608 results about "Poisson's ratio" patented technology

The invention provides a macroscopic finite element simulation analysis method and device for a sealing element considering plastic deformation, and belongs to the field of sealing element design. The method comprises the following steps: acquiring an engineering stress-strain curve of a plastic material in a compression state; converting the engineering stress-strain curve into a real stress-strain curve; determining a yield limit, and taking a strain point corresponding to the yield limit as a demarcation point of elasticity and plastic deformation; an elastic section of a real stress-strain curve is extracted, the elastic modulus is calculated, and the Poisson's ratio is obtained through axial and transverse strain measurement in a uniaxial compression test; a true stress-strain curve plastic section is extracted, and a multi-linear isotropic hardening model is established; constructing a complete elastic-plastic constitutive model covering the elastic deformation area and the plastic deformation area; the stress distribution, the strain response and the contact performance of the plastic sealing element in a compression deformation state are simulated. According to the method and the device provided by the invention, the problem that the result does not conform to the reality due to the fact that only elastic modulus and Poisson's ratio are used in existing sealing element simulation can be solved.

The invention relates to the field of geological exploration and geotechnical engineering, provides a rock mass dynamic mechanical parameter sensing method and system based on while-drilling parameters in order to dynamically obtain rock mass dynamic mechanical parameter characteristics in situ in real time in the drilling process, and provides a rock mass dynamic mechanical parameter sensing method and system based on while-drilling parameters by using multi-modal signals such as vibration, acoustic emission, torque and bit pressure through uniform characteristic engineering and multi-task learning. The instantaneous elastic modulus, the dynamic Poisson's ratio, the transient uniaxial compressive strength, the cohesive force and the internal friction angle can be synchronously and dynamically predicted in single drilling, and the limitation that only a single static parameter is estimated in a traditional method is broken through; a rock mass dynamic mechanical parameter acquisition model constructed on the basis of a multi-modal adaptive graph attention sequential network can effectively couple the physical proximity and the statistical association relationship of a sensor, and integrates expansion sequential convolution and a time perception Transform module, so that the characterization capability of emergencies (such as jamming / friction resistance) and long-term trends is considered on the premise of low time delay; therefore, the prediction accuracy is improved.

The invention discloses a breakable rock-soil granular material triaxial test simulation method based on a lattice spring-discrete element coupling framework, which comprises the following steps: establishing a triaxial test model rectangular boundary condition, and generating a non-breakable spherical rock-soil granular material in the boundary; replacing the generated non-crushable spherical particle material with rock-soil particles considering particle crushing based on a lattice spring-discrete element coupling frame, and assigning parameters; replacing wall bodies on the two sides of the rectangular boundary condition with a large number of bonded spherical particles to generate a flexible membrane boundary; and applying confining pressure to the boundary of the generated flexible membrane, and carrying out shear simulation. According to the method, the Young modulus and the Poisson's ratio can be matched in a high-precision mode, the heterogeneity of elastic response is reduced, strength degradation and friction characteristics are simulated, and the calculation efficiency is greatly improved.

The invention relates to the technical field of crustal stress measurement, in particular to a rock core three-dimensional crustal stress measurement system and method based on multi-source data. The method comprises the following steps: acquiring well wall damage information, and identifying a damage type in the well wall damage information; multiple sections of core samples are selected based on the well wall damage information, and overburden pressure parameters are determined based on the multiple sections of core samples; a rock mechanics experiment is conducted on the rock core sample, rock mechanics parameters are generated, and the rock mechanics parameters comprise the Poisson's ratio, the Young modulus, the uniaxial compressive strength value and the tensile strength value. According to the method, the difference value of the maximum stress and the minimum stress is combined with the multi-source coupling constraint principal stress interval, the intersection points are identified through the topological visualization graph, the numerical range of the maximum principal stress and the minimum principal stress can be accurately determined, and then the information of the three-dimensional crustal stress is obtained.

