10 results about "Multiple stress" patented technology

The invention discloses a roadway roof damage time prediction method and system, and belongs to the technical field of mine rock mechanics and safety engineering. Comprising the following steps: recognizing a roof rock stratum structure and lithology of each layer through drilling peeping, and drilling a representative rock sample; determining the crack initiation strength and peak strength of the rock sample through a uniaxial compression test; selecting a plurality of stress levels between the axial strain and the acoustic emission signal to carry out a creep test, synchronously monitoring the axial strain and the acoustic emission signal, and determining an accelerated creep starting moment as the damage time under the stress according to the abrupt change characteristics of the axial strain and the acoustic emission signal; establishing a stress-failure time relation model of each lithology; finally, selecting a corresponding model to predict the damage time of rocks at different layers of the roof according to the actual rock stratum structure and ground stress state of the roadway; according to the method, accurate and reliable time prediction of the progressive damage process of the roadway roof is realized.

The invention relates to a metal material strain rate effect measurement method based on multiple stress relaxation, which comprises the following steps: carrying out a standard quasi-static stretching or compression test on a material sample at a constant strain rate to obtain a stress-strain curve; analyzing a strain range according to a stress-strain curve, and determining a stress relaxation frequency N to be developed and a corresponding relaxation strain value sequence epsilon i, i = 1... N; a material sample is taken to be subjected to a tensile or compression test at a set strain rate, stress relaxation lasts for relaxation time delta t when the strain sequentially reaches values in each relaxation strain value sequence, and after each stress relaxation, the tensile or compression test is performed according to the set strain rate; obtaining a stress-plastic strain rate curve corresponding to each relaxation strain epsilon i; and obtaining a stress-strain curve corresponding to each strain rate. Stress-strain curves corresponding to different plastic strain rates in a quasi-static range can be obtained through a single sample.

The utility model discloses a ball bearing outer ring structure with stress dispersion grooves, which comprises an outer ring body, the middle part of the inner circumferential surface of the outer ring body is provided with a raceway, the outer circumferential surface of the outer ring body is provided with a plurality of stress dispersion grooves at intervals along the circumferential direction, the plurality of stress dispersion grooves are all annularly arranged, and the stress dispersion grooves are arranged in the raceway. The cross sections of the multiple stress dispersion grooves are semicircular, stress can be effectively dispersed, meanwhile, new stress concentration points are prevented from being generated at the edges of the grooves, the machining technology is relatively simple, the cost is low, the depth of the multiple stress dispersion grooves is 1 / 4 of the wall degree of the outer ring body, and the stress dispersion effect is good. And the distance between two adjacent stress dispersion grooves is 8mm. The stress dispersion grooves with specific structures are formed in the outer ring of the bearing, so that the stress concentration phenomenon generated in the working process of the bearing is effectively reduced, the bearing capacity of the bearing is improved, the service life of the bearing is prolonged, and the requirements of modern mechanical equipment on high-performance bearings are met.

The present application aims to reveal the influence mechanism of stress level and stress gradient on the behavior of metal material hot salt corrosion, and provides a force-chemical coupling test method and device of metal material considering stress gradient, aiming at the technical defects that mechanical load and corrosion environment are difficult to be controlled simultaneously in the existing research. First, a variable cross-section tensile deposited salt sample is designed, which can form different stress level and stress gradient distribution areas under a single loading condition. Second, the hot salt corrosion test under external stress is carried out under the condition of controlled temperature by artificially depositing the molten salt formed in the simulation of marine environment on the surface of the sample and applying external tensile load. Finally, the corrosion morphology, oxide film structure and element distribution of the sample are systematically characterized and quantitatively analyzed. The test method of the present application is simple, highly repeatable, can realize the comparative analysis of corrosion behavior under multiple stress states, and significantly improves the efficiency and accuracy of stress-corrosion synergistic effect research.

The invention provides a shield tunnel aerodynamic effect stress field response characteristic calculation method and device, and relates to the technical field of shield tunnels, and the method comprises the steps: obtaining a plurality of stress value data of a plurality of longitudinal sections of a tunnel; respectively calculating to obtain an average value of each section; respectively calculating to obtain a first correction coefficient set and a second correction coefficient set of each section; respectively constructing a circumferential stress characteristic model of the aerodynamic effect of each section; fitting the circumferential stress characteristic models of the plurality of sections to obtain a full-tunnel stress characteristic model; and the angle and the longitudinal distance of the to-be-measured point location are substituted into the full tunnel stress characteristic model, and the stress value and the acceleration value of the aerodynamic effect of the to-be-measured point location are calculated respectively. According to the method, the stress value and the acceleration value, generated by the aerodynamic effect, of each point position of the whole tunnel can be obtained only by arranging a limited number of monitoring devices to the multiple sections of the tunnel, and the arrangement number of the monitoring devices of the tunnel is reduced.

