CN113205858B - Dynamic simulation model and method for simulating flutter environment hinge mechanism movement molecule - Google Patents
Dynamic simulation model and method for simulating flutter environment hinge mechanism movement molecule Download PDFInfo
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Abstract
The invention relates to a molecular dynamics simulation model and a molecular dynamics simulation method for simulating a flutter environment hinge mechanism movement, belonging to the technical field of molecular dynamics; the simulation model comprises a pressure head, a base body and springs, wherein the pressure head is arranged right above the base body, and the two springs are respectively arranged at the bottom of the base body along the Z direction and the Y direction. In the simulation method, a molecular dynamics simulation model is firstly constructed; then, forced sinusoidal vibration is applied to the Y direction and the Z direction of the pressure head, and meanwhile, horizontal speed Vs is applied to the pressure head, and collision sliding friction is started under a micro-regular ensemble; and finally, performing simulation calculation to obtain the position coordinates of the pressure head and the base body under different vibration frequencies and the friction force curve received by the pressure head in the collision sliding process. Compared with the traditional molecular dynamics model for researching vibration, the model provided by the invention is more close to the actual working condition, and the accuracy of a simulation result is improved.
Description
Technical Field
The invention belongs to the technical field of molecular dynamics, and particularly relates to a molecular dynamics simulation model and a molecular dynamics simulation method for simulating movement of a hinge mechanism in a flutter environment.
Background
The spacecraft repeatedly enters and exits the earth shadow during the orbit running, the alternating range of the temperature is wide, and the alternating range of the temperature changes along with the changes of orbit height, seasons and the like, so that the space mechanism is subjected to repeated and intense temperature alternation, and a large amount of internal force is accumulated in the material due to the long-term and intense temperature alternation, so that the low-frequency vibration of the mechanical structure is caused. And because of the existence of space microgravity environment, gravity is smaller than other acting forces, the spaceflight mechanism is easy to shake due to friction moment, and can not quickly recover to the balance position, but does irregular shake near the balance position, so that the vibration of the mechanism is caused, collision friction is caused, and the movement and stability of precision equipment are seriously influenced.
For the ground environment, the simulation of microgravity is difficult, the cost is high, the dynamic friction process is difficult to observe in an experimental mode, and the numerical simulation method becomes an effective way for solving the problem. The molecular dynamics method is a method of a widely applied calculation complex system at present, so far, researchers build a plurality of force field models suitable for different material systems, greatly improve the capability and accuracy of calculating complex system structures and thermodynamic properties, and simulate the movement of particles in the system, thereby having definite physical basis. Meanwhile, dynamic characteristics and thermodynamic statistics data of the system can be obtained, and an important basis is provided for theoretical analysis of related research.
The collision sliding friction is one of friction studies, and the existing friction study based on molecular dynamics, such as article The Influence of Vertical Vibration on Nanoscal Friction published in journal A Molecular Dynamics Simulation Study, volume 8, phase 3 and 129, is used for studying the influence of vibration on the nanoscopic friction through molecular dynamics, indicating that certain frequency dependence exists in friction force, and considering the influence of pressure head vibration on friction through applying forced vibration to a pressure head, but neglecting the phenomenon that a matrix generates follow-up due to the pressure head vibration. Under the actual working condition, the shaft hole can generate a flutter phenomenon due to the vibration of the pin shaft, so that the follow-up of the shaft hole is ignored by simply considering the vibration of the pin shaft, and the actual movement process cannot be represented. According to the invention, a molecular dynamics simulation model is established, forced sinusoidal vibration is applied to the pressure head to simulate the vibration of the pin shaft, and meanwhile, springs are applied to the Y direction and the Z direction of the matrix to simulate the follow-up of the shaft hole, so that the simulation analysis of tribology research in the flutter environment is performed.
Disclosure of Invention
The technical problems to be solved are as follows:
in order to avoid the defects of the prior art, the invention provides a dynamic simulation model for simulating the motion molecular dynamics of a hinge mechanism in a flutter environment and a construction method thereof, wherein a microscopic mechanism of friction and abrasion of the hinge mechanism in the flutter environment is simulated through a pressure head and a matrix, and the influence of vibration on the friction force of the hinge mechanism is analyzed.