The invention discloses an energy-absorbing reinforced honeycomb structure with the Poisson's ratio capable of being adjusted positively and negatively and a design method, and relates to the field of honeycomb structures. Two horizontal outer ribs and four inclined outer ribs of the honeycomb structure form a hexagon; the two ends of the first arc-shaped inner rib are connected with the left upper vertex and the left lower vertex of the hexagon and are concave towards the left vertex of the hexagon; the second arc-shaped inner rib is connected with the right upper vertex and the right lower vertex of the hexagon and is concave towards the right vertex of the hexagon; two ends of one horizontal inner rib are respectively connected with the left vertex of the hexagon and the first arc-shaped inner rib, and two ends of the other horizontal inner rib are respectively connected with the right vertex of the hexagon and the second arc-shaped inner rib; and the circular ring is embedded in the convex parts of the two arc-shaped inner ribs. According to the honeycomb structure, the positive Poisson's ratio honeycomb and the negative Poisson's ratio honeycomb are fused through the two horizontal inner ribs, so that the inner ribs and the outer ribs are mutually balanced, the circular ring design is added, and the structural strength is improved; through the thickness parameter design of the inner ribs and the outer ribs, flexible transformation of the positive Poisson's ratio or the negative Poisson's ratio is achieved on the premise that light weight and high strength are guaranteed.

The invention discloses a multi-wave chromatography and reflection combined detection method and device for a thin-covering-layer urban active fault and a medium. The method comprises the steps that longitudinal wave seismic data and transverse wave seismic data are collected; recording vertical component data based on the longitudinal wave seismic data for first arrival travel time pickup and tomography inversion to obtain a longitudinal wave velocity structure model Vp; extracting Rayleigh surface wave frequency dispersion through the vertical component data and carrying out multichannel surface wave analysis inversion to obtain a transverse wave velocity structure model Vs; calculating a longitudinal and transverse wave velocity ratio parameter structure model Vp / Vs, and calculating to obtain a Poisson's ratio parameter structure model v; obtaining a longitudinal wave (P wave) reflection profile and a transverse wave (S wave) reflection profile; identifying and summarizing into an interpretation fracture set Fc, and recording key elements; and by taking the interpretation fracture set Fc as a structural skeleton, completing unified registration and superposition display on Vp, Vs, Vp / Vs and v, a longitudinal wave reflection profile and a transverse wave reflection profile, and outputting a shallow underground structure comprehensive interpretation map of the thin covering layer region.

The invention discloses a plane matrix type high folding and unfolding bionic antenna truss structure with a negative Poisson's ratio effect, and relates to the technical field of space folding and unfolding mechanisms, the plane matrix type high folding and unfolding bionic antenna truss structure comprises a plurality of cell elements and a plurality of cell element connecting rods, transverse cell elements are connected through the cell element connecting rods, and longitudinal cell elements are fixedly connected through adjacent cell element cross beams; the cell element connecting rods are hinged to the cell elements on the two sides respectively, and the cell elements are three-level positioning inwards-concave hexagonal cell elements; the folding and unfolding antenna truss structure is in a folded state during launching, transportation and silent latency and is in an unfolded working state during on-orbit task execution, the high folding and unfolding ratio characteristic of the antenna provides bionic improvement inspiration for various urgent properties such as stealth and size reduction of a satellite antenna structure, the shape of the antenna folding and unfolding array can be changed in a multi-stage mode, and the antenna folding and unfolding array is suitable for large-scale popularization and application. Therefore, the functions of optimal frequency band adjustment, optimal area expansion, switching of different scanning ranges and the like are realized.

The invention relates to the technical field of mechanical metamaterials, in particular to a negative Poisson's ratio cell element with an embedded symmetrical broken subcell structure, which comprises a concave hexagonal main body, the concave hexagonal main body comprises two horizontal cell walls and inclined cell walls arranged at two ends of the two horizontal cell walls, and the central points of the two inclined cell walls are bent towards one side close to the central points of the horizontal cell walls; the number of the bent wall rods is two, and the two bent wall rods are symmetrically arranged in the inwards-concave hexagonal body. The inherent contradiction that the stretching performance must be sacrificed when the rigidity of a traditional concave honeycomb structure is improved is successfully solved, and the negative Poisson's ratio effect and the energy absorption capacity of the structure can be further improved while the structural rigidity is enhanced.

