438 results about "Shear strength" patented technology

The invention relates to the field of tunnel engineering geology and support design, and discloses a weak surrounding rock tunnel deformation risk discrimination method based on shear expansion-shear constitutive, which comprises the following steps: constructing a nonlinear coupling model between a shear expansion angle and shear stress, normal stress and joint parameters, and obtaining the shear expansion angle; establishing a volumetric strain rate discrimination formula; inverting an initial crustal stress tensor field; reconstructing an irregular tunnel boundary; constructing a risk level discrimination model, and outputting a risk level; supporting schemes such as supporting rigidity, anchor rod parameters and spraying layer thickness are matched according to the risk grades; establishing a model to predict a risk trend; a support adjustment suggestion is generated; collecting monitoring data to dynamically correct model parameters; and all the modules are integrated in a deployment system. According to the method, the coupling relation between the shear expansion angle and the shear strength is introduced, the coupling type constitutive discrimination model is established, the risk grading system and the support correction strategy associated with the support response are constructed, and active early warning of the high-risk section and dynamic adjustment of the support rigidity are achieved.

Provided are a solder alloy, a solder ball, a preformed solder, a solder joint, and a circuit, which are excellent in wettability and shear strength, suitable in failure mode, capable of suppressing the growth of an intermetallic compound at a bonding interface even after multiple reflow soldering, excellent in drop impact resistance, and suitable in the shape of a bump. The solder alloy has an alloy composition comprising, in mass%, 0.10 to 3.00% of Ag, 0.80 to 6.00% of Cu, 0.08 to 0.60% of Ni, 0.0010 to 0.0150% of Ge, and the balance of Sn. It is preferable that the alloy composition further contains 0.1% or less of at least one of Bi, Sb, In, Zn, Ga, Mn, Cr, Co, Si, Ti, and rare earths in total.

The invention discloses an angle steel connecting piece shear strength prediction method and system based on a physical information neural network, electronic equipment and a storage medium thereof. The method comprises the following steps: establishing a database containing a plurality of groups of test data based on a numerical simulation result of an angle steel connecting piece finite element model verified by a push-out test; embedding an angle steel connecting piece shear bearing capacity physical constraint condition based on an elastic foundation beam theory into a loss function of the data-driven neural network model DNN; training the neural network embedded with the physical constraint condition by using a database, and adjusting and selecting a physical item weight factor and a model learning rate so as to construct a shear bearing capacity prediction model of a physical information neural network (PINN); predicting the shear strength of the angle steel connecting piece by using the trained physical information neural network (PINN) shear capacity prediction model; according to the prediction method and system, the electronic equipment and the storage medium thereof provided by the invention, the accuracy and reliability of the shear resistance prediction of the angle steel connecting piece can be improved.

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 invention relates to the technical field of metal material fracture resistance testing, in particular to a prediction method for interface fracture toughness of a polar region ship composite steel plate, which comprises the following steps: S1, preparing a composite steel plate; s2, carrying out a three-point bending fracture test; s3, performing an interfacial shear strength test; s4, data analysis and model construction: performing fitting analysis on the obtained fracture toughness data of the large-size sample and the obtained shear strength data of the small-size sample, determining undetermined parameters, and constructing a mathematical model between the interface fracture toughness and the interface shear strength of the composite steel plate; and S5, verifying the accuracy of the model. According to the method, the mathematical model is established by analyzing the correlation between the shear strength measured by the small-size interface shear sample and the fracture toughness measured by the large-size fracture sample, and the model has the advantages of simplicity in construction, rapidness in use and the like, so that rapid prediction and evaluation of the fracture toughness of the composite steel plate are realized, the test process is greatly simplified, and the test efficiency is improved. And the research and production efficiency is improved.

The invention relates to the technical field of slope reinforcement, and provides a micro pile combination reinforcement method for a highway expansive soil slope, which comprises the following steps: when the current stability safety coefficient, the current uplift bearing capacity, the current shear strength and the current flexural bearing capacity all meet the corresponding preset conditions, taking the current design size parameter as the final design size parameter; and according to the final design size parameters, the grouting amount of each hole in a first pile of the steel pipe pile assembly and the grouting amount of each hole in a second pile of the cast-in-place pile assembly are determined, and the steel pipe pile assembly is constructed on the slope bottom face of the expansive soil slope according to the grouting amount of each hole in the first pile. And then a cast-in-place pile assembly is constructed on the slope face of the expansive soil slope according to the grouting amount of each hole in the second pile. According to the method, the influence of the expansive soil property on design and construction of the micro piles is fully considered, interaction and combined arrangement of the micro cast-in-place piles and the micro grouting steel pipe piles are integrated, the safety and reliability of slope reinforcement are guaranteed, material waste caused by excessive conservative is avoided, and operability is high.