The technical scheme of the invention is as follows: a simulation model for simulating the motion molecular dynamics of a flutter environment hinge mechanism is characterized in that: the device comprises a pressure head, a base body and a spring, wherein the pressure head is of a cylindrical structure and is used for simulating the movement of a central shaft of a hinge mechanism; the base body is of a cuboid structure and is arranged below the pressure head through a spring and used for simulating the follow-up of a shaft hole in the hinge mechanism; the axial direction of the pressure head is parallel to the top surface of the basal body;
the springs comprise a first spring and a second spring, wherein the axial direction of the first spring is arranged along the Z direction and is vertically fixed at the center of the bottom surface of the base body to simulate the Z-direction movement in the hinge; the second spring is axially arranged along the Y direction and is vertically fixed at the center of the bottom edge of the side wall of the base body to simulate Y-direction movement in the hinge.
A construction method of a dynamic simulation model of a motion molecule of a hinge mechanism in a simulated flutter environment is characterized by comprising the following specific steps:
step one: setting boundary conditions of a system in simulation software according to the motion characteristics of a hinge mechanism, and selecting an atomic interaction potential function; setting initial conditions of the system, namely an initial position and an initial speed; selecting a time step and constructing a molecular dynamics simulation model;
step two: the follow-up state of the base body along with the vibration of the pressure head is realized by arranging springs in the Y direction and the Z direction of the base body;
step three: applying forced sinusoidal vibration to the Y direction and the Z direction of the pressure head, applying horizontal speed Vs to the pressure head, and starting collision sliding friction under a micro regular ensemble;
step four: and D, performing molecular dynamics simulation calculation on the collision sliding friction process performed under the micro-regular ensemble in the step three, and counting calculation results to obtain the position coordinates of the pressure head and the matrix under different vibration frequencies and the friction force curve received by the pressure head in the collision sliding process.
The invention further adopts the technical scheme that: in the first step, the specific steps for constructing the molecular dynamics simulation model are as follows:
step 1: establishing a pressure head and matrix model for simulating the hinge mechanism in software according to the motion characteristics of the hinge mechanism; the substrate comprises a fixed layer, a constant temperature layer and a Newton layer, and atoms in the range of the bottom of the substrate and the opposite sides a of the X direction are set as fixed layer atoms; setting atoms in a range of a above the bottom fixed layer as atoms of the constant temperature layer, and absorbing heat generated in the friction process; the rest atoms in the matrix are set as Newton layer atoms; atoms in the constant temperature layer and the Newton layer follow Newton's second law of motion;
step 2: setting the X direction and the Y direction of the simulation area as periodic boundary conditions so as to reduce the size effect;
step 3: the interaction between atoms is obtained through the interaction potential function between atoms of different elements in the system;
step 4: setting initial velocities of all atoms in the system according to a Maxwell-Boltzmann energy distribution function, thereby establishing initial velocities of atomic distribution of the pressure head and the matrix, wherein the initial velocities correspond to temperatures of respective equilibrium states; setting the system temperature as 300K, and selecting the integral step length as 1fs;
step 5: after the setting of the steps 1-4 is completed, under the regular ensemble NVT, according to the initial position and initial speed of each atom in the set system, calculating potential energy, position and speed of each atom in the system according to the selected potential function, and carrying out balance constraint on the pressure head and the matrix atoms so as to enable the initial model of the system to reach a balance state; and after the system relaxation is completed, carrying out internal equilibrium state evolution on the system under the micro regular ensemble (NVE) to enable the system to reach an equilibrium state.
The invention further adopts the technical scheme that: in the step 1, a crystal model with a matrix of nonmetallic silicon is constructed by utilizing LAMMPS software, the crystal lattice structure of the silicon is a diamond structure, the lattice constant a is 0.543nm, the model corresponds to crystal directions [100], [010] and [001] in the X, Y and Z directions respectively, and the sizes of the directions are 50a multiplied by 16a multiplied by 25a, and 162416 silicon atoms are contained; the pressure head is cylindrical with the radius of 8a, and the material is diamond.
The invention further adopts the technical scheme that: the upper half atoms of the pressure head are removed, only the cylindrical structure of the half part is remained in calculation, and the pressure head contains 30679 carbon atoms after removal.
The invention further adopts the technical scheme that: in the step 3, three interaction potentials are included: si-Si atoms, C-C atoms, and C-Si atoms.
The invention further adopts the technical scheme that: the interactions between the Si-Si atoms are fitted by a Tersof multi-body potential function; the interaction between the diamond indenter and the silicon substrate atoms is described using a Morse potential.