The invention discloses a self-adaptive impact-resistant protective metamaterial with a Poisson's ratio autonomous constraint function, which comprises a PMP honeycomb, the PMP honeycomb comprises a plurality of honeycomb unit cell structures, and each honeycomb unit cell structure comprises a hexagonal thin-wall structure I and a hexagonal thin-wall structure II internally connected in the hexagonal thin-wall structure I. The invention further discloses a preparation method of the self-adaptive impact-resistant protective metamaterial with the Poisson's ratio autonomous constraint function. Compared with an SHC honeycomb, the PMP honeycomb has the advantages that the dynamic Poisson ratio of the PMP honeycomb is relatively stable in the whole crushing process, and the initial fluctuation range is only 0.1. In addition, the average dynamic Poisson's ratio of the PMP honeycomb is relatively small, indicating that the PMP honeycomb is almost free of transverse deformation without additional assistance. After the PMP honeycomb is compressed to be densified, the transverse length of the PMP honeycomb is only increased by 3.5%. Wherein the PMP honeycomb has better self-constraint capability, so that the PMP honeycomb has a more stable energy absorption mode.

The invention discloses a sandwich structure based on chiral pressure torsion and negative poisson ratio honeycomb compounding, and relates to the technical field of mechanical metamaterials. The sandwich structure comprises an upper skin layer, a core layer and a lower skin layer, the core layer is formed by alternately compounding three-dimensional chiral compression-torsion cell elements and negative poisson ratio honeycomb cell elements which are periodically arranged, and the chiral compression-torsion cell elements form a bidirectional torsion stress network through spiral connecting rods; the negative Poisson's ratio honeycomb cell element is of a concave polyhedron structure and is nested with a butterfly-like substructure, and energy is absorbed through transverse contraction and folding deformation in a cooperative mode. The sandwich structure has a multi-stage energy dissipation mechanism: the chiral compression-torsion unit disperses impact energy through spiral deformation, the butterfly-like substructure elastically shrinks at low strain and slides and folds at high strain, and the energy absorption efficiency is enhanced through friction and plastic deformation; the structural parameters can be subjected to gradient regulation and control according to the impact strength, the lightweight rate and the deformation mode, and high design flexibility and working condition adaptability are achieved.

The invention provides an intelligent prediction method and system for settlement of a TBM penetrating through a pebble stratum, and belongs to the technical field of stratum settlement prediction. The method comprises the following steps: acquiring ground surface monitoring point position information, excavation surface position information and burial depth, inputting the information into a first deep neural network model, and acquiring and outputting tunnel vault displacement, haunch convergence and ground surface settlement; the second deep neural network model takes a position coordinate formed by earth surface monitoring point position information, excavation surface position information and burial depth and earth surface settlement as input, and outputs earth surface elastic modulus and Poisson ratio; obtaining stress-strain components of ground surface settlement, and constructing a control equation and boundary conditions based on the stress-strain components, the elastic modulus and the Poisson's ratio; obtaining prior geological information by using the residual error of the control equation; and by taking the control equation, the boundary condition and the prior geological information as constraint conditions, obtaining a settlement prediction value when the TBM passes through the pebble stratum based on the tunnel vault displacement, and realizing accurate prediction of the settlement of the pebble stratum.

The invention relates to the technical field of tire simulation design, in particular to a method, system and equipment for calculating contribution of tire parts to camber rigidity and a storage medium. The method is based on a finite element model and comprises the following steps: firstly, carrying out two-dimensional axial symmetry modeling and inflation analysis on a tire, rotating to generate a three-dimensional model, then establishing contact with a rigid road surface, applying rated inflation pressure and load, and carrying out steady-state rolling and camber working condition simulation to obtain reference camber rigidity comprising all parts; and then target parts such as a tread, a belted layer and sidewall rubber are selected, the Young modulus of the target parts is reduced to 0.01%-5% of a design value, the analysis is repeated on the premise that the Poisson's ratio of the target parts and other parts and boundary conditions are kept unchanged, and the camber rigidity of the target parts after degradation is obtained. The camber rigidity contribution value and contribution rate of the camber rigidity are calculated by comparing the difference value of the camber rigidity of the two working conditions and combining the occurrence frequency of the target component in the tire structure, and quantitative stripping of the camber rigidity influence of each component is achieved. According to the method, the component-level contribution spectrum can be quickly obtained on the premise of controllable errors, and an effective basis is provided for directional optimization design of the tire camber rigidity performance.

