A method for calculating the dynamic characteristics of brake wheels considering temperature

Abstract

The present invention relates to the field of aviation landing gear design, and in particular to a method for calculating the dynamic characteristics of a brake wheel taking temperature into consideration. The method comprises the following steps: step 1: calculating the equivalent connection stiffness between adjacent component blocks of a pressure disc block, a static disc block 1, a static disc block 2, a static disc block 3, and a pressure disc block of a brake housing; step 2: importing a brake wheel component from a CATIA model; step 3: dividing the brake housing into five component blocks, and setting the material properties of the brake wheel component; meshing all the brake wheel components, and assembling and positioning each brake wheel component according to an actual assembly position; step 4: establishing a mass center reference point, a motion reference point, a wheel mass center reference point, a ground reference point of a brake housing fixed point, and a piston motion reference point of the upper brake wheel component and component blocks; step 5: establishing rigid body constraints, connection units, and contact effects for the brake wheel component and component blocks; and applying boundary conditions for solving the problem.

Description

Technical Field

[0001] The present invention relates to the field of aviation landing gear design, and in particular to a method for calculating the dynamic characteristics of a brake wheel taking temperature into consideration. Background Art

[0002] Aircraft landing gear systems are complex, multi-degree-of-freedom dynamic systems. During braking, wheel speeds fluctuate dramatically over a short period of time due to the combined effects of the braking torque and the combined torque between the tire and the ground. Simultaneously, components such as the brake housing, cylinder seat, and brake disc experience impact and elastic deformation under the influence of the braking torque. Therefore, the braking process is a typical dynamic process for the wheels. Analyzing the transient characteristics of the braking torque and the brake vibration response requires a detailed analysis of the braking process from a structural dynamics perspective.

[0003] The braking process is a typical dynamic process, one involving frictional heat generation and transfer. Given a specific brake wheel structure and material, the dynamic properties of each component, such as mass / moment of inertia, stiffness, and damping, are also determined. Typically, as braking time increases, the brake disc temperature continues to rise while the disc speed continues to decrease. The brake disc friction coefficient is a variable that is influenced by factors such as friction linear velocity, temperature, pressure, and humidity. When the brake pressure remains constant, changes in the brake disc friction coefficient also alter the friction torque generated on the friction surface. This changing friction torque, acting through the brake disc on the brake wheel, can cause dynamic responses in the brake wheel structure, reduce speed, and increase temperature. These effects, in turn, influence the state of the brake disc friction surface (temperature, pressure, and speed), thus affecting the change in the friction coefficient. Therefore, the braking process is a complex, time-varying, coupled thermodynamic process.

[0004] There are two main methods for calculating the dynamic characteristics of brake wheels in the existing technology: one is to use classical formulas for calculation, and the other is to use multi-body dynamics software, numerical simulation software or finite element software for simulation modeling and calculation. The calculation of the dynamic characteristics of brake wheels using classical formulas mainly focuses on the calculation of braking torque. This method uses a comparative estimation method to take the time and space average values ​​of the friction coefficient of the brake material to calculate the average braking torque and average deceleration rate. It cannot accurately describe the real-time braking characteristics of the brake wheel that change with time and temperature conditions. For the calculation of brake temperature, the average volume temperature method is generally used, that is, the braking energy is divided by the weight and specific heat capacity of the brake disc for calculation. It is impossible to obtain the brake disc temperature that changes with time. There is no correlation between the calculation of braking torque and brake temperature. Therefore, it is impossible to obtain the braking characteristics (brake torque, brake temperature) of the brake wheel that change with time and initial braking conditions. The calculation results are inaccurate and cannot reflect the vibration characteristics of the product. The following problems exist in the simulation modeling and calculation method: the mainstream multi-body dynamics software at home and abroad does not have the function of calculating the temperature field and the average body temperature, nor does it have the function of defining the complex friction coefficient affected by multiple parameters such as temperature, speed and pressure, making it difficult to describe the dynamic characteristics of the brake wheel when the speed, temperature, pressure and other parameters change drastically; the mainstream numerical simulation software at home and abroad is difficult to refine the structure when establishing the dynamic model of a complex assembly, and requires the modeler to have extremely professional dynamics and mathematical knowledge, the modeling workload is huge, the work efficiency is low, and the model quality is difficult to guarantee; and when using finite element software for modeling, since the speed, temperature and contact state of the brake wheel change drastically during the braking process of the aircraft (usually within 10 to 30 seconds, the speed drops from about 300 km / h to 0, and the temperature rises from the ambient temperature to about 1000°C), the explicit temperature displacement coupling method is usually used to analyze the process, but due to the limitation of the unit size, the stable incremental step size is usually 10 -7 ~10 -9 For problems within 10 to 30 seconds, the computational complexity is enormous, typically requiring approximately 60 days to solve. To improve the efficiency of explicit temperature-displacement coupling calculations for long-duration, high-speed friction problems, mass scaling is currently commonly used to increase the stable incremental step size. However, this method is prone to energy distortion and large negative temperature values ​​during braking, which are difficult to control. Therefore, the lack of efficient and accurate methods for calculating the dynamic characteristics of brake wheels has been a key constraint in their design. Summary of the Invention

[0005] To address various deficiencies in the existing brake performance calculation technology, the present invention proposes a method for calculating the dynamic characteristics of a brake wheel that takes temperature into account. This method can accurately calculate the braking torque of the brake wheel and the acceleration amplitude of each component, providing technical support for the brake wheel design phase and reducing repeated iterations during the design process.

