77 results about "High strain rate" patented technology

The invention discloses a method for evaluating damage evolution of an underground structure under the action of a sudden explosion load, and relates to the technical field of civil engineering and engineering disaster prevention, and the method is characterized by comprising the following steps: S1, simulating the underground structure based on an explosion load, a geometric boundary and material parameters, and constructing a unified constitutive model; and S2, introducing a pressure-related strength criterion of a Dwark-Prasugrel criterion into the unified constitutive model so as to describe the influence of confining pressure on the shear strength. The technical problem to be solved by the invention is to provide the method for evaluating the damage evolution of the underground structure under the action of the burst explosion load, so that the key pain points such as pressure correlation, high strain rate effect, material random discreteness, damage softening energy consistency and the like are difficult to consider at the same time in the existing analysis method. A set of damage evolution evaluation method and implementation system which can be implemented from the material level to the structure level is established, and quantitative prediction and engineering grading judgment of the whole process of crack initiation, expansion to instability failure of the underground structure are supported.

The application belongs to the field of laser advanced manufacturing technology, and particularly relates to a method for connecting flat holes by pulse laser impact, a device thereof and application. The method for connecting flat holes by pulse laser impact comprises the following steps: placing bottom die, lower layer plate with sandglass-shaped through hole, upper layer plate, absorbing layer and constraint layer in sequence from bottom to top; clamping and fixing each layer by using a workpiece clamping system; placing the sandglass-shaped through hole region at the center of the pulse laser spot; under the pressure of the pulse laser impact wave, the upper layer plate is plastically deformed at high strain rate and impacts the upper inclined surface of the sandglass-shaped through hole of the lower layer plate, so that high-speed shear deformation occurs, thereby generating a metallurgical welding effect; with the continuous deformation of the upper layer plate, when the upper layer plate flows into the cavity of the sandglass-shaped through hole, an interlocking structure with small upper part and large bottom part is formed between the upper layer plate and the lower inclined surface of the sandglass-shaped through hole of the lower layer plate, thereby generating a mechanical riveting effect; the method provided by the application is used for welding and riveting of thicker or larger-thickness-difference plates.

The invention provides a method for measuring the dynamic hardness of a material based on bullet impact indentation. The method comprises the following steps: carrying out decontamination and polishing treatment on the surface of a target material; measuring the elastic modulus of the to-be-measured area; the hard spherical projectile is launched to impact the to-be-measured area to form an impact pit, and the springback speed of the projectile is measured in situ; measuring geometric parameters of the impact pit; establishing a contact force model of the elastic unloading section impacted by the projectile; and with the springback speed and the geometric parameters of the pit as input, obtaining the maximum loading force through a contact force model, and finally calculating the dynamic hardness. The dynamic Myer hardness is calculated by measuring the bullet rebound speed and pit parameters through the bullet impact indentation test without depending on real-time data acquisition of a high-frequency force / displacement sensor, so that the problem of strain rate upper limit caused by hardware limitation in the traditional technology is solved, and the blank of dynamic Myer hardness measurement under the high strain rate is filled up.

The invention relates to the field of urban rail transit engineering and structural dynamics, and provides an interlayer and strain rate coupled subway tunnel lining dynamic mechanical property evaluation method and system, and the method comprises the following steps: 1, preparing an interlayer-containing cement-based cylindrical sample; step 2, applying strain rate loading, and collecting original data; step 3, reconstructing stress-strain response, and performing criterion of stress balance and constant strain rate; 4, acquiring the energy absorption rate, the dynamic compressive strength and the yield inflection point strain, and recording the failure form type; 5, establishing a statistical damage model and inverting model parameters; step 6, extracting an initial damage coefficient and a damage rate, and establishing an empirical regression formula; and step 7, constructing an evaluation index set, performing grading evaluation, and outputting material optimization and process suggestions. According to the scheme, the design, checking calculation and rapid evaluation capabilities of the subway tunnel lining under high strain rate working conditions such as impact or explosion are remarkably improved.

