39 results about "Three point flexural test" patented technology

The invention belongs to the technical field of impact fatigue performance detection, and particularly relates to a Hopkinson rod three-point bending sample-based constant-amplitude impact fatigue device, which comprises a dynamic indentation system, an energy absorption system, a strain measurement system and a pressure data acquisition system, and is characterized in that the dynamic indentation system comprises kinetic energy application equipment, an impact rod, an incident rod and a three-point bending test bed; the strain measurement system comprises a strain gauge and a dynamic strain acquisition instrument which are electrically connected, the pressure data acquisition system comprises a force transducer and a data acquisition instrument which are electrically connected, and the energy absorption system comprises a flange, a sleeve and a mass block. The device depends on the Hopkinson rod technology, the momentum well design is ingeniously fused, the problem of secondary loading is effectively avoided, constant-amplitude impact fatigue loading is achieved, key parameters such as the yield point, the elastic limit and the breaking strength of the material are accurately measured, and the reliability and safety of the material are comprehensively evaluated.

The invention belongs to the technical field of weld joint hot crack evaluation, and particularly relates to an efficient evaluation method for weld joint hot crack sensitivity based on machine vision. A welding hot crack is manufactured by carrying out a three-point bending test on the back of a welding seam in the later solidification period, the welding seam part is transversely covered and scanned by means of a laser rectangular surface light source, a high-resolution CCD is used for collecting a welding seam picture under laser irradiation in real time, and edge information of a crack and shadow combination is recognized through an image processing algorithm. And calculating the crack rate to evaluate the heat crack sensitivity of the weld. The technical problems that an existing hot crack evaluation method is tedious in procedure and low in detection efficiency are solved.

The invention discloses a method for determining interlayer tensile strength of a ceramic matrix composite based on a three-point bending test. The method comprises the following steps: acquiring the geometric dimension of an original sample and determining the carbon fiber trend of the original sample; treating and bonding the bonding surface of the original sample to obtain a to-be-tested sample; the geometric dimension of the three-point bending clamp is obtained, and the placement mode of the to-be-tested sample is determined; a standard three-point bending test is carried out, and the maximum loading force in the test process is obtained; and calculating the breaking strength of the to-be-tested sample by using a three-point bending stress formula. A to-be-tested sample is prepared by bonding a plurality of original samples, a standard three-point bending test is carried out by using the to-be-tested sample, and finally, the interlayer tensile strength of the original samples is calculated by using a three-point bending beam stress expression, so that the problems that a test sample is difficult to prepare and a test result is inaccurate in an existing standard test method are solved; the efficiency and the precision of measuring the interlayer tensile strength of the ceramic matrix composite material are improved.

The invention relates to the technical field of wind power bearing fatigue performance test, and discloses a wind power sliding bearing fatigue performance evaluation method comprising the following steps: S1, building a sliding bearing model based on a finite element, and analyzing the residual stress of interference fit between a shaft sleeve and a pin shaft in a sliding bearing; the stress state of the sliding bearing under the oil film pressure in the service environment is determined; s2, calculating axial structural stress distribution of the shaft sleeve, and solving structural stress amplitudes before and after oil film loading through difference; and S3, designing a three-point bending test, and calculating a structural stress value of a shaft sleeve section corresponding to a unit load by adopting finite element simulation. Aiming at the service safety of the sliding bearing in the wind power system, the stress concentration phenomenon possibly existing in the dissimilar material interface under the coupling influence of the working load and the interference fit residual stress and the transverse constraint characteristic of the multi-source gradient load acting on the dissimilar material interface state are fully considered; and the fatigue reliability of the sliding bearing coating and the nearby area is reasonably quantified.

The present invention proposes a method for measuring and calculating the interlaminar shear strength of heterogeneous multilayer composite plates, which is used to solve the problem that the existing interlaminar shear strength test method of composite materials is only applicable to single-layer composite plates or isotropic laminates. The steps of the present invention are: starting from the pure bending theory, a normal stress calculation formula for pure bending of a rectangular cross-section composite plate composed of three layers of plates with different moduli and different thicknesses is constructed; according to the normal stress calculation formula, a shear stress calculation method for the neutral plane position and any position in the thickness direction of the composite plate is established; and the calculation formula for the normal stress, neutral plane position and interlaminar shear stress distribution of an n-layer rectangular cross-section composite plate in pure bending is derived. The present invention combines the maximum load and interlaminar failure position measured by the three-point bending test to accurately calculate the shear stress distribution and interlaminar shear strength of the heterogeneous multilayer rectangular cross-section composite plate; it breaks through the limitations of the existing interlaminar shear strength test method and fills the gap in this field.

