17 results about "Split-Hopkinson pressure bar" patented technology

According to the repeated impact test device for multiple impact tests and the loading waveform control method, a special-shaped impact rod is adopted to replace a traditional cylindrical impact rod, the end, making contact with the impact rod, of an incident rod is designed into a cone, and the diameter of the end face of the incident rod with the special-shaped end is consistent with that of the end face of the special-shaped impact rod; aiming at the requirements of the tested material and structure on the loading waveform, the waveform with different forms and different rising edges can be realized by designing the cone angle and the shape of a cone or designing a complex curve profile, a multi-segment cone and the like, and the accurate control of the loading waveform is realized; according to the automatic multi-impact test device based on the split Hopkinson pressure bar, the defect that disposable accessories need to be replaced in a traditional waveform shaping control method can be overcome, it is guaranteed that the waveform meets the test requirement during impact loading every time, the amplitude is constant, the waveform is consistent, stable and reliable, the test precision and efficiency are improved, and the test cost is reduced. The device can be applied to automatic multiple impact tests based on the split Hopkinson pressure bar.

The invention discloses a rock dynamic pressure-torsion experimental device and method based on a Hopkinson pressure bar, and belongs to the technical field of rock mechanics dynamic testing. The device mainly comprises a split Hopkinson pressure bar system and a spiral conversion mechanism, wherein the spiral conversion mechanism consists of a spiral (4) and a screw sleeve (5) which are meshed with each other; the screw (4) is fixedly connected with the incident rod (2), the screw sleeve (5) is fixedly connected with one end of a cylindrical rock sample (6), and the other end of the sample is fixedly connected with the transmission rod (7). The core is that the lead angle of the screw pair is greater than the equivalent friction angle of the screw pair under the impact load, so that the screw pair is ensured to be non-self-locked; and the sample (6) is of a hollow thin-wall cylinder structure. The method comprises the following steps: driving the spiral (4) to advance by utilizing axial stress waves generated by the split Hopkinson pressure bar, and driving the hollow sample to rotate by the screw sleeve in a forced constraint state, so as to synchronously apply dynamic axial compression and torsional shear combined load.

The invention relates to the field of computational mechanics, in particular to a method for calibrating bonding strength parameters during simulation of a brittle solid material, and failure strength data of the brittle solid material is obtained at a preset dynamic strain rate through a split Hopkinson pressure bar (SHPB) iterative test. The failure strength under a certain strain rate is used as an initial bonding strength parameter, and then the bonding strength parameter is updated according to the failure strength of the previous time and the current time in each iteration. And then, constructing a target function, performing parameter optimization by utilizing a simulated annealing algorithm, and judging whether updated bonding strength parameters are accepted or not by adjusting the temperature and the search step size and calculating the increment of the target function. If accepting, continuing iteration until the temperature is lower than the set value, and finally reserving the bonding strength parameter as the calibration value. Based on the calibration method provided by the invention, the real bonding strength of the material can be effectively approached, and the precision and reliability of parameter calibration are improved.

The present invention discloses a method for automatic positioning and fragment screening of rocks applicable to a Hopkinson bar, comprising the following steps: S1: Using a specimen positioning device to accurately position and impact-crush the specimen; the specimen positioning device includes a hollow housing, and mounting through-holes matching the incident bar and the transmission bar are respectively formed on the front and rear sides of the housing; an electromagnetic impact device and an arm for clamping the specimen are provided inside the housing, the electromagnetic impact device is located on the left side wall or the rear side wall of the housing, the arm is rotatably arranged between the front and rear side walls of the housing, and the end of the arm close to the specimen is located below the electromagnetic impact device; S2: Automatically collecting the fragments after crushing the specimen into an automatic screening device for screening, and the automatic screening device is located below the specimen positioning device. The present invention can not only improve the accuracy and scientificity of the test of the dynamic mechanical properties of the specimen under the action of impact load, but also avoid the potential threat caused by the high-speed splashing of the fragments.

The embodiment of the invention provides a tunnel blasting unit consumption design method considering rock critical energy storage. The method is applied to the technical field of tunnel construction and data processing and comprises the steps that a rock test sample is collected, the energy storage limit of rock in different stress states is analyzed through a split Hopkinson pressure bar test, and a stress-strain empirical model of the rock test sample is constructed; on the basis of the stress-strain empirical model of the rock test sample, a blasting vibration method is adopted to calculate the fracture range of the explosive in the rock under the action of stress waves in the rock blasting process, and the rock crack length is obtained; explosive performance parameters are obtained, an explosive unit consumption equivalent design model is established according to the crack length and the explosive performance parameters, and explosive design unit consumption of tunnel blasting in different states is obtained through calculation. In this way, the method focuses on the significant difference of the energy storage limits of the rocks in different stress states, tunnel blasting explosive unit consumption design is guided based on the rock energy storage limits, and the method has important significance on cost reduction and efficiency improvement.