The invention relates to the field of buildings, and discloses a prefabricated pipe pile stand column steel supporting node and a construction method thereof.The prefabricated pipe pile stand column steel supporting node comprises a prefabricated pipe pile stand column, a pile head is arranged at the top of the prefabricated pipe pile stand column, a micro-expansion concrete filling core is arranged in the prefabricated pipe pile stand column, and the bottom end of the micro-expansion concrete filling core is fixedly connected with a round thin steel plate through anchor bars; the top ends of the anchor bars are fixedly connected with anchor plates, overflow holes are formed in the anchor plates, and the top faces of the anchor plates are exposed out of the pile head. Longitudinal steel reinforcement frameworks and transverse stirrups are arranged in the pile head to form a steel reinforcement mesh cage, a micro-expansion concrete filling core is poured by adopting a layered pouring and layered vibrating process, and end hook type steel fibers are doped, so that concrete shrinkage can be compensated, cracks are inhibited, and meanwhile, the bending strength and the shearing strength of the pile head are enhanced; and the load of the steel support can be uniformly transmitted to the prefabricated tubular pile stand column through the anchor plate, so that the node has reliable bearing capacity and crack resistance.

The invention discloses a slope structural surface roughness coefficient testing method. The method comprises the core steps of structural surface pretreatment, rebound detection, contour curve drawing, roughness measurement and the like. Measuring areas are divided and identified, an average rebound value is obtained by using a rebound apparatus, a surface profile is drawn in combination with a profile curvimeter, and a roughness coefficient JRCn is read by using a multi-range roughness ruler and an electronic subdivision technology; in addition, parameters such as rock wall strength and normal stress can be obtained through a point load instrument, a vibrating wire strain gauge and the like, shear strength is calculated in combination with a Barton-Bandis mode, data of multiple measuring areas are integrated, and dynamic correction results of environmental parameters are associated. According to the method, the test precision and efficiency are improved, data integration and full-period management are realized, and a reliable basis is provided for slope stability evaluation.

The invention relates to the technical field of geotechnical engineering anchoring, in particular to a method for testing the degradation characteristic of the bearing performance of a recyclable anchor rod under cyclic loading. The method comprises the following steps: preparing a unit body sample anchor-rock interface unit body sample, simulating weathered soft rock according to a specific ratio, pouring a self-compacting concrete anchoring body, and curing and forming; setting a combined parameter of a reference load ratio and a load cycle index, applying a triangular wave cyclic load to simulate a traffic condition, and executing a pull-out test to collect load-displacement data; constructing a two-parameter coupled shear strength degradation model based on test data, and proposing a shear stress-displacement curve model; an anchor rod load transfer control equation is established in combination with the Poisson effect, and shear stress distribution of the anchoring section is iteratively solved by adopting a discrete recursion method; the model is verified through a foundation pit engineering case, the ultimate bearing capacity degradation law of the anchor rod under long-term cyclic loading is predicted, and it is proved that the model can guide engineering safety design. According to the method, the coupling characterization of the cyclic load parameter and the interface degradation mechanism is realized.

The invention discloses a pull rivet connecting piece and a lantern ring preparation method and application thereof, the pull rivet connecting piece comprises a pull rivet and a lantern ring, and a preformed directional deformation protrusion is arranged on the cylinder wall of the lantern ring and located in a preset bulging deformation area. In the rivet pulling process, the directional deformation protrusion preferentially generates radial plastic deformation when being axially compressed, so that a drum-shaped locking structure which is accurate in position and uniform in shape is formed, and the lantern ring is integrally formed through a local plastic deformation process and can be prepared through an internal reaming method or an external die assembly extrusion method. According to the lantern ring, it can be ensured that radial plastic deformation is evenly spread in the circumferential direction of the lantern ring through the directional deformation protrusions designed through the pre-forming structure, controllability and predictability of the deformation process are greatly improved, consistency, reliability and convenience of pull-rivet connection are kept through the design, the tensile strength and the shear strength of connection are remarkably improved, and the service life of the lantern ring is prolonged. The method is suitable for occasions with high reliability requirements.

