289 results about "Tension stress" patented technology

The invention relates to the technical field of pumped storage power station water diversion systems, and discloses a method and device for determining a pressure pipeline reinforcement ultra-high performance concrete lining structure. The method comprises the steps that internal pressure information, radius information and lining thickness information of a target water channel, the design tensile strength of a tensile steel bar, the tensile stress borne by ultra-high performance concrete and the lining section area per unit length are obtained; calculating circumferential stress information of the target water channel based on the internal pressure information and the radius information; based on the circumferential stress information and the lining thickness information, the tensile force resultant force of the lining section in unit length is determined; determining the total sectional area of the tensile steel bars based on the tensile resultant force of the section of the lining in unit length, the designed tensile strength of the tensile steel bars, the tensile stress of the ultra-high performance concrete and the section area of the lining in unit length; determining the number of to-be-assembled reinforcements based on the total sectional area of the tensile reinforcements; and the pressure pipeline reinforcement ultra-high performance concrete lining structure is determined based on the number of the to-be-assembled steel bars and a preset steel bar arrangement rule.

The invention relates to the technical field of arc shaped energy-gathered blasting parameter design, and provides an arc shaped energy-gathered blasting parameter design method under a complex crustal stress condition, which comprises the following steps: establishing a double-hole blasting three-dimensional model comprising a rock mass, an arc explosive, an energy-gathered pipe and coupled air, applying a crustal stress boundary condition and carrying out stress initialization; setting material model parameters based on the test data; performing fluid-structure interaction dynamic response numerical simulation on the model by adopting LS-DYNA to obtain stress and strain response caused by blasting; and establishing evaluation indexes based on tensile stress, compressive stress and through crack formation, carrying out sensitivity analysis and optimization adjustment on key blasting parameters such as blast hole spacing, delayed detonation time, explosive loading amount and coupling coefficient, and finally determining an optimal blasting parameter combination in different stress states. The method can effectively meet the blasting operation requirement under the complex ground stress condition, the presplitting quality and the rock mass stability are remarkably improved, and the method has wide engineering application prospects.

The invention relates to the technical field of image processing, in particular to a concrete crack detection method for bridge engineering, which comprises the following steps: acquiring a crack area and a main tensile stress direction; dividing the crack region into a plurality of crack sub-regions; dividing the crack sub-region into a plurality of local crack sub-regions; according to the extension direction of the local crack sub-region and the main tensile stress direction, the harmful degree of the crack sub-region is obtained; according to the extension direction and the harmful degree of the adjacent crack sub-regions, the splicing degree between the adjacent crack sub-regions is obtained, and a plurality of harmful cracks are obtained; and evaluating the quality of the bridge according to the distribution positions, the harmful degrees and the areas of all the harmful cracks in the bridge. According to the method, the formation reason of the harmful crack in the bridge is analyzed, the characteristics of the harmful crack are extracted, the harmful crack is obtained according to the characteristics of the harmful crack, and the accuracy of evaluating the bridge quality is further improved according to the distribution of the harmful crack and the size of the harmful crack.

The invention discloses a prestressed anchor cable tension stress compensation device and a construction method, and relates to the technical field of anchor cable tension. The compensation problem is solved; the structure specifically comprises a concrete cushion layer, a fixed end is arranged on the inner wall of the concrete cushion layer, a plurality of anchor cables are limited on the inner wall of the fixed end, a hydraulic force application mechanism is arranged on one side of each anchor cable, and a limiting lock catch is arranged on the outer wall, located on one side of the hydraulic force application mechanism, of the fixed end; the axis of the anchor cable, the axis of the fixed end and the pulling force direction of the hydraulic force application mechanism are parallel and all perpendicular to the bearing face of the concrete cushion layer, the hydraulic force application mechanism comprises a shell fixed to the bearing face of the concrete cushion layer and a hydraulic oil cylinder fixed to the inner side of the shell, and the inner wall of the hydraulic oil cylinder is in sliding fit with a hydraulic piston. Graded tensioning and regulation of the pre-stressed anchor cable can be achieved, the final pre-stress is compensated before pre-stress construction is finished, and the situation of stress loss can be effectively avoided.