The invention relates to the technical field of fiber concrete performance detection methods, in particular to a method for testing the bonding strength of chopped fibers and an ultra-high performance concrete matrix under the action of bending stress. The method comprises the following steps: firstly, respectively cutting notches in the midspan positions of two opposite side surfaces of a test piece; applying tensile forces in opposite directions to the two ends of the test piece until a through crack appears between the two notches; performing a three-point bending test on the test piece subjected to tensile failure; and finally, obtaining the maximum load according to a load-time curve, and calculating to obtain the bonding strength of the chopped fibers and the ultra-high performance concrete matrix under the action of bending stress. According to the measurement result obtained by the method disclosed by the invention, the bonding strength of the chopped fiber and the ultra-high performance concrete matrix under the action of bending stress can be intuitively and accurately detected, and the technical problem that a test method which cannot truly reflect the bonding performance of the chopped fiber and the ultra-high performance concrete matrix is lacked in the prior art can be solved; and the method has ideal popularization and application prospects.

The utility model discloses a building material small component Hopkinson pressure bar system three-point bending test device, which ingeniously supports a sample through a three-point bending chuck, utilizes a pair of pressure heads of the chuck to be contacted and matched with the sample, and applies an acting force through an incident bar of a Hopkinson pressure bar system, so that the sample is not prone to deformation when the sample is tested. The device is restrained between an incident bar of the Hopkinson pressure bar system and a three-point bending chuck connected with a transmission bar, and according to the scheme, the pair of pressure heads are ingeniously arranged to be of a detachable interval adjusting structural form, so that the device can adjust the time loading interval by adjusting the interval between the pair of pressure heads; the device is simple in structure, reliable in implementation and flexible in application, and can be applied to dynamic load tests of small components of building materials.

The utility model discloses a three-point bending test device for a test sample. The three-point bending test device comprises a bearing assembly, a locking assembly and a bending mechanism, the bearing assembly is provided with a base, a first bearing piece, a second bearing piece and a stop piece. The first bearing piece and the second bearing piece are oppositely arranged on the base. The first bearing member and the second bearing member bear the test sample. The stop piece is arranged on the first bearing piece and the second bearing piece. And the long edge of one side of the test sample sheet is propped against the stop piece. The locking assembly is provided with a locking piece and an adjusting piece. The locking piece is located on the side, away from the second bearing piece, of the first bearing piece. And the adjusting piece is connected with the locking piece. The adjusting piece adjusts the distance between the locking piece and the first bearing piece, and the short edge of one side of the test sample piece abuts against the locking piece. The bending mechanism is arranged above the bearing assembly. The bending mechanism is provided with a lifting assembly and a bending pressing head. The lifting assembly is connected with the bending pressing head. The bending pressing head is located between the first bearing piece and the second bearing piece. According to the utility model, the test operation is simplified, and the test efficiency is improved.

The invention provides a cross-scale prediction method for the high-temperature bending strength of an additive manufacturing hard alloy. The bending strength of an additive manufacturing hard alloy cutter material in a high-temperature state can be accurately predicted. The method comprises the following steps: firstly, determining modeling parameters based on a scanning electron microscope image and a stereology principle; identifying defects in the microstructure of the additive manufacturing hard alloy based on a visual identification method; building a microstructure model of the additive manufacturing hard alloy by utilizing the determined parameters; defects obtained through visual identification are added in the built microscopic structure model through Boolean subtraction, and building of the defect-containing additive manufacturing hard alloy microscopic structure model is completed; embedding a cohesion unit into the built model to simulate the stress state and evolution condition of the microstructure of the material under the action of the thermal load; then, a macroscopic homogenization model of the defect-containing additive manufacturing hard alloy is built, and a three-point bending test model is built; and finally, obtaining the bending strength of the material by using a three-point bending model. The invention belongs to the field of simulation prediction.