[0006] The technical solution is as follows:

[0007] A method for calculating the mechanical characteristics of a brake wheel taking temperature into consideration comprises the following steps:

[0008] Step 1: Calculate the equivalent connection stiffness between the adjacent parts of the brake housing, including the pressure disc, static disc 1, static disc 2, static disc 3, and pressure disc;

[0009] Step 2: Import the following brake wheel parts from the CATIA model: cylinder seat, brake housing, rotor disc, stator disc, pressure plate, compression plate, piston, wheel, and axle. Establish reference points for each part at the center of mass of the cylinder seat, rotor disc, stator disc, pressure plate, compression plate, and piston, and record them as RP-QGZ, RP-DP, RP-JP, RP-YJP, RP-CYP, RP-HS, RP-JL, and RP-LZ respectively;

[0010] Step 3: Based on the assembly relationship between the brake housing and the static disc, pressure disc, and compacting disc, the brake housing is divided into the following five parts blocks along the symmetry plane of the dynamic disc: pressure disc block, static disc block 1, static disc block 2, static disc block 3, and compacting disc block, denoted as KT-YJP, KT-JP1, KT-JP2, KT-JP3, and KT-CYP;

[0011] Step 4: Set the material properties of the brake wheel part;

[0012] Step 5: Mesh all brake wheel parts, define temperature-displacement coupling elements, and enable the second-order accuracy option.

[0013] Step 6: Assemble and position each brake wheel component according to the actual assembly position;

[0014] Step 7: Establish the center of mass reference point, motion reference point, wheel center of mass reference point, ground reference point of the brake housing fixed point, and piston motion reference point of the upper brake wheel parts and parts blocks;

[0015] Step 8: Create rigid body constraints for the brake wheel parts and part blocks;

[0016] Step 9: Define connection units for each brake wheel part, part block and its reference point;

[0017] Step 10: Define contact interactions between all brake disc friction surfaces; define contact interactions between the brake housing parts and the brake disc;

[0018] Step 11: Set the additional moment of inertia at the wheel center of mass reference point based on the braking energy and braking speed;

[0019] Step 12: Define the temperature-displacement coupling analysis step; set the output frequency of field data and history data;

[0020] Step 13: Set boundary conditions;

[0021] Step 14: Apply initial rotational speed to the wheel and all reference points of the rotor, apply initial temperature to all parts and reference points, apply piston thrust to the piston, and start solving.

[0022] Furthermore, in step 1, the equivalent connection stiffness includes: equivalent torsional stiffness and equivalent tensile stiffness.

[0023] Furthermore, in step 1, the specific calculation process of the equivalent torsional stiffness and the equivalent tensile stiffness is as follows:

[0024] a) In the parts operation interface: Create corresponding data points by sequentially entering the coordinates of the center of mass of the pressure plate, static plate 1, static plate 2, static plate 3, and pressure plate relative to the brake housing after actual assembly;

[0025] b) dividing the brake housing through the above data points along the centerline of the brake housing;

[0026] c) Select the above data points in sequence to establish reference points YJP, JP1, JP2, JP3, and CYP; establish reference point QGZ at the intersection of the brake housing and cylinder seat mating plane and the brake housing centerline;

[0027] d) Couple the above-mentioned reference points and the corresponding cutting surfaces, the brake vehicle housing and the cylinder seat matching planes respectively;

[0028] e) Fix any reference point in the brake housing block and apply an axial torsional displacement of amplitude A to the reference point next to it. With the remaining degrees of freedom fixed, calculate the axial support reaction torque at the fixed reference point.

[0029] The equivalent torsional stiffness is equal to the axial support reaction torque divided by the axial torsional displacement;

[0030] F) Fix any reference point in the brake housing block and apply an axial displacement of amplitude B to the adjacent reference point, while keeping the remaining degrees of freedom fixed. Calculate the axial support reaction force at the fixed reference point.

[0031] The equivalent tensile stiffness is equal to the axial support reaction force divided by the axial displacement.

[0032] Furthermore, in step nine, the connection unit includes: establishing a connection unit between reference points of five parts of the brake housing according to the structural relationship of the brake housing, and the connection unit type is a cylindrical pair;

[0033] Establish connection relationships between the reference points of the five part blocks: the pressure plate, static plate 1, static plate 2, static plate 3, pressure plate, and the shell. The connection unit type is cylindrical pair.

[0034] Establish a connection unit between the cylinder seat piston hole reference point and the piston reference point, and the connection unit type is a cylindrical pair;

[0035] Establish a connection unit between the cylinder seat mass center reference point and the KT-YJP block reference point, and the connection unit type is welding;

[0036] Establish a connection unit between each moving plate reference point and the wheel center of mass reference point, and the connection unit type is a cylindrical pair;

[0037] Establish a connection unit between the center of mass reference point on the cylinder seat and the axle reference point, and the connection unit type is hinged;

[0038] A connection unit is established between the wheel center of mass reference point and the axle reference point, and the connection unit type is hinged.