The invention relates to the field of steel member engineering, in particular to a high-strength steel combined multi-chamber box-section bent steel member and a manufacturing method thereof, and the manufacturing method comprises the following specific steps: S1, obtaining the design form of the steel member; s2, preparing an outer side chamber of the steel member; s3, prestress is applied to the outer side chamber in the axial direction of the outer side chamber so that the outer side chamber can be bent to a first form, a first eccentric value of the first form is obtained, and the first eccentric value is larger than the designed eccentric value; s4, top pressure towards the inner side of the bend is applied to the first form to a second form, the second form is in a pre-tightening state, a second eccentric value of the second form is obtained, and the second eccentric value is smaller than the designed eccentric value; s5, the outer side chamber is kept in the second form, and the matched inner side chamber is welded to obtain the steel member; and S6, after the force is unloaded, the inner side chamber is subjected to pre-tensile stress, the outer side chamber is subjected to pre-compressive stress, and the steel member is obtained. Pre-tensile stress is applied to the inner side of the steel member, pre-compressive stress is applied to the outer side of the steel member, and therefore the axial compression buckling ultimate load of the bent steel member is increased.

The invention discloses a construction method of a fan blade dynamic load experiment table, which comprises the following steps of: pre-burying a fixing piece in a bottom plate foundation, and arranging a prestressed tendon corrugated pipe; concrete is poured into the bottom plate foundation, curing is completed, and the bottom plate is formed; a truss required by the anchor bolt cage is arranged on the bottom plate; installing and fixing a prestressed steel strand and a prestressed tendon corrugated pipe of the dynamic load test bed; base steel bars are bound and fixed in a layered mode, and a construction hole channel steel formwork is installed and fixed; pouring construction is conducted from the bottom face of the bottom plate to the truss and the preset height area in sequence, and a base is formed; three groups of prestressed components are respectively arranged in three axial directions of the base and are connected with the three groups of prestressed tendons; and the three sets of prestressed tendons are alternately tensioned according to a preset tensioning sequence, so that the prestress of the three sets of prestressed tendons sequentially reaches 30%, 60% and 100% of the specified tensioning stress. The anti-fatigue performance and the anti-cracking performance of the base are improved in three directions, and the overall mechanical property of the base is good.

The invention relates to a shear key arrangement device and method for improving the crack resistance of a bridge deck in a hogging moment area of a steel-concrete combined continuous beam bridge, and belongs to the technical field of bridge engineering. Comprising a steel beam, a concrete bridge deck slab and stud shear keys arranged between the steel beam and the concrete bridge deck slab, and the rigidity of the shear keys can be adjusted according to needs so as to improve the stress performance of a concrete slab in a hogging moment area. According to the shear connectivity requirement, the total shear bearing capacity of the studs is calculated, the number of the studs is calculated according to the diameter of the selected stud type, the tensile stress of the concrete in the hogging moment area is calculated and compared with the designed allowable stress, and rigidity adjustment of the shear keys is achieved by changing the diameter and the number of the studs. And meanwhile, the total strength of the stud is kept unchanged. According to the scheme, the stress performance of the concrete slab in the hogging moment area of the steel-concrete combined continuous beam bridge can be effectively improved, meanwhile, the construction process is simplified, the safety is improved, the cost is reduced, the material performance is fully utilized, and the user experience is improved.

The invention provides an X-type six-roller mill plate shape forecasting method, and belongs to the technical field of metallurgical rolling. The method comprises the following steps: collecting equipment parameters of the X-type six-roller mill, strip characteristic parameters and corresponding rolling process parameters; dividing units and solving influence coefficients; solving the plastic deformation of the strip; carrying out iterative calculation on the roll system elastic deformation model and the strip plastic deformation model until convergence; forecasting the transverse distribution value of the pre-tensile stress of the strip during rolling; and strip outlet plate shape transverse distribution during rolling is forecasted. According to the method, on the basis of the strip plastic deformation model and the roll system elastic deformation model, the pre-tensile stress after rolling is calculated, and then strip shape forecasting is achieved.