The application is a kind of alignment and support device for split Hopkinson pressure bar and sample, which comprises a main frame for containing sample, the side of the main frame is hollowed out, respectively used for horizontal abutting of incident bar and transmission bar from both sides of the hollowed-out part, and a plurality of frame connecting columns are embedded in the bottom of the main frame for supporting the lower part of the sample. The support device effectively improves the misalignment of the pressure bar and sample caused by the weight of the sample, greatly reduces the required steps of the test, and helps the auxiliary support of the sample with heavy weight.

The utility model discloses a pore water pressure testing device for a one-dimensional SHPB (split Hopkinson pressure bar) test of a discrete material. The pore water pressure testing device comprises an undrained boundary device and a pore water pressure gauge, a discrete material placing area is arranged in the middle of the undrained boundary device, the two ends of the undrained boundary device are oppositely connected with a shooting rod and a reflecting rod respectively, a radial threaded hole is formed in the side wall of the middle of the corresponding placing area, and a stainless steel filter screen is arranged at the bottom of the threaded hole; the pore water pressure gauge comprises a sensor shell, a conversion cylinder, a sensor pressure head and a cable, the cable is located at one end of the sensor shell and integrally connected with the sensor shell, the sensor pressure head is arranged at the other end of the sensor shell, the interior of the sensor pressure head is of an internal thread structure, the outer wall of the conversion cylinder is of an internal thread structure, and one end of the conversion cylinder is connected with the sensor pressure head in a matched mode. And the other end is matched and connected with the threaded hole to press the stainless steel filter screen on the discrete material. The one-dimensional impact loading device can be used for researching the mechanical property of a discrete material in a saturated state in a one-dimensional impact loading process.

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 relates to the technical field of rock mechanics testing, and discloses a dynamic and static combined loading rock critical energy consumption density testing method. The method comprises the following steps: preparing and screening a rock test piece, fixing the rock test piece between an incident bar and a transmission bar of the split Hopkinson pressure bar system, and ensuring that the incident bar and the transmission bar are coaxial; applying confining pressure and axial pressure to the test piece to enable the test piece to be in a preset three-dimensional static stress state; starting the system, setting initial impact air pressure to impact the test piece, and collecting a strain signal; determining a critical impact air pressure and a corresponding critical strain signal which enable the test piece to reach a set damage state; and crushing energy consumption is calculated based on the critical strain signal, and critical energy consumption density is obtained through conversion. The method fits the actual stress scene of the rock, improves the accuracy and reliability of the test, and can provide technical support for the design and construction of underground engineering.

The invention provides a low transmissivity-energy absorption curtain grouting material proportion design method, and relates to the technical field of underground engineering and blasting engineering. Determining the primary and secondary sequence of the influence of each factor on the rheological property; determining the primary and secondary sequence of the influence of each factor on the physical performance through an indoor test; adopting a split Hopkinson pressure bar test to obtain a primary-secondary sequence of the influence of each factor on the energy absorption performance; determining an optimal matching scheme according to the orthogonal test result, and verifying the rationality of the optimal matching scheme by combining the theoretical analysis of the transmission and reflection performance; and a blasting test is carried out, the actual damping effect of the grouting curtain adopting the optimal matching scheme is detected, and the damping rate of the grouting curtain is calculated. According to the technical scheme, the problems that in actual engineering, the proportion of grouting materials is difficult to determine, and the damping effect of the grouting curtain is difficult to quantify are solved, the blasting vibration peak value of the buried pipeline under the blasting vibration effect is effectively reduced, and a guarantee is provided for underground pipe network protection and blasting engineering safety construction.

The invention discloses a rock stress wave attenuation characteristic analysis method based on a split Hopkinson pressure bar device. Comprising the following steps: 1, preparing a test device; step 2, test design and execution; step 3, data acquisition; step 4, data analysis; 5, attenuation characteristic analysis; step 6, calibrating constitutive parameters; step 7, verifying the method; according to SHPB test data analysis of rock rod samples with different lengths and the same length, the attenuation characteristics of stress waves in rocks are obtained. Based on a Maxwell model and a standard linear solid (SLS) model, a quantitative mapping relation between time domain and frequency domain attenuation characteristics of rock stress waves is established, and a time-frequency determination method of constitutive parameters of the Maxwell model based on SHPB test data and a univariate step-by-step solving method of constitutive parameters of the standard linear solid (SLS) model are provided.

The invention relates to the technical field of geotechnical engineering, and discloses a rock mass three-dimensional visualization and disaster early warning method based on velocity structure tomography. The method comprises the following steps: acquiring mechanical signals and fracture data of a rock mass under different load effects by utilizing devices such as acoustic emission monitoring and a split Hopkinson pressure bar, inverting the internal speed structure change of the rock mass by adopting a delay double-difference tomography technology, constructing a three-dimensional visual model of a rock mass fracture partition, and finally determining the fracture partition of the rock mass in combination with a rock mass fracture mechanism and a spatio-temporal evolution law. And establishing a disaster early warning mechanism. According to the invention, the problem that the traditional monitoring technology cannot accurately capture the crack extension and dynamic fracture partition in the rock mass in real time is solved, reliable technical support can be provided for rock mass stability evaluation and disaster prevention and control in the scenes of mining, tunnel engineering and the like, and the engineering safety and production efficiency are improved.

