128 results about "Critical stress" patented technology

A method of determining the fatigue life of a welded structure, including the steps of: creating a 3D coarse mesh model of the welded structure to be analyzed; analyzing the coarse mesh model using an FEA model to generate FEA data; identifying a critical stress location on the coarse mesh model having a through thickness stress distribution, based on the FEA data; post processing the FEA data in the middle portion of the through thickness stress distribution while excluding the through thickness stress distribution near the edges of the identified critical stress location to determine a peak stress; and determining a fatigue life of the welded structure at the identified critical stress location, dependent on the determined peak stress.

The invention discloses a testing system for critical pressure during thermal explosion of explosives. The testing system comprises a pressure-resistance heating unit, a pressure control unit, a sample loader unit, a decomposed product detection unit and a computer; the pressure-resistance heating unit comprises a single-cavity heating furnace body, wherein a temperature sensor which is connected with the computer is arranged in a furnace cavity, and temperature, temperature rise speed and pressure of the single-cavity heating furnace body are controlled by the computer; the pressure control unit comprises a high-pressure gas cylinder, a pressurizing gas channel pipe, a pressurizing electromagnetic valve, a heat conduction layer extension edge pressurizing pipe, a pressure-releasing gas channel pipe, a pressure-releasing electromagnetic valve, a safety valve gas channel pipe, a safety valve and a pressure sensor; the sample loader unit comprises an L-shaped bracket, a stepping motor, two fixed pulleys, a steel wire rope, a furnace cover, a sample reservoir bracket and a sample reservoir; the decomposed product detection unit comprises an infrared sensor which is arranged in the sample reservoir; and the computer is provided with a data acquisition card, a graphic display control and a data processing unit and can be used for identifying the critical state of thermal decomposition to combustion or explosion and acquiring a critical pressure parameter.

The invention relates to an on-line testing device for high temperature and high pressure rock physical property and percolation mechanism nuclear magnetic resonance. The on-line testing device comprises a nuclear magnetic resonance on-line testing module, a rock fluid displacement module (comprising core holder compatible with nuclear magnetic resonance tests) and a computer control and data processing module, a nuclear magnetic resonance testing system and a rock fluid displacement system are combined into a whole through computer control, formation temperature and pressure are simulated, rock displacement tests are carried out under high temperature and high pressure conditions, and real-time nuclear magnetic resonance signals are measured on line to obtain rich rock parameters (porosity, permeability, reservoir forming critical pressure, wettability and the like). The on-line testing device serves as a device for oil gas reservoir forming geological research and oil gas target assessment, and the purposes of analyzing core physical properties and percolation mechanism from micro perspective are achieved.

The expansion machine flowrate of a vapor compression system is regulated to directly control the supercritical pressure in the high pressure component of the transcritical system. The expansion machine is directly linked to a recompressor which recompresses the vapor phase of the expanded flow. By controlling the flowrate of the recompressor with a first valve, the flowrate of the expansion machine can be controlled to control the massflow rate through the expansion machine and therefore the high pressure of the system.

The invention discloses a melamine resin and polyurea resin double-shell microcapsule and a preparing method and application thereof. The preparing method includes the steps that a melamine prepolymer, a chain extender and an emulsifying agent are added into a reactor by the mass ratio of 100:5:20-100:10:30, and stirred at a low speed at the room temperature until the melamine prepolymer, the chain extender and the emulsifying agent are completely dissolved, the pH value is adjusted to be one to six, a curing agent and core material homogeneous phase mixture is added, an emulsifying machine is used for emulsifying and stirring under the ice-bath condition, and emulsification is conducted continuously; the temperature of a water bath is raised to be 40 DEG C or above, a turbulent stirring paddle is used for stirring, a reaction continues to be conducted, the pH value is adjusted to be larger than or equal to six, and the reaction is stopped to obtain the double-shell microcapsule with the particle size of 0.1-300 micrometers, wherein an outer shell is made of melamine resin, and an inner shell is made of polyurea resin. A core material is protected by two shell materials, storage stability of the microcapsule can be improved, and the water mass content of the double-shell microcapsule is smaller than or equal to 5%; the critical stress is 0-900 mN, and the mechanical property is good.

The invention provides a method for testing the fracture toughness of rattan canes based on a three-point bending mode. The method comprises the following steps: preparing a sample, and regulating a water content rate so as to obtain a sample of which the water content rate is 10-12%; recording a load-crack opening displacement (PV) curve, measuring actual crack depths, and calculating critical loads PQ and critical stress intensity factors KQ. According to the method provided by the invention, the crack opening displacement is measured by a C.O.D Gauge, and the test precision is improved. Aiming at the characteristics of the rattan materials, the sampling method for testing the fracture toughness of rattan canes is ensured, and the measured results having high accuracy and good reproducibility are obtained. The calculation method for testing the fracture toughness of rattan cane, provided by the invention, provides qualitative and quantitative bases for the utilization of the rattan canes.