The invention belongs to the technical field related to structure optimization, and discloses a cross-scale topological optimization method of an auxetic metamaterial with a specified deformation mode, which comprises the following steps: (1) according to a given metamaterial function target, introducing an elastic tensor component constraint condition to establish a negative Poisson's ratio microstructure topological optimization model; (2) gradually changing the volume rate constraint of the initial microstructure to obtain a series of negative Poisson's ratio gradient microstructures with different equivalent densities; (3) constructing a multi-phase material interpolation model based on a Kriging model, constructing an auxetic metamaterial cross-scale topological optimization model with a specified deformation mode, and deducing the sensitivity of a target function to design variables; and (4) calculating and updating the design variable until the output meets the convergence condition, and outputting the auxetic metamaterial with the target deformation mode. According to the method, the limitation that the deformation mode of the traditional auxetic metamaterial cannot be locally regulated and controlled is overcome, and the design efficiency of the cross-scale design problem of the two-dimensional auxetic metamaterial under the complex condition is improved.

The invention relates to the technical field of bearing life calculation, in particular to a transmission bearing installation pre-tightening amount calculation method and system, and the method comprises the steps: S1, building a finite element mesh model of a transmission housing and a shaft through finite element simulation software based on predefined material attributes; the material attributes comprise elastic modulus, Poisson's ratio and thermal expansion coefficient of the transmission shell and the shaft; s2, based on the actual working condition of transmission assembly life simulation analysis, importing the finite element mesh model of the transmission shell and the shaft into a pre-constructed multi-body dynamics simulation model of the transmission shell, and establishing node connection between the finite element mesh model of the transmission shell and the shaft and a transmission part in the multi-body dynamics simulation model; s3, setting a detection object and a design variable, and adopting a preset strategy to obtain a target mapping curve of the detection object and the design variable; compared with the prior art, the optimal relation between the pre-tightening amount and the service life of the bearing can be quickly determined, so that the service life of the bearing is maximized.

The present invention discloses an X-shaped negative Poisson's ratio local resonance module and its supporting metamaterial disc structure. The X-shaped negative Poisson's ratio local resonance module includes an X-shaped structural wall, an X-shaped negative Poisson's ratio structural unit and a local oscillator, wherein the local oscillator includes a soft coating layer and a cylindrical core, and the local oscillator is fixed on the X-shaped negative Poisson's ratio structural unit in an embedded form; the supporting metamaterial disc structure is composed of a plurality of X-shaped negative Poisson's ratio local resonance modules. The X-shaped negative Poisson's ratio structural units are circumferentially distributed around the outer wall of the inner circular ring column in the X-shaped structural wall to the inner wall of the outer circular ring column, and the outer wall of the inner circular ring column and the inner wall of the outer circular ring column are connected by the X-shaped structural unit wall. The X-shaped negative Poisson's ratio local resonance module is installed on a beam-type or tube-type base structure through the inner circular ring column. The present invention can achieve multi-scale and multi-level vibration suppression through the X-shaped negative Poisson's ratio local resonance module, improve the stability of the disc-shaped parts, and is easy to install and convenient to process.

A star-shaped negative Poisson's ratio honeycomb structure with double stress platforms comprises a plurality of star-shaped cell elements which are periodically arranged in the same plane in the transverse direction and the longitudinal direction, and each star-shaped cell element comprises a quadrangular star-shaped structure, a circular structure and two double-arrow-shaped structures; the quadrangular star-shaped structure is formed by connecting eight inclined cell walls end to end, so that a closed hollow structure which is symmetrical in the up-and-down and left-and-right directions is formed; the circular structure is embedded in the quadrangular star-shaped structure and intersects with four concave points of the quadrangular star-shaped structure; the two double-arrow-shaped structures are located on the left side and the right side of the quadrangular star-shaped structure respectively, each double-arrow-shaped structure comprises two long cell walls and two short cell walls, and the intersection point of the two long cell walls coincides with the inward concave point of the quadrangular star-shaped structure. Under the action of longitudinal compression, the double-stress-platform characteristic is shown, the good negative Poisson's ratio effect is achieved, the structural bearing capacity and the energy absorption efficiency can be improved, and the double-stress-platform metamaterial belongs to the technical field of mechanical metamaterials.