The utility model discloses an angle measuring device for a three-point bending test, which comprises a protractor and a bending angle measuring and fixing device, the bending angle measuring and fixing device comprises a fixing plate and fixing lugs, the fixing lugs are arranged on two sides of the upper part of the fixing plate, a force applying roller is fixedly arranged between the fixing lugs, and the force applying roller is fixedly connected with the protractor. The protractor is arranged on the lower portion of the fixing plate, the center point of the protractor corresponds to the center position of a tested sample, the protractor and the tested sample are arranged on the two sides of the fixing plate respectively, the tested sample is arranged on the lower side of the force application roller, and the angle of deformation of the tested sample is measured through the protractor. According to the angle measuring device, the deformation angle is measured in the test process, inaccurate measurement caused by material rebound after the test is avoided, the angle measuring device is not connected with the tested sample, and the situation that the tested sample is deformed and the test result is affected due to the fact that the angle measuring device generates force on the tested sample is avoided.

The application relates to the technical field of quasi-brittle material mechanical property testing and constitutive inversion, in particular to an inversion analysis method of a quasi-brittle material tensile softening constitutive under monotonic loading, which comprises the following steps: collecting unilateral notched beam specimen size parameters and monotonic loading three-point bending test data; establishing a two-dimensional numerical model comprising an undamaged area and a cohesive crack area; constructing a segmented linear tensile softening constitutive subroutine comprising an elastic stage and a softening stage; integrating the two-dimensional numerical model and the subroutine, iteratively inverting constitutive parameters through an optimization algorithm, and outputting a final segmented linear tensile softening constitutive after the simulation data and the test data reach a preset fitting degree. The method can improve the constitutive inversion accuracy, adapt to the nonlinear fracture characteristics of quasi-brittle materials, and provide reliable support for material performance evaluation.

This invention relates to the field of fatigue performance testing technology for wind turbine bearings, and discloses a method for evaluating the fatigue performance of wind turbine sliding bearings, comprising the following steps: S1, establishing a sliding bearing model based on finite element method, and analyzing the residual stress of the interference fit between the bushing and the pin in the sliding bearing, as well as the stress state of the sliding bearing under oil film pressure during service; S2, calculating the circumferential stress distribution of the bushing and solving for the structural stress amplitude before and after oil film loading by subtraction; S3, designing a three-point bending test, and using finite element simulation to calculate the structural stress value of the bushing section corresponding to the unit load. This invention addresses the service safety of sliding bearings in wind power systems, fully considering the stress concentration phenomenon that may exist at the interface of dissimilar materials under the coupling effect of working load and interference fit residual stress, and the lateral constraint characteristics under the state of multi-source gradient load acting on the interface of dissimilar materials, and reasonably quantifies the fatigue reliability of the sliding bearing coating and surrounding area.

The present application discloses a method for evaluating the low-temperature toughness of ultra-high-strength steel parts. The method for evaluating the low-temperature toughness of ultra-high-strength steel parts includes: obtaining the maximum deformation strain rate of the ultra-high-strength steel parts to be tested: performing a room temperature dynamic three-point bending test on the ultra-high-strength steel parts to be tested, thereby obtaining room temperature test results: performing a low-temperature dynamic three-point bending test on the ultra-high-strength steel parts to be tested, thereby obtaining low-temperature test results: evaluating the low-temperature toughness of the ultra-high-strength steel parts to be tested based on the room temperature test results and the low-temperature test results. The method for evaluating the low-temperature toughness of ultra-high-strength steel parts of the present application uses a dynamic three-point bending test method, which can simulate the high strain rate deformation conditions of the parts during a collision process, conduct dynamic three-point bending tests under room temperature and low-temperature environments, and evaluate the low-temperature toughness of the parts by comparing the test results.

This application belongs to the field of fracture toughness testing under corrosive environments, and specifically discloses a method for calibrating the stress intensity factor loading rate in fracture toughness testing under corrosive environments. The method includes: preparing a specimen and creating a pre-crack; using a corrosive solution to create a pre-corrosive environment at the crack tip; establishing a corrosive environment on a testing machine and performing a three-point bending test on the specimen in the corrosive environment at a preset testing machine loading rate to obtain the specimen's yield strength; loading the specimen in the corrosive environment using multiple different testing machine loading rates to 60%-90% of the yield strength, and recording the force-time curves for each loading; calculating the corresponding stress intensity factor loading rate based on the force-time curves and performing linear fitting to obtain the corresponding functional relationship. This application solves the problem that when conducting fracture toughness testing under corrosive environments, it is impossible to directly set the stress intensity factor loading rate, and existing calibration methods cannot accurately reflect the coupling effect of the corrosive environment.