The invention discloses a method for measuring the oil well pipe corrosion cracking critical stress intensity and sensitive factor. It adopts U-type loading hook to do static loading-unloading closed loop movement to the pin-and-hole of the twin cantilever (DCB) sample before and after the sulfide stress corrosion cracking test, makes the firmer chisel, loads the DCB perpetuity shift sample and obtains the loading and the relate curve of the shift at the same time; it quantity measures the DCB sample firmer chisel initial level loading, firmer chisel loading DCB actual cantilever shift and the critical level loading value after the test.

A blast/impact mitigation shield includes, in one example, a first body including a damping material in a solid state and which transitions to a viscous fluid state when stressed beyond a critical stress and a second body including damping material in a solid state and which transitions to a viscous fluid state when stressed. A plunger plate has blades extending outwardly therefrom and is located between the first and second bodies.

The invention relates to a flexure testing method and a flexure testing device for quantitatively characterizing the interface binding property of thin-film material and belongs to the technical field of property characterization of experimental mechanics and material mechanics. The method is characterized in that uniaxial compression is performed to a sample in the axial direction through a universal material testing machine, and the stress strain values of the sample are recorded; meanwhile, the cross section of the sample is observed synchronously in real time through a CCD camera during the loading process, and stripping characteristics such as critical stress, deflexion and crack length can be recorded in real time during the flexure process; and a relation between the coating and plating-substrate stress strain history and the stripping characteristics is established to characterizing the interface binding property of the coating and plating-substrate. According to the device, the CCD camera, a monitor, an image processing card, a computer, a data processing card, a load sensor and the universal material testing machine are connected in sequence. The invention has the advantages of simple principle, simplicity in sample preparation, clear model, easiness in operation, and the like.

The invention discloses a method for qualifying liquid loading of a gas well for use in the development process of gas reservoirs and condensate gas reservoirs. Corresponding oil-water ratios at different time are calculated with daily production data of the gas well in order to obtain corresponding critical pressure gradients, and the critical pressure gradients are compared with a pressure gradient test curve for analysis. If the maximum value of the test pressure gradient curve surpasses the critical pressure gradient value, liquid loading in a shaft occurs; on the contrary, if the maximum pressure gradient value is lower than critical pressure gradient values, liquid loading does not exist in the shaft even the pressure gradient curve fluctuates. Critical pressure gradients under different oil-water ratio conditions are calculated through a substance balance state equation model and a critical pressure gradient model by using daily test data of the gas reservoirs and condensate gas reservoirs, and the critical pressure gradients are compared with the pressure gradient curve to judge whether liquid loading occurs in the shaft or not, so that various errors caused by direct manual qualitative analysis are avoided, and the accuracy of liquid loading judgment is increased.

Using information about the position, orientation, and shape of a crack appeared in a judged material and information about the structure of the judged material as parameters, the stress intensity factor K_I of the crack is found. Based on the stress intensity factor K_I, hydrogen embrittlement cracking of the judged material is judged. The crack growth rate and possibility of brittle fracture can be judged by comparing the stress intensity factor K_I with the critical stress intensity factor K_IH for crack initiation or the critical stress intensity factor K_IC-H for brittle fracture about the temper embrittled steel which absorbs approximately 2.0 ppm hydrogen.

The invention relates to a method for preparing silica aerogel by supercritical drying with a high-pressure liquid medium, which comprises the following steps of: (1) adding silicon tetrachloride and water to perform reaction with stirring under the acidic condition that the pH is between 3 and 5, adjusting the pH to be between 8 and 10 by using ammonia water, adding the water and ethanol to perform hydrolysis and polycondensation reaction to form alcogel; (2) loading the alcogel into a high-pressure reaction kettle, filling the high-pressure liquid medium into the reaction kettle, and slowly raising the temperature to reach supercritical pressure after the reaction kettle is filled with the high-pressure liquid medium; and (3) slowly releasing gas medium while slowly raising the temperature until the pressure in the kettle and external atmosphere are balanced, opening the reaction kettle, taking the sample out and drying the sample. The method has the advantages of readily available raw materials, simple process and low cost, solves the problem of easy shrinkage cracking of the SiO2 aerogel when dry, and can stably improve the reaction speed at the same time.