[0039] Furthermore, in step 10, the contact interaction between the friction surfaces of the brake discs includes: contact interaction between the pressure disc and the movable disc, between the movable disc and the static disc, and between the movable disc and the pressure disc;

[0040] The contact interactions between the brake housing parts and the brake disc include: the contact interactions between the pressure disc and the KT-CYP block, the static disc 1 and the KT-JP1 block, the static disc 2 and the KT-JP2 block, the static disc 3 and the KT-JP3 block, and the pressure disc and the KT-YJP block.

[0041] Furthermore, in step 11, the additional moment of inertia I is calculated as follows:

[0042]

[0043] Where E is the braking energy of a single wheel; V is the wheel braking speed; R gd is the tire rolling radius.

[0044] Furthermore, in step 12, the field data includes: displacement U, velocity V, acceleration A, support reaction force, support reaction moment, concentrated force, contact pressure, and node temperature; and the output frequency is 1 time / 0.1s.

[0045] Furthermore, in step thirteen, the boundary conditions are as follows: the axis reference point RP-LZ is completely fixed.

[0046] Furthermore, in step 14, the initial rotation speed ω is calculated as follows:

[0047] The calculation formula of piston thrust F is as follows:

[0048] F=P×π×r 2

[0049] Where P is the brake pressure and r is the effective cross-sectional radius of the piston.

[0050] Beneficial effects:

[0051] 1) The brake housing is the main force transmission component of the brake torque. Its stiffness characteristics have a huge impact on the dynamic characteristics of the brake wheel. A stiffness distribution that does not match the pressure plate, static plate, and pressure plate will significantly affect the various frequencies of the vibration system composed of the pressure plate, static plate, pressure plate, and brake housing. The present invention divides and couples the brake housing and calculates the relative stiffness in sections based on the force transmission relationship between the brake housing and the pressure plate, static plate 1, static plate 2, static plate 3, and pressure plate. This method is more accurate and efficient in calculating the stiffness of complex structures than conventional empirical formula calculation methods, and has strong engineering practical value.

[0052] 2) The present invention divides the brake housing into several structural blocks, defines each structural block as a rigid body, and uses connection units with axial stiffness and axial torsional stiffness to reconnect the structural blocks together, thereby proposing a specific and feasible method for implementing the idea of ​​the concentrated mass method in structural dynamics in general finite element software.

[0053] 3) The present invention combines the multi-rigid body dynamics calculation concept of multi-body dynamics with the transient temperature field calculation concept in finite element software, and proposes a specific modeling process and key methods for the brake wheel dynamics model based on general finite element software, thereby realizing the accurate calculation of the time-varying braking torque, brake temperature field, and component acceleration response that can take into account the influence of initial temperature and braking energy. The method for calculating the brake wheel brake dynamics characteristics considering temperature proposed by the present invention is more accurate than the currently commonly used multi-body dynamics calculation method; by rigidifying many components and discretizing the key parts with finite division and calculating the relative stiffness, a dynamic model of the brake wheel assembly level is constructed, avoiding the problem of excessive calculation caused by too small a stable incremental step size when using the finite element explicit algorithm; the calculation method of the present invention is compared with the conventional finite element explicit temperature displacement coupling method, and the stable incremental step size is increased from 10 -7 ~10 -9 s increased to 10 -5s, the model calculation efficiency of the same problem is improved by more than 100 times; and because mass scaling is not used, the energy accuracy of the calculation method of the present invention is higher. Compared with conventional numerical modeling methods, the calculation method of the present invention does not require modelers to have extremely professional mechanics and mathematics skills. It only requires basic finite element software operation capabilities and engineers who are relatively familiar with the force transmission relationship of brake wheel products. The skill level requirements for personnel are greatly reduced, and the model complexity and accuracy are higher. Therefore, whether compared with empirical calculation methods or with multi-body dynamics software, numerical simulation software or conventional finite element software simulation, the present invention has comprehensive advantages in terms of calculation accuracy, efficiency, and requirements for personnel level. Therefore, the present invention has extremely high engineering practical value for the calculation of brake wheel brake dynamic characteristics.

[0054] 4) The method for calculating the brake dynamic characteristics of a brake wheel considering temperature proposed in the present invention can be used to evaluate the compatibility of the brake wheel structure and the brake materials used therein under various complex working conditions combined with temperature and braking energy, and to calculate the braking torque, brake temperature, and vibration acceleration of the main components that change with time. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the specific implementation scheme of the present invention, the specific drawings of the scheme will be described below.

[0056] Figure 1 Schematic diagram of the brake wheel structure;

[0057] Figure 2 It is a schematic diagram of the modeling process;

[0058] Figure 3 This is a schematic diagram of the calculation and segmentation of the brake housing's equivalent stiffness;

[0059] Figure 4 This is a schematic diagram of the brake housing cut into blocks;

[0060] Figure 5 It is a schematic diagram of the coordinate system of the brake wheel dynamics model;

[0061] Figure 6 It is a schematic diagram of the connection unit of the brake wheel dynamics model;

[0062] Figure 7 is the braking torque curve;

[0063] Figure 8 It is the axial acceleration (A1) history curve of the cylinder seat piston motion reference point;

[0064] Figure 9 It is the radial acceleration (A2) history curve of the cylinder seat piston motion reference point;

[0065] Figure 10 It is the tangential acceleration (A3) history curve of the cylinder seat piston motion reference point. DETAILED DESCRIPTION

[0066] In order to make the technical solutions and advantages of the present invention more clearly understood, the technical solutions in the embodiments of the present invention will be described in detail and completely in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0067] The present invention is described in further detail below with reference to the accompanying drawings:

[0068] The brake wheel generally includes a wheel assembly and a brake device. The brake wheel is installed on the axle of the main landing gear of the aircraft and is used for takeoff, landing, taxiing, turning, braking and supporting the aircraft. The brake device provides the braking torque of the aircraft. The brake device generally includes a cylinder seat assembly, a brake housing, a dynamic disc, a static disc, a pressure disc, a clamping disc, and a piston assembly. Several evenly distributed pressure cups are usually fixed to the end of the brake housing, which cooperate with the bottom surface of the pressure disc. Since the number and combination of pistons, dynamic discs and static discs in the brake wheel and the brake device are complex and changeable, this embodiment describes a brake device with 4 commonly used dynamic discs, 3 static discs, 1 clamping disc, 1 pressure disc, and 5 pistons. See. Figure 1 .

[0069] In order to solve the various defects in the calculation of brake wheel dynamic characteristics in the existing technology, the present invention proposes a method for calculating the dynamic characteristics of brake wheels based on the finite element method, which takes into account the influence of multiple factors such as temperature, speed, and pressure. It can accurately calculate the braking torque, braking temperature, and acceleration amplitude of each component of the brake wheel, provide technical support for the brake wheel scheme design stage, and reduce repeated iterations in the design process. Using the finite element analysis software ABAQUS, the present invention proposes a method for calculating the dynamic characteristics of brake wheels considering temperature. The modeling process is shown in Figure 2 The specific steps are as follows:

[0070] Step 1: Calculation of brake housing equivalent stiffness

[0071] The calculation of the equivalent stiffness of the brake housing includes the calculation of the equivalent torsional stiffness and the equivalent tensile stiffness. The specific process of this step is as follows:

[0072] 1.1 Establishing a static analysis model for the brake housing

[0073] Following the basic ABAQUS software workflow, create a static analysis model containing only one brake housing part. Complete basic operations, including importing parts, defining materials, assembling, setting analysis steps, interactions, setting loads and boundaries, and meshing. Note: During assembly, ensure the centerline of the brake housing aligns with the X-axis.

[0074] 1.2 Cutting parts

[0075] In the parts operation interface: according to the coordinates of the center of mass of the pressure plate, static plate 1, static plate 2, static plate 3, pressure plate and brake housing after actual assembly relative to the brake housing, enter their coordinates in sequence to establish corresponding data points; divide the brake housing along the center line of the brake housing through the above data points to obtain 5 internal surfaces, see Figure 3 .

[0076] 1.3 Establishing calculation reference points

[0077] In the assembly operation interface: select the above data points in sequence to establish reference points YJP, JP1, JP2, JP3, and CYP; establish reference point QGZ at the intersection of the brake housing and cylinder seat matching plane and the brake housing centerline.

[0078] 1.4 Establish coupling constraints

[0079] In the interaction interface, create five coupling constraints using reference points CYP, JP1, JP2, JP3, and YJP and their corresponding five internal surfaces. Create a coupling constraint using reference point QGZ and the mating surfaces of the brake housing and cylinder base. These six coupling constraints are kinematic, with degrees of freedom (DOFs) U1, U2, U3, UR1, UR2, and UR3.

[0080] 1.5 Calculation of equivalent torsional stiffness:

[0081] In the load operation interface, select a reference point each time and apply a fixed constraint to it; then apply a smaller axial torsional displacement to the reference point on its right, usually between 0.001 and 0.01 rad, and the remaining degrees of freedom are fixed; no boundaries or loads are applied to the remaining reference points; submit the calculation to obtain the axial support reaction torque RM1 of the fixed reference point divided by the axial torsional displacement, which is the equivalent torsional stiffness D44 of the two adjacent part blocks.

[0082] In this embodiment, when calculating the relative torsional stiffness of the reference points QGZ and YJP, in the load operation interface, a fixed boundary is set for QGZ (the boundary of QGZ is set to U1=U2=U3=UR1=UR2=UR3=0), and an axial torsional displacement of 0.001rad is applied to YJP (the boundary of YJP is set to UR1=0.001, U1=U2=U3=UR2=UR3=0). No boundaries or loads are set for the other reference points, and the axial support torque of QGZ is obtained by submission for calculation. When calculating the relative torsional stiffness between YJP and JP1, in the load operation interface, a fixed boundary is set for YJP (the boundary of YJP is set to U1=U2=U3=UR1=UR2=UR3=0), and an axial torsional displacement of 0.001rad is applied to JP1 (the boundary of JP1 is set to UR1=0.001, U1=U2=U3=UR2=UR3=0). No boundary or load is set for the other reference points, and the axial support torque of YJP is submitted for calculation. The torsional stiffness between two adjacent reference points can be obtained by operating in this order. In this embodiment, the pressure cup does not participate in the transmission of the braking torque, so there is no need to calculate the torsional stiffness of the pressure cup relative to the reference point YJP; when the pressure cup participates in the transmission of the braking torque, the torsional stiffness of the pressure cup relative to the reference point YJP needs to be calculated. At this time, the pressure cup and the pressure plate can be fixed to 1.6 to calculate the equivalent tensile stiffness:

[0083] Each time a reference point is selected, a fixed constraint is applied to it; an axial displacement is then applied to the reference point to its right, and the remaining degrees of freedom are fixed; no boundaries or loads are applied to the remaining reference points; the axial support reaction force of the fixed reference point obtained by calculation is divided by the axial displacement, which is the equivalent tensile stiffness of the two adjacent parts. In this embodiment, when calculating the relative tensile stiffness of RP-KT-QGZ and RP-KT-YJP, RP-KT-QGZ uses a fixed boundary (the boundary of RP-KT-QGZ is set to U1=U2=U3=UR1=UR2=UR3=0), and an axial (U1) displacement of 0.1mm is applied to RP-KT-YJP (the boundary of RP-KT-YJP is set to U1=0.001, U2=U3=UR1=UR2=UR3=0), and no loads or boundaries are set for the remaining reference points; the axial support reaction force of RP-KT-QGZ is calculated. For example, when calculating the relative tensile stiffness of RP-KT-YJP and RP-KT-JP1, RP-KT-YJP uses a fixed boundary (the boundary of RP-KT-YJP is set to U1=U2=U3=UR1=UR2=UR3=0), an axial displacement of 0.1mm is applied to RP-KT-JP1 (the boundary of RP-KT-JP1 is set to U1=0.001, U2=U3=UR1=UR2=UR3=0), and no load or boundary is set for the other reference points; the calculation is submitted to obtain the axial support reaction of RP-KT-YJP.

[0084] By operating in this order, the tensile stiffness between two adjacent reference points can be obtained.

[0085] In this embodiment, the equivalent torsional stiffness and equivalent tensile stiffness between each component block are shown in Table 1 and Table 2.

[0086] Table 1 Equivalent torsional stiffness between each component block calculated

[0087] Adjacent reference points QGZ-YJP YJP-JP1 JP1-JP2 JP2-JP3 JP3-CYP Torsional stiffness D44 (N*mm / rad) <![CDATA[6.412x10 10 ]]> <![CDATA[6.49x10 10 ]]> <![CDATA[6.468x10 10 ]]> <![CDATA[6.462x10 10 ]]> <![CDATA[6.462x10 10 ]]>

[0088] Table 2 Calculated equivalent tensile stiffness between the various parts of the brake housing

[0089] Adjacent reference points QGZ-YJP YJP-JP1 JP1-JP2 JP2-JP3 JP3-CYP Tensile stiffness D11 (N / mm) <![CDATA[3.034x10 4 ]]> <![CDATA[1.537x10 7 ]]> <![CDATA[1.362x10 7 ]]> <![CDATA[1.362x10 7 ]]> <![CDATA[1.375x10 7 ]]>

[0090] Step 2: Importing Geometry

[0091] According to the basic operation process of ABAQUS software, the cylinder seat, brake housing, dynamic disc, static disc, pressure plate, clamping plate, piston, wheel and axle were imported from the CATIA model and renamed QGZ, KT, DP, JP, CYP, YJP, HS, JL and LZ respectively.

[0092] In the parts operation interface, the reference points of each part are located at the center of mass of the cylinder base, movable plate, stationary plate, pressure plate, clamping plate, and piston; in this embodiment, they are defined as RP-QGZ, RP-DP, RP-JP, RP-YJP, RP-CYP, RP-HS, RP-JL, and RP-LZ, respectively.

[0093] Step 3: Cut the brake housing

[0094] In the part operation interface, according to the assembly relationship between the brake housing and the static plate, pressure plate, and compacting plate, cut the brake housing symmetrically with the dynamic plate facing the surface; save each cut segment as a new part and define the corresponding name, see Figure 4 .

[0095] In this embodiment, the brake housing is divided into five sections, each of which is saved as a new part, which are defined as KT-YJP, KT-JP1, KT-JP2, KT-JP3, and KT-CYP respectively. Corresponding reference points are established in the newly generated five parts according to the center positions of the static plate, pressure plate, and clamping plate, which are defined as KT-YJP, KT-JP1, KT-JP2, KT-JP3, and KT-CYP respectively. The corresponding relationships are shown in Table 3.

[0096] Table 3 Correspondence between the names of the cut blocks of the brake housing and the reference points

[0097] Adjacent positions of segmentation block names Reference point name Reference point coordinate source KT-YJP KT-YJP RP-YJP KT-JP1 KT-JP1 RP-JP1 KT-JP2 KT-JP2 RP-JP2 KT-JP3 KT-JP3 RP-JP3 KT-CYP KT-CYP RP-CYP

[0098] Step 4: Material Settings

[0099] According to the basic operation process of ABAQUS software, all parts / part blocks involved in the assembly are defined and assigned material properties (which should include density, elastic modulus, Poisson's ratio, linear expansion coefficient, specific heat capacity, and thermal conductivity) based on the actual material properties.

[0100] Step 5: Mesh processing

[0101] According to the basic operation process of ABAQUS software, all parts / part blocks involved in the assembly are meshed; the mesh size is 1 to 4 mm, the element type is temperature-displacement coupling element, and the second-order accuracy option is turned on.

[0102] Step 6: Assembly

[0103] 6.1 Adding Parts

[0104] According to the basic operation process of ABAQUS software, the wheel, cylinder seat, brake housing cut pieces (KT-CYP, KT-JP1, KT-JP2, KT-JP3, KT-YJP), clamping plate, movable plate, static plate, pressure plate, and piston are added to the assembly in sequence; the movable plate is added 4 times, the static plate is added 3 times, and the piston is added 5 times.