The invention discloses a low-corrosion halogen-free soldering flux for aluminum-based part brazing and a preparation method of the low-corrosion halogen-free soldering flux, and belongs to the technical field of halogen-free welding materials.The low-corrosion halogen-free soldering flux comprises, by mass, 4-6 parts of oxalic acid, 1-2 parts of triethanolamine, 0.8-1.5 parts of Tween-80, 4-6 parts of polyvinylpyrrolidone, 0.3-1 part of compound nano cerium oxide, 0.5-1.5 parts of chitosan oligomer and the balance deionized water. And the welding spot oxidation resistance and the interface self-repairing capability are further improved. Through the synergistic effect of four mechanisms of complexing, oxidation prevention, wetting and film forming, the flux achieves efficient film removal, excellent wetting, no corrosion residue and stable film forming protection, is high in shear strength, low in welding spot porosity and clean in surface after welding, and is suitable for electronic packaging, heat exchanger manufacturing and high-reliability aluminum welding occasions.

The invention relates to a test tool and method for testing the shear strength of a material interface. The tool comprises a chuck, a fixing block, a base and a sliding block, a guide rail groove is formed in the base, one side of the guide rail groove is connected with the sliding block, and the other side of the guide rail groove is connected with the fixing block; the fixing block is provided with a fixing hole and a fixing block threaded hole, a pin penetrates through the fixing hole, the sample hole and the sliding block hole to fix the sample, and a bolt is fixed to the base through the fixing block threaded hole. The sliding block is provided with a sliding block sliding rail, a sliding block threaded hole and a sliding block hole, and the sliding block sliding rail is arranged in the guide rail groove of the base and fixed through a bolt; the chuck is located on the lower side of the base and serves as a device for connecting the base and the stretcher. According to the invention, the interface shear strength performance test can be carried out on the sample with any thickness, the bonding surface of the sample is always kept parallel to the axial force line in the initial sample mounting process and the tensile test process, and the bonding surface of the sample base material and the lap joint material in the initial test state is prevented from being abnormally damaged.

To provide a high strength stainless clad steel plate excellent in stress corrosion cracking resistance and low temperature toughness and a producing method thereof.SOLUTION: A stainless clad steel plate comprises a base material and a laminating material formed on the base material, wherein the laminating material has a specific composition, the base material has a specific composition, a yield strength of 620 MPa or more, a tensile strength of 700 MPa or more, and an absorbed energy of 47 J or more when a Charpy impact test is conducted at -40°C, and the clad steel sheet has a shear strength of SH: 0.87×((t+T)×YSC-T×YSB) / t or more, a yield strength of 620 MPa or more, and a tensile strength of 700 MPa or more.SELECTED DRAWING: None

The invention discloses an anchor rod or anchor cable mounting device and method for inhibiting failure of an anchoring interface, and relates to the technical field of roadway supporting. The device comprises an annular body, a conical protrusion structure, a pulse press-in device, a fluid flushing system and a guide stabilizer, and is suitable for various hole diameters and different surrounding rock types. The construction method using the device comprises the following steps: drilling a hole by a drilling machine to mount an anchor rod or an anchor cable, evaluating the drilling hole, determining a test environment and boundary conditions, performing a drilling hole compression test to simulate confining pressure to obtain a stress deformation response curve, and determining the bonding performance and the shear strength through a pull-out test. The size of the conical protrusion is determined by combining lithology and crustal stress characteristics, the device is installed to a drilling target section, the pulse pressing-in device is started, the conical protrusion structure is pressed into the hole wall of a drilling hole to form a continuous groove, and when a fluid washing system is started to remove dust and chippings, a guiding stabilizer is connected, so that the drilling target section is formed. It is ensured that the device retreats from a drill hole at a constant speed, cleaning operation in the hole is completed, and finally the prefabricated anchor rod is inserted to form a high-adhesion and high-shear-resistance complete anchoring structure.

The invention discloses a full-underground multifunctional full-scale test loading device, and belongs to the technical field of large structural mechanical tests. The integrated counter-force mechanism comprises a counter-force wall which is arranged in the circumferential direction; the quick-release waterproof loading mechanism is arranged in the counter-force wall and is electrically connected with the control system; and the auxiliary system is arranged on the inner side of the quick-release waterproof loading mechanism. The device can be used for carrying out loading tests on large components with various section forms, such as shield tunnels, subsurface tunnels, pipe galleries, large-diameter pipelines and the like, and the utilization rate of the platform is remarkably improved. According to the integrated counter-force mechanism, the compressive strength, the shear strength and the impermeability of the counter-force well wall are greatly improved, the underwater test function is added, and meanwhile a foundation is provided for performance upgrading of a loading system in the later period.