The invention discloses a rock unconventional reservoir carbon dioxide fracturing temperature field simulation method and system, and belongs to the technical field of oil and gas exploitation. Rock unconventional reservoir parameters and wellbore parameters are obtained, fluid physical property parameters of carbon dioxide fracturing fluid flowing in a wellbore are determined, and a multi-dimensional physical partition model is constructed; the unconventional reservoir is divided into a plurality of physical areas including a fluid flowing area, a static fluid area, a solid area and a porous medium area; thermal boundary conditions of all physical areas are coupled through an energy conservation equation, stratum elasticity modulus and Poisson's ratio are added to the thermal boundary conditions, a thermal-force coupling equation is constructed, carbon dioxide fracturing construction parameters obtained in real time are estimated, temperature field distribution nephograms of carbon dioxide fracturing fluid at different moments in the shaft flowing process are obtained, and the temperature field distribution nephograms of the carbon dioxide fracturing fluid at different moments are calculated. According to the method, the temperature distribution rule of different fracturing stages in the shaft-crack direction can be truly reflected.

The invention relates to the technical field of machining simulation, in particular to a composite material ring piece low-stress machining method based on finite element analysis. The method comprises the following steps: constructing a two-dimensional finite element model of the composite material ring piece; grid division is carried out on the geometric model, and the structure is decomposed into units; setting boundary conditions and loads of the simulation model; defining material attributes including density, thermal conductivity, specific hot melting, elastic modulus, Poisson's ratio, plasticity and creep; setting processing and heat treatment parameters, including processing procedures, processing amount, heat treatment temperature and time; the simulation model is operated, and the response of the geometric model under the given boundary and loading condition is obtained; and analyzing an operation result, summarizing an influence rule of machining parameters and heat treatment setting on machining stress, and optimizing a machining scheme. According to the method, a stable component low-stress machining scheme can be rapidly obtained through an analogue simulation technology for the machining process of the composite material ring piece, and high-precision machining of the large-size fiber reinforced composite material ring piece is achieved.

The invention discloses a three-dimensional composite negative Poisson's ratio unit cell structure, a metamaterial and a design method.The three-dimensional composite negative Poisson's ratio unit cell structure comprises two inwards-concave units which are perpendicular to each other, the inwards-concave units comprise an outer inwards-concave unit and an inner inwards-concave unit which are the same in shape but different in size, and the inner inwards-concave unit is located in the outer inwards-concave unit; each corner of the external concave unit is connected with each corner of the internal concave unit through a connecting rod in a one-to-one correspondence manner, two cell element connecting rods are arranged at each concave corner outside the external concave unit, and a set included angle is formed between the two cell element connecting rods; the structure shows two stress platform stages, so that impact energy can be absorbed and buffered step by step more easily, and compared with a traditional structure, the energy absorption capacity is higher.

The invention discloses a soil-pile foundation collaborative response seismic liquefaction discrimination device and method based on seismic oscillation time-frequency characteristics, and the method comprises the steps: building a multi-field coupling evolution model comprising a soil body domain, a fluid domain and a structural body, constructing a variable-scale grid architecture through a finite element method, balancing the high sensitivity and calculating the load, and carrying out the calculation of the load. Meanwhile, the fluid domain is directly coupled with the soil body unit through the shared node, and the Poisson's ratio is dynamically calibrated according to the void ratio. The multi-field coupling modeling mode can accurately simulate a soil-water-structure collaborative response mechanism, the problem of time-frequency characteristic mismatch caused by a scale effect in the prior art is avoided, and the strength degradation law and the aging characteristic of the in-situ soil body are accurately reflected. Compared with a traditional physical model which cannot reproduce nonlinear dynamic response under complex geological conditions, the method has the advantages that accurate description of high void ratio and low permeability of the soft sand is realized through numerical modeling, and the reliability of seismic liquefaction judgment results is further improved.

The invention discloses a three-dimensional negative Poisson's ratio metamaterial structure and a manufacturing method thereof, the three-dimensional negative Poisson's ratio metamaterial structure comprises a plurality of unit cell structures which are mutually connected to form an array structure, and the unit cell structures on the same layer of the array structure are connected through first connecting pieces; each unit cell structure comprises an inwards-concave unit and two semi-inwards-concave units, the two semi-inwards-concave units are clamped on the inwards-concave unit to form two inwards-concave units which are perpendicular to each other, each inwards-concave unit comprises a first inwards-concave structure and a second inwards-concave structure, the second inwards-concave structures are located in the first inwards-concave structures, and the second inwards-concave structures are located in the second inwards-concave structures. Each corner of the first concave structure is connected with each corner of the second concave structure in a one-to-one correspondence manner through a connecting rod; the manufacturing process can be simplified while the energy absorption performance of the metamaterial is improved, and the production and manufacturing efficiency is improved.