The utility model relates to the technical field of material performance testing, and particularly discloses a three-point bending test device convenient to adjust, which comprises a pressure head, a movable mounting seat, a locking handle, a bolt, a connecting piece and a fixed support. The pressure head is vertically located at the center right above the three-point bending test device, movable mounting seats are mounted on two sides of the fixed support, the movable mounting seats are connected with the fixed support through bolts, locking handles are mounted on two sides of each movable mounting seat, the movable mounting seats move on a working surface, and the locking handles are connected with the fixed support through bolts. According to the utility model, the span of the movable mounting seat can be adjusted through the driving of the locking handle, so that the effective test range of materials is enlarged, and the bending performance data of materials with different widths under the loading condition can be conveniently measured.

The invention discloses a wood lowest strength area positioning method based on ultrasonic detection and visual inspection parameters, and belongs to the technical field of wood structure engineering. The positioning method comprises the following steps: calculating the propagation velocity v of ultrasonic waves in wood; the dynamic elastic modulus E of the wood is calculated, and rho is the air-dry density of the wood; measuring the size K of the maximum wood section in a flat bending three-point bending test span l, and meanwhile, placing the maximum wood section near a loading point; carrying out flat bending three-point bending damage to obtain the three-point bending strength f of each test material; and substituting actual measurement samples fi, Ei and Ki into the multiple linear regression model to estimate a regression coefficient of the multiple linear regression model, positioning the lowest-strength areas of other woods according to an obtained multiple regression equation, and determining the positions of four-point (three-point) bending test loading points. The positioning method provided by the invention is universal and feasible, and can realize accurate positioning of the lowest strength area before a four-point (three-point) bending test.

The invention discloses a method for evaluating tensile strength of a brittle solid material soaked in rainwater, which comprises the following steps of: selecting the brittle solid material to process two types of samples, performing a tensile test on the first sample to obtain a tensile stress and strain curve and tensile strength, determining initial damage by CT scanning microcracks and fitting a relationship; performing a three-point bending test on the second sample to obtain fracture toughness and fitting a relationship; and determining equation parameters to predict the tensile strength of the material under different water saturations. According to the method, a relation equation containing stress, strain and water saturation is established based on fracture damage mechanics, and the tensile strength of the water saturation material is represented through the maximum stress value of a stress-strain relation curve of the material under different water saturations.

Improved test for characterizing interface toughness in mode II and associated test specimen. The specimen (10) has an initial notch (40) extending across the entire width of the specimen (10) parallel to its plane P. The specimen comprises three parts following each other longitudinally in a contiguous manner, namely a thin part (11) of thickness H0, a thick part (13) of thickness H2, with H2 > H0, and an intermediate transition part (12) of variable thickness H1, located between the thin part (11) and the thick part (13).The initial notch (40) is capable of propagating into the intermediate portion (12) and possibly into the thick portion (13) parallel to plane P when the specimen (10) is subjected to a three-point bending test, with a first support (21) located under the thin portion (11), a second support (22) located under the thick portion (13), and a load (30) applied to the thick portion (13) between the first support (21) and the second support (22). Figure to be published with the abbreviation: Figure 6.

The invention discloses a hydrate sediment fracture toughness testing system, and belongs to the technical field of hydrate sediment fracture toughness testing, the system comprises a sample synthesis unit, a three-point bending test unit and a direct shear test unit, the three-point bending test unit is detachably connected to the sample synthesis unit, and the direct shear test unit is detachably connected to the sample synthesis unit. The method is used for measuring the I-type fracture toughness of the hydrate sediment; the direct shear test unit can be detached to replace the three-point bending test unit, is connected to the sample synthesis unit and is used for measuring the II-type fracture toughness of the hydrate sediment. In the testing process, a horizontal loading mode is adopted, so that the influence of gravity on fracture toughness is eliminated. In order to reduce the influence of friction force on fracture toughness, the system adopts a design scheme of a three-point bending bracket, a sliding base and a guide rail. In addition, the hydrate has the characteristic of being easy to decompose at normal temperature and normal pressure, the sample synthesis unit can realize synthesis of the hydrate, and it is ensured that the hydrate is not decomposed in the testing process.