The invention relates to the technical field of metal connection, and discloses a welding forming process of an aluminum alloy copper bar and a terminal, which comprises the following steps: sequentially carrying out mechanical cleaning, chemical oil removal and chemical activation pretreatment on the surfaces to be welded of an aluminum alloy base material and a brass terminal; the aluminum-based brazing filler metal foil and the potassium fluoroaluminate scaling powder are sequentially arranged between the aluminum alloy base material and the brass terminal, and an assembly to be welded is assembled; and finally, placing the assembly in hot pressing equipment under vacuum or inert atmosphere protection, carrying out constant-temperature and constant-pressure treatment at the temperature of 600-630 DEG C and under the pressure of 5-15 MPa, cooling, relieving the pressure, and molding. According to the method, a metallurgical bonding transition layer which is compact in structure and free of welding defects is formed at an aluminum-copper dissimilar metal interface under the combined action of liquid-phase filling and solid-phase diffusion, and a prepared welding joint has mechanical shear strength superior to that of an aluminum alloy base material and extremely low interface contact resistance; and reliable connection with high strength and high conductivity is realized.

The invention discloses a hybrid control method and device for a shear strength test of a rock mass structural plane, and relates to the technical field of physical property analys.The hybrid control method comprises the steps that the stress accumulation state before shear failure is simulated by controlling shear force to be increased or kept according to a preset function relation; judging whether a first condition for converting from the first mode to the second mode is met or not in real time, switching to the second mode when the first condition is met, controlling the position of the sample to remain unchanged, and simulating a stress release state during shear failure; judging whether a second condition for converting from the second mode to the third mode is met or not in real time; when a second condition is met, switching to a third mode, controlling the sample to slide at a constant rate, and simulating a stress retention state after shear failure; and when the accumulated slippage distance of the sample reaches a preset limit value, ending the test. According to the method, full-stage mechanical behaviors from the moment before damage to the moment after damage are reproduced, and accurate data support is provided for slope stability analysis and anti-sliding design.

Methods of tuning one or more properties of a multipart structural adhesive composition, the method including providing a Part 1 of the multipart structural adhesive; providing at least a first sub-Part 2 and a second sub-Part 2 of the multipart structural adhesive; and causing to be formed the multipart structural adhesive by combining the Part 1, the first sub-Part 2, and the second sub-Part 2, wherein the amount, ratio, or both of the first sub-part 2 and the second sub-Part 2 impact the one or more properties of the multipart structural adhesive composition, wherein the amounts or ratios of the Part 1, the first sub-Part 2 and the second sub-Part 2 affect the one or more properties of the multipart structural adhesive composition, and wherein the multipart structural adhesive has an overlap shear strength of at least about 0.75 MPa (109 psi).

The invention belongs to the technical field of structural material design, and particularly relates to a method for determining an allowable value of an aviation composite material structure. The method mainly comprises the following steps: correcting a tension-compression strength allowable value according to a first ratio of the breaking strength of a single-side lap joint tension-compression test to the breaking strength of a single composite material tension-compression test; a plurality of second ratios of the shear failure strength of the composite materials with different thicknesses to the shear failure strength of a single composite material are formed through bonding, and the shear strength allowable value is corrected; correcting the allowable value of the tensile strength according to a plurality of third ratios of the tensile breaking strength of the composite materials with different thicknesses formed by screw connection to the tensile breaking strength of a single composite material; and correcting the allowable value of the compression strength according to a plurality of fourth ratios of the compression breaking strength of the composite materials with different thicknesses after impact breaking to the compression breaking strength of a single composite material. A basis is provided for relatively reasonable, safe and effective design of the composite material structure.

The invention provides a system and a method for detecting the mechanical property of a micro area of a composite material structure, and belongs to the technical field of material mechanical testing equipment. Comprising a fixing base and testing equipment, a clamping device is arranged in the fixing base and used for fixing a tiny test piece, force generated by the testing equipment is transmitted to the tiny test piece, a pressing disc is arranged in the testing equipment and controlled by a servo motor to move, and force is applied to the tiny test piece fixed in the clamping device; and an improved short beam shearing method is adopted for interlayer shearing performance testing. The bottleneck problem in the aspect of testing the interlayer shear strength of the composite material in a specific small area in the current composite material industry is solved, an important testing means is provided for research and development of the composite material, and experiments prove that the measurement repeatability error of the system is smaller than 2%, the standard requirement is completely met, and the system has a wide application prospect.

