodman contact units between the pile and soil and on a weak layer and a potential slide surface layer, wherein the anti-slide pile adopts C25 concrete; and adopting a mole-coulomb constitutive model when establishing an entity side slope and the entity anti-slide pile, and simulating both a one-dimensional truss and an implantable truss by using a linear elasticity constitutive model. The beneficial effects of the present invention are that the three-dimensional side slope model establishing method for study on the anti-slide pile position is provided and the best burying point of the anti-slide piles in a real project is obtained by combination of mathematical modeling and reality.

The invention discloses a deformation analysis method of an expanded-base uplift pile group considering a reinforcement effect. The analysis method comprises the following steps: based on an elastic mechanics theory, a pile foundation load transfer principle and a thin-wall concentric cylinder shear deformation model, deducing a deformation nonlinear analytical solution expression of the expanded-base uplift pile group considering a reinforcement effect, and giving out specific calculation steps. The accuracy and effectiveness of the method are proved by comparing the calculation result of theanalytical solution with the suite of the measured data and the finite element simulation result. Calculation results show that the influence of the soil body performance, the pile end expanding bodyand the pile length on the deformation of the reinforced effect expanded-base uplift pile group is remarkable. Along with the increase of the elasticity modulus of the soil body, the increase of thepile end expanding body and the increase of the pile length, the uplift displacement reduction rate of the pile group is increased.

The invention discloses a tunnel mechanical behavior analysis method based on tunnel secondary lining surface strain. The method uses a homogeneous ring tunnel model in an elastic mechanics theory, utilizes the secondary lining surface strain at the positions of a tunnel vault, a tunnel shoulder, a tunnel haunch and a tunnel springing, a stress equation set of a simplified double-layer circular ring is deduced based on a geometric equation, a compatibility equation and a stress balance equation, and an MATLAB solving program is written to obtain a stress value inside the double-layer circular ring, and therefore the axial force and the bending moment of the tunnel secondary lining are derived. Finite element software ANSYS is utilized to establish an entity unit load-structure model of the tunnel, numerical calculation under elastic constitutive is carried out, and a structure correction coefficient is determined through comparison with actual engineering. The problems that a traditional sensor is high in loss rate in the long-term operation process of a tunnel, and tunnel full-life mechanical detection cannot be carried out are solved. The method is of great significance in reflecting the long-term mechanical properties of the tunnel by using the secondary lining surface strain and giving full play to the advantages of the fiber grating sensor.

The invention discloses a method for predicting fractured reservoir stress evolution based on a fractured continuum model, and the method comprises the following steps: building a simulated physical model based on geological parameters, construction parameters, boundary conditions and initial conditions, and determining basic parameters; establishing a natural fracture random distribution model, and calculating permeability of grids corresponding to natural fractures; establishing a stress balance equation and a continuity equation based on elastic mechanics, a finite element method and a seepage theory, and substituting the permeability into the stress balance equation and the continuity equation; and establishing a non-planar hydraulic fracture, a discrete stress balance equation and a continuous seepage equation based on a finite element method to obtain a discrete form of the discrete equation and the continuous equation, and calculating the distribution state of reservoir stress corresponding to each age limit. According to the method, stress prediction can be carried out in the later period of fractured reservoir development, a reliable guiding effect is provided for repeatedfracturing design and infilled well design, and development of oil and gas development theoretical research can be promoted.