To construct a sound coke oven by using silica bricks which are hardly chipped and have damage resistance.SOLUTION: Provided is a method for sorting silica bricks for constructing a coke oven, the method comprising sorting silica bricks that satisfy all of the following conditions i) to iii): i) a bending strength of 7MPa or more and 15MPa or less, ii) a shape parameter m in a Weibull distribution of the bending strength of 5 or more, and iii) a ratio of a dynamic modulus of elasticity to a square of the bending strength of 80 or more SELECTED DRAWING: None

The present invention discloses a method for constructing a compacted clay type I fracture size effect equation considering the friction effect, and relates to the technical field of core wall crack research of earth-rock dams. The present invention at least includes the following steps: S1: determining the friction coefficient between the support material and the sample; S2: conducting a compacted clay type I fracture size effect test; S3: calibrating the singular terms, non-singular terms, and third high-order terms of the stress field at the tip of the type I fracture sample. The present invention considers the influence of support friction in the traditional three-point bending test, introduces DIC to calibrate the coefficients of the Williams series expansion after considering the support friction, and constructs a compacted clay type I fracture toughness size effect equation considering the friction effect in combination with the MMTS criterion, so as to realize the prediction of compacted clay type I fracture toughness and type I fracture process zone at the engineering scale.

This utility model relates to the field of vehicle door anti-collision beam technology, and more particularly to a three-point bending test device for a vehicle door anti-collision beam, comprising: a support, a first fixing block, a second fixing block, a first support assembly, a second support assembly, and a pressure head. The first fixing block and the second fixing block are respectively connected to both ends of the vehicle door anti-collision beam, forming an integrated anti-collision beam structure; the top of the first support assembly and the second support assembly are respectively provided with a first arc portion and a second arc portion; the integrated anti-collision beam structure is disposed on the first support assembly and the second support assembly. When the press drives the pressure head to apply a load to the center of the vehicle door anti-collision beam, the first fixing block and the second fixing block rotate around the contact point of the first arc portion and the second arc portion as the rotation fulcrum. The advantage of this utility model is that, since the axial height of the first support assembly and the second support assembly can be adjusted independently, it is possible to achieve a test where the support points on both sides of the vehicle door anti-collision beam are not at the same height.

The present invention discloses a hydrate sediment fracture toughness testing system, which belongs to the technical field of hydrate sediment fracture toughness testing. The system includes a sample synthesis unit, a three-point bending test unit and a direct shear test unit. The three-point bending test unit can be detachably connected to the sample synthesis unit and is used to measure the type I fracture toughness of the hydrate sediment; the direct shear test unit can be detachably replaced by the three-point bending test unit and connected to the sample synthesis unit to measure the type II fracture toughness of the hydrate sediment. During the test, horizontal loading is adopted to eliminate the influence of gravity on fracture toughness. In order to reduce the influence of friction on fracture toughness, the system adopts a design scheme of a three-point bending bracket, a sliding base and a guide rail. In addition, hydrates are easy to decompose at room temperature and pressure. The sample synthesis unit can realize the synthesis of hydrates and ensure that the hydrates do not decompose during the test.

This invention discloses a method for testing Type I fracture under cyclic thermodynamic loading. It couples a three-point bending test with stress-temperature cycling, extending the three-point bending test to thermodynamic experimental conditions. By measuring the peak load S in the three-point bending test and the elastic modulus E in the final stress-temperature cycle, the fracture energy Gc of the Type I fracture of the specimen under cyclic thermodynamic loading can be effectively calculated. This helps to accurately reflect the bearing capacity and fracture propagation mode of the fractured surrounding rock in compressed gas storage caverns under cyclic thermodynamic loading. The method couples stress and temperature cycles and measures the change in the elastic modulus of the specimen under cyclic stress and temperature. This method has the advantages of simple steps, quick and convenient testing, and strong practicality. It is easy to operate, has a wide range of applications, and can be combined according to different actual working conditions to meet the needs of Type I fracture testing under different specimen materials, loading temperatures, and loading conditions.