The invention discloses a deep-sea high-pressure multi-strain-rate load test device and an operation method, and relates to the technical field of deep-sea load tests.The deep-sea high-pressure multi-strain-rate load test device comprises a base, a containing structure used for containing a test piece is arranged on the base, and a low-strain-rate load loading device used for stretching the test piece is arranged on the base; a dynamic impact structure for performing high strain rate impact on a test piece is arranged on the base, a pressurizing device is arranged below the base, the pressurizing device is used for injecting water into the accommodating structure and pressurizing the accommodating structure, and the pressurizing device can inject water into the accommodating structure, so that the water pressure in the accommodating structure is increased, and the water pressure in the accommodating structure is increased to a deep sea high-pressure environment; the low-strain-rate load loading device can enable the test piece to be stretched in various low-strain-rate states, and the dynamic impact structure is matched to spread high-strain-rate impact to the test piece, so that the test piece can be subjected to a combined test in a deep sea environment.

The invention provides a coal body strain synchronous in-situ monitoring device and method based on true triaxial impact, and relates to the field of coal body dynamic testing and structural damage monitoring. Comprising a sample bearing module, an impact loading module, an internal fiber bragg grating dynamic strain monitoring module, a surface strain gauge monitoring module, a synchronous data acquisition module, a microscopic crack detection module and a macroscopic failure analysis module, the impact loading module is used for applying a transient impact load with a set impact speed to the gas-solid coupling coal sample, and the internal fiber bragg grating dynamic strain monitoring module is embedded with at least one fiber bragg grating sensing grating point along three mutually orthogonal directions of the gas-solid coupling coal sample respectively. The damage evolution mechanism of the gas-solid coupling coal body under the high strain rate condition is disclosed, and a means is provided for risk analysis of the rock burst-coal and gas outburst hybrid power disaster.

This invention discloses a load testing device and method for high strain rate tensile testing. The device includes an elastic rod (1), strain gauges (2), a tensile testing machine (3), a clamp connector (4), and a data acquisition unit (5). One end of the elastic rod is fixed to the lower crossbeam (31) of the tensile testing machine, and one end of the specimen (6) is connected to the other end of the elastic rod through the clamp connector. The other end of the specimen is fixed to the upper crossbeam (32) of the tensile testing machine. Several strain gauges are spaced apart on the elastic rod, and the output ends of the strain gauges are connected to the data acquisition unit. Each strain gauge independently transmits its stress signal to the data acquisition unit. This invention can obtain ideal and reliable dynamic mechanical property data by decomposing the transmission and superposition of stress waves during material tensile testing at high strain rates, reducing the oscillation effect of load signals, obtaining the true stress loaded on the sample, and improving the accuracy of test results.

The utility model discloses Hopkinson bar test equipment based on a rubber band transmitting device. The Hopkinson bar test equipment comprises a base, a platform, a clamp, a transmitting device, an incident bar, a transmission bar, an absorption bar and a damper, a plurality of bases are arranged at the bottom of the platform, and a launching device is arranged at the end of the upper side; the launching device comprises a shell, a bullet, a positioning pile and a rubber band; the bottom of the shell is fixed on the platform, a track is arranged in the shell, and stretching tracks are arranged on two sides; the bullet is positioned in the track and can translate along the track; handles are arranged on two sides of the bullet, are positioned in the stretching track and can translate along the stretching track; the positioning piles are fixed on the platform on the two sides of the launching device; the two ends of the rubber band are arranged on the two positioning piles in a sleeving mode respectively and penetrate through the track and the stretching track. According to the utility model, the mechanical property test cost of the material under the condition of high strain rate can be reduced, the stability and repeatability of the test are improved, and the test equipment is more compact and is convenient to transport, install and use.