Provided are a solder alloy, a solder paste, a solder ball, and a solder joint which have a low melting point, are excellent in ductility, shear strength, and heat cycle resistance, further suppress the occurrence of open defects, and in addition, have reduced residual voids even at the time of joining in a large area. A solder alloy has an alloy composition of, by mass %, Bi: 35.0 to 68.0%, Sb: 0.1 to 2.0%, Ni: 0.010 to 0.050%, Ge: 0.007 to 0.090%, with the balance being Sn. Preferably, the alloy composition further contains, by mass %, at least one of Co, Ti, Al, Mn, As, Fe, Pd, Zn, Zr, Pb, In, Ce, P, and Ga: 0.1% or less in total. Further, this solder alloy can be suitably used for solder pastes, solder balls, and solder joints.

The application relates to the technical field of brazing, and discloses a Zr-Ti-Hf-Ni-Cu-Co six-element medium-entropy alloy brazing filler metal for pure titanium and titanium alloy brazing and a use method. The Zr-Ti-Hf-Ni-Cu-Co six-element medium-entropy alloy brazing filler metal provided by the application has the following weight percentage of components: Ti: 9.5-13.9; Ni: 5.5-9.5; Cu: 5.0-9.5; Co: 2.0-8.5; Hf: 0.0-2.0; and Zr: the balance. The application has the following technical effects: the liquidus temperature of the brazing filler metal is between 769 DEG C and 782 DEG C, the brazing filler metal is easy to be shaped into an amorphous brazing filler metal alloy, and the shear strength of a pure titanium-titanium alloy joint obtained by brazing at a temperature of 810 DEG C-828 DEG C for 10 minutes reaches 243-280 MPa.

The anti-tripping composite structure embedded sleeve comprises a body and a stainless steel sleeve, the body is of a tubular structure with one end opened and the other end sealed, external threads, used for being combined with the interior of a sleeper, on the outer circumferential wall of the body are single continuous threads, and the stainless steel sleeve is embedded in the inner wall of the body. And the internal thread on the inner wall of the stainless steel sleeve is combined with the internal thread on the body to form a continuous thread with a consistent thread shape. By optimizing the structure of the pre-embedded sleeve, the torsional shear strength and the tensile strength of the internal thread are further enhanced, the surface hardness of the internal thread of the pre-embedded sleeve is increased, the friction coefficient is reduced, and the service life of the pre-embedded sleeve is prolonged. The potential safety hazard that the pre-embedded sleeve made of the glass fiber reinforced nylon 66 composite material is tripped in construction assembly and operation is solved, and the situation that the surface of the internal thread is scratched due to friction and shearing in the fastening process of the pre-embedded sleeve and a screw spike under the conditions that hard impurities are mixed in the pre-embedded sleeve and water is accumulated and ice is formed is avoided; and the risk of potential failure of the pre-embedded sleeve is further caused.

The invention discloses a forging forming process for an aluminum casting chassis supporting arm implanted with a steel plate framework, and relates to the technical field of metal composite material forming. The method comprises the following steps: 1, pretreating a steel plate framework; 2, assembling the mold; 3, performing semi-solid extrusion; 4, sequentially carrying out segmented heat treatment of solid solution at 535 DEG C for 2 hours, water quenching and aging at 175 DEG C for 8 hours; and 5, the cooling rate is controlled to be 5 DEG C / min under a 0.15 T rotating magnetic field, and solidification is completed. Through a quadruple synergistic mechanism of micro anchoring structure-gradient coating-semi-solid extrusion-segmented heat treatment, the shear strength of a composite interface reaches 60-105 MPa, the tensile strength of a final component reaches 311-322 MPa, the fatigue life is prolonged to 120 million times from 500 million times, the lightweight target that the weight is reduced by 50% compared with that of a pure steel part is achieved, and the production cost is reduced. The defects of insufficient strength, infirm aluminum / steel interface bonding, pore shrinkage and brittle phase of a traditional aluminum casting piece are overcome.

The present application relates to the field of building, specifically to a composite panel-type tie member and a shear performance calculation method; comprising a steel core layer and outer cover layers located on both sides of the steel core layer to clamp and position the steel core layer; the outer cover layers are made of GFRP material, and the sizes of the two outer cover layers correspond; the size of the steel core layer is smaller than that of the outer cover layer, and the steel core layer and the outer cover layer have an equal proportion corresponding relationship; after the centers of the steel core layer and the outer cover layer are aligned, the gap area between the edges of the outer cover layers and the edges of the steel core layer is filled with bonding material. The tie member has high shear strength and stiffness, and effectively reduces the influence of wallboard thermal bridge effect.

