81 results about "Fracture failure" patented technology

The invention relates to an aero-engine stator part crack critical dimension comprehensive determination method and system, and belongs to the technical field of aviation, the method comprises the following steps: obtaining an aero-engine typical hot end stator part geometric model and material parameters, and carrying out static strength analysis according to fluid-thermal-solid coupling load characteristics in actual working conditions; inserting an initial crack into a first principal stress plane of a dangerous part of the real component, carrying out crack propagation simulation to determine a crack propagation path, and calculating a critical crack size of a dangerous point; analyzing critical crack sizes under different failure modes, such as cooling failure and buckling failure; and integrating analysis results under the multi-failure mode, and determining a comprehensive critical dimension as a final judgment standard. According to the method, through combination of fracture failure and function failure analysis, accurate judgment of the critical dimension of the crack is realized, limitation of a traditional single fracture criterion is broken through, comprehensive function failure analysis is realized, the accuracy of a maintenance decision is remarkably improved, and a scientific basis is provided for condition-based maintenance decision.

The invention relates to the technical field of polymer foam materials, in particular to a preparation method of gradient cross-linked pearl wool microcellular foamation.According to a gradient cross-linked network constructed through a two-stage cross-linking technology, collaborative optimization of the performance of a surface layer and the performance of a core part of the material is achieved, a compact three-dimensional net-shaped structure is formed in a high-cross-linking-degree area of the surface layer, and the core part of the material is expanded; the surface hardness, wear resistance and tear resistance of the material are remarkably enhanced, external impact and friction damage are effectively resisted, the low-crosslinking-degree area of the core part retains the moderate movement capacity of a polymer chain, the material is endowed with excellent energy absorption characteristic and flexibility, and the material has good mechanical properties when bearing complex stress. Stress dispersion can be achieved through surface layer-core part synergistic deformation, fracture failure caused by local stress concentration is avoided, meanwhile, a gradient cross-linked network provides a controllable melt strength gradient field for supercritical fluid foaming, and therefore accurate control over the size and distribution of foam holes is achieved in the single-time foaming process.

The invention provides an ice damage multi-physical synchronous measurement system. The ice damage multi-physical synchronous measurement system comprises a motion monitoring control system, an ice load measurement system, a non-contact deformation measurement system, a temperature and pressure monitoring system, a high-speed camera shooting acquisition system, a multi-physical quantity measurement synchronous triggering acquisition system and a multi-degree-of-freedom self-adaptive measurement integrated mobile platform, the motion monitoring control system is used for monitoring and feeding back displacement, speed and output force of the impact head in the execution process controlled by the servo control system; the ice load measuring system comprises a load force sensor which is used for calibrating system errors in the same experimental environment and providing output compensation for the motion monitoring control system; and the high-speed camera acquisition system is used for recording transient image information in the ice material fracture failure process and measuring and calculating the crack propagation speed through proportional calibration. Important parameters in the submerged jet flow and mechanical cooperation ice damage test process can be accurately monitored and recorded, and the accuracy and repeatability of the test are guaranteed.

The invention provides a bulletproof structure and a preparation process thereof. The bulletproof structure comprises a ceramic layer plate, a titanium alloy layer plate, an aramid fiber layer plate, an ultra-high molecular weight polyethylene layer plate and a honeycomb heterogeneous anti-impact layer which are sequentially stacked, the ceramic layer plate and the titanium alloy layer plate, the titanium alloy layer plate and the aramid fiber layer plate, and the aramid fiber layer plate and the ultra-high molecular weight polyethylene layer plate are connected through a large-surface-density polyurethane resin adhesive film; wherein the ceramic laminate is made of nano modified B4C ceramic or nano modified TiB2 ceramic. The impact resistance of the base body can be improved, incoming projectiles are partially eroded and decomposed in the residence stage of the ceramic plate, then a large number of cracks are formed on the surfaces, conical fracture failure is achieved, bullet energy is decomposed greatly, the projectiles are eroded to deform and break, high temperature of combustion of the projectiles is blocked, and the impact resistance of the ceramic plate is improved especially for large-momentum and high-invasion-force projectiles. The invention particularly relates to a 12.7 mm armor-piercing combustion bomb and a kinetic energy warhead below.

