52 results about "Coulomb friction" patented technology

The invention discloses a tunnel rock-soil deformation identification method and system, relates to the technical field of tunnel and underground engineering monitoring and early warning, and remarkably improves the reliability and timeliness of tunnel weak surrounding rock deformation risk identification. In the abrupt change response link, a time domain convolutional network and a displacement acceleration self-adaptive strengthening mechanism are introduced, so that the capturing capability of the system on nonlinear displacement surge is improved in a leap-over manner; according to the method, the acceleration component is focused and the physical constraint weight is applied, so that the sudden change event is locked in real time, and accidents such as unstability of the tunnel face are prevented from being missed in report; in order to solve the problem of point cloud registration distortion of a joint development area, the geological law of a rock mass structural plane is fused into a registration algorithm, and overall deformation misjudgment caused by rock mass local dislocation is inhibited from the source through a Gaussian mixture model coupling normal elastic deformation threshold and a tangential coulomb friction criterion; the measurement precision of laser scanning in a fracture zone and a fault zone breaks through environmental limitation, and a reliable basis is provided for supporting decision.

The novel high-damping foil aerodynamic bearing with the negative Poisson's ratio effect is mainly characterized in that a 3-D double-V-shaped honeycomb supporting structure serves as a flexible supporting unit and is integrally formed through 3D printing, and damping material silica gel is poured into the bearing. In the operation process, a high-pressure gas film generated by a wedge-shaped space formed by matching of the rotor rotating at a high speed and the top foil can cause deformation of the 3-D double-V-shaped honeycomb supporting structure in the radial direction, and the negative Poisson's ratio effect is stimulated. At the moment, coulomb friction is generated between the supporting structure and the top foil and between the supporting structure and the bearing sleeve, meanwhile, shrinkage deformation of the supporting structure is limited by damping material silica gel poured in the supporting structure, and internal friction is generated in the damping material silica gel to consume energy. Therefore, coupling of the 3-D double-V-shaped honeycomb supporting structure and the damping material silica gel can provide proper rigidity and high damping capacity for the foil aerodynamic bearing.

The application discloses a composite material structure bushing reinforcing method based on electromagnetic loading, which uses electromagnetic loading to complete the bushing reinforcement of the composite material structure, and obvious beneficial effects are obtained compared with traditional methods. The method proposes a process parameter calculation method for the reinforcement process of the structure to solve the problem that existing devices and methods cannot be applied to the bushing reinforcement of the composite material structure. The radial compressive stress around the hole is obtained through the Lame formula and the elastic stress-strain relationship of the composite material, and then the total resistance of dynamic extrusion friction in the reinforcement process is obtained through the Coulomb friction theory, and the process parameters are determined in combination with the mathematical model of the electromagnetic force. The application can realize the calculation of the reinforcement process parameters of the composite material bushing with different structures and sizes, and is used for guiding the reinforcement of the dynamic cold extrusion composite material bushing structure.

The invention discloses a pile-soil interface shearing algorithm considering related characteristics of a soil body state. The pile-soil interface shearing algorithm is suitable for calculating pile side friction resistance after a pile foundation is driven in offshore engineering. The method mainly comprises the following steps: (1) transferring stress and strain tensors obtained by calculation of a constitutive model considering that rigidity and strength parameters of a soil body change along with the state of the soil body to a soil and structure interface shear model; (2) assuming that a soil and structure contact interface is in a simple shearing state, and iteratively solving the normal strain of the interface; and (3) calculating the normal stress and the interface tangential stress through the calculated normal strain, and considering the influence of the strength change of the pile-side soil body on the interface shear strength. According to the method, the soil constitutive model related to the state is introduced on the basis of traditional coulomb friction, constitutive responses of the soil in different confining pressure and shear strain states can be reflected, pile-soil interface mechanical behaviors are calculated, and the influence of soil characteristics on the interface behaviors is reflected more reasonably.