The invention relates to the technical field of foundation piles, in particular to a precast pile stress detection system and a reinforcing and deviation rectifying method.The precast pile stress detection system comprises a plurality of pile bodies, every two vertically adjacent pile bodies are spliced, and each pile body comprises a reinforcement cage, a lower connecting flange, an upper connecting flange and a concrete pile body poured outside the reinforcement cage; the lower connecting flange is located at the head end of the concrete pile body, and the upper connecting flange is located at the tail end of the concrete pile body. A sleeve structure at a preset position is embedded into a reinforcement cage of the precast pile, reliable centering performance of an upper pile body and a lower pile body can be guaranteed through matching of a reinforcement and a hole in a flange, meanwhile, relative matching of the position of the sleeve structure is guaranteed, a complete and independent U-shaped channel is formed, a steel rope penetrates through the U-shaped channel, and the tensile stress of the steel rope is monitored by monitoring the change of the tensile stress data of the steel rope. The method can be used as a basis for judging whether the pile body is inclined or bent or not, early warning can be achieved, and reinforcing and deviation rectifying are conducted by additionally arranging the steel rope in the bending direction.

The invention relates to an outer cylinder prestress reinforced composite material pipe and a design method thereof, and belongs to the technical field of fluid conveying pressure pipelines. The pipeline comprises an outer cylinder, a middle steel cylinder and a concrete inner cylinder, the pipe diameter is 1600-5000 mm, the outer cylinder is composed of a composite material formed by mixing multiple layers of annularly-wound glass fibers and epoxy resin and is prestressed, the glass fibers account for 50%-70% of the volume of the outer cylinder, the equivalent elastic modulus, the Poisson's ratio and the tensile strength are calculated, mechanical analysis of the composite material is simplified, and the tensile strength of the composite material is improved. The middle steel cylinder is configured as a supporting layer, and the concrete inner cylinder is configured as a pressure-resistant and fluid channel. Based on the thick-wall cylinder theory, the prestress of the outer cylinder enables the concrete inner cylinder to be pressed in advance, the internal pressure tensile stress is counteracted, and the cracking risk is reduced. Under regulation and control of prestress, the outer cylinder bears main circumferential tension, tension of the middle steel cylinder is reduced, and cooperative bearing is achieved. The composite pipe has high strength, light weight and corrosion resistance, the problems that a traditional pipe is prone to cracking, high in steel consumption and short in service life are solved, and safety, durability and economical efficiency are remarkably improved.

The invention discloses an integrated thickness section gradient performance control steel member and a manufacturing method and application thereof, and belongs to the technical field of automobile and mechanical part manufacturing. The technical problems that in the prior art, when the gradient performance control steel component is prepared, hot pressing forming or welding or laser sintering or other modes are needed, the manufacturing process is complex, consumed time is long, and cost is high are solved. The method realizes performance gradient control of the same steel plate, and can be used for manufacturing parts requiring performance gradient such as an automobile anti-collision beam. The manufacturing method comprises the steps that 1, a steel plate is cut according to the unfolding size of a part; 2, the steel plate is subjected to cold machining to form a cambered surface in a bending deformation or roll bending deformation mode, and a tension stress mode and a compression stress mode are generated respectively; and 3, the steel plate is finely machined according to the part size requirement, and part manufacturing is completed. By means of the method, the steel part with the integrated thickness section gradient performance control function can be prepared, and complex processes such as steel plate hot stamping forming, welding and laser sintering are not needed.

The invention discloses welding deformation preventing equipment and method for steel-concrete composite bridge manufacturing, and relates to the technical field of steel-concrete composite bridge welding manufacturing, the welding deformation preventing equipment comprises a working frame, supporting columns, short transverse plates and long transverse plates, heat preservation assemblies are symmetrically arranged at the top of the working frame, and the heat preservation assemblies continuously preserve heat for a cross beam when the cross beam is welded with a plurality of longitudinal beams; and the heat preservation assembly comprises a heat preservation box, a heating pipe and a vertical rod, and a material receiving plate is fixedly arranged on the right side face of the working frame. The two heat preservation assemblies are symmetrically arranged on the top of the workbench. According to the heat preservation assembly, the temperature uniformity of a welding area and an adjacent area is maintained, the welding cooling rate difference is reduced, the tensile stress generated due to local rapid shrinkage and the pressure stress caused by subsequent welding extrusion are reduced, and the thermal stress gradient can be remarkably reduced through constant-temperature control; and accumulated deformation caused by repeated expansion and shrinkage inconsistency of the cross beam in the welding process is restrained.