The invention belongs to the technical field of ductile metal fracture analysis, provides an explicit cohesion phase field material point method, and provides a brand new numerical calculation method for metal dynamic fracture damage research. In the method, aiming at the problems of large deformation and high-speed impact in ductile metal spallation and penetration failure, a cohesion phase field material point method and a marble compliant contact algorithm are innovatively provided. The cohesion phase field model can well describe the damage softening and fracture behaviors of the tough metal. The marble compliant contact algorithm effectively suppresses the problems that the speed of impacting the contact surface is over-oscillated and the normal vector outside the contact surface is difficult to calculate. Then, a control equation of dynamic fracture of the ductile metal is deduced through a Lagrange equation, and the control equation of the coupling displacement and cohesion phase field model is discretized in a material point method framework; and finally, a phase field-displacement field interlaced solution strategy is adopted to stably and efficiently solve the problems of contact, large deformation and other strong nonlinear large-scale ductile fracture damage.

The utility model discloses a universal joint lightweight forge piece forging die which comprises an upper pressing die and a lower fixed die which correspond to each other up and down, a cross-shaped die cavity is defined between the bottom face of the upper pressing die and the top face of the lower fixed die, the cross-shaped die cavity comprises a center cavity and four shaft cavities, and the structures of the cross-shaped die cavity in the upper pressing die and the lower fixed die are symmetrical up and down; a protruding block is arranged at the center of the bottom face of the center cavity in the lower fixed die, the top face of the protruding block is a round face, four ribs are evenly arranged on the edge of the round face of the protruding block, and the outer end of each rib is connected with the inner end of one shaft cavity. According to the utility model, the internal structure of the cross-shaped die cavity is improved, so that the strength of the easy-to-fail part of the universal joint forge piece is enhanced, the deformation resistance is increased, the stress is reduced when the universal joint forge piece is stressed, the fracture failure rate of the universal joint in the use process is reduced, and the purposes of prolonging the service life of the universal joint and reducing the failure rate of the universal joint are achieved; meanwhile, the weight of the universal joint forge piece is effectively reduced, and the purpose of light weight is achieved.

The present invention discloses a method for identifying the initiation, expansion, and fracture failure of asphalt fatigue cracks. The present invention uses a dynamic shear rheometer to perform a scanning test on an asphalt sample, collects torque T and deflection angle #imgabs0# data, and sequentially obtains the asphalt fatigue crack length a and the energy release rate G during the asphalt fatigue crack growth process. Finally, based on the evolution relationship between the asphalt fatigue crack length a and the number of cyclic loading cycles N, the dividing point between the fatigue crack initiation process and the expansion process is calculated, and the peak point of the energy release rate G is used as the critical point of asphalt fatigue failure. The present invention systematically solves the current problems of dividing asphalt into different fatigue stages under dynamic shear fatigue loads and determining the critical point of fatigue failure, and can finely analyze the fatigue process and behavioral characteristics of asphalt materials.

The present invention provides a method for calculating the equivalent strength of reinforced concrete, which includes establishing an equivalent compressive model of reinforced concrete material; calculating the elastic limit stress and strain of reinforced concrete and the peak strength and strain of reinforced concrete; calculating the fracture failure strength and strain of reinforced concrete; an equivalent tensile model of reinforced concrete material; calculating the peak strength and strain of reinforced concrete and the yield strength and strain of reinforced concrete. In the established equivalent compressive model of reinforced concrete material, the compressive model determined by three key points can accurately and efficiently express the compressive mechanical properties of reinforced concrete material. In the established equivalent tensile model of reinforced concrete material, the compressive tensile model determined by two key points can accurately and efficiently express the tensile mechanical properties of reinforced concrete material. The established equivalent constitutive model of reinforced concrete has few parameters, is simple to calculate, and can quickly calculate the strength of reinforced concrete material.