The invention relates to the technical field of Hopkinson pressure bar experiments, in particular to a split Hopkinson pressure bar experiment system for low-temperature in-situ observation, which comprises a low-temperature box, refrigeration equipment, an incident bar and a transmission bar, strain gauges are arranged on the incident bar and the transmission bar, and the two strain gauges are electrically connected with a dynamic strain meter. The low-temperature box comprises a shell, an internal channel arranged in the shell and a secondary refrigerant chamber formed between the inner surface of the shell and the outer surface of the internal channel. The refrigerating equipment is used for cooling a secondary refrigerant, and the secondary refrigerant circularly flows between the secondary refrigerant chamber and the secondary refrigerant box through a pump and a pipeline; the internal channel comprises a longitudinal pipeline, transverse pipelines and a vertical pipeline, the two transverse pipelines are fixedly communicated with the left side and the right side of the longitudinal pipeline, and the incident bar and the transmission bar extend into the longitudinal pipeline through the two transverse pipelines respectively. According to the invention, a secondary refrigerant can be prevented from entering a microscopic hole of the test piece, experimental errors are reduced, and working efficiency is improved.

The invention discloses a human body protector effectiveness evaluation and design method considering a strain rate effect, and the method comprises the steps: carrying out a split Hopkinson pressure bar experiment on a candidate protection material, and obtaining the dynamic mechanical performance data of the candidate protection material under a simulated human body impact working condition and a high strain rate condition; establishing a strain rate related constitutive model of the material based on the experimental data; implanting the constitutive model parameters into a preset human body impact biomechanical finite element model to define material attributes of the protector component; running simulation calculation, and outputting a biomechanical evaluation index for evaluating the protection efficiency of the protector; and based on the evaluation indexes, performing quantitative evaluation and design optimization on the protection efficiency of density and / or thickness parameters of different materials and protectors. According to the method, the accuracy of efficiency evaluation and parameter design of the human body impact protection tool under the dynamic impact working condition can be improved, and a technical basis is provided for parameterization and material selection of the human body impact protection tool.

The application discloses a kind of establishment methods of multi-joint rock mass dynamic cumulative damage constitutive model under cyclic impact, comprising the following steps: S1, field rock sample collection and pretreatment, for the geological characteristics of open-pit mine multi-joint rock mass, collect the rock sample of different joint dip angle, joint development degree, process and maintain sample, prepare standard test piece that meets the requirement of split hopkinson pressure bar dynamic compression test;S2, carry out cyclic impact indoor test, using split hopkinson pressure bar system to different joint dip angle standard test piece cyclic impact load, determine the stress-strain relationship of test piece under different cyclic impact times, peak strength, failure mode, obtain the basic parameters of multi-joint rock mass dynamics.This model considers the influence of multiple factors, fits the engineering practice, has high prediction accuracy, the method is easy to popularize, can support mine blasting parameter optimization and slope protection, adapt to various open-pit mine working conditions.

The application discloses a rock stress wave attenuation characteristic analysis method based on a split Hopkinson pressure bar device. The method comprises the following steps: step one, test device preparation; step two, test design and execution; step three, data acquisition; step four, data analysis; step five, attenuation characteristic analysis; step six, constitutive parameter calibration; and step seven, method verification. According to the SHPB test data analysis of rock bar samples with different lengths and the same length, the attenuation characteristics of stress waves in rocks are obtained. Based on the Maxwell model and the standard linear solid (SLS) model, a quantitative mapping relationship between the time domain and the frequency domain of the rock stress wave attenuation characteristics is established, a time-frequency determination method of the Maxwell model constitutive parameters based on the SHPB test data is proposed, and a single-variable step-by-step solution method of the standard linear solid (SLS) model constitutive parameters is proposed.

The present application belongs to the technical field of building materials, and relates to a seawater coral reef sand concrete damage effect test method. The present application determines the reference compressive strength through a uniaxial compression test, determines the driving parameters for formal impact by using a split Hopkinson pressure bar combined with pre-impact closed-loop calibration; based on the stress balance criterion, the effective waveform is screened to calculate the dynamic stress peak value, and the fragment dimension of the test piece is extracted; after normalization, the three are fused to calculate the damage effect index. The method effectively solves the problems of dynamic load mismatch, waveform distortion interference and single index difficulty in quantifying the irregular characteristics of crushing, realizes multi-dimensional comprehensive quantification of static reference, dynamic response and crushing form, and improves the repeatability of impact test data and the objective comparability of damage evaluation of different proportioning materials.