262 results about "Fatigue fractures" patented technology

The invention relates to a processing method of bolts, in particular to a processing method of high-strength bolts. SCM440 and 42CrMoVNb materials are adopted for producing the high-strength bolts. The method is characterized by selecting materials, spheroidizing the materials, acid cleaning the materials and drawing wires from the materials until the materials retract to the required diameter, carrying out extrusion molding on the materials 3-4 times on a multi-station cold forging machine to form the required bolt heads and shanks, carrying out rolling to obtain the required threads and thread length and realizing the required hardness and strength through thermal processing and quench tempering. The processing method in which the cold extruding process of the invention is adopted improves the strength of the bolts, achieves the hardness and strength required by the 12.9-class and 14.9-class high-strength bolts, solves the problems of delayed fracture and fatigue fracture of the bolts under high strength, ensures the bolts to be reliably connected and not to be easily fractured during use, prolongs the lives of the bolts and meets the use requirements of various industries in the society for the high-strength bolts.

The invention relates to a device and a method for a multi-axis fretting fatigue test of a steel wire. The device comprises a base frame, a pull-torsion fatigue system, a swing loading system and a condition monitoring system, wherein the base frame comprises a base, support stand columns, bearing beams and support fixture blocks, the support stand columns are symmetrically arranged on the base; the bearing beams are respectively arranged on the tops of the support stand columns; the support fixture blocks are respectively arranged in the middle parts of the support stand columns; the pull-torsion fatigue system comprises a support system, a torsion driving system and a pull-pull fatigue system; the swing loading system comprises a swing driving system and a loading system; the condition monitoring system comprises a fretting measurement system, an axial fatigue load measurement system, a torsion measurement system and a swing measurement system. The torsion angle of the fatigue steel wire can be obtained through a crank-link mechanism by adjusting the eccentric position of an eccentric block; the multi-axis fretting fatigue test of the steel wire can be realized in the composite motion modes such as pull-pull fatigue, torsion and variable crossing angle swing and the like; the device and the method are used for disclosing the multi-axis fretting fatigue fracture mechanism of the steel wire, and carrying out quantitative evaluation on multi-axis fretting fatigue damage evolution and multi-axis fretting fatigue life of the steel wire.

A peripheral stent with individual segments reduces the occurrence of fatigue fracture failure seen in vessels and tubes having bending and twisting movement. Segments can be attached via connecting fibers that biodegrade and offer the segments freedom of movement. The segments are balloon-expandable but will not be crushed by external forces placed upon the stent. Hinges and struts provide the stent with a plastic deformation during expansion and remain elastic if exposed to an oval shape. The segments overlap each other to provide improved scaffolding of the vessel wall and a greater flexibility during delivery. A composite stent having both balloon-expandable and self-expanding character has application in the venous system.

The invention discloses a processing technology for a high-strength large hexagon head bolt used for a steel structure and belongs to a processing technology for a high-strength connecting piece. The high-strength large hexagon head bolt is processed by less or non cutting including one time of hot forging forming and three times of cold extrusion forming, wherein the hot forging forming is bolt rail forming. The first time of cold extrusion forming is screw forming, the second time of cold extrusion forming is upper screw thread section forming, and the third time of cold extrusion forming is thread forming. The invention mainly adopts the cold extrusion process for bolt production, improves the strength of the bolt, optimizes the production process of the bolt, overcomes the delay fracture and fatigue fracture of the high-strength bolt, ensures that the bolt is not easy to fracture in the use process and reliably connected, prolongs the service life of the bolt and can more meet the use requirement for the high-strength large hexagon head bolt used for the steel net frame bolt ball node in modern society.

The invention provides a process for manufacturing a high-strength (above) bolt. The process comprises the following steps: selecting a proper steel material, and cutting out a cylindrical blank with proper size; molding the head part and the rod part of the bolt by adopting cold extrusion technology; heating; manufacturing the rod part, including coarse grinding and fine grinding; detecting injury by magnetic powder; manufacturing screw; and performing surface mechanical reinforcement and corrosion resistance treatment. The process solves the technical problems of insufficient strength and fatigue fracture which are easily generated on the bolt existing in the prior art for manufacturing the high-strength bolt, and is a high-strength bolt manufacturing process capable of improving tensile and fatigue strength resistance of the bolt.