The invention relates to a phase change clay fracture performance and failure characteristic test device, a prefabricated crack soil beam test piece, a servo motor, a sensor and a camera unit are arranged on a three-point / four-point bending moment loading frame, and the servo motor and the sensor are connected with a data acquisition unit. The invention also relates to a phase change clay fracture performance and failure characteristic test method. According to the invention, the compressive fracture process of the phase-change clay can be truly simulated, the fracture performance and damage characteristics of the phase-change clay in various complex fracture modes (including I-type, II-type and I-II-type fracture modes) can be accurately and reliably measured, and a premise can be provided for research of the fracture characteristics of the phase-change clay and analysis of core wall fracture damage and hydraulic fracture problems.

The present application relates to a kind of spot I type nugget fracture failure constitutive model construction method, belong to the fracture mechanics and numerical simulation method technical field of spot welding joint.The technical scheme of the present application is: the parameter construction of constitutive model is carried out, parameter is directly used for spot welding joint related finite element simulation;Spot welding joint is bonded with uniaxial tensile fixture, and the tensile experiment of nugget fracture form is completed under tensile testing machine and the load-displacement curve and maximum load are recorded;Finite element model is constructed and tensile displacement is calculated;Convert and correct stress-displacement curve in combination with measured nugget area, solve maximum tensile stress and fracture energy, parameter is substituted into model and the precision of replacement connection mode is verified.The beneficial effects of the present application are: the accurate construction of spot I type nugget fracture failure constitutive model is realized, which provides standardized mechanical parameter support for spot welding joint structure reliability design and welding process optimization, and significantly improves the accuracy and engineering application value of finite element simulation.

The invention discloses a material deformation simulation parameter measurement method and device based on a GISSMO failure model, a computer system and a storage medium. By combining experimental data with simulation calibration of a GISSMO failure model, high-precision parameterization representation of material deformation and fracture behaviors is realized. A real stress-strain curve (including an elastic stage and a plastic stage) obtained by a tensile fracture experiment is compared with a simulation curve (including an elastic stage, a plastic stage and a failure stage) output by a GISSMO model, so that the full-process simulation precision of the material from elastic deformation and plastic flow to fracture failure is ensured; and the problem of rigidity overestimation or deformation prediction deviation caused by neglecting the failure stage in the traditional method is solved.

A kind of casting method of large lip, it is related to mining machinery technical field, in order to prevent lip fracture failure, by using easy cutting piece on large heat riser, adopt impact form to remove riser, on the premise of meeting basic feeding, as far as possible to reduce the generation of surface microcracks from the source, further, customer standard requires that surface crack should not be less than 7mm, before quenching and tempering, all cracks found are removed by welding repair or grinding, in the process of heat treatment, two Φ120-Φ160mm reinforcing bars are set to prevent crack caused by deformation, after quenching and tempering, all defects greater than 3mm are removed by grinding, etc., suitable for wide range of popularization and application.

The invention provides a fastening connection system reliability dynamic modeling method which comprises the following steps: establishing a reliability model of fracture failure and loosening failure of a single threaded connection pair to obtain the reliability of the single threaded connection pair in different failure modes; based on a multi-competitive failure mode of a single threaded connection pair, establishing a dynamic reliability model of the fastening connection system under consideration of dynamic degradation by introducing an exponential decay model; wherein the exponential decay model is used for representing the decay process of the bolt pre-tightening force and strength along with time; and constructing a general generation function of each threaded connection pair for performing dynamic reliability calculation on the dynamic reliability model of the fastening connection system, and determining an optimal maintenance interval. According to the method, the multi-competition failure problem of fracture failure and loosening failure of a single threaded connection layer is effectively solved, the method better conforms to engineering practice, calculation is convenient and easy, implementation is easy, and engineering technicians can conveniently master the method.