The invention further adopts the technical scheme that: in the second step, when the flutter environment is simulated, the pressure head vibrates to cause the change of the position of the substrate, so that the spring is deformed, the force generated by the deformation of the spring is uniformly applied to each atom of the substrate fixing layer, and the follow-up state of the shaft hole along with the vibration of the shaft in the hinge mechanism can be simulated; the stiffness coefficients of the first spring and the second spring are K1 and K2 respectively.
The invention further adopts the technical scheme that: the force generated by the deformation of the spring is as follows:
F＝K×(X 1 -X 0 )
wherein: k is the stiffness coefficient of the spring, X 0 X is the initial centroid position of the substrate 1 Is the instantaneous centroid position of the substrate during movement.
The invention further adopts the technical scheme that: in the third step, the motion characteristics of the hinge mechanism are simulated, irregular collision of the shaft is equivalent to the coupling of forced vibration applied by the cylinder pressure head in the Y direction and the Z direction, and the vibration amplitudes of the vibration in the Y direction and the Z direction are Ay and Az respectively; the frequencies are fy and fz respectively; simultaneously, the rotation movement of the shaft is equivalent to the horizontal sliding of the pressure head along the surface of the matrix; applying sinusoidal forced vibration and sliding speed Vs in the horizontal direction to the pressure head in the Y direction and the Z direction by utilizing a fix move command of LAMMPS software, and starting a collision sliding friction process under a micro regular ensemble; according to the spring stiffness K1 and K2 set in the second step, the natural frequencies of the Y direction and the Z direction of the matrix are calculated according to the following formula:
wherein: k is the rigidity coefficient of the spring, and M is the mass of the matrix;
and (3) changing the vibration frequency of the pressure head, calculating to obtain the position coordinates of the pressure head and the base body and the friction force born by the pressure head in the collision sliding process under different vibration frequencies according to the related parameters set in the step (A) and the interaction potential functions among different element atoms in the selected system, and performing simulation analysis of tribology research under the flutter environment.
Advantageous effects
The invention has the beneficial effects that: according to the motion characteristics of a hinge mechanism in a space environment, irregular collision of a shaft is equivalent to coupling of forced vibration applied by a cylindrical pressure head in the Y direction and the Z direction, and rotation motion of the shaft is equivalent to horizontal sliding of the pressure head along the surface of a substrate, so that irregular shaking of a pin shaft due to friction moment in the space microgravity environment is simulated; meanwhile, the invention is provided with the springs at the bottom of the matrix along the Y direction and the Z direction, the pressure head causes the position change of the matrix to finally deform the springs due to vibration, and the force generated by the deformation of the springs is uniformly applied to each atom of the matrix fixing layer, so that the actual working condition that the shaft hole follows the vibration of the pin shaft is simulated.
Compared with the traditional molecular dynamics model for researching vibration, the model provided by the invention is more close to the actual working condition, and the accuracy of a simulation result is improved. The invention compares the coordinate difference curve of the base body and the pressure head in the collision sliding process under the condition that the base body has a spring when fz=52.6 GHz (shown in figure 5). From the graph 5 (a), it can be known that the coordinate difference curve between the ram and the substrate in the state that the substrate is free of springs is basically consistent with the forced vibration curve applied by the ram; however, when the base body is provided with a spring, the base body can be seen to have a certain follow-up, so that relatively severe relative vibration is caused. Meanwhile, as can be seen from fig. 5 (b), the friction force of the base body in the state of having or not having the spring is also greatly different, the average friction force in the state of having the spring is 29.66nN, and the average friction force in the state of not having the spring is 59.38nN, so that the follow-up process of the base body along with the vibration of the pressing head is not neglected.
Drawings
FIG. 1 is a simplified illustration of a hinge mechanism;
FIG. 2 is a simulation model of a simulated hinge structure according to the present invention;
fig. 3 is a schematic diagram of a motion process simulation model of a hinge mechanism in a simulated flutter environment.
FIG. 4 is a flow chart of the invention simulating the movement of a flutter environment hinge mechanism;
fig. 5 is a graph comparing the results of the presence or absence of a spring at fz=52.6 GHz;
FIG. 6 is a graph showing the comparison of the coordinate difference and the friction result at fz=36.6 GHz and fz=52.6 GHz in the example of the present invention;
FIG. 7 is a cross-sectional view of a matrix transient defect structure during simulation of the present invention.
Reference numerals illustrate: 1. the hole, 2, the axle, 3, the pressure head, 4, the base member.
Detailed Description
The embodiments described below by referring to the drawings are illustrative and intended to explain the present invention and should not be construed as limiting the invention.