[0105] 6.2 Determine the coordinate system

[0106] For the convenience of modeling, the center point of the brake housing and the cylinder seat mating surface can be set as the origin of the coordinate system (0, 0, 0); the wheel axle axis is set as the X axis, and the side where the brake housing is located is the positive direction of the X axis; the Y axis is the vertical direction; the aircraft heading is defined as the positive direction of the Z axis, see Figure 5 The calculation unit system is mm;

[0107] 6.3 Parts Positioning

[0108] According to the basic operation process of ABAQUS software, based on the brake wheel assembly relationship and the above-mentioned coordinate system agreement, the cylinder seat, brake housing cutting blocks (KT-CYP, KT-JP1, KT-JP2, KT-JP3, KT-YJP), pressure plate, movable plate 1, static plate 1, movable plate 2, static plate 2, movable plate 3, static plate 3, movable plate 4, pressure plate, piston 1, piston 2, piston 3, piston 4, and piston 5 are positioned.

[0109] 6.4 Definition of the piston reference point on the cylinder base

[0110] Depending on the number of pistons, additional piston motion reference points must be defined on the cylinder base. In this example, there are five pistons. Five reference points are defined at the center of the piston hole bottoms on the cylinder base. These points are named RP-QGZ-HS1, RP-QGZ-HS2, RP-QGZ-HS3, RP-QGZ-HS4, and RP-QGZ-HS5. These five reference points are added to the set Set-RP-QGZ-HS.

[0111] 6.5 Definition of the wheel and cylinder block reference points on the axle

[0112] According to the coordinates of the center of mass of the cylinder seat and the wheel, define two reference points, named RP-LZ-QGZ and RP-LZ-JL respectively.

[0113] Step 7: Define the interactions

[0114] 7.1 Rigid Body Constraints

[0115] According to the basic operation process of ABAQUS software, all added parts / part blocks are defined as rigid bodies.

[0116] The specific operations are as follows:

[0117] 1) Rigidization of parts and part blocks

[0118] According to the basic operation process of ABAQUS software, rigid body constraints are established for piston 1, piston 2, piston 3, piston 4, piston 5, brake housing cutting blocks (KT-YJP, KT-JP1, KT-JP2, KT-JP3, KT-CYP), pressure plate, movable plate 1, static plate 1, movable plate 2, static plate 2, movable plate 3, static plate 3, movable plate 4, and clamping plate relative to the reference points of their respective parts.

[0119] 2) Treatment of cylinder seat

[0120] According to the basic operation process of ABAQUS software, a rigid body constraint of the cylinder seat to the part center of mass reference point RP-QGZ is established, and the set Set-RP-QGZ-HS is added to the binding node set of the rigid body constraint.

[0121] 3) Axle treatment

[0122] According to the basic operation process of ABAQUS software, a rigid body constraint of the wheel axle to the end face center reference point RP-LZ is established; then the reference points RP-LZ-JL and RP-LZ-QGZ are added to the binding node set of the rigid body constraint.

[0123] 7.2 Defining connection units

[0124] According to the basic operation process of ABAQUS software, the connection unit is established between the reference points according to the relative motion relationship of each part and the connection relationship of each part block. Figure 6 ; The specific operations are as follows:

[0125] 1) Connect the reference points of each cutting block of the brake housing

[0126] Based on the structural relationships of the brake housing, connection elements are established between the reference points of each cutout (KT-CYP, KT-JP1, KT-JP2, KT-JP3, and KT-YJP) of the brake housing. The connection element type is a cylindrical pair, and the cylindrical pair properties are elastic connections with axial D11 and axial torsional D44. The D11 and D44 stiffness values ​​of each cylindrical pair are defined according to the parameters in Tables 1 and 2. The stiffness definitions and corresponding relationships of each cylindrical pair are shown in Table 4.

[0127] Table 4 Stiffness properties of each connection element

[0128]

[0129] 2) Connect the reference points of the cutting blocks of the compression plate, static plate 1, static plate 2, static plate 3, pressure plate and shell

[0130] Define the connection elements between the pressure plate reference point and the KT-CYP block reference point, the static plate 1 reference point and the KT-JP1 block reference point, the static plate 2 reference point and the KT-JP2 block reference point, the static plate 3 reference point and the KT-JP3 block reference point, and the pressure plate reference point and the KT-YJP block reference point. The connection element type is cylindrical pair, with no attributes.

[0131] 3) Connect the piston and cylinder seat

[0132] Define connection units between the five reference points RP-QGZ-HS1, RP-QGZ-HS2, RP-QGZ-HS3, RP-QGZ-HS4, and RP-QGZ-HS5 on the cylinder seat and their corresponding five piston reference points. The connection unit type is cylindrical pair with no attributes.

[0133] 4) Connect the cylinder block to the KT-YJP block

[0134] Define a connection unit between the center of mass reference point RP-QGZ on the cylinder seat and the reference point of the brake housing KT-YJP block. The connection unit type is welding.

[0135] 5) Connect the rotor and the wheel

[0136] Define the connection units between the movable plates 1, 2, 3, and 4 and the wheel mass center reference point RP-JL. The connection unit type is cylindrical pair, and UR1 is a rigid property.

[0137] 6) Connect the cylinder seat and the axle

[0138] Define a connection element between the center of mass reference point RP-QGZ on the cylinder seat and the axle reference point RP-LZ-QGZ. The connection element type is hinged, and the hinge attribute is axial torsional stiffness D44.