The invention relates to the technical field of basalt fiber anchor rods, and discloses a high-toughness-shear-resistant basalt fiber anchor rod which comprises a rod body, annular grooves are evenly formed in the axial outer wall of the rod body, a limiting mechanism is arranged on the lower portion of the outer wall of the rod body in a sleeving mode, an abutting mechanism is arranged on the portion, located above the limiting mechanism, of the outer wall of the rod body, and the limiting mechanism comprises a lock. The lockset is arranged on the lower portion of the outer wall of the rod body in a sleeving mode, a round hole is formed in the middle of the lockset, the inner wall of the round hole is slidably connected with the rod body, and horizontal sliding grooves are symmetrically formed in the two sides of the bottom end of the lockset. When the tensile strength of the anchor rod is close to the ultimate tensile strength of the anchor rod, fracture failure of the anchor rod is avoided through the interlocking, anti-sliding and relocking effects among the lockset, the clamping piece and the convex bodies on the surface of the basalt fiber anchor rod, and surrounding rock deformation energy absorption is achieved. The shear-resistant sleeve can effectively disperse shear force and improve shear strength, and meanwhile brittle failure caused by local stress concentration is avoided.

The invention relates to a steel fracture cleaning solution as well as a preparation method and application thereof, and relates to the technical field of fracture failure analysis. The steel fracture cleaning solution comprises the following components: citric acid, hydrochloric acid, glycerol, a corrosion inhibitor and water. According to the fracture cleaning fluid, the raw materials are extremely easy to obtain, the cost is low, and the fracture cleaning fluid has extremely high use value. In addition, the invention further elaborates the preparation and application scenarios of the steel fracture cleaning fluid in detail. When the steel fracture cleaning solution prepared by the invention is used for cleaning a steel fracture sample in a service state, the cleaning time can be remarkably shortened, and the cleaning efficiency is improved. And after processing, a fracture observation surface with a large-area oxide layer effectively removed can be obtained, so that the real morphology of the steel fracture is precisely reduced, related information of corrosion components of the steel fracture is obtained, and reliable basic data is provided for subsequent steel performance evaluation and failure analysis.

This invention provides a method, apparatus, computer equipment, and medium for predicting the failure of a wheel disc, relating to the field of digital twin technology. The method includes the following steps: conducting a uniaxial quasi-static tensile test on a tensile test specimen to obtain the engineering stress-strain curve of the wheel disc; converting the engineering stress-strain curve into a true stress-strain curve; constructing a wheel disc failure prediction model under deterministic conditions based on the true stress-strain curve; performing sensitivity analysis on the quantified parameters of uncertainty; obtaining sample data under different working conditions through finite element calculation based on key parameters; constructing a maximum strain proxy model for the wheel disc based on the sample data; inputting the key parameters into the maximum strain proxy model to obtain the confidence interval of the wheel disc's rotational speed at the time of failure. This scheme, by constructing a maximum strain proxy model for the wheel disc, achieves high-precision full-domain simulation of the wheel disc's failure process, solving the problems of limited test measurement points and insufficient simulation accuracy.

The application discloses a kind of based on ENDB sample dynamic fracture toughness testing device, including test auxiliary device and Hopkinson bar experimental device, Hopkinson bar experimental device includes incident bar and transmission rod, test auxiliary device includes load transmission structure, dial, support seat component, sample fixing assembly and auxiliary fixing assembly, dial, sample fixing assembly and support seat are fixed by distance adjusting component of three through three connections.This application can accurately adjust the included angle α between loading rod and prefabricated crack, so that the dynamic fracture toughness test of a variety of different angles III and I, III mixed type can be realized, the dynamic fracture toughness test experiment of a variety of diameter sizes ENDB sample can be satisfied, and a certain fracture failure play space is reserved between dial and sample, to improve sample damage effect and the accuracy of experimental results.The whole device has no direct or indirect contact with the outside world, reduces the loss of energy, improves the accuracy of experimental results.