The embodiment provides a method for constructing a simulation model of motion molecular dynamics of a hinge mechanism in a simulated flutter environment, which comprises the following steps:
step one, setting boundary conditions of a system according to motion characteristics of a hinge mechanism, selecting an atomic interaction potential function, setting initial conditions and related simulation parameters of the system, and constructing a molecular dynamics simulation model;
the method comprises the following substeps:
step 1, simplifying a hinge mechanism model according to the motion characteristics of the hinge mechanism; the simplified hinge mechanism is a cylindrical ram and a rectangular base, as shown in fig. 2, according to the motion characteristics of the hinge mechanism. A crystal model of nonmetallic silicon (Si) is constructed by utilizing LAMMPS software, the lattice structure of the silicon is a diamond structure, the lattice constant a is 0.543nm, the model corresponds to crystal directions [100], [010] and [001] in X, Y and Z directions respectively, and the sizes of the directions are 50a multiplied by 16a multiplied by 25a, and 162416 silicon atoms are contained. A cylindrical ram with a radius of 8a was then constructed, the material being diamond, and the upper half of the ram was removed for a total of 30679 carbon atoms in the ram to save computational time. In addition, in order to prevent the matrix from shifting, atoms in the range of the bottommost part and the two sides a of the matrix are set as fixed layer atoms (fixed); setting atoms in a range of a above the bottom fixed layer as atoms of the constant temperature layer to absorb heat generated in the friction process; the rest atoms are Newton layer atoms; atoms within the isothermal layer and the newton layer follow newton's second law of motion.
Step 2, setting boundary conditions of the system; because of the limitations of computer performance, algorithm efficiency and accuracy, in order to reduce the size effect caused by the fact that the scale of the simulation system is far smaller than the actual scale, only a certain volume of material can be selected as a primitive cell, molecular dynamics calculation is executed according to boundary conditions, and the periodic boundary conditions are adopted in the X and Y directions in the embodiment;
step 3, selecting an atomic interaction potential function; in the molecular dynamics simulation calculation, selecting a proper potential function is a necessary condition for obtaining an accurate result, so far, molecular dynamics development has established a plurality of force field models suitable for different material systems, consulting related documents, and selecting potential functions among different elements to describe the interaction among atoms. There are three different interaction potentials in this example: si-Si atoms (atomic potential function within the silicon substrate), C-C atoms (internal atomic potential function of the indenter), and C-Si atoms (potential function between the indenter and the substrate). The hardness of diamond is much greater than Si, so the diamond indenter can be considered a rigid body, ignoring interactions between C-C atoms; with reference to the related literature, for covalent systems with diamond cubic structure, the influence of covalent bonds and bond angles should be considered, which is good for the teroff multi-gesture function, the simulation process of the embodiment selects the teroff multi-gesture function to fit the interaction between Si-Si atoms; the Morse potential was chosen to describe the interaction between the diamond indenter and the silicon substrate atoms.
Step 4, setting initial conditions of the system and related simulation parameters; the initial condition is the speed and position of each atom of the system when the simulation is started, and the molecular dynamics calculation essence is the process of carrying out integral solution on the equation according to the initial value. The principle of initial velocity generation of atoms in the system is: and multiplying the random number by the average speed of atoms according to a random number generation speed set generated by the specified temperature to obtain the atomic speed conforming to Maxwell-Boltzmann. Assigning an initial velocity to the established indenter and matrix atoms according to a Maxwell-Boltzmann energy distribution function, the velocity corresponding to the temperature of their equilibrium state; the system temperature is set to 300K and the integration step size is selected to be 1fs. Since the ram material set in this embodiment is rigid, the initial speed is not set for it; if the ram is made of a non-rigid material, an initial velocity needs to be set.
After the setting of the conditions is completed, under a regular ensemble (NVT), according to the initial position and initial speed of each particle in the set system, potential energy, position and speed of each atom in the system are calculated according to the selected potential function, and balance constraint is carried out on the pressure head and the matrix atoms so that the initial model of the system reaches a balance state. After the relaxation of the system is completed, the internal equilibrium state evolution is carried out on the system under a micro-regular (NVE) system, so that the system reaches an equilibrium state, and the preparation is made for the simulation of the subsequent collision sliding friction process.