The invention discloses a vibration isolating support structure of a damping spring floating track bed and an installation method thereof, which comprises a pre-buried sleeve (9) and a vibration isolator component (10). The pre-buried sleeve (9) is cast in a floating plate type track bed body (14) as a whole, bearing convex tables (3, 4 and 17) are fixedly arranged in the pre-buried sleeve (9), a pre-buried anchor bar (8) which extends into the bed body is arranged outside of the pre-buried sleeve (9), and the vibration isolator component (10) is arranged in the pre-buried sleeve (9) and can support the floating plate type track bed body (14) and isolate the vibration of the floating plate type track bed body (14) through the pre-buried sleeve (9). The vibration isolating support structure can provide emergency safety measures under the extreme condition, so that when the fatigue fracture of a large quantity of support springs occurs suddenly, the local settlement of the floating plate type track bed can be limited within the safety limit range of a few millimeters, thereby preventing the spring breakage accident to endanger the safe running of trains, and greatly improving the security coefficient of the floating plate type track bed.

The invention, which belongs to the hydraulic system of the airplane, discloses a method for determining a fatigue life index of a hydraulic conduit. The method comprises: (1), a monitoring point easily causing a fatigue fracture is found out; (2), a tested piece the same as that of an airplane is employed; (3), a rated working pressure of a system is applied into the tested piece; (4), a foil gauge and an acceleration sensor are loaded at the monitoring point; (5), an output frequency of a vibrating table is controlled to be an inherent frequency of the tested piece; (6), output amplitudes of the vibrating table are controlled to be set successively in a range from 0,75 sigma b to sigma -1 in a descending order according to stress values generated on the conduit, a stress value and an acceleration value at the monitoring point are measured, and the number of times of cycling of the tested piece in a fracture mode is recorded; (7), according to the stress value and the number of times of cycling or the acceleration value and the number of times of cycling, a fatigue life curve of the tested piece is fitted; and (8), a stress value or acceleration value of a position close to a horizontal line on the fatigue life curve is a fatigue life index control value of a hydraulic conduit. With the method, reasonability, reliability, and durability of the airplane hydraulic system pipeline design can be evaluated effectively.

The invention discloses a friction fatigue monitoring device and a method of heavy-loading scraper conveyer chain wheels under vibration impact. The friction fatigue monitoring device comprises a base support, a driving system, a circular chain tensioning system, an impact loading system, a coal slime scattering system, and a monitoring system; the driving system comprises a low-speed servo motor, a first low-speed coupler used for connecting the low-speed servo motor with a torque sensor, a second low-speed coupler used for connecting the torque sensor with a transmission shaft, a roller A connected with the transmission shaft, driving chain wheels connected with the roller A, driven chain wheels connected with a roller B via key connection, a circular chain used for winding the driving chain wheels and the driven chain wheels; the circular chain tensioning system comprises a liner and a horizontal electric cylinder connected with a tail frame; the impact loading system comprises an impacting plate connected with a vertical electric cylinder; and the coal slime scattering system comprises a sieve and a vibration exciter. The friction fatigue monitoring device is capable of stimulating friction fatigue fracture of heavy-loading scraper conveyer chain wheels under vibration impact, and monitoring chain wheel fatigue damage and chain wheel wear situations.

The invention discloses a water-liquid nitrogen alternate fatigue fracturing and heat collection rate improving method for hot dry rock. The water-liquid nitrogen alternate fatigue fracturing and heatcollection rate improving method for the hot dry rock includes: first using high pressure water for fracturing the hot dry rock through jet nozzles in short time so as to form a major fracture, and then stopping hydraulic fracturing, injecting liquid nitrogen into the major fracture through the jet nozzles, and under the circumstance that the hot dry rock containing water generates extremely hugetemperature difference approximating 400 DEG C during the liquid nitrogen gasification process, enabling internal particles of the hot dry rock to generate various degrees of shrinkage distortion through the temperature difference so as to generate microfractures, and simultaneously fracturing the hot dry rock once more by using the expanded nitrogen which is obtained after the gasification and can easily enter the microfractures; repeating the above steps, respectively using the water and the liquid nitrogen for alternately performing fatigue fracturing so as to keep continuous quantity increase and dimension enlargement and achieve interconnection for the fractures of the hot dry rock, and thereby forming a complex and interconnected fracture seam net between an injection well and production wells; and finally, using the water as a heat carrying medium for exploiting geothermal energy. The water-liquid nitrogen alternate fatigue fracturing and heat collection rate improving method for the hot dry rock solves the problem that existing hydraulic fracturing causes blocking to a fracture channel, and improves heat collection rate.