The invention relates to the technical field of intelligent inspection of rail transit, and discloses a compensation method for joint friction force of a mechanical arm of a metro underbody inspection robot, which comprises the following steps of: acquiring angular velocity, angular position and temperature data in real time through a joint angle and temperature sensor, and establishing an improved LuGre friction force dynamic model; a temperature correction term is introduced to accurately characterize coulomb friction, viscous friction and a Stribeck effect. A recursive least square algorithm is adopted to realize online identification of model parameters, a predicted friction force compensation item is introduced into a servo control loop, and unmodeled disturbance correction is realized in combination with PID control, sliding mode control and an extended Kalman filter. And in the low-speed interval, a gain coefficient is adopted to enhance friction compensation and inhibit joint crawling. According to the method, trajectory tracking errors can be remarkably reduced in a complex environment, and the operation stability and detection precision of the inspection robot are improved.

The invention discloses a self-adaptive identification and compensation method for friction nonlinear characteristics of a feeding system of a numerical control machine tool. According to the method, parameters of a LuGre friction model are initialized by collecting an actual position signal, an actual speed signal, an actual current signal and an instruction position signal of a feeding system; friction parameter self-adaptive identification is carried out based on motion state segments, coulomb friction parameters and viscous friction parameters are updated by adopting a least square method in a constant speed stage, and bristle rigidity parameters, bristle damping parameters and Stribeck speed parameters are updated by adopting an extended Kalman filter in an acceleration stage and a deceleration stage; generating a friction force estimation value according to the identified friction parameter, converting the friction force estimation value into a compensation current signal, and adding the compensation current signal to a servo driver current instruction after phase lead compensation. According to the method, the friction characteristic change can be adaptively identified on line, tracking errors and vibration caused by friction nonlinearity are effectively inhibited, and the machining precision and stability of the numerical control machine tool are improved.

The utility model discloses a shockproof damping device for a bridge, and relates to the technical field of bridge damping. The damping device comprises two mounting plates, a mounting seat is fixedly connected between the two mounting plates, a viscous damper is movably connected to the inner side of the mounting seat through a rotating shaft, and a damping support is fixedly connected to one side of each mounting plate; a main buffering assembly is arranged on one side of the mounting plate and comprises a supporting ring fixedly connected to one side of the damping support. Through the coupling effect of the friction dampers of the main buffering assembly and the first springs, dual energy consumption of coulomb friction and elastic deformation is generated in the initial vibration stage, the peak acceleration is effectively reduced, the eight friction dampers distributed at equal angles form an annular buffering array, omni-directional dissipation of horizontal vibration in any direction is achieved, and the vibration damping effect is improved. The three-dimensional supporting structure of the damping support is matched, and the stress concentration phenomenon of a traditional one-way damper is eliminated.

The invention discloses a modeling method of a manual transmission with a flywheel and a clutch based on a Modelica language, which comprises the following steps of: building a flywheel model, and constructing a derivative of flywheel rotating speed to time; building a clutch model based on the hyperbolic tangent coulomb friction model, and calculating clutch output torque; building a main shaft model, calculating main shaft torque according to the loss type of the gearbox, and building a derivative of main shaft rotating speed to time; building an auxiliary shaft model, and calculating the rotating speed and torque of the auxiliary shaft according to the rotating speed of the driving shaft and the hyperbolic tangent friction model; calculating a driving shaft torque according to the gearbox loss type, and establishing a driving shaft model; and establishing a power loss model of the gearbox, and calculating the power loss of the gearbox by considering the influence of the power loss. According to the external input engine torque, the driving shaft rotating speed and the inherent characteristics of all the components, an equation is established and solved to obtain the rotating speed and the torque of all the components, finally, the power loss of the whole working process of the manual transmission is calculated, and the modeling difficulty of the manual transmission can be reduced.