Step two, arranging a spring in each of the Y direction and the Z direction of the substrate to realize the follow-up state of the substrate along with the vibration of the pressing head;
under the vibration environment, the shaft hole is also in a vibration state due to the continuous vibration of the pin shaft, a spring (shown in figure 3) is respectively arranged at the bottom of the base body along the Y direction and the Z direction, the change of the position of the base body caused by the vibration of the pressure head finally causes the spring to deform, and the force generated by the deformation of the spring:
F＝K×(X 1 -X 0 )
wherein: k is the stiffness coefficient of the spring, X 0 To calculate the initial mass center position of the matrix, X 1 Is the instantaneous centroid position of the substrate during movement. The force is applied to each atom of the fixed layer (fixed) uniformly to drive the matrix to move so as to simulate the follow-up state of the hole caused by the vibration of the shaft. The spring stiffness coefficients are K1, K2, respectively, the magnitude of which depends on the stiffness of the member to which the hinge structure is connected, given k1=600n/m and k2=400n/m in this embodiment. Through the setting of the step, the substrate can generate corresponding follow-up due to the vibration of the pressure head, and the substrate is more close to the real working condition.
Step three, applying forced sinusoidal vibration to the Y direction and the Z direction of the pressure head, and simultaneously applying a horizontal speed Vs to the pressure head;
as shown in fig. 1, according to the motion characteristics of the hinge mechanism in a space environment, the irregular collision of the shaft is equivalent to the coupling of forced vibration applied by the cylinder pressure head in the Y direction and the Z direction, and the vibration amplitudes of the vibration in the Y direction and the Z direction are Ay and Az respectively; the frequencies are fy and fz respectively; simultaneously, the rotation motion of the shaft is equivalent to the horizontal uniform-speed sliding of the pressure head along the surface of the matrix; while applying a sliding velocity Vs in the horizontal direction to the indenter by a fix move command of LAMMPS software, a sinusoidal forced vibration is applied to the indenter in the Y direction and Z direction (as shown in fig. 3), the horizontal sliding velocity of the indenter is vs=50m/s, and the amplitude of the forced vibration applied in the Y direction and Z direction is ay=az=0.55 nm, according to the spring rates K1, K2 set in step B, according to the formula:
wherein: k is the stiffness coefficient of the spring, and M is the mass of the matrix. Natural frequencies of the Y direction and the Z direction of the matrix can be calculated, and different ram vibration frequencies are adjusted to study the influence of the vibration frequency on the friction force. Given k1=600n/m, k2=400n/m according to this example, the natural frequencies of the substrate in the Y and Z directions are calculated to be 44.9GHz and 36.6GHz, respectively, according to the formula. In this embodiment, with reference to the single variable principle, fz=36.6 GHz and fz=52.6 GHz are selected under the condition of fy=50 GHz, and the influence of different Z-direction vibration frequencies on the friction force in the collision sliding process is studied.
D. Data processing and visualization processing
And performing molecular dynamics simulation calculation on the self-written program file through LAMMPS software. According to the system boundary conditions, atomic interaction potential functions and the like set in the step A, according to a Verlet integral algorithm, carrying out molecular dynamics simulation calculation in a collision sliding process under a micro-regular ensemble, and calculating a calculation result to obtain position coordinates of a pressure head and a substrate under different vibration frequencies and friction force curves (shown in fig. 6) born by the pressure head in the collision sliding process, wherein when fz=36.6GHz, resonance phenomenon occurs because Z-direction vibration frequency of the pressure head is equal to Z-direction natural frequency of the substrate, and a coordinate difference curve between the pressure head and the substrate finally converges; whereas fz=52.6 GHz, it can be seen that a more intense vibration occurs; from fig. 6 (b), it can be analyzed that the average friction force in the flutter environment has a certain frequency dependence; and simultaneously, the OVITO software is used for carrying out visual analysis on the data of molecular dynamics simulation, so that atomic transient structural defects (shown in fig. 7) generated in the collision sliding process can be intuitively seen.
Although embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives, and variations may be made in the above embodiments by those skilled in the art without departing from the spirit and principles of the invention.