The application relates to a kind of high strain rate under fiber concrete material dynamic axial tensile performance test method, comprising: setting Hopkinson tensile rod device, using the verified Hopkinson tensile rod device to pulse wave is applied to test piece, and the deformation of resistance strain gauge is collected;The deformation is converted into voltage signal, for calculating the strain of resistance strain gauge and the average compressive stress of test piece;Based on strain and average compressive stress, determine the dynamic tensile stress-strain relationship of test piece, according to the dynamic tensile stress-strain relationship of test piece, the dynamic tensile stress time history and dynamic axial strain time history are point by point corresponding pairing on time axis, and the dynamic tensile stress-strain curve of test piece under high strain rate is obtained.The application can make the performance test of fiber concrete and other materials under high strain rate more easily realized, provide the basis for the dynamic performance characterization of material, help the application and popularization of high-performance materials under extreme working conditions such as explosion impact.

The invention discloses a treatment process for improving the three-point bending fatigue limit of a thin-wall titanium alloy test piece, and relates to the field of metal material processing for improving the anti-fatigue performance, and the treatment process comprises the following steps: pretreating a TC4 titanium alloy sheet to obtain a test piece; processing the test piece by using ultrafast laser shock peening; setting a load, and respectively carrying out three-point fatigue tests on the test piece before and after strengthening; and calculating the bending fatigue limit of the test piece before and after strengthening, and carrying out strengthening mechanism analysis and comparison. According to the method, a thin-wall TC4 titanium alloy three-point bending test piece can be subjected to impact strengthening by optimizing the combination of femtosecond laser energy and impact times, a gradient structure and residual compressive stress are introduced to a surface layer by utilizing high-strain-rate plastic deformation induced by ultrafast laser, fatigue crack initiation is inhibited, meanwhile, expansion of a heat affected zone and deformation of the test piece are avoided, and the impact strength of the thin-wall TC4 titanium alloy three-point bending test piece is improved. Therefore, the bending fatigue performance is improved.

The application discloses a high-speed current-carrying strain experiment device, which comprises a base, a protection tube and an electric wire. The protection tube is horizontally arranged on the top of the base and fixedly installed at both ends of the base. The electric wire is arranged in the protection tube and extends along the axis of the protection tube. The electric wire is insulated from the protection tube and the base. The arc part of a test piece is used for sleeving the outer circumferential surface of the axial middle part of the protection tube. Insulating pads are arranged between two long plates. The two long plates are provided with conductive blocks, insulating blocks and jacks in sequence on the side away from the insulating pads. The jacks are screw-connected with the base and used for pressing the long plates on the insulating pads. The bottom ends of the two conductive blocks are arranged outside the base and form wiring ends for connecting a power supply, so that the test piece can carry current when being impacted by a shock wave. The experiment device solves the problems that the upper limit of the strain rate that can be applied to the test piece by the current experiment device is low and the material cannot carry current under high strain rate.

The application discloses a cylindrical RM instability strength measurement experiment system and method, and belongs to the technical field of fluid mechanics. The cylindrical RM instability disturbance growth material strength measurement experiment system comprises an experiment device and a measurement system; the experiment device comprises a driving sleeve and a preset disturbance target, and the preset disturbance target is coaxially arranged in the driving sleeve. The cylindrical RM instability strength measurement experiment system and method provided by the application can precisely measure the disturbance growth speed, amplitude, interface morphology and other parameters when high-precision impact loading disturbance targets and filling media in the disturbance targets in the driving sleeve cylindrical implosion are carried out, the strength of the material is calculated by using fluid dynamics numerical simulation of different strength constitutive models or parameters and taking the experimentally measured disturbance data as convergence basis, and the established cylindrical RM instability disturbance growth material strength measurement experiment system and method have important significance for the strength research of materials under conditions of high pressure, high strain rate, large strain and the like.