The invention belongs to the technical field of unconventional oil and gas innovation for increasing output, and discloses a shale gas horizontal-well refracturing temporary-plugging critical pressure test method. The shale gas horizontal-well refracturing temporary-plugging critical pressure test method comprises the following steps that shale gas reservoir rock samples are collected, and the rock samples are cut into the same size specifications; geological parameters of the shale gas reservoir rock samples are collected, a pressure curve of initial fracturing construction of a shale gas well is analyzed, and closure pressure of a reservoir stratum is obtained; the rock samples are divided into three groups, each group of shale gas reservoir rock samples are overlaid according to upper, middle and lower layers, and quantitative temporary plugging additives are evenly laid between every two adjacent rock samples; the overlaid rock samples are connected with test pipelines, and displacement is conducted on temporary plugging overlaid rock sample created fractures by using slickwater; and effects of the different temporary plugging additives, the temporary plugging additive sealing and plugging lengths and the fracture widths on temporary plugging critical pressure are analyzed quantitatively. According to the shale gas horizontal well refracturing temporary plugging critical pressure test method, under the condition of formation effective closure stress, the temporary plugging critical pressure of different types and amounts of the temporary plugging additives on a hydraulic fracture can be tested conveniently, and reference standards for optimization selection and optimization design of the temporary plugging additives are provided.

A method is described for determining when a ceramic component on a platform should be replaced. The method includes determining the parameters v_o, K_c, n, and ψ_r for the component, where v_o and n are empirically determined parameters, K_c is a critical stress intensity factor, ψ_r is a geometry factor for the material in the form of the component, determining a relationship of between platform operational parameters to the generation of stress at the surface of interest of the component, determining an initial crack size of a crack within the component at installation, tracking operational parameters of the platform throughout a course of usage of the component, calculating the corresponding stress at the crack location due to the tracked operational parameters, and calculating a numerical solution that illustrates a crack growth rate velocity and tracks a size of the crack over time.

The invention discloses an explosive grain thermal explosion critical pressure measurement apparatus, for solving the problem of high-temperature pressure measurement of explosive grains under a thermal stimulus effect and providing a means for critical pressure measurement when the explosive grains explore under the thermal stimulus effect. The apparatus is mainly composed of a simulated cook-off bomb, a guide tube, an air tap, an adapter, a nut, a pressure sensor and sealing rings. The measurement apparatus measures the thermal explosion critical pressure of the explosive grains through the general pressure sensor by use of a guide tube gradient cooling method and can be applied to research on safety of the explosive grains under the thermal stimulus effect.

The invention relates to a method for measuring the primary particle combination strength in an aggregate body in superfine or nanometer tungsten carbide powder. The steps are as follows: (1) on a universal dynamic tester, the superfine or nanometer tungsten carbide powder is added into a single-way or double-way continuous steel or hard alloy compressed mould; (2) according to pressures and displacements during compression process automatically recorded by a computer, the relation curve of a green density and a pressure is drawn, so that a critical pressure presented at a turning point is determined; (3) according to the relative density of the aggregate body and the like, the porosity degree between the aggregate bodies are calculated; (4) the primary particle combination strength of the tungsten carbide or the aggregate body strength of the tungsten carbide are calculated according to the critical pressure. In the method of the invention, general dynamic test equipment is used, and the operation is simple and convenient.

A NC system for a superconducting material insulation covered device comprises a numerical control device, a servo system and a measurement feedback system, wherein, the numerical control device receives information of requirement for superconducting material insulation covered, compiles and sends the information to the CPU of the numerical control device for memorizing and processing, the instructions of location and speed are sent to the servo system through the output device. The servo system, after power amplification and filtering plastic processing, converts the instructions from the numerical control device into the linear displacement and the angular displacement campaign of executive institutions. The measurement feedback system detects the current operation value of an AC servo motor and feedbacks to the numerical control device; wherein, the numerical control device compares the prior operation value with value of orders, and outputs the order that meets the requirement of the setting value to the servo system. The invention can realize superconducting material with lower irreversible strain (for example, the Bi-2223 high-temperature superconducting material with the critical stress of 230 MPa, MgB on the critical stress of 465 MPa2 superconducting material) to safely and accurately cover an insulation material with lower mechanical strength.

The invention relates to a method and device for monitoring fault tectonic stress. The method for monitoring fault tectonic stress comprises following steps: stress sensor installation, fault pre-fabrication, load application, critical stress of fault instability determination, theoretical value and experimental value comparison and analysis, and precursory information of fault instability acquisition; the device for monitoring fault stress comprises a fault analogue simulation test platform and a fault stress sensor. According to the device, by use of the stress sensor vertically installed on a fault surface, the normal stress and shearing stress of the fault surface are monitored; through the establishment of a fault dynamic module, the functional relations between the normal stress and shearing stress of the fault surface and horizontal load and vertical load are calculated; the errors between experimental values and theoretical values are analyzed; the critical stress value of fault instability is determined; the device and method provide theoretical basis and experimental data support for researching dynamic disasters such as rock burst and pressure bump caused by fault slip instability in study fields of geotechnical engineering and mining engineering, and provide pre-cursor information for predicting and preventing dynamic disasters.