Claims (6)
1. A construction method of a simulation model for simulating the motion molecular dynamics of a flutter environment hinge mechanism is characterized by comprising the following steps: the simulated flutter environment hinge mechanism motion molecular dynamics simulation model comprises a pressure head, a base body and a spring, wherein the pressure head is of a cylindrical structure and is used for simulating the motion of a central shaft of the hinge mechanism; the base body is of a cuboid structure and is arranged below the pressure head through a spring and used for simulating the follow-up of a shaft hole in the hinge mechanism; the axial direction of the pressure head is parallel to the top surface of the basal body; the springs comprise a first spring and a second spring, wherein the axial direction of the first spring is arranged along the Z direction and is vertically fixed at the center of the bottom surface of the base body to simulate the Z-direction movement in the hinge; the second spring is axially arranged along the Y direction and is vertically fixed at the center of the bottom edge of the side wall of the base body to simulate Y-direction movement in the hinge;
the construction method comprises the following specific steps:
step one: setting boundary conditions of a system in simulation software according to the motion characteristics of a hinge mechanism, and selecting an atomic interaction potential function; setting initial conditions of the system, namely an initial position and an initial speed; selecting a time step and constructing a molecular dynamics simulation model;
step two: the follow-up state of the base body along with the vibration of the pressure head is realized by arranging springs in the Y direction and the Z direction of the base body; when the flutter environment is simulated, the pressure head vibrates to cause the change of the position of the substrate, so that the spring is deformed, the force generated by the deformation of the spring is uniformly applied to each atom of the substrate fixing layer, and the follow-up state of the shaft hole along with the vibration of the shaft in the hinge mechanism can be simulated; the stiffness coefficients of the first spring and the second spring are K1 and K2 respectively; the force generated by the deformation of the spring is as follows:
F＝K×(X 1 -X 0 )
wherein: k is the stiffness coefficient of the spring, X 0 X is the initial centroid position of the substrate 1 The instantaneous mass center position of the matrix in the motion process;
step three: applying forced sinusoidal vibration to the Y direction and the Z direction of the pressure head, applying horizontal speed Vs to the pressure head, and starting collision sliding friction under a micro regular ensemble; simulating the motion characteristics of a hinge mechanism, and equating the irregular collision of the shaft to the coupling of forced vibration applied by a cylinder pressure head in the Y direction and the Z direction, wherein the vibration amplitudes of the vibration in the Y direction and the Z direction are Ay and Az respectively; the frequencies are fy and fz respectively; simultaneously, the rotation movement of the shaft is equivalent to the horizontal sliding of the pressure head along the surface of the matrix; applying sinusoidal forced vibration and sliding speed Vs in the horizontal direction to the pressure head in the Y direction and the Z direction by utilizing a fix move command of LAMMPS software, and starting a collision sliding friction process under a micro regular ensemble; according to the spring stiffness K1 and K2 set in the second step, the natural frequencies of the Y direction and the Z direction of the matrix are calculated according to the following formula:
wherein: k is the rigidity coefficient of the spring, and M is the mass of the matrix;
changing the vibration frequency of the pressure head, calculating to obtain the position coordinates of the pressure head and the base body and the friction force born by the pressure head in the collision sliding process under different vibration frequencies according to the related parameters set in the first step and the interaction potential functions among different element atoms in the selected system, and performing simulation analysis of tribology study under the flutter environment;
step four: and D, performing molecular dynamics simulation calculation on the collision sliding friction process performed under the micro-regular ensemble in the step three, and counting calculation results to obtain the position coordinates of the pressure head and the matrix under different vibration frequencies and the friction force curve received by the pressure head in the collision sliding process.
2. The method for constructing the simulated model of the dynamic simulation of the motion molecular dynamics of the hinge mechanism in the simulated flutter environment according to claim 1, which is characterized in that: in the first step, the specific steps for constructing the molecular dynamics simulation model are as follows:
step 1: establishing a pressure head and matrix model for simulating the hinge mechanism in software according to the motion characteristics of the hinge mechanism; the substrate comprises a fixed layer, a constant temperature layer and a Newton layer, and atoms in the range of the bottom of the substrate and the opposite sides a of the X direction are set as fixed layer atoms; setting atoms in a range of a above the bottom fixed layer as atoms of the constant temperature layer, and absorbing heat generated in the friction process; the rest atoms in the matrix are set as Newton layer atoms; atoms in the constant temperature layer and the Newton layer follow Newton's second law of motion;
step 2: setting the X direction and the Y direction of the simulation area as periodic boundary conditions so as to reduce the size effect;
step 3: the interaction between atoms is obtained through the interaction potential function between atoms of different elements in the system;
step 4: setting initial velocities of all atoms in the system according to a Maxwell-Boltzmann energy distribution function, thereby establishing initial velocities of atomic distribution of the pressure head and the matrix, wherein the initial velocities correspond to temperatures of respective equilibrium states; setting the system temperature as 300K, and selecting the integral step length as 1fs;
step 5: after the setting of the steps 1-4 is completed, under the regular ensemble NVT, according to the initial position and initial speed of each atom in the set system, calculating