The invention discloses a construction method and device of a three-dimensional rock mechanics model and application of the three-dimensional rock mechanics model. The method comprises the steps that rock mechanics attribute field data of a single well in a target oil reservoir are obtained; correcting the rock mechanical property field of the single well; constructing a one-dimensional rock mechanics model based on the corrected rock mechanics attribute field data of the single well; and performing longitudinal discretization processing on the one-dimensional rock mechanical model to construct a three-dimensional rock mechanical model. The rock mechanics modeling method is combined with rock mechanics indoor experiments and fractured well ground stress parameters, and Young modulus and Poisson's ratio dynamic and static data conversion and difference correction of various mechanical parameters are carried out in the modeling process. Quality control of various parameters in the modeling process is achieved, and the precision of the rock mechanical model is improved.

The invention belongs to the technical field of mechanical metamaterials, and particularly discloses an energy-absorbing three-dimensional metamaterial with interactive combination of positive and negative Poisson's ratio structures, which comprises a plurality of microcosmic unit structures, each microcosmic unit structure comprises a reverse four-chiral auxetic structure and a bionic diagonal bracing structure, and the reverse four-chiral auxetic structures and the bionic diagonal bracing structures are arranged in an interactive combination manner. According to the technical scheme, the microscopic unit structures are three-dimensional structures and are simple in structure, the lattice metamaterial obtained by combining the microscopic unit structures has good isotropic characteristics and has three-stage strain hardening characteristics under the compression effect, the plastic deformation capacity is enhanced, the energy absorption capacity of the structures is effectively improved, and the energy absorption efficiency of the structures is improved. And the bearing capacity is relatively high. The structure size of the metamaterial can be flexibly adjusted according to an actual scene, and the metamaterial can be used as a part or a structural member to be flexibly applied to different fields.

The invention relates to the technical field of tunnel monitoring, and discloses an advanced monitoring method and system based on an existing tunnel, and the method comprises the steps: obtaining a proper hole measurement position, depth and direction according to an analysis result; monitoring the displacement and stress change of the surrounding rock in real time, and analyzing according to the monitored surrounding rock data to obtain surrounding rock parameters such as elastic modulus, Poisson's ratio, friction angle and cohesive force of the surrounding rock; and the geological analysis system analyzes the unfavorable geologic body, and starts the advanced horizontal equipment for detection and verification. The system comprises an existing tunnel data acquisition module, an existing tunnel data calculation module and a geological forecast scheme module. Through the combination of the geological analysis system and the detection equipment, the state of the unfavorable geologic body can be more accurately judged, and the reliability of geological forecast is improved; early warning is given out in time, the construction scheme is adjusted, collapse, water burst and other disasters caused by unfavorable geologic bodies are effectively avoided, and construction safety is ensured.

The invention discloses a dual-mode touch sensor capable of realizing quantitative detection of elastic modulus and a method. A dual-mode sensing device of the dual-mode touch sensor detects a pressure strain electric signal when the surface of a detected object generates force deformation, and a data acquisition and processing device acquires the electric signal and performs data processing according to a specific elastic modulus detection model, so that quantitative detection of the elastic modulus of the material is realized. The method comprises the steps that a measured object is placed on a platform, and the axis of a sensor is kept perpendicular to a measured surface; positive pressure is loaded at the top of the probe at a constant speed to push the spherical probe to be pressed into the to-be-measured object at a constant speed; a voltage signal is collected through the data collecting and processing device, and the model measures the Poisson's ratio and detects the elastic modulus. According to the dual-mode touch sensor and the method, the Poisson's ratio of the material is accurately measured, the elastic modulus is quantified, a robot can recognize the mechanical performance of an unknown material, and finer perception and interaction are achieved.

The invention discloses a tunnel rock mass water burst and mud burst prediction method and system based on an XGBoost-RF fusion algorithm, and belongs to the technical field of geological disaster prediction. The method comprises the following steps: firstly, preprocessing seismic wave data, and extracting various geological response characteristics including longitudinal wave velocity, wave velocity variation coefficient, Poisson's ratio and the like; then respectively training an XGBoost model and a random forest model, and carrying out probability fusion through a soft voting strategy; and finally, outputting a risk level classification result based on the weighted probability. The core innovation of the invention lies in that the feature fine recognition capability of the XGBoost model and the anti-noise characteristic of the random forest model are effectively combined through algorithm fusion, and the probability calibration and weight optimization mechanism is adopted, so that the recognition precision of middle and high risk categories is remarkably improved. Experiments show that according to the method, the average recall rate of key categories on a test set reaches 0.9925, the overall accuracy rate is 0.990, and the problems that a traditional method is high in high-risk geologic body missed judgment rate and insufficient in generalization ability are effectively solved.