The present application relates to the field of ocean engineering and mechanical engineering technology, in particular to a fan blade crack propagation analysis method and device considering real marine environment. The method considers real marine environment working conditions, performs dynamic simulation analysis on the fan blade, determines the load distribution information borne by the fan blade and loads it on the finite element model of the fan blade, determines the fatigue hot spot area according to the finite element fatigue damage analysis result and performs crack arrangement. Through the finite element simulation result, the stress intensity factor of the crack tip is calculated and crack propagation simulation is performed to evaluate the fracture failure risk of the fan blade under real marine environment. The fan blade crack propagation analysis idea under complex stress conditions is proposed, which can prevent equipment failure and risk caused by blade fracture, provide a scientific basis for fan maintenance and operation, and thus reduce economic losses caused by fan blade failure.

The present application relates to the technical field of virtual reality tactile feedback, and discloses a preparation method of a virtual reality multi-modal tactile feedback hardware device, which comprises the following steps: a serpentine structure driving unit is prepared through wire winding and setting; the serpentine structure driving unit is embedded and cast in a flexible base, and then electrical connection and a power supply module integration are completed to obtain a tactile feedback hardware device capable of independent multi-channel driving. The serpentine structure driving unit is prepared by adopting a wire winding and setting process, which replaces a traditional plate cutting processing mode, can effectively avoid burrs and micro-cracks generated at the edges of the driving unit, completely retains the material performance of the shape memory alloy, significantly improves the fatigue life and deformation precision of the driving unit, and reduces the risk of fracture failure in the long-term use process.

The invention discloses a method for determining size-effect-free fracture parameters of an MGPCC material and a method for evaluating the performance of the MGPCC material, and belongs to the technical field of material performance evaluation. The method specifically comprises the following steps: firstly, preparing MGPCC test pieces with different sizes, seam height ratios and span-height ratios, and carrying out a three-point bending fracture test to obtain related data; then calculating the equivalent crack length and the virtual crack propagation amount, and further determining fracture parameters, such as fracture toughness KIC and tensile strength ft; and a mean value and a standard deviation are obtained through normal distribution statistical analysis, and finally the size-effect-free fracture parameters are determined. According to the method, the influence of various factors on fracture parameters is comprehensively considered, the normal distribution hypothesis is verified by adopting K-S verification, and the reliability of data is ensured. The fracture failure curve is constructed based on the determined fracture parameters, the fracture failure type of the MGPCC material can be accurately evaluated, and a scientific basis is provided for engineering design.

The application relates to a tunnel structure connecting joint capable of crossing an earthquake fracture zone, which comprises a hole body, a lining and a waterproof protective layer, the lining is composed of a plain concrete layer and a steel plate layer, the steel plate layer comprises an outer steel plate, a rubber layer and an inner steel plate, the outer steel plate and the inner steel plate are tightly attached to the rubber layer respectively but are not fixedly connected, the steel plate layer is arranged in the center of the plain concrete layer and is continuously arranged along the tunnel section, the concrete strength grade of the joint area is lower than that of the non-joint area, so that the ductility and energy consumption capacity are enhanced, compared with the prior art, under the action of small earthquakes and medium earthquakes, the steel plate layer and the plain concrete layer work together to ensure the overall rigidity and strength of the joint, under the action of large earthquakes and extremely rare earthquakes, the two longitudinal steel plates can relatively slide to drive the expansion and contraction of the concrete layer in the joint, the two transverse steel plates can extrude the rubber layer to dislocate and deform, tunnel fracture and damage are avoided, and post-earthquake repair is facilitated.