The invention relates to the technical field of constructional engineering, and provides an analysis method considering tangential and normal coupling effects of a steel tube-concrete interface, which comprises the following steps: S1, constructing a finite element model of contact between a steel tube and concrete, with the inner wall surface of the steel tube as a principal surface and the outer surface of the concrete as a subordinate surface; s2, simulating a steel tube-concrete tangential behavior by adopting a coulomb friction model, and endowing the finite element model with a tangential contact attribute; s3, on the basis of normal contact attributes, a penalty function is adopted to define the mutual relation of steel pipe-concrete normal contact; and S4, analyzing the mechanical behavior of the finite element model based on the correlation. The method comprehensively considers the normal and tangential behaviors of the contact surface of the steel pipe and the concrete, improves the simulation accuracy, and improves the numerical analysis precision of the model.

The invention provides a gas dynamic pressure bearing and a motor, the gas dynamic pressure bearing comprises a bump foil, a top foil and a bearing seat, the bump foil comprises a bump foil main body and a wave arch, the radial inner end of the wave arch is connected with the bump foil main body, the radial outer end of the wave arch protrudes towards the bearing seat, the inner circumferential wall of the bearing seat is provided with a limiting groove, and the limiting groove is connected with the bump foil main body. The radial outer ends of the wave arches can be clamped in the limiting grooves, and elastic support for the bump foil can be formed through contact between the inner walls of the limiting grooves and the radial outer ends of the wave arches; the top foil is arranged on the inner periphery of the bump foil, the bump foil is provided with a bump foil inner wall, and the bump foil inner wall is in surface contact with the top foil. According to the gas bearing, surface contact is formed between the inner wall of the bump foil and the top foil, the contact area between the bump foil and the top foil is increased, the friction resistance of the bearing is increased, the gas bearing can have enough coulomb friction damping to dissipate redundant energy when being vibrated and impacted, and the operation stability of a system is improved.

The invention discloses a composite anti-interference and anti-skid motion control method for a four-footed inspection robot, and relates to the technical field of robot control. The method comprises the following steps: establishing a quadruped robot single rigid body dynamic model influenced by uncertain disturbance and constrained by a coulomb friction cone, and correspondingly establishing a tracking error system model of equivalent motion of the quadruped robot; designing a disturbance observer based on a tracking error system model, and performing active lumped estimation and compensation on disturbance caused by uncertainty in an external environment and a system; designing a composite anti-interference model prediction control method according to the tracking error model of the equivalent motion of the quadruped robot; and the recursion feasibility of the composite anti-interference model prediction control method and the stability of a closed-loop system are verified. According to the control method, the adverse effect of multi-source uncertain interference on robot motion control can be relieved, the control precision of the robot is improved, meanwhile, the foot end acting force is limited to be within the anti-skid feasible range, and the posture stability of the robot is better maintained.

The invention relates to the technical field of machining, and discloses a chamfering tool metal dead zone shape prediction method based on a slip line theory. The method comprises the steps that firstly, a chamfering cutting edge right-angle cutting slip line field model is constructed, a right-angle cutting coordinate system is established with an S1 point as an original point, then an S1 point Moire circle model is established based on the plastic deformation theory, and the size of an included angle omega 1 formed by a metal dead zone boundary S1S3 and a chamfering S1S2 is solved in combination with the Coulomb friction theorem; and then determining a slope relational expression of the line segment S2S3 and the line segment DN through a geometrical relationship, establishing an equation to solve the height of a shunt point, and finally solving the length 1 of the lower boundary of the metal dead zone, thereby realizing prediction of the shape of the metal dead zone. According to the method, the mathematical relationship between the parameters of the cutting edge of the chamfering tool and the shape of the metal dead zone is established particularly for the shape of the dead zone of the cutting edge of the chamfering tool, so that the boundary of the dead zone can be represented according to the parameters of the cutting edge of the chamfering tool, and the prediction effect of the shape of the metal dead zone of the chamfering tool is achieved.