[0139] 7) Connect the wheel and axle

[0140] Define a connection unit between the wheel reference point RP-JL and the axle reference point RP-LZ-JL. The connection unit type is hinged and has no attributes.

[0141] 7.3 Definition of frictional contact

[0142] Define the contact interactions between the pressure plate and movable plate 1, movable plate 1 and static plate 1, static plate 1 and movable plate 2, movable plate 2 and static plate 2, static plate 2 and movable plate 3, movable plate 3 and static plate 3, static plate 3 and movable plate 4, and movable plate 4 and the pressure plate. The contact interaction properties include the following:

[0143] 1) Tangential behavior properties: Penalty function, isotropy, check slip rate correlation, pressure correlation, and temperature correlation; and obtain friction coefficient data based on the number of material sample tests.

[0144] 2) Heat conduction: List, distance-dependent; enter 3000, 0 in the list below;

[0145] 3) Heat generation: Parameters are default; two sets of data are 0 and 0.1.

[0146] 7.4 Definition of brake housing-block contact

[0147] Define the contact interactions between the pressure plate and KT-CYP block, the static plate 1 and KT-JP1 block, the static plate 2 and KT-JP2 block, the static plate 3 and KT-JP3 block, and the pressure plate and KT-YJP block. The contact interaction properties include the following attributes:

[0148] 1) Tangential behavior properties: penalty function, isotropy, friction coefficient 0.15.

[0149] 2) Heat conduction: List, distance-dependent; enter two sets of data: 200, 0; 0, 0.1 in the list below.

[0150] 7.5 Definition of Piston Contact

[0151] Define the contact interactions between the five pistons and the pressure plate. The contact interaction properties include the following:

[0152] 1) Tangential behavior properties: penalty function, isotropy, friction coefficient 0.15.

[0153] 2) Heat conduction: List, distance-dependent; enter two sets of data: 200, 0; 0, 0.1 in the list below.

[0154] 7.6 Additional moment of inertia

[0155] The additional moment of inertia I is set at the wheel center of mass reference point RP-JL.

[0156]

[0157] I is the additional moment of inertia I.

[0158] E is the braking energy of a single wheel.

[0159] V wheel brake speed.

[0160] R gd is the tire rolling radius.

[0161] Step 8: Set up the analysis steps

[0162] 8.1 Define the explicit temperature-displacement coupling analysis step

[0163] Define the physical time length of the solution according to the braking time (can be extended appropriately); the solution step size is set to a fixed step size of 10 -5 s, and the rest are default.

[0164] 8.2 Setting Field Output

[0165] The displacement, velocity, acceleration, support reaction force, support reaction moment, concentrated force, contact pressure, and node temperature of the entire model are set to be accurately output once every 0.1s.

[0166] 8.3 Process Output

[0167] The energy range of the entire model is accurately output once every 0.0001s.

[0168] The acceleration, velocity and displacement history of the piston motion reference point on the cylinder seat are accurately output once every 0.0001s.

[0169] The reaction torque history of the wheel axle reference point is accurately output once every 0.01s.

[0170] Step 9: Load Setting

[0171] 9.1 Boundary Conditions

[0172] Completely fix the axis reference point RP-LZ.

[0173] 9.2 Braking speed setting

[0174] In the initial analysis step, the initial rotational speed ω is applied to the reference points of the wheel and all rotors;

[0175]

[0176] 9.3 Initial brake temperature setting

[0177] In the initial analysis step, set the initial temperature T for all reference points and element nodes;

[0178] Note: Temperature T is the initial brake temperature required for analysis.

[0179] 9.4 Piston thrust setting

[0180] A piston thrust F is applied to all piston connection units, and the piston thrust F can be defined as a time-dependent amplitude curve.

[0181] F=P×π×r 2

[0182] F is the piston thrust.

[0183] P is the brake pressure.

[0184] r is the effective cross-sectional radius of the piston.

[0185] Step 10: Solve

[0186] Create an analysis task and submit it for solution.

[0187] Step 11: View the results

[0188] Open the ABAQUS result visualization module and view the field output and process output data respectively.

[0189] Field output: Output temperature NT11, displacement U, velocity V, and acceleration A in the field output.

[0190] Torque history: In the historical output, select the counter torque RM1 of the output shaft reference point SET-LZ, which is the braking torque output by the brake device.

[0191] Acceleration history: Select to output the acceleration A1, A2, and A3 of the cylinder seat piston motion reference point in the history output.

[0192] In this embodiment, the output braking torque curve is shown in Figure 7 .

[0193] The axial acceleration (A1) history curve of the cylinder seat piston motion reference point is shown in Figure 8 .

[0194] The radial acceleration (A2) history curve of the cylinder seat piston motion reference point is shown in Figure 9 The tangential acceleration (A3) history curve of the cylinder seat piston motion reference point is shown in Figure 10 .

