16 results about "Three point flexural test" patented technology

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.

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 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.

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

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.

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 invention provides a method for calculating the flexural capacity of a fiber reinforced concrete beam, and relates to the technical field of structural health monitoring. According to the method, after sweep frequency excitation is carried out on the mid-span section of the fiber reinforced concrete beam, vibration response signals are synchronously collected and discrete wavelet transformation is carried out on the vibration signals, the energy of each high-frequency sub-band is calculated, the first three high-frequency sub-bands with the maximum energy serve as selected frequency bands, and then a three-point bending test is carried out on a sample to calculate the actual flexural capacity. Constructing a polynomial regression model by taking the main resonant frequency, the selected frequency band energy and the selected frequency band total energy as input characteristics and taking the actual bearing capacity as an output label, verifying the model performance on a test set, evaluating and optimizing the polynomial regression model by adopting a root-mean-square error and a decision coefficient, so that a vibration signal is highly associated with the actually measured bearing capacity, and finally obtaining a vibration signal. And the actual bearing capacity of the fiber reinforced concrete beam with the to-be-detected flexural bearing capacity can be calculated through vibration signal analysis.

The invention relates to the technical field of mechanical property testing and constitutive inversion of quasi-brittle materials, in particular to an inversion analysis method for tensile softening constitutive of quasi-brittle materials under monotonic loading, which comprises the following steps: collecting size parameters of a unilateral notched beam test piece 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 piecewise linear stretching and softening constitutive subprogram comprising an elastic stage and a softening stage; and integrating the two-dimensional numerical model and the subprogram, iteratively inverting constitutive parameters through an optimization algorithm, and outputting a final piecewise linear stretching softening constitutive after simulation data and test data reach a preset goodness of fit. According to the method, the constitutive inversion accuracy can be improved, the nonlinear fracture characteristics of the brittle material are matched, and reliable support is provided for material performance evaluation.

To provide a shock absorbing floor material superior in load resistance, while having an absorbing effect by a soft layer.SOLUTION: The shock-absorbing floor material includes an upper floor material, an underfloor material provided below the upper floor material, and an intermediate material provided between the upper floor material and the underfloor material, wherein the underfloor material is formed of a resin material and has a foamed structure, the intermediate material is formed of a material containing a thermoplastic resin and an inorganic filler, and a strain (ε (σ max)) at which a bending strength becomes maximum in a three point bending test according to JISK7074 is 0.5% or more and a bending modulus of elasticity is 1 GPa or more.SELECTED DRAWING: Figure 1

The utility model provides a round bar three-point bending test tool, which comprises a mounting seat, a support block and an upper pressure head, two moving seats are symmetrically and slidably arranged at the top of the mounting seat, each moving seat is provided with a locking piece for locking the moving seat and the mounting seat, the top of the support block is provided with an accommodating groove, the bottom of the support block is provided with a clamping groove, and the upper pressure head is arranged in the accommodating groove. The top of each moving seat is provided with a protruding block clamped with the supporting block, the top of the upper pressing head is connected with a connecting piece, the upper pressing head is connected with the output end of the mechanical testing machine through the connecting piece and located above the two moving seats, the bottom of the upper pressing head is detachably connected with a lower pressing head, and the bottom of the lower pressing head is provided with a pressing groove matched with a round bar. The problem that in the prior art, when three-point bending experiments are carried out on round bar test pieces with different diameters, the same tool is used for testing the round bar test pieces, and consequently the precision of a detection result is not accurate enough is solved.

The invention discloses a method for improving bending resistance of a TPMS (Tire Pressure Monitor System) sandwich structure by utilizing variable density topological optimization, which comprises the following steps of: constructing a function rho TPMS (t) of a TPMS structure contour surface threshold value t and a relative density rho TPMS by utilizing polynomial fitting; dividing the relative density field after variable density topological optimization into a plurality of sections, and constructing a function matrix rho (x) by using polynomial fitting; mapping rho (x) and rho TPMS (t) to construct a TPMS structure wall thickness gradient function matrix t (x), generating variable-thickness TPMS cell elements and splicing the variable-thickness TPMS cell elements to realize multi-section variable-density optimization design of a TPMS core layer; a photosensitive resin panel and a core layer are subjected to 3D printing, a three-point bending test is carried out and compared with a numerical result, and the method for improving the bending resistance of the TPMS sandwich structure through variable-density topological optimization is provided. According to the method for improving the bending resistance of the TPMS sandwich structure through variable-density topological optimization, the sandwich structure obtains higher bending resistance, meanwhile, light weight of the structure is guaranteed, and efficient utilization of materials is achieved.