The application discloses a robot friction parameter identification method and device, a terminal and a medium. The method comprises the following steps: acquiring a dynamic speed threshold of a robot joint; identifying a static friction coefficient, a coulomb friction coefficient and a critical speed in a low-speed section where the speed of the robot joint is lower than the dynamic speed threshold; and identifying a viscous friction coefficient in a medium-high speed section where the speed of the robot joint is higher than the dynamic speed threshold, in combination with the obtained static friction coefficient, the coulomb friction coefficient and the critical speed. The application has the advantage that higher-precision robot friction parameters can be obtained, thereby facilitating the construction of a high-precision robot friction model.

The application discloses a parameter identification device and method based on a Lugre friction model. The method comprises the following steps: creating a PID closed-loop control system configured with the Lugre friction model, drawing a first characteristic curve of output rotating speed w and friction torque F fric ; identifying Coulomb friction and stribeck speed of the friction torque F fric according to the first characteristic curve; obtaining a peak voltage Umax input by a servo motor; inputting a speed extremely slowly changing identification voltage to the servo motor, the identification voltage rising from an initial voltage to the peak voltage Umax at first and then falling from the peak voltage Umax to a negative peak voltage Umax; obtaining a displacement S between the servo motor and a controlled object, and drawing a second characteristic curve of the displacement S and the identification voltage; identifying bristle stiffness coefficient σ0 according to the second characteristic curve; creating a current loop of the servo motor in the PID closed-loop control system; drawing a third characteristic curve of displacement response of the servo motor; and identifying bristle damping coefficient σ1 according to the third characteristic curve.

The invention relates to the technical field of computers, in particular to a variable damping control method and device based on a continuous friction model. The method comprises the following steps: acquiring construction parameter data of a continuous friction model; wherein the constructed parameter data comprises a nonlinear dynamic coefficient, coulomb friction, maximum static friction, turning speed, a viscous friction coefficient and an actual rotating speed of the motor; constructing a continuous friction model based on the construction parameter data; based on a continuous friction model, determining a differential function of friction torque to speed; determining a variable damping coefficient based on the differential function of the friction torque to the speed and a preset adjustment principle of an additional damping coefficient; determining the voltage of a permanent magnet synchronous motor of the space optical pointing servo system based on the variable damping coefficient; and controlling the permanent magnet synchronous motor of the space optical pointing servo system based on the voltage of the permanent magnet synchronous motor. Through the configuration mode, the control precision of the space optical pointing servo system can be improved.

The present invention discloses a method for identifying mechanical parameters of a robot joint servo system. The method models the robot joint servo system as a whole, considers the influence of transmission elements represented by harmonic reducers on motion and torque, performs equivalent conversion on the torque and moment of inertia on the output side of the joint, and establishes a new integrated joint model on the side of the joint servo motor; an expanded sliding mode observer is designed according to the integrated joint model, and the moment of inertia, load torque and viscous friction parameters of the system are expanded into new state variables. The three mechanical parameters can be identified simultaneously through an observer, and the Coulomb friction component of the system can be identified when unloaded. In addition, the present invention designs a sliding mode gain self-correction coefficient based on the rate of change of the observed quantity, which can increase the convergence speed of the algorithm while obtaining higher identification accuracy.

The present invention is directed to a connection structure of a combined rotor bolt group, and discloses a method for evaluating the anti-slip ability of the connection of the combined rotor bolt group. Starting from ultrasonic detection technology, based on the measured pre-tightening force distribution of the rotor bolts, according to Coulomb's friction law, the local friction force under the action of the pre-tightening force is solved, and according to the phases of the bolts, the obtained local friction forces are vectorially summed to establish a calculation method for evaluating the anti-slip ability of the connection of the combined rotor bolt group. This method can be used to evaluate whether the bolt group after tightening meets the anti-slip performance requirements of the connection structure, and at the same time, the positions where slip and dislocation are likely to occur in the bolt group connection can also be determined by this method, which has important guiding significance for further improving the stability of the combined rotor bolted structure.