The application discloses a treatment process for improving the three-point bending fatigue limit of a thin-walled titanium alloy test piece, relates to the field of improving fatigue resistance of metal material processing, and comprises the following steps: pretreating a TC4 titanium alloy sheet to obtain a test piece; performing laser shock peening on the test piece by using ultrafast laser; setting a load; performing three-point bending fatigue experiments on the test piece before and after the peening; calculating the bending fatigue limits of the test piece before and after the peening; and performing strengthening mechanism analysis and comparison. The process can perform peening on the three-point bending test piece of the thin-walled TC4 titanium alloy by optimizing the combination of femtosecond laser energy and peening times, introduce gradient structure and residual compressive stress in the surface layer by using the high strain rate plastic deformation induced by the ultrafast laser, inhibit the initiation of the fatigue cracks, avoid the expansion of the heat affected zone and the deformation of the test piece, and thus improve the bending fatigue performance of the test piece.

This application discloses a method, apparatus, and electronic device for predicting fracture strain in metallic materials. The method includes first determining the stress triaxiality and Lode angle of the metallic material under test based on the stress state at the test point; then constructing a stress fracture prediction model based on the correlation function between fracture strain and stress triaxiality and Lode angle; next, coupling this model with the Johnson-Cook fracture model to form a thermo-mechanical-strain rate coupled fracture prediction model; and finally, determining the target fracture strain based on this model. This approach not only overcomes the limitation of insufficient consideration of the Lode angle in existing fracture models but also achieves efficient model construction with very few parameters to be calibrated. The model is applicable to fracture prediction under complex stress, high temperature, and high strain rate multi-field coupling, significantly improving prediction accuracy while enhancing the model's engineering applicability and robustness, providing a reliable fracture assessment tool for cutting-edge engineering scenarios such as advanced manufacturing and extreme environment equipment design.

The invention relates to a method for testing a fracture track of a metal material under a multi-field coupling effect. The method comprises the steps of sample preparation, high-temperature speckle preparation, sample loading, strain field acquisition, fracture morphology observation, data processing and fracture model establishment. By constructing a new fracture test method under the action of multi-field coupling, the problems of lack of physical field coupling factors, non-uniform test systems, limitation of fracture models and the like at present are effectively solved. A coupling loading test system capable of synchronously applying complex stress, high strain rate and transient high temperature is established, and real simulation of the multi-physical field coupling effect under the actual disaster working condition is achieved; a metal material fracture test system with universality and comparability is formed; key data support is provided for building a fracture model comprehensively considering the stress three-dimensional degree, the strain rate effect and temperature softening, the accuracy and reliability of fracture track prediction of the steel structure under the extreme disaster are remarkably improved, and an important basis is provided for engineering disaster resistance design and safety evaluation.

The present application belongs to the technical field of energetic materials and active fragment materials, and more particularly relates to an energetic composite connector based on hard alloy and tungsten-containing amorphous alloy, a preparation method and application thereof. The penetration ability and damage effect of energetic materials are fully considered, and the present application selects hard alloy as the penetration part and tungsten-containing amorphous alloy composite material as the fragment part. The hard alloy has high hardness and high fracture toughness, and can effectively penetrate the shell; the amorphous alloy composite material has high strength, high energy density and good plastic deformation capacity, can deflagrate at a high strain rate and release a large amount of energy, and produce a large amount of fragments to cause damage to the target. The integration of the preparation and connection of the hard alloy penetration part and the amorphous alloy composite material fragment part can be realized by discharge plasma sintering, thereby solving the technical problems that the inert energetic materials in the prior art cause the personnel and weapon equipment to suffer losses due to "hitting but not destroying" the target.

This invention provides a metal wire forming device for manufacturing dish racks, relating to the field of metal wire drawing technology. It includes a frame, a guiding mechanism, a lubrication mechanism, a drum drawing mechanism, wire, and a coating mechanism. The guiding mechanism includes multiple fixed rollers mounted on one side of the top of the frame via rotating rods and movable rotating rollers on the other side. The fixed and rotating rollers are staggered to form a wire channel, through which the wire passes to the right and enters the coating mechanism. This solution ultimately achieves lubrication of the wire and the inner wall of the drawing die using lubricating oil during the wire drawing operation. The lubricating oil is liquid; after covering the wire surface, it forms a continuous and stable lubricating film, effectively isolating the wire from direct contact with the drawing die, reducing the coefficient of friction. Furthermore, the lubricating oil can fill the microscopic gaps between the drawing die and the material in real time as the wire deforms, adapting to high strain rate drawing processes.