The invention relates to a material local damage quantitative evaluation method based on multi-scale mechanical parameters. Comprising the following steps: acquiring an original three-dimensional grayscale image in a free state; applying a micro-amplitude load to obtain a loaded three-dimensional grayscale image; calculating a local strain field after applying the micro-amplitude load by adopting DVC, and constructing an initial Poisson's ratio field: introducing macroscopic damage to the sample, and repeating the steps of scanning in a free state and under the micro-amplitude load and constructing the Poisson's ratio field to obtain a Poisson's ratio field after damage; carrying out registration on the image; in the registered image, calculating a gray scale entropy; determining a minimum volume unit through a sliding window method; determining a minimum analysis unit, and constructing a quantitative damage index model; and generating a three-dimensional damage distribution diagram according to the damage index. The resolution bottleneck of traditional nondestructive testing is broken through, precise positioning and quantitative evaluation of submicron damage are achieved, and a new means is provided for research of a material damage evolution mechanism.

The method comprises the following steps: according to a response relationship between coal seam gas and a Poisson's ratio parameter, acquiring a complete vibration signal of a heading machine seismic source by means of a high-definition distributed optical fiber sound wave sensing system, and extracting longitudinal waves and transverse waves in a heading seismic record; poisson ratios at different positions are obtained through the longitudinal waves and the transverse waves. And finally, accurately corresponding the Poisson's ratio parameter to the gas content condition, thereby detecting the gas enrichment area, and exploring the gas risk in a certain range in front of and on two sides of the tunneling working face in real time. And the gas risk of the area is predicted by collecting excavation-following seismic records in front of and on the two sides of the excavation working face. Compared with the prior art, the method has high accuracy for solving the outburst problem dominated by gas and has a large monitoring range, meanwhile, the method is not prone to being affected by other signals due to the processing mode that data are overlaid along with excavation for multiple times, limitation in the prior art is overcome, and the early warning effect is improved.

The invention discloses a mechanical metamaterial cell element with a zero Poisson's ratio property, and belongs to the technical field of mechanical metamaterials. The upper top plate and the lower bottom plate are symmetrically arranged, the upper cleat nail set and the lower cleat nail set are arranged at the four corners of the inner side faces of the upper top plate and the lower bottom plate, the elastic body set is connected through the upper cleat nail set and the lower cleat nail set, and the flexible hinge component set is arranged at the midpoint position of four side lines of the upper top plate and the lower bottom plate. The flexible hinge component set keeps inward pre-bending through the pre-tension of the elastomer set, and when the cell element bears an axial load, the flexible hinge component set generates coordinated inward bending deformation, so that the cell element shrinks in the axial direction, the transverse size is kept stable, the axial zero Poisson's ratio characteristic is achieved, and meanwhile the energy absorption capacity is achieved. The cell element is based on elastic deformation, has self-recovery capability and long cycle life, adopts modular design, is convenient to assemble, disassemble and maintain, and is suitable for application scenes of aerospace buffer devices, biomedical implants, precise instrument supporting structures and the like.

The invention relates to the technical field of coal mining and rock mechanics numerical simulation, and discloses a stress field reconstruction method of a plane strain numerical simulation model for coal mining, and the method comprises the following steps: firstly, obtaining an actually measured vertical stress increment and an actually measured bearing pressure peak value position of a stope face; then, an initial plane strain numerical simulation model is constructed, the space error between the peak position of the simulated bearing pressure and the actual measurement position meets a preset threshold value by adjusting the excavation step pitch, and therefore the numerical simulation calculation state is locked to eliminate space-time dislocation; a simulation strain increment is extracted in a locked state, a theoretical vertical stress difference equation is constructed based on an elastic mechanics plane strain constitutive relation, and a parameter inversion equation set is established in combination with multi-measurement-point data; and solving the corrected elastic modulus and Poisson's ratio by using a least square optimization algorithm. According to the method, through physical state locking and incremental theory inversion, system errors are effectively eliminated, and the reconstruction precision and mechanical preciseness of the mining-induced stress field are improved.