A method for calculating the joint motion parameters of a quasi-hyperbolic manipulator using a nonlinear mixed friction model relates to the field of joint mechanics calculation in robotics. Although the traditional calculation model can describe the relationship between friction force and relative motion speed or contact surface positive pressure to a certain extent, it ignores the nonlinear characteristics of friction force, resulting in large errors in motion parameters and unable to meet the current design requirements for high-precision manipulators with the rapid development of industrial automation technology. Therefore, in order to improve the accuracy of the calculation of the joint motion parameters of the manipulator, the present invention proposes a method for calculating the joint motion parameters of a quasi-hyperbolic manipulator using a nonlinear mixed friction model. The friction model is based on the Gauss friction model and combines the Coulomb friction model, the viscous friction model and the Stribeck friction model to provide a more accurate pre-calculation method for the subsequent structural design of the manipulator, the manufacturing of rods and fuselage, and the trajectory control of the end effector.

The invention provides an actuator clamping force determination method, device and equipment and a readable storage medium, and relates to the technical field of automobiles. The method comprises the steps that according to the stress conditions of a motor, a ball bearing, a planetary gear set, a thrust bearing, a ball screw and a brake pad in the forward clamping and reverse releasing process of the actuator, a stress analysis model of the actuator in the forward clamping and reverse releasing process is constructed; according to the stress analysis model, the equivalent coulomb friction coefficient during forward clamping and reverse releasing, the clamping force during forward clamping and the clamping force during reverse releasing are obtained; and according to the equivalent coulomb friction coefficients during forward clamping and reverse releasing, the clamping force during forward clamping and the clamping force during reverse releasing, the target clamping force of the actuator at the target angular displacement is determined. According to the method and the device, the estimation accuracy of the target clamping force of the actuator at the target angular displacement is improved, so that the accurate updating of the rigidity characteristic is realized.

The invention provides a dynamic motion control method, system and device for an electric movable caster, and relates to the technical field of dynamic motion control methods for electric movable casters, and the method comprises the steps: employing a time-varying load inertia method to add the initial rotational inertia and the additional equivalent inertia of the movable caster, and obtaining the real-time equivalent rotational inertia of the movable caster; a coulomb friction model is adopted to construct the real-time friction force of the movable caster, and a dynamic model is constructed to calculate the angular acceleration of rotation of the movable caster; when the real-time angular acceleration is smaller than the lower limit threshold value, the angular acceleration of the movable trundle is increased through feedforward compensation, and when the real-time angular acceleration is larger than the upper limit threshold value, the angular acceleration of the movable trundle is reduced through reverse braking. Real-time loads are combined, friction torque is accurately represented, and the limitation of a traditional fixed friction coefficient model is overcome; current control and motion response are associated, and accurate torque distribution is achieved.

The present application belongs to the technical field of design of support plates inside an aircraft engine air intake casing, and specifically relates to a support plate structure inside an aircraft engine air intake casing, in which an elastic sheet is arranged in the cavity of the support plate, and the two ends of the elastic sheet are bent toward each other, forming a V-shape as a whole, forming two elastic arms. The outer side of each elastic arm relies on the elastic force of the elastic sheet to rest against the side wall of one side of the support plate cavity. When the aircraft engine is working and the support plate is subjected to severe aerodynamic loads, the vibration response amplitude of the support plate can be reduced through joint surface damping and Coulomb friction damping, thereby reducing the vibration stress borne by the support plate, reducing vibration of the support plate, and avoiding cracks and breakage on the support plate.

The invention discloses an on-line measurement method and device for the friction coefficient of a pantograph-catenary system contact pair, and relates to the technical field of electrified railway pantograph-catenary state monitoring and tribological testing, and the method comprises the steps: enabling a pantograph head sliding plate to be equivalent to an elastic beam structure with two fixed ends, and deducing a mechanical model of the pantograph head sliding plate; a vertical strain signal, a longitudinal strain signal and vibration acceleration signals at the two ends of the sliding plate in the running process of the sliding plate are synchronously collected through strain sensors and acceleration sensors which are arranged in a distributed mode; calculating a vertical acting force and a longitudinal friction force based on the vertical strain signal and the longitudinal strain signal, performing inertia force dynamic compensation by using the vibration acceleration signal, and restoring a real normal contact force and a real tangential friction force; and according to the Coulomb friction law, the dynamic friction coefficient of the pantograph-catenary system contact pair is obtained by calculating the ratio of the real tangential friction force to the real normal contact force. According to the invention, direct and on-line measurement of the pantograph-catenary friction coefficient can be realized, and the wear state of the sliding plate and the wire can be evaluated more scientifically.