The invention belongs to the technical field of material science foundation, and discloses a single twinborn system dominated twinborn transmission probability prediction method. According to the method, aiming at the condition that a single twin system is started preferentially under specific texture and force field conditions, the uniqueness of the twin system is limited and activated, and a three-dimensional matrix expression system of specific twin system spatial orientation is constructed. And based on a judgment rule that twin crystal faces and twin directions of the two crystal grains are parallel, calculating the minimum orientation difference capable of realizing parallel twin systems among the crystal grains. According to the method, the twinborn orientation difference is provided as a key physical quantity for quantifying the twinborn transmission capability, and the regulation and control mechanism of single twinborn system activation on local stress redistribution is disclosed by eliminating the interference of a non-activated twinborn system. The method is applicable to a twin-dominated deformation system at low temperature or high strain rate, and provides a micromechanical basis for optimizing strain coordination at the grain boundary.

The present application relates to the field of urban rail transit engineering and structural dynamics, and provides a sandwich and strain rate coupled subway tunnel lining dynamic mechanical property evaluation method and system, the method comprising the following steps: step 1, preparing a cement-based cylindrical sample containing a sandwich; step 2, applying a strain rate loading and collecting original data; step 3, reconstructing the stress-strain response and performing stress balance and constant strain rate criteria; step 4, obtaining energy absorption rate, dynamic compressive strength and yield inflection point strain, and recording the failure mode type; step 5, establishing a statistical damage model and inverting the model parameters; step 6, extracting the initial damage coefficient and damage rate, and establishing an empirical regression formula; step 7, constructing an evaluation index set, performing a grading evaluation, and outputting material optimization and process recommendations. The present scheme significantly improves the design, checking and rapid evaluation capability of subway tunnel lining under high strain rate conditions such as impact or explosion.

The invention discloses a preparation method and application of a hierarchical zinc-based negative electrode material, and belongs to the technical field of preparation of electrochemical materials. The zinc-based negative electrode material is prepared by an accumulative roll-bonding method, one or more dissimilar metals and a zinc plate are subjected to hot-pressing rolling, an interface alloy layer is formed on a contact surface, and the nano-level zinc-based negative electrode material is obtained by repeated roll-bonding. Wherein crystal grains are obviously refined through hot pressing, uniform regulation and control of a crystal structure are achieved through high-strain-rate rolling, orientation heterogeneity is eliminated, and the electroplating stripping performance in charge-discharge circulation is effectively improved. The synergistic effect of the nanolayer alloy structure and the unipolar mode texture feature fully releases the electrochemical advantages of high ion diffusion rate, excellent conductivity, low polarization and the like. The technology has the characteristics of simple process, low cost, easiness in large-scale production and the like. The prepared zinc-based negative electrode material successfully solves the key problems of dendritic crystal growth, side reaction and the like caused by non-uniform deposition of zinc ions, and the cycling stability of the electrode is remarkably improved.

The application relates to the field of tungsten alloy preparation, in particular to a method for preparing a tungsten alloy with a dual-phase nanotwin structure through ultrahigh strain rate deformation. The method is characterized in that: a proper thickness of a constraint layer is applied to the front and back surfaces of a tungsten alloy sample to constrain laser shock waves, control the reflection and refraction paths and impact force of the laser shock waves; then laser impact treatment is carried out with a laser with a beam diameter of 1-5 mm, a pulse width of 1-10 ns, a wavelength of 300-800 nm, a laser energy of 100-300 J and a repetition frequency of 0.1-10 Hz; and the tungsten alloy sheet is prepared from the following components in mass percent: Ni 3-8%; Fe 1.2-3.5%; and the balance being W and inevitable impurities. In the dual-phase nanotwin structure tungsten alloy prepared by the method, the hardness of tungsten particles is increased by 60-80%, the hardness of the gamma-(Ni, Fe) binder phase is increased by 10-20%, and the ultimate tensile strength is increased by 5-10 times, and the preparation process is simple, efficient, low in cost and pollution-free.