The invention relates to the technical field of landslide disaster treatment, and discloses a cutting section landslide treatment method and structure based on a steel corrugated plate, which adopts an innovative combined structure of the steel corrugated plate and a reinforced concrete lining to realize advantage complementation of flexibility and rigidity; wherein the steel corrugated plate can effectively resist external soil pressure and flexibly absorb settlement deformation of a foundation by virtue of extremely high axial compressive strength and excellent deformation adaptive capacity, and meanwhile, the steel corrugated plate is used as a supporting template of a concrete structure, so that the aim of quickly implementing protection is fulfilled; the reinforced concrete lining greatly improves the overall rigidity and the shear strength of the structure, and the problem that a pure steel structure is prone to local instability is fundamentally avoided; and the two synergistically form a strong retaining system, so that the treatment effect is lasting and stable, and potential safety hazards are thoroughly solved.

The application discloses a brazing process for realizing connection of hard alloy and steel dissimilar materials by using low-silver foil brazing filler metal and application thereof, realizes connection between the hard alloy and the steel, fully gives play to the advantages of the hard alloy and the steel, avoids precipitation of hard and brittle phases at a weld interface, solves the problem of excessive dissolution of base materials, and has the characteristics of high shear strength. The application provides a brazing process for realizing connection of hard alloy and steel dissimilar materials by using low-silver foil brazing filler metal, compared with other welding technologies, the brazing process has good welding effect, low production cost, safety and environmental protection. Meanwhile, the shear strength at a welding position is high, and the corrosion resistance is excellent, and the brazing process is especially suitable for welding of the hard alloy and the steel in a shield tunneling machine cutter.

The application discloses an automatic testing system for single-fiber interfacial shear strength, which comprises a single fiber with a resin drop, a clamp assembly for vertically fixing the single fiber and stretching the resin drop, and a testing system for detecting the single-fiber interfacial shear strength; the clamp assembly comprises a fixing frame for fixing two ends of the single fiber and movable along the direction of a single-fiber fixing shaft, and a pair of cutters located on both sides of the connection between the fiber and the resin drop; the testing system comprises a resin drop length acquisition module, a shearing force acquisition module, a motion control module and a calculation module. The application further provides an automatic testing method. The system provided by the application can effectively improve the detection accuracy and efficiency of the single-fiber interfacial shear strength.

This invention provides a method for calculating the bearing capacity of tunnel anchors based on the rock mass quality index BQ, comprising the following steps: S1, obtaining the surface and strata conditions of the anchor site area, as well as the structural types of the main cable and tunnel anchor, and establishing a two-dimensional planar model and a three-dimensional spatial model; S2, statistically analyzing the rock strata composition and proportion on the side of the anchor body through model intersection and segmentation; S3, calculating the rock mass quality index BQ and the corrected index CBQ for each rock stratum on the side of the anchor body according to the strata conditions; S4, calculating the comprehensive rock mass quality index KBQ based on the proportion of each rock stratum on the side of the anchor body and the corrected index CBQ, and calculating the shear strength parameter; S5, calculating the allowable pull-out load on the side of the anchor body without through shear or local shear stress failure based on the shape parameters of the anchor body and the shear strength parameter on the side of the anchor body. This invention proposes a method for calculating the allowable pull-out load of tunnel anchors based on the rock mass quality index BQ, which can accurately evaluate the bearing performance of tunnel anchors.

The application belongs to the technical field of lead-free tin paste, and particularly relates to high-performance lead-free tin paste, a preparation method and application thereof; the high-performance lead-free tin paste comprises lead-free alloy powder, carbon nanotube composite and fluxing agent in a mass ratio of 12-15:0.5-1:84.5-87; the carbon nanotube composite comprises carbon nanotubes, carbon nanohorns, nano indium tin oxide, quaternary ammonium salt surfactant and liquid rosin; the fluxing agent comprises, in terms of mass percentage, hydrogenated rosin 30-40%, activating agent 5-10%, thixotropic agent 4-8%, stabilizer 1-5% and solvent to make up the balance to 100%; the high-performance lead-free tin paste provided by the application has low welding point cavity rate, high shear strength and good temperature cycle impact resistance.