This invention discloses a multi-axis robot control method and system suitable for clean environments, specifically relating to the field of robot program control technology. It addresses the problem of unexpected end-effector vibration in existing multi-axis robots during trajectories involving steering and micro-amplitude reciprocating adjustments due to mismatch in the fixed-parameter friction model. By statistically analyzing the sign change rate of the encoder's original counting signal, joints whose statistical pattern transitions from a unimodal distribution to a bimodal distribution accompanied by a sign reversal are identified as target joints. Before the target joint's motion direction reverses, a micro-amplitude bidirectional trial motion is superimposed, and the trial asymmetry is calculated. When the trial asymmetry exceeds a preset threshold, the driving torque feedback value during the reversal period is extracted and subjected to time-frequency transformation. The offset of the sideband energy ratio on both sides of the meshing frequency before and after reversal is compared to assess the degree of lubrication state deviation. Based on the degree of lubrication state deviation, the Coulomb friction term in the feedforward friction compensation model is corrected and used for multi-axis linkage control in the next cycle.

The invention provides a self-adaptive variable-impedance self-return control method and system for a steer-by-wire system based on coulomb friction compensation and particle swarm optimization, and belongs to the field of steer-by-wire. In order to solve the problems that mechanical decoupling exists in a steer-by-wire system, the aligning torque of vehicle tires cannot be transmitted to a steering wheel, and the steering and returning burden of a driver is increased; an existing self-aligning control method depends on a preset steering wheel rotating speed-rotating angle curve idealized open-loop instruction model, and switching delay between a torque mode and a rotating speed mode has the problem that operation smoothness, predictability and safety of a driver are affected. Impedance torque in different environments is obtained through self-adaptive variable impedance control, and final active aligning torque is obtained by adding coulomb friction force, so that a steering wheel can accurately and stably return to the center position; condition judgment logic is set for self-aligning state switching, an active aligning mode is rapidly triggered after the intention of a driver is recognized, and the preventer is accidentally activated in the normal steering process.

The present application provides a method and device for real-time monitoring of the health status of a hydraulic plunger pump, which belongs to the field of aviation hydraulics. The method includes: determining a first relationship between the total leakage of the hydraulic plunger pump and the operating parameters of the electrostatic actuator, and screening the follow-up parameters based on the dynamic change characteristics of the operating parameters with the working condition and health status of the hydraulic plunger pump; adjusting the first relationship of the total leakage of the plunger pump based on the follow-up parameters to obtain a second relationship; calculating the plunger pump torque based on the second relationship in combination with the law of conservation of energy; optimizing the plunger pump torque calculation formula based on the correlation between the viscous friction torque, the Coulomb friction torque and the follow-up parameters; monitoring the real-time operating parameters of the plunger pump, calculating the first coefficient and the second coefficient based on the real-time operating parameters, and inputting the first coefficient and the second coefficient into a neural network to construct a state monitoring model to evaluate the operating status of the plunger pump. The method and device provided by the present application can realize real-time monitoring of the operating status of the hydraulic plunger pump.

The application provides a processing method and system of angle-dependent friction sliding in a folder, comprising: obtaining attribute information of a target device, and constructing a three-dimensional CAE model according to the attribute information of the target device; in the three-dimensional CAE model, constraint conditions and gravity loading conditions are applied; based on the constraint conditions and the gravity loading conditions, a counterforce between a contact surface of the target device and a support is calculated through a finite element steady-state statics module of a structure analysis software; a condition under which the target device does not slide is obtained according to the counterforce and a Coulomb friction law; whether a friction coefficient of the contact surface satisfies the condition under which the target device does not slide is judged; if yes, no relative sliding occurs between the target device and the contact surface of the support; if not, relative sliding occurs between the target device and the contact surface of the support, and a friction structure design is optimized or a reverse support structure is added; and the counterforce requirement under different inclination angles is quantified through finite element analysis.