The present application relates to a kind of high-strength steel non-isothermal liquid nitrogen cooling deformation performance test method and testing device.High-strength steel non-isothermal liquid nitrogen cooling deformation performance test method, it is cooled to sample using liquid nitrogen jet, follow-up cooling, and carry out non-isothermal tensile test.The performance test method includes the following steps: S1, preliminary preparation;S2, high temperature heating;S3, non-isothermal stretching.The present application can obtain high-temperature hot forming limit under the condition of liquid nitrogen rapid cooling and high strain rate, can accurately capture the yield strength mutation and forming limit inflection point of material under the condition of rapid cooling, realize accurate prediction of high-temperature non-isothermal forming of sheet metal, while two sub-experiments are verified, by from microstructure to explore the influence of liquid nitrogen rapid cooling and high strain, strain rate on the change of organization before hot stamping quenching and pressure holding process of high-temperature sheet, finally explore the influence law of liquid nitrogen injection process on sheet forming quality.

The invention provides a material dynamic stress-strain relation measuring method and system for bullet impact indentation, and the method comprises the steps: pre-processing a target material, and executing N times of hard spherical bullet impact target material tests; taking the indentation radius and residual depth of the pit as test data as input, and calculating and obtaining corresponding representative plastic strain according to the geometrical relationship that the spherical indenter of the hard spherical projectile generates the indentation on the target material; the bullet impact speed, the rebound speed and the pit geometric parameters which serve as test data serve as input, and representative stress is obtained through calculation; and performing data fitting on the representative plastic strain and the representative stress to obtain a dynamic stress-strain relationship of the target material. The technical bottleneck of direct measurement of the stress-strain relation under the ultrahigh strain rate is broken through, a representative stress-strain method in a quasi-static scene is innovatively expanded to the dynamic field, dependence on a preset constitutive model is not needed, and the dynamic stress-strain relation of the material is directly derived through test data.

The invention provides a device and a method for analyzing stress and strain of a material at an ultrahigh strain rate, and relates to the technical field of material analysis at the ultrahigh strain rate. The material stress-strain analysis equipment under the ultrahigh strain rate comprises a transmitting tube, an impact block, a fixed bracket, a bearing base and a to-be-tested sample, an impact channel is formed in the fixing support, the bearing base is fixedly arranged at the impact channel of the fixing support, and a speed detector used for monitoring the flight speed of the impact block is arranged on the side, away from the bearing base, of the fixing support. The impact block is arranged in the launching tube, the impact block can penetrate through the impact channel to impact one side of the bearing base, and a plurality of samples to be tested are arranged on the other side of the bearing base; and a DISAR probe is arranged on the to-be-tested sample. The technical effect that more material dynamic parameters can be obtained through a single test is achieved.

A foldable electronic device may include a flexible display panel and a display cover layer that fold along a bend axis. The display cover layer may be formed from one or more glass layers. For example, a thin glass layer may form an outer surface of the display and may extend across the bend axis. A non-Newtonian material may be interposed between the glass layer and the display panel to help protect the display panel from damage when the glass layer is impacted by an external object or a drop event. The non-Newtonian layer may have a low modulus of elasticity at low strain rates (e.g., during folding and unfolding) and a high modulus of elasticity at high strain rates (e.g., when an object impacts the display) to prevent the cover glass from puncturing the underlying display layers.

The invention relates to the technical field of rock mass engineering simulation experiments, and provides a true three-dimensional similar simulation device and method capable of applying controllable temperature and impact load, temperature can be applied to the similar simulation device through a temperature module, the temperature range can be automatically set, and the spatial distribution condition of a temperature field in a box body of the simulation device can be controlled; the high-energy pulse dynamic load module can apply a high-strain-rate dynamic load to the similar simulation device, can automatically set the energy range of the dynamic load, and can control the occurrence frequency and the position in the similar simulation device; the temperature module, the high-energy pulse dynamic load module and the true three-dimensional mechanical static load module can act on the coal rock similar simulation device at the same time, so that the coal rock stress-strain condition under the environment of complex temperature, mine vibration load and three-dimensional static load is simulated.