The invention relates to the technical field of material performance testing, and discloses a metal material creep performance testing method and a test piece. The test piece is provided with a first uniform-section section, a second uniform-section section and a third uniform-section section of which the diameters are sequentially decreased, and high-temperature corrosion dynamic data of the metal material under multiple stress levels can be obtained at the same time by analyzing the high-temperature corrosion creep morphology of the three uniform-section sections with different diameters. Due to the fact that the first annular V-shaped groove, the second annular V-shaped groove and the third annular V-shaped groove which are different in configuration are formed in the fourth uniform-section section with the minimum section diameter, data support is provided for analyzing the interaction mechanism of high-temperature corrosion and creep loads by analyzing the high-temperature corrosion creep morphology of the three annular V-shaped grooves. By adopting the method for testing the creep property of the metal material, the influence of the machining precision, the material consistency, the test load and the environmental individual difference between the parallel pieces on the test result is reduced, the test efficiency is improved, and the test cost is saved.

The invention discloses a fractured rock mass true triaxial pulse grouting test control system and test method considering a slurry-rock coupling effect, and belongs to the technical field of fractured rock mass grouting reinforcement, a true triaxial grouting test platform comprises a first mounting body, a second mounting body, a third mounting body, a fourth mounting body, a plurality of stress loaders and a plurality of loading pressure heads, the plurality of stress loaders are in one-to-one correspondence with the plurality of loading pressure heads; the pulse grouting pump is connected between the slurry storage tank and the slurry conveying pipe, and the slurry conveying pipe is suitable for being communicated with the fractured rock mass. Therefore, by coupling the true triaxial grouting test platform and the pulse grouting system, the complex stress environment of the fractured rock mass of the underground engineering can be accurately reproduced, the pulse pressure grout with a certain frequency is provided for the fractured rock mass, the grout diffusion range is remarkably enlarged, the rock mass grouting efficiency is improved, and the grouting efficiency of the fractured rock mass is improved. And the coupling effect of grouting pressure and fracture deformation can be synchronized, the grouting reinforcement effect of the fractured rock mass is improved, and the reliability and accuracy of experimental data can be improved.

The invention belongs to the technical field of material performance testing, and provides a method for testing metal hydrogen absorption and hydrogen diffusion parameters in a stress field, which comprises the following steps: extracting and dehydrogenating, processing into a sample, compressing and loading, carrying out gas-phase hydrogen charging, controlling the hydrogen concentration, carrying out short-time and long-time heat preservation diffusion in stages, and testing the sample. Hydrogen distribution at the beginning before hydrogen charging, after hydrogen charging and after short-time and long-time heat preservation is measured in sequence, stress distribution of the self-loading sample is analyzed through a finite element method, hydrogen absorption rates at different stress positions are calculated, a relation expression that the hydrogen absorption rates change along with parameters such as stress is fitted, and the relation between hydrogen chemical potential and stress is established; a finite element model is constructed, distribution after hydrogen filling is used as an initial state, a flux equation is adopted, stress-related diffusion coefficients are adjusted in an iterative mode, simulated short-time diffusion distribution is matched with actual test data, and the change rule of a diffusion system along with stress is determined. The application can meet the requirements of high-temperature testing, simultaneous testing of various stresses and the like.

A kind of small bin jump-digging construction method crossing over operating subway tunnel, comprising the following steps: the soil layer between new tunnel and existing structure in construction area is reinforced by pile body and ring beam reinforcement scheme, and multiple stress release holes are drilled at intervals to replace the traditional direct excavation of foundation pit operation mode, the stress release holes are drilled sequentially and at intervals, and then the soil between the holes is excavated to form a foundation pit, the extrusion stress of the soil excavation is released into the interstice of the stress release holes, which can effectively reduce the ground rebound caused by large-area excavation unloading, effectively control the rebound and uplift deformation of the underlying tunnel caused by foundation pit excavation, and at the same time, the stress release function of the stress release holes is maintained by the continuous maintenance of the form of the stress release holes by the retaining wall slurry, and the foundation pit is excavated one by one in this state, so that the construction deformation is always small, and the safety construction environment of the new tunnel is ensured, which facilitates the tunnel construction and ensures the construction safety and operation safety of the tunnel passing through the area.

The application relates to an anti-seismic pipeline hanger deformation risk early warning method and related equipment, and relates to the technical field of pipeline hanger stress detection. In the method, historical data of an anti-seismic pipeline hanger are acquired, the historical data including time, uniformly distributed load per unit length, span and cross-section modulus; the daily stress of the anti-seismic pipeline hanger is calculated according to the historical data; the daily stress is decomposed into multiple stress cycles, each stress cycle including stress size and the number of occurrences; the three-dimensional model of the anti-seismic pipeline hanger is applied to the seismic load determined by the response spectrum analysis to obtain the seismic stress of the anti-seismic pipeline hanger; the cumulative damage index of the anti-seismic pipeline hanger is calculated according to the fatigue contribution of the multiple stress cycles and the seismic stress; and the remaining life of the anti-seismic pipeline hanger is predicted based on the cumulative damage index and the current damage accumulation rate, and the current damage accumulation rate is determined by the multiple stress cycles. The anti-seismic pipeline hanger deformation risk early warning is more comprehensive and accurate.