The application relates to the technical field of bending test equipment, in particular to a high-load material welding bending test device for multi-source data acquisition based on multi-point sensing feedback, which comprises an upper pressure head assembly, a bending roller assembly, a multi-point sensing assembly and a data acquisition and processing assembly. The upper pressure head assembly is detachably assembled on the upper load end of a pressure testing machine and is used for applying bending load to a welding material sample to be tested. The bending roller assembly is detachably assembled on the lower load end of the pressure testing machine and is used for receiving the sample to be tested and cooperating with the upper pressure head assembly to form a three-point bending test structure. In the high-load material welding bending test device for multi-source data acquisition based on multi-point sensing feedback, a detachable structure is adopted, the device is directly assembled on a conventional large-load pressure testing machine with a large on-site stock based on dovetail cooperation structure, a special welding bending test equipment does not need to be separately purchased, and equipment purchase investment is effectively reduced.

The invention discloses a method for testing the crack resistance of a prefabricated curved plate of a thin-wall concrete irrigation canal. The method comprises the following steps: measuring key dimension parameters of the prefabricated concrete curved plate; building a three-point bending test loading platform; performing stress state classification on the prefabricated curved plates according to the position of the action point of the resultant force of the water pressure; calculating a horizontal positioning parameter of a load acting point and a base supporting height parameter, and completing positioning of loading and supporting; calculating a loading maximum value based on a bidirectional load synthesis effect, and applying the load according to a set loading rate; calculating a fatigue lower limit equivalent value under the action of a bidirectional load, and implementing multi-cycle fatigue loading; after the loading is stopped, the cracking or damage state of the prefabricated concrete curved plate is observed, the crack width is detected, and an anti-cracking performance evaluation conclusion is given in combination with standard requirements. According to the method, the synthetic action of water pressure, top pressure beams and live loads in different directions in actual loads is comprehensively considered, and the crack resistance of the prefabricated bent plates of different sizes is accurately and directly evaluated.

The invention discloses a flame tube flanging simulation piece test fixture, which comprises an upper pressure head assembly, a lower support platform and two groups of support positioning seats detachably positioned and mounted on the lower support platform. The upper pressure head assembly is used for being connected with an upper chuck of test equipment, and the lower supporting platform is used for being connected with a lower chuck of the test equipment. The two groups of supporting and positioning seats are oppositely arranged at intervals and are used for cooperating to stably support and position a to-be-tested flame tube flanging simulation piece, and the upper pressure head assembly is used for stably, eccentrically and downwards pressing the simulation piece supported on the two groups of supporting and positioning seats so as to carry out an eccentric three-point bending test and a downwards pressing fatigue test on the simulation piece. One set of clamp can meet the requirements of eccentric three-point bending and pressing fatigue tests of a flame tube flanging simulation piece at the same time, meanwhile, universal tests of the test pieces can be achieved by replacing different supporting and positioning bases, it is guaranteed that composite acting force except bending cannot be generated when the simulation piece is loaded, and the flame tube flanging simulation piece is suitable for being applied to actual production engineering.

The present invention aims to provide a zirconia sintered body having a high fracture toughness value measured by the SEPB method and high mechanical strength, and at least one of the methods for producing the same. A sintered body is provided, comprising zirconia containing a stabilizer, wherein the monoclinic fraction of the sintered body is 0.5% or more, and the three-point bending strength determined by a three-point bending test in accordance with JIS R 1601 is greater than 1450 MPa.

The utility model discloses a three-point bending experiment device for a Hopkinson pressure bar system of a recycled concrete large component, which is skillfully characterized in that a limiting block is arranged on a machine table, and a pair of oppositely arranged fixed pressure head brackets is further arranged on one side surface of the limiting block; the movable pressure head connected with the incident bar of the Hopkinson pressure bar system is used for applying acting force to the sample (the sample between the movable pressure head and the fixed pressure head) on the bracket, so that the three-point bending test of the sample is convenient and reliable to implement; according to the scheme, a force sensor is further installed between the movable pressure head and the incident bar through a transition piece, so that when the incident bar applies acting force, test parameters can be recorded timely and efficiently through feedback of the force sensor.