The invention belongs to the field of hydraulic forming devices, and discloses a hydraulic-pneumatic mixed forming device which comprises a female die, a pressure bin, a piston and an electromagnetic driving assembly. The piston is inserted into the pressure bin in an axially movable mode. A to-be-machined part is clamped and fixed between the female die and the pressure bin in the forming process, a forming cavity is defined by the female die and the to-be-machined part, the pressure bin, the piston and the to-be-machined part are matched to form a pressure cavity, and the pressure cavity is filled with a forming medium. The electromagnetic driving assembly generates pulse driving force to drive the piston to move at a high speed in the pressure bin, transient high pressure is applied to the forming liquid in the pressure cavity, the forming liquid rises to make contact with a to-be-machined part to be vaporized and expanded to achieve secondary pressurization, and the plastic deformation capacity of a material is improved through the high-strain-rate effect and the high-temperature softening effect of metal. According to the device, a high-speed dynamic loading mode is achieved through the electromagnetic driving assembly and the phase change of the forming liquid, the strain localization phenomenon in the material forming process is effectively restrained, and the forming limit of low-plasticity materials is broken through.

A method for measuring high-strain-rate dynamic hardness of a material surface based on AFM knocking belongs to the technical field of solid mechanical property testing and high-speed machining, and comprises the following steps: S1, enabling a material to generate plastic deformation at a high strain rate by an AFM probe; s2, accurately measuring an applied load and a material deformation amount; and S3, performing post-processing analysis to calculate the dynamic hardness of the material. Compared with an existing method for testing the mechanical property of the material under the high strain rate, the method has the advantages that the strain rate of plastic deformation is increased on the basis of ensuring nanoscale deformation of the material, and the dynamic mechanical property response condition of the surface of the material is accurately measured. Therefore, the test method provided by the invention promotes the development of the high-strain-rate mechanical property of the surface of the test material under the nanoscale.

The present application belongs to the field of jointed rock mass dynamics and engineering technology, and particularly relates to an experimental method for studying dynamic mechanical properties of jointed rock mass under multi-stress state. The method is carried out by using a split Hopkinson pressure bar system combined with a loading system, and a coordinate system is established with the length direction of the split Hopkinson pressure bar as the X axis, the width direction of the split Hopkinson pressure bar as the Y axis, and the height direction of the split Hopkinson pressure bar as the Z axis. The loading system can load the loading chamber from the X axis, Y axis and Z axis directions respectively. The method specifically comprises the following steps: 1. preparing a cubic full-penetrating cross jointed rock mass sample; 2. selecting a corresponding test mode according to the site working condition; 3. biaxial test; 4. triaxial test; and 5. data analysis. The present application simulates the working conditions of the excavated area and the unexcavated area, thereby studying the dynamic mechanical properties of the rock mass under high strain rate and triaxial stress, and thus providing a basis for the design of underground engineering such as tunnels.

The invention discloses a PBS / glass fiber filter paper composite diaphragm with excellent impact resistance and a preparation method thereof, and the method comprises the following steps: uniformly dispensing a polyborosiloxane-ethanol dispersion liquid on the surface of a glass fiber filter paper diaphragm, and drying to obtain the PBS / GF / D composite diaphragm. The prepared PBS / GF / D composite diaphragm shows unique and excellent impact resistance while retaining the inherent porous morphology characteristic of the GF / D substrate. When the composite diaphragm is subjected to high-strain-rate impact load, the PBS component in the composite diaphragm is subjected to rapid structural response, the viscosity and modulus are instantly improved, the composite diaphragm can be converted into a hard solid state from a flexible state within an extremely short time, impact energy is effectively absorbed, impact force is dispersed, and therefore excellent impact resistance is achieved.