The invention relates to construction and application of a concrete nonlinear microscopic fracture analysis model under temperature change. In order to solve the technical problem that in the prior art, the coupling effect of the temperature change and the size effect is not considered at the same time, so that the size-effect-free tensile strength and fracture toughness of the concrete after high temperature are accurately determined through small-size test data, relative size and temperature coupling variables are introduced; constructing a virtual crack propagation amount calculation model aiming at the lightweight aggregate concrete and the common concrete; establishing a microscopic fracture theory based on small-size test piece test data inversion size-effect-free material parameters; introducing normal statistical analysis to determine a 95% guarantee rate confidence interval; and constructing a fracture failure whole curve and a peak load prediction model. Unification of test standards is achieved, the influence of the size effect is effectively eliminated, the prediction precision of the mechanical property of the concrete after high temperature is remarkably improved, and reliable technical support is provided for safety evaluation of the concrete structure after a fire disaster.

The present invention belongs to the field of abrasive belt grinding technology. Currently, the grinding method for gears is usually grinding with a grinding wheel, and the grinding direction is along the gear axis. Since the texture direction of most gear grinding is along the axis, this direction is sensitive to bending fatigue stress and easily causes bending fatigue fracture failure of the gear. Therefore, grinding along the gear tooth profile direction is selected. At the same time, due to the involute tooth profile of the gear, the tooth groove width corresponding to the part below the pitch circle to the root circle is small, and the general abrasive belt grinding mechanism is large in size and difficult to grind. If a particularly small abrasive belt grinding mechanism is used, the efficiency and performance cannot be guaranteed. Therefore, a precision abrasive belt grinding mechanism for constant linear speed grinding along the gear tooth profile direction is proposed, which includes a workbench, a clamping device base is provided on the top of the workbench, a clamping device is provided on the clamping device base, and a rib is provided on the clamping device.

The utility model relates to a reinforced mould pressing tray which comprises a panel, first foot piers and a brace plate, the lower portion of the panel and the first foot piers are integrally formed, the length of the first foot piers is larger than the width of the first foot piers, and the brace plate is located below the first foot piers and fixedly connected with the first foot piers. The length direction of the first foot pier is perpendicular to the length direction of the fixed brace plate. The length direction of the first foot piers is perpendicular to the length direction of the brace plate fixedly connected with the first foot piers, when the pallet fork is perpendicular to the brace plate to push the pallet, the length direction of the first foot piers is the same as the stress direction, the structural strength of the first foot piers in the stress direction is improved due to the longer length, the first foot piers are not prone to fracture and damage, and the service life of the pallet is prolonged. The problem that a tray foot pier is prone to breakage when a pallet fork is pushed is solved.

The utility model relates to permanent magnet synchronous motor technical field especially relates to a kind of anti-fracture elastic buffer type motor terminal, comprising: straight insertion piece pin, elastic buffer structure and crimping cavity, the bottom of straight insertion piece pin is connected with the one end of elastic buffer structure, the other end of elastic buffer structure is connected with the top of crimping cavity, the inner wall lower part of crimping cavity is provided with anti-withdrawal boss, anti-withdrawal boss center is provided with wire inlet, the inner wall upper part of crimping cavity is provided with grid recess.The utility model is added elastic buffer structure between straight insertion piece type pin and the crimping cavity of lead-out wire, release and isolation of temperature or vibration stress are realized, block mechanical stress conduction to straight insertion piece pin, fundamentally solve the problem of pin root fracture failure caused by vibration of traditional terminal.By adopting the structure that anti-withdrawal boss and net-shaped recess cooperate, make motor lead-out line end and wiring terminal connection more stable, not easy to loosen, have better conductive effect.

The invention discloses an MGPCC fracture performance evaluation method and system based on an improved boundary effect model, and belongs to the technical field of material fracture performance testing. On the basis of a traditional boundary effect model, influence parameters of a macro-fine-micro level are fused, a more accurate improved model is constructed, then fracture parameters of a material are calculated, and the fracture performance of the material is evaluated. And a fracture and failure curve is constructed by combining different types of test pieces (sizes, fracture height ratios and span-height ratios), and the fracture and failure types are accurately evaluated. According to the method, multi-level factors are integrated, so that the model is more practical, the evaluation accuracy is improved, the fracture behavior can be effectively predicted, a basis is provided for engineering design and safety evaluation, and the method has important significance in promoting scientific application of an MGPCC material in the engineering field.