The invention relates to a shotcrete support parameter adaptability design method considering blasting damage, and belongs to the technical field of tunnel engineering. The problems that the friction coefficient value is empirical, parameter design is not matched with the actual working condition and the design accuracy is low due to neglecting of the shape change of the surface of the surrounding rock caused by blasting damage in the prior art are solved. According to the technical scheme, the method comprises the steps of quantifying a surrounding rock roughness coefficient and calculating a friction coefficient through multi-angle image acquisition and image recognition; the lining thickness is determined by combining the clearance requirement, the deformation allowance and the blasting damage risk; establishing a two-way unequal-pressure elastic mechanical model, and solving lining stress distribution based on a stress function and coulomb friction constraint; and taking support cost minimization as a target, and inversely solving the optimal concrete strength grade and reinforcement ratio by adopting an optimization algorithm. Accurate self-adaptive design of support parameters is realized, stress calculation precision is improved, safety is guaranteed, and cost is reduced.

The invention discloses a method for calculating joint motion parameters of a hypoid mechanical arm by using a nonlinear mixed friction model, and relates to the field of joint mechanics calculation of robotics. Although a traditional calculation model can describe the relation between the friction force and the relative movement speed or the positive pressure of the contact surface to a certain degree, the nonlinear characteristic of the friction force is ignored, large errors exist in movement parameters, and the current design requirement for a high-precision mechanical arm for rapid development of the industrial automation technology cannot be met. In order to improve the calculation precision of the joint motion parameters of the mechanical arm, the invention provides a method for calculating the joint motion parameters of the hypoid mechanical arm by using a nonlinear mixed friction model, the friction model is based on a Gauss friction model and is combined with a coulomb friction model, a viscous friction model and a Stribeck friction model, and the joint motion parameters of the hypoid mechanical arm are calculated. And a more accurate pre-calculation means is provided for subsequent structural design of the mechanical arm, manufacturing of a rod piece and a machine body and track control of an end effector.

The present invention belongs to the technical field of passive vibration reduction, and relates to a passive nonlinear energy-consuming control structure and method for flutter suppression of aircraft wall panels, comprising: a linear stiffness spring, a moving contact, and a static contact; one end of the linear stiffness spring is connected to the inner wall of the aircraft wall panel, and the other end is connected to the moving contact, the moving contact is slidably connected to the static contact, and the static contact is fixedly connected to the aircraft frame; Coulomb friction exists between the moving contact and the static contact; an angle is provided between the connecting line of the two ends of the linear stiffness spring and the vertical line of the wall panel; the present invention combines the linear stiffness spring with a Coulomb friction slider, so that when the aircraft wall panel flutters, the linear stiffness spring transfers the wall panel flutter nonlinearly to the Coulomb friction slider for energy consumption, and the slider plays a role in damping and suppressing the wall panel flutter; the present invention adopts reliable and commonly used springs and Coulomb friction sliders to achieve flutter suppression, so the present invention has a simple structure, low implementation difficulty, high reliability, and low implementation cost.

A forging defect prediction apparatus includes a processor. The processor is configured to calculate, based on a stress applied to a plurality of analysis meshes configuring a molded object model, a surface pressure of each of the analysis meshes, determine that a friction coefficient is Coulomb friction when the surface pressure of each of the analysis meshes is equal to or less than a predetermined threshold value and determine that the friction coefficient is shear friction when the surface pressure is greater than the predetermined threshold value, analyze the analysis mesh while switching the determined friction coefficient, and predict whether the defect phenomenon that occurs in the molded object model occurs based on a surface angle between surfaces of adjacent ones of the analysis meshes.