An effective volume V_ep of a member is calculated with a stress correction amount σ_corr added to an effective stress (stress amplitude) σ_ip at each position of the member so that a fatigue strength of the member varying corresponding to an average stress varying depending on the position of the member is apparently constant at a value when the average stress on the member is 0 (zero) irrespective of the position of the member, and a cumulative fracture probability P_fp due to fatigue of the member is derived using the effective volume V_ep of the member.

In an extruder or a kneader, load (torque T) values on an input shaft portion of a screw shaft are detected by a load detector installed on the input shaft portion, then an overload condition is determined from a load mean value (T_a) and a load amplitude value (T_w) of the detected load values, and the issuance of an “abnormal” alarm and/or the stop of rotation of the screw shaft are (is) performed when an overload duration time (t₀) of maintaining the overload condition exceeds a set time (t_s). In this way the screw shaft is protected from fatigue fracture caused by application thereto of such a load as does not exceed a designed mechanical strength but causes fatigue fracture.

The invention relates to a test method for simulating a working mechanism of a drilling rig for gas drilling, and the method is used in the field of petroleum and gas drilling. The method comprises an erosion abrasion test method for the drilling rig for gas drilling, a force-bearing test method for the drilling rig for gas drilling and a fatigue fracture test method for the drilling rig for gas drilling, wherein the erosion abrasion test method for the drilling rig for gas drilling comprises the following steps: 1) before testing, fixing a testing derrick on a cement foundation and weighting out the weight of the drilling rig on a test section before testing; 2) starting different combinations of fans and then adjusting and controlling the air pressure and air quantity required by the test; 3) stopping blowing after testing for a period of time and recording the delta 2 at the moment; and 4) taking out the drilling rig on the test section and then weighting the drilling rig, thereby acquiring the abrasion loss of the drilling rig on the test section within unit time. The invention provides a convenient test method for researching the related problems of the working mechanism of the drilling rig for gas drilling in the gas drilling process, such as erosion abrasion, force-bearing and fatigue fracture failure of the drilling rig for gas drilling, and the like.

The invention discloses a preparation method for a high-strength foundation bolt. Processing steps comprise a step of casting of a rod material, wherein chemical components of a rod material blank comprise, by weight, 0.27 to 0.36% of C, 0.25 to 0.33% of Mn, 0.05 to 0.08% of V, 0.25 to 0.35% of Si, 0.01 to 0.04% of W, no more than 0.025% of P, no more than 0.035% of S, 0.45 to 0.60% of Ni, 0.20 to 0.30% of Sn and 0.45 to 0.65% of Cu, with the balance being Fe. According to the invention, a cold extruding process is used for processing of the bolt, so strength of the bolt is improved, a hardness number and a strength value required by a 12.9 high-strength bolt are reached, the problems of delayed fracture and fatigue fracture of the bolt under high stress are overcome, and the bolt has reliable connection and hardly breaks during usage, has a prolonged service life and meets usage demands for high strength bolts by a variety of industries in society.

The invention belongs to the technical field of bridge engineering, and relates to multi-axial fatigue fracture test equipment for a bridge expansion joint material and an implementation method of the multi-axial fatigue fracture test equipment. The fatigue fracture test equipment comprises an external frame, a transmission device, a concrete member, the expansion joint material, a temperature sensor and a normal loading device, wherein the concrete member comprises a fixed concrete member and a movable concrete member between which a slit used for accommodating the expansion joint material is reserved; the movable concrete member is used for realizing horizontal movement; the normal loading device comprises a solid rubber wheel which is used for realizing normal loading; the acting force of the wheel to the expansion joint material is simulated through a cylinder and a motor. Compared with the prior art, the fatigue fracture test equipment can sufficiently simulate the actual working condition of the expansion joint material under the combined action of bridge expansion change and vehicle load, so that the fatigue performance of the material under different expansion quantity, vehicle load and expansion frequency can be studied.