The present invention provides a reverse construction method for frame columns that are subjected to alternating tension and compression forces, and relates to the technical field of frame column construction. The frame columns are constructed using the reverse construction method, and by reserving frame column reinforcement and connecting steel plates, other layer structures are constructed first, and the frame beam reinforcement is rationally configured to serve as a temporary cantilever beam. After the main structure forms an overall force-bearing system and the deformation is stable, the frame column is constructed. The present invention effectively avoids the risks of fracture and damage of the frame column due to the huge tension in the early stage and buckling and instability due to the huge pressure in the later stage, effectively reduces the additional pressure transmitted to the bottom steel beam of the frame column, and further improves the structural safety redundancy. The present invention does not require the addition of temporary supports, making construction more convenient and more cost-effective. At the same time, it avoids the risk of cracking of the beams and slabs connected to the frame columns, and has universal applicability and economy in solving the complex force and deformation problems of the vertical components of the main structure.

The embodiment of the specification provides a material mesoscopic fracture failure simulation method, sample material pairs are sheared according to a preset shearing strategy, a stress evolution process of the sample material is measured, a temperature evolution process and a mesoscopic organization deformation evolution process of the sample material are synchronously measured, evolution process data of the mesoscopic organization is collected, a mesoscopic simulation model is built, attribute data of the sample material is acquired, model parameters of the mesoscopic simulation model are trained in combination with the attribute data of the sample material, the shearing strategy and the evolution process data, after training, future period evolution processes of stress, temperature and mesoscopic organization deformation generated by the shearing strategy implemented on the current material are predicted by using the mesoscopic simulation model, whether the sheared material produces fracture failure is judged based on the future period evolution processes of the stress, the temperature and the mesoscopic organization deformation, and the advance and effectiveness of the material fracture failure simulation are improved.

The utility model discloses a novel light weight structure of a transmission shaft universal joint forging, which comprises a central part and four journals arranged along the circumference of the central part in an array mode, the included angle between two adjacent journals is 90 degrees, the upper surface and the lower surface of the central part are respectively provided with a groove, the two grooves are identical in structure and are symmetrical up and down, the bottom of each groove is round, and the bottom of each groove is provided with a through hole. A groove opening of the groove is a square with four vertexes and four edges of arc transition structures, the side wall of the groove is in curved surface transition from the groove opening to the groove bottom, and vertical projections of the four vertexes of the square are located on the center lines of the four shaft necks respectively. According to the utility model, by improving the structure of the universal joint forge piece, the strength of the easy-to-fail part is enhanced, the deformation resistance is increased, the stress is reduced when the universal joint is stressed, and the fracture failure rate of the universal joint is reduced by 2.5%, so that the aims of prolonging the service life of the universal joint and reducing the failure rate of the universal joint are fulfilled; meanwhile, the depths and the shapes of the grooves in the two sides are enlarged, the weight of the forge piece is effectively reduced, the weight of a single forge piece can be reduced by 0.1 Kg, and the purpose of light weight is achieved.

This invention relates to piezoelectric MEMS fans and their stress optimization design, fabrication, and chip in the field of MEMS actuators. The piezoelectric MEMS fan includes a support frame and at least one piezoelectric motion arm extending from the support frame. The piezoelectric motion arm has multiple stress-dispersing openings, and the distribution pattern of these openings is configured to disperse stress concentration within the piezoelectric motion arm during vibration. This invention designs a specific stress-dispersing opening pattern on the piezoelectric motion arm, which is optimized based on vibration stress field analysis. This pattern effectively disperses and releases the alternating stress borne by the motion arm during long-term high-frequency vibration, especially alleviating stress concentration in critical areas such as the root, thereby greatly suppressing the initiation and propagation of fatigue cracks and reducing performance degradation and the probability of fracture failure.