A high-strength aluminum alloy laser additive repair method based on multi-dimensional stress regulation relates to the field of laser additive repair technology. By laser prestressing the bottom and surface of the repair area, a compressive stress layer of a certain thickness is formed at the bottom of the repair area. The pre-set compressive stress layer and the tensile stress generated by the deposited layer after the repair are offset, reducing the residual stress level and the deformation of the repaired part. After the compressive stress layer is pre-set on the surface of the repair area, the surface strengthening effect generated improves the fatigue performance of the part during service and extends its reliability service cycle. This method can reduce pores, eliminate cracks, and increase the fatigue life of the repair area. Without changing the original dynamic characteristics and usage function of the high-strength aluminum alloy structure, it performs in-situ additive repair on the surface defective areas, thereby extending its service life, reducing the maintenance cost of high-value-added parts, and increasing the service fatigue life of the repair area.

The invention relates to the field of geotechnical engineering monitoring. The invention provides a vibrating wire type stress meter and application thereof in tunnel surrounding rock stress monitoring. The device comprises a shaft sleeve, a steel bar, a fixing part, a steel string and an excitation sensing module, the end of the steel bar is located in the shaft sleeve, and the fixing part and the steel string are axially arranged in the shaft sleeve. Fixing parts are arranged at the two ends of the steel string, and the ends, away from the steel string, of the fixing parts are connected with the steel bars. The excitation sensing module is arranged above the steel string and installed outside the shaft sleeve. Wherein the middle part of the steel string is a twisted section, and two ends of the steel string are linear sections. According to the invention, the steel string preferentially releases geometric deformation under the action of axial tensile stress through the pre-arranged twisting section in the middle of the steel string, thereby effectively enlarging the amplitude change caused by micro stress, enhancing the response sensitivity of the steel string, breaking through the structural limitation that the stability and the sensitivity of a traditional stress meter are difficult to achieve at the same time, and improving the reliability of the stress meter. The method is suitable for high-reliability and high-precision application scenes in tunnel surrounding rock stress monitoring.

The present application provides a pre-stressed anti-vibration hammer and a pre-stress determination method and system, the pre-stressed anti-vibration hammer comprising a gapped steel strand, an assembly integrated hammer head and an anchoring clamp, wherein the gapped steel strand comprises a central layer round wire, a middle layer molded wire and an outer layer round wire from inside to outside; a gap is provided between the central layer round wire and the middle layer molded wire, and the gap is filled with a lubricating grease, such that the friction resistance between the central layer round wire and the middle layer molded wire is reduced, and pre-applying a stress to the central layer round wire is facilitated; the middle layer molded wire is of an arch structure, and the arch body structure increases the moment of inertia for a circle center, such that the bending rigidity of the steel strand is enhanced; and two ends of the central layer round wire are connected with the assembly integrated hammer head, the anchoring clamp is assembled in a hollow portion of one end of the assembly integrated hammer head away from the central layer round wire, and is configured to clamp the central layer round wire to which a target stress is pre-applied, a tensile stress generated by an impact load firstly counteracts the tensile stress generated between the outer layer round wire and a middle layer strand after the stress is pre-applied, and the bending rigidity of the steel strand can be increased.

The invention relates to the technical field of coated steel plate production, in particular to a high-straightness coated steel plate and a production method thereof. During production, the following processes are controlled: 1) finishing, namely determining finishing inlet tension T1, finishing outlet tension T2 and finishing rolling force F according to the thickness h and yield strength sigma s of strip steel, and ensuring that a tensile stress value formed by a tension roller is greater than a pressure stress value formed by the rolling force; and 2) coiling: adopting double coiling mechanisms to ensure that the strip steel does not generate longitudinal warping when the strip steel passes through a second turning roller and is coiled. Based on the forming mechanism of the plate shape defect, stable control over the plate shape of the coated steel plate finished product is achieved by improving the finishing parameter adaptation degree and improving the coiling equipment and technology, and great significance is achieved for improving the straightness of the coated steel plate finished product and improving the production efficiency and product competitiveness of the coated steel plate.

The utility model discloses an anchoring crack surrounding rock internal osmotic pressure-stress-deformation deep layer sensing device which comprises a plurality of hollow rod bodies, adjacent rod bodies are connected through a tensile stress sensor, through holes are formed in the side faces of the rod bodies, osmotic pressure monitoring assemblies communicated with the through holes are arranged in the rod bodies, and end axial force monitoring assemblies are arranged at the outer ends of the rod bodies. The data acquisition component is in communication connection with the tensile stress sensor, the osmotic pressure monitoring component and the end axial force monitoring component at the same time, and the data acquisition component is also in communication connection with the data processing component. The device can realize cooperative monitoring of internal and external transmission deformation and pore water pressure in the rock mass under the action of disturbance stress, and realizes comprehensive perception of the stability and safety of the rock mass.

The tension adjusting bolt-steel belt prestress device comprises a tension steel belt and a tension adjusting bolt assembly, the two ends of the tension steel belt are fixed to the two ends of the bamboo beam through fastening assemblies correspondingly, and the tension adjusting bolt assembly is used for sharing tension borne by wood fibers on the lower layer of the bamboo beam to be reinforced. Therefore, the reinforcing effect is achieved; the tension adjusting bolt assembly is arranged in the middle of the bamboo-wood beam, located between the tension steel belt and the tension adjusting bolt assembly and used for adjusting the distance between the tension steel belt and the wood beam, so that the tensioning degree of the tension steel belt is adjusted, prestress is applied to the bamboo-wood beam, initial deformation can be effectively reduced by applying prestress to the beam, and the tensile strength of the bamboo-wood beam is improved. The influence caused by creep deformation can be reduced or eliminated by applying prestress in the using stage, and two-stage deformation control is achieved, so that deformation of the bamboo beam is controlled, stress distribution of the section is adjusted, beam bottom tensile stress is reduced, the overall bearing capacity of the bamboo beam is improved, and the damage form of the beam is improved.

The invention relates to the field of structural reinforcement and new construction, in particular to a grid material oblique arrangement method for improving the shock resistance of a concrete structure. Comprising the following steps: preparing grids; the grids obtained in the step S1 are obliquely arranged on the surface of a concrete matrix; spraying a bonding layer on the upper part of the grid, so that the grid is bonded with the concrete matrix; scraping mortar on the upper part of the bonding layer; the fiber direction of the grid is changed to be approximately consistent with the main tensile stress direction of an earthquake, so that the fiber efficiently transfers force along a main stress trace line, the shear strength and stability of a concrete structure are improved, meanwhile, concrete is sprayed on the upper portion of the grid, a concrete base body and the grid are bonded together, a layer of mortar is further coated on the upper portion of the bonding layer in a blade coating mode, and the structure is compact. And the grid, the bonding layer and the mortar form a composite protective layer of the concrete structure, so that the stability of the concrete structure can be further improved.

The invention relates to the technical field of laser welding, in particular to a laser welding seam post-processing method which comprises the following steps: step 1, standing a laser-welded seam; and 2, at least one time of weld joint mechanical shock treatment is conducted on the weld joint subjected to standing treatment in the step 1. Compared with the prior art, the method has the advantages that equipment used in the method is simple, the process control difficulty is low, and residual tensile stress on a welding seam after laser welding is effectively removed, the grain structure of the welding seam is improved and the corrosion resistance and mechanical property of a welded material are improved through mechanical impact type post-treatment under certain parameters.

This invention relates to a double-sided welding process for U-rib plates used in the construction of orthogonal steel structure bridges or the reinforcement of dangerous bridges. The process includes: welding the inner weld of the U-rib plate in the patch section using a small, dedicated U-rib welding robot via gas metal arc welding (GMAW); removing the welding wire feeder and the GMAW robot from the opening of the next adjacent patch section; cleaning the root of the outer weld of the patch section; welding the outer joint of the U-rib plate using GMAW; and using ultrasonic impact to impact the outer weld of the patch section to reduce welding tensile stress. This invention addresses the problem of double-sided welding of the inner and outer joints of the U-rib patch section in orthogonal steel structure bridges, offering both economic and social benefits.

The present invention discloses a vibration mechanical forging assisted arc cladding remanufacturing method for large pile legs of marine engineering equipment. In this method, during the arc cladding process, a high-hardness cemented carbide ball is used to forge the high-temperature cladding layer. By controlling the strain rate, deformation layer thickness, dynamic recovery and dynamic recrystallization processes, the coarse columnar crystals in the cladding layer are effectively eliminated, the grains are refined, irregular pore defects and residual tensile stress are reduced, the mechanical properties of the metal repair layer are improved, and the strength and plasticity are improved at the same time, so that the repair layer can also have high mechanical properties without rolling and heat treatment. In addition, the present invention can perform transverse forging in the vertical cladding direction of the cladding layer through the reciprocating vibration of the impact gun, forming a larger forging area, effectively improving the regulation effect on the microstructure of the cladding metal, more effectively achieving the shape regulation of the cladding layer metal, and improving the mechanical properties of the repair layer.

The present application relates to the technical field of structural engineering and discloses a limited-slippage connecting structure and a construction method of the connecting structure. The limited-slippage connecting structure comprises a prefabricated plate, a concrete plate, a welding nail and a flexible sleeve. The concrete plate is arranged on the prefabricated plate, the welding nail is located in the concrete plate, the welding nail comprises a nail column and a nail head arranged at one end of the nail column, the other end of the nail column is connected with the prefabricated plate, and the flexible sleeve is sleeved on the nail column. The limited-slippage connecting structure can provide a proper slippage amount, effectively reduce the tensile stress of the concrete plate, and improve the long-term performance and durability of the concrete plate. At the same time, the limited-slippage connecting structure also has an anti-lifting effect to resist the separation and lifting of the concrete plate, reduce the sudden increase of the partial segment shear force caused by the excessive release of the combined effect, and improve the stress state of the transition section concrete plate.

The utility model relates to the technical field of geotechnical engineering and railway construction, and particularly discloses a vibration reduction and deformation resistance steel sheet pile for deep foundation pit engineering close to an existing railway line, which comprises a steel sheet pile, a vertical load-bearing steel bar, a connecting component, a vibration isolation and reduction interlayer and a protective steel plate. By adopting a composite structure form of steel sheet piles, vibration isolation and reduction interlayers and vertical load-bearing steel bars, the structure reinforcing function and the vibration isolation function are organically combined, and a brand-new supporting structure system is formed; the vertical stressed steel bars are matched with the vibration isolation and reduction interlayer and the damping spring shock absorbers, the vertical stressed steel bars mainly share tensile stress to improve the stress state, the vibration isolation and reduction interlayer mainly absorbs vibration energy to weaken vibration transmission, and the comprehensive performance of the steel sheet pile is remarkably improved through the combined action of the vibration isolation and reduction interlayer and the damping spring shock absorbers; meanwhile, according to the scheme, by optimizing arrangement of the vertical load-bearing steel bars, selection of vibration isolation and reduction materials and arrangement of connecting components, the whole structure has the good reinforcing effect and vibration reduction performance, and construction convenience and economical efficiency are taken into consideration.

The present application belongs to the technical field of wind power equipment connecting structure, and particularly relates to a threaded connection assembly, a blade device and a wind power equipment. The threaded connection assembly comprises: an inner threaded connecting piece; and an outer threaded connecting piece, a radially outer side surface of the outer threaded connecting piece is provided with an outer thread, the outer thread is threadedly matched with the inner thread, in the axial tensile stress direction of the outer threaded connecting piece, the outer thread and the inner thread form a plurality of threaded areas, and an axial gap exists between the front side surface of the outer thread of the outer thread and the rear side surface of the inner thread of the inner thread adjacent to the front. Wherein, in the axial tensile stress direction, the axial gap in the threaded area in the front is greater than the axial gap in the threaded area in the rear. Through the technical scheme of the present application, different axial gaps are arranged between the threads in different threaded areas, so as to change the stress distribution according to the axial tensile stress change, so that the overall stress distribution is more uniform, which is beneficial to prolong the service life and reduce the maintenance cost.

The invention provides a method for reducing internal cracks of a soft reduction continuous casting billet, which comprises the following steps: S1, establishing a three-dimensional finite element model comprising a casting billet and a pair of reduction rollers, and the three-dimensional finite element model is used for simulating stress distribution in a deformation process when the casting billet is subjected to soft reduction processing under the reduction rollers; s2, a three-dimensional finite element model is adopted, and the shear stress distribution condition of the casting blank within the brittleness temperature range under each set of soft reduction machining parameters is simulated; the maximum chamfering angle corresponding to the situation that the longitudinal corner of the machined casting blank does not collapse serves as the optimal chamfering angle; and S3, a three-dimensional finite element model is adopted, the tensile stress distribution condition of the casting blank in the brittleness temperature range under the soft reduction machining parameters is simulated, and the chamfer length when the maximum tensile stress in the brittleness temperature range is minimum is taken as the optimal chamfer length. By optimizing the chamfering structure of the casting blank, solidification of the edge blank shell is effectively avoided, and the internal defect rate of the casting blank is reduced.

The utility model discloses an anti-fracture lifting table transmission shaft, which relates to the technical field of lifting tables, and comprises a movable component and a fixed component, the bottom end of the movable component and the top end of the fixed component are installed in a sliding manner, and the fixed component comprises a fixed shaft. Meanwhile, a plurality of reinforcing ribs are evenly distributed on the inner wall of the movable shaft in the axial direction, the bending resistance and torsional rigidity of the movable shaft are enhanced, when the transmission shaft is vibrated or impacted, the high-damping filler can absorb energy, reduce the vibration amplitude and improve the stability of the transmission shaft, the movable shaft meets the overall strength requirement, meanwhile, the weight of the shaft is reduced, and the rotational inertia is reduced; and meanwhile, the nitriding layer is additionally arranged on the outer wall of the movable shaft, so that the hardness and the wear resistance of the shaft surface can be improved, residual compressive stress can be generated on the surface, part of tensile stress generated during working is counteracted, the fatigue life of the transmission shaft is further prolonged, and the fracture resistance of the transmission shaft is further improved.

This invention discloses a ribbed prestressed concrete composite floor slab and its design method, relating to the field of prefabricated building structure design technology. The method includes calculating the total bearing capacity of prestressed steel bars required in the primary load-bearing direction and the total bearing capacity of ordinary steel bars required in the secondary load-bearing direction, based on the span and load parameters of the target floor slab. The reserved extension lengths of the two types of steel bars are determined according to the precast portion and the total thickness of the composite. The types, spacing, tensile stresses, and precise curve trajectory coordinates of the prestressed steel bars within the precast concrete are designed in detail, and the types, spacing, and arrangement coordinates of the ordinary steel bars are also designed. An internal reinforcement space model of the precast portion is generated based on the coordinate parameters of all steel bars, and a three-dimensional structural model of the ribbed precast template is generated by combining the geometric boundaries. This method achieves refined reinforcement design and digital expression of manufacturing information.

According to the prestress anchoring structure and method, through the mode of drilling large and small anchor rod holes, namely the mode of drilling a large hole in an excavation part of an extended tunnel and drilling a small hole in a surrounding rock part of the extended tunnel, an anchor rod is integrally divided into two parts, and application of prestress and grouting of the anchor rod are carried out in a segmented mode; the anchor rods of the surrounding rock part of the extended tunnel still have high tensile stress, so that the stability of the surrounding rock is effectively controlled, and the construction safety is ensured; in addition, the combination of the high-elasticity sleeve and the non-return component is adopted, and the application of the axial prestress of the anchor rod in a narrow area can be realized; compared with a common anchor rod, the prestress anchoring structure and the anchoring method can more effectively control the stability of surrounding rock mass after tunnel expanding excavation in the tunnel expansion project, guarantee the project safety and have high practical value.

The invention discloses a method for reducing residual stress of a rail web of a steel rail, and belongs to the technical field of steel rails. The residual stress of the rail web of the steel rail is reduced by controlling the parameters of the tempering temperature, the heating time, the heat preservation time and the cooling mode in the tempering treatment. Research on steel rail web residual stress is a key field for guaranteeing safe operation of railways. The residual stress of the steel rail mainly originates from a manufacturing process and a service environment, a rail web easily forms pressure stress due to the fact that the cooling speed is higher than that of a rail head in the cooling process, the middle of a rail bottom generates tensile stress due to cooling lag, and the risk of bending deformation of the steel rail is increased due to the asymmetric distribution, so that the research on reducing the residual stress is very necessary.