The invention provides a method for performing online measurement on fatigue crack propagation of organic glass and belongs to the fields of fatigue fracture mechanics test technologies and digital image technologies. According to the method, a transmission-type caustic optical technology is adopted, a CCD camera is utilized to online and continuously collect propagation processes of shadow spot images and cracks nearby crack tips of an organic glass testpiece containing cracks under different fatigue circle periods, image processing and condition selection are performed on shadow spot images in a cache region of a computer in real time, and the crack length and the crack tip stress strength factor are calculated. A caustic optical testing technology adopted in the method refers to non-contact real-time measurement, is high in intuition, simple in geometrical optics model, easy in stress strength factor calculation, convenient in data processing and accurate and reliable in test result; compared with a traditional fatigue crack propagation measurement method, the method provided by he invention is capable of omitting tedious processes of manually measuring the crack length and solving out the stress strength fact range, and avoiding the influence of crack length halt measurement on the test result.

There is derived an index FS (P) obtained by integrating the product of a probability distribution function f (√{square root over ( )}area_max) of an inclusion size √{square root over ( )}area_max of a part and a “size S (P, √{square root over ( )}√{square root over ( )}area_max) of a region of the part” where a stress amplitude σ of an acting stress exceeds a stress amplitude σ_w of a fatigue strength at each location in the case of a load being applied under a loading condition P set previously by an operator over the inclusion size √{square root over ( )}√{square root over ( )}area_max of the part with the whole region of a range where a probability distribution of the inclusion size √{square root over ( )}area_max exists set as an integral range.

A screw engagement portion between a pulley and a shaft is provided with a thread in a direction to increase the tightening torque when the pulley is driven. A breakable part broken by the axial tension produced when the tightening torque acting on the screw engagement portion is above a predetermined value, is also provided. The stress to break the breakable part is mainly a tensile stress. The tensile stress is substantially uniformly distributed in a cross section and, hence, the stress distribution of the breakable part can be relatively precisely predicted and analyzed. Consequently, the necessity of determining aspects of the breakable part, such as dimension, material, and the like, by trial and error is reduced. The breakable part can be broken without being subject to fatigue fracture.

The invention relates to a lightening protection device for a wind generating set blade. A hub is provided with a fixed lightening receiving contact device which is contacted with a lightening protection wiring board; one end of the lightening protection wiring board is fixed to the root of the blade; the fixed lightening receiving contact device comprises a lightening protection carbon brush support connected with the hub; a carbon brush is fixed on the lightening protection carbon brush support, and is connected with an electrode; and the carbon brush and the electrode are directly contacted with the lightening protection wiring board. The fixed lightening receiving contact device is arranged in the hub, the fixed lightening protection wiring board is arranged on the root of the blade, the contact surfaces of the two lightening protection parts slide mutually when the hub and the blade move relatively, and the lightening current in the blade is smoothly led out. A lightening protection lead is prevented from torsion and fatigue fracture, the set can be effectively prevented from suffering lightening due to fracture of a lightening protection wire, the safety and the stability of the set are improved, the maintenance cost of the lightening parts of the set blade is reduced, and the operating efficiency of the set is improved.

The present invention discloses a longitudinal-transverse type core wound rail sampling and fracture analysis method, which comprises: detecting a position of a transverse fatigue crack inside a rail head of a longitudinal-transverse type core wound rail; pressing the transverse fatigue crack to expose a core wound transverse fatigue fracture, observing a macroscopic morphology of the transverse fatigue fracture, and determining a core wound type; cutting the core wound rail from the transverse fatigue fracture surface along a longitudinal surface to obtain a preliminary sample; unclosing a longitudinal fatigue crack of the preliminary sample to obtain a two coupling longitudinal fatigue fracture sample, and observing a position and a size of a fatigue source of the longitudinal fatigue fracture; washing the two coupling longitudinal fatigue fracture sample, and adopting a scanning electron microscopy to observe a microscopic morphology of a fatigue source of the longitudinal fatigue fracture; and adopting a micro-zone energy spectrometer to obtain chemical components of the fatigue source of the longitudinal fatigue fracture and determine types and sources of foreign substances. The longitudinal-transverse type core wound rail sampling and fracture analysis method has a characteristic of simple operation.