Claims

1. A method for calculating the mechanical characteristics of a brake wheel taking temperature into consideration, characterized by: The method comprises the following steps: Step 1: Calculate the equivalent connection stiffness between the adjacent parts of the brake housing, including the pressure plate, static plate block 1, static plate block 2, static plate block 3, and pressure plate block, including the equivalent torsional stiffness and equivalent tensile stiffness. The calculation process is as follows: a) In the parts operation interface: Create corresponding data points by entering the coordinates of the center of mass of the pressure plate, static plate 1, static plate 2, static plate 3, and pressure plate relative to the brake housing after actual assembly; b) Cut the brake housing through the above data points along the centerline of the brake housing; c) Select the above data points in sequence to establish reference points YJP, JP1, JP2, JP3, and CYP; establish reference point QGZ at the intersection of the brake housing and cylinder seat mating plane and the brake housing centerline; d) Couple the above reference points and the corresponding cutting surfaces, the brake vehicle housing and the cylinder seat matching planes respectively; e) Fix any reference point in the brake housing block and apply an axial torsional displacement of amplitude A to the reference point next to it. With the remaining degrees of freedom fixed, calculate the axial support reaction torque at the fixed reference point. The equivalent torsional stiffness is equal to the axial support reaction torque divided by the axial torsional displacement; F) Fix any reference point in the brake housing block and apply an axial displacement of amplitude B to the adjacent reference point. Calculate the axial support reaction force at the fixed reference point while keeping the remaining degrees of freedom fixed. The equivalent tensile stiffness is equal to the axial support reaction force divided by the axial displacement; Step 2: Import the following brake wheel parts from the CATIA model: cylinder seat, brake housing, rotor disc, stator disc, pressure plate, compression plate, piston, wheel, and axle. Establish reference points for each part at the center of mass of the cylinder seat, rotor disc, stator disc, pressure plate, compression plate, and piston, and record them as RP-QGZ, RP-DP, RP-JP, RP-YJP, RP-CYP, RP-HS, RP-JL, and RP-LZ respectively; Step 3: Based on the assembly relationship between the brake housing and the static disc, pressure disc, and compacting disc, divide the brake housing into the following five parts blocks along the symmetry plane of the dynamic disc: pressure disc block, static disc block 1, static disc block 2, static disc block 3, and compacting disc block, denoted as KT-YJP, KT-JP1, KT-JP2, KT-JP3, and KT-CYP; Step 4: Set the material properties of the brake wheel part; Step 5: Mesh all brake wheel parts, define temperature-displacement coupling elements, and enable the second-order accuracy option. Step 6: Assemble and position each brake wheel component according to the actual assembly position; Step 7: Establish the center of mass reference point, motion reference point, wheel center of mass reference point, ground reference point of the brake housing fixed point, and piston motion reference point of the upper brake wheel parts and parts blocks; Step 8: Create rigid body constraints for the brake wheel parts and part blocks; Step 9: Define connection units for each brake wheel part, part block and its reference point; Step 10: Define contact interactions between all brake disc friction surfaces; define contact interactions between the brake housing parts and the brake disc; Step 11: Set the additional moment of inertia at the wheel center of mass reference point based on the braking energy and braking speed; Step 12: Define the temperature-displacement coupling analysis step; set the output frequency of field data and history data; Step 13: Set boundary conditions; Step 14: Apply initial rotational speed to the wheel and all reference points of the rotor, apply initial temperature to all parts and reference points, apply piston thrust to the piston, and start solving.

2. The method according to claim 1, wherein: In the step nine, the connecting unit includes: establishing a connecting unit between reference points of the five parts of the brake housing according to the structural relationship of the brake housing, wherein the connecting unit type is a cylindrical pair; Establish connection relationships between the reference points of the five part blocks: the pressure plate, static plate 1, static plate 2, static plate 3, pressure plate, and the shell. The connection unit type is cylindrical pair. Establish a connection unit between the cylinder seat piston hole reference point and the piston reference point, and the connection unit type is a cylindrical pair; Establish a connection unit between the cylinder seat mass center reference point and the KT-YJP block reference point, and the connection unit type is welding; Establish a connection unit between each moving plate reference point and the wheel center of mass reference point, and the connection unit type is a cylindrical pair; Establish a connection unit between the center of mass reference point on the cylinder seat and the axle reference point, and the connection unit type is hinged; A connection unit is established between the wheel center of mass reference point and the axle reference point, and the connection unit type is hinged.

3. The method according to claim 2, wherein: In the step 10, the contact interaction between the friction surfaces of the brake discs includes: contact interaction between the pressure disc and the movable disc, between the movable disc and the static disc, and between the movable disc and the pressure disc; The contact interactions between the brake housing parts and the brake disc include: the contact interactions between the pressure disc and the KT-CYP block, the static disc 1 and the KT-JP1 block, the static disc 2 and the KT-JP2 block, the static disc 3 and the KT-JP3 block, and the pressure disc and the KT-YJP block.

4. The method according to claim 3, wherein: In the step 11, the additional moment of inertia I is calculated as follows: Where E is the braking energy of a single wheel; V is the wheel braking speed; R gd is the tire rolling radius.

5. The method according to claim 4, characterized in that: In the step 12, the field data includes: displacement U, velocity V, acceleration A, support reaction force, support reaction moment, concentrated force, contact pressure, and node temperature; and the output frequency is 1 time / 0.1s.

6. The method according to claim 5, characterized in that: In step thirteen, the boundary conditions are as follows: the axis reference point RP-LZ is completely fixed.

7. The method according to claim 6, characterized in that: In step 14, the initial speed ω is calculated as follows: ; The calculation formula of piston thrust F is as follows: Where P is the brake pressure and r is the effective cross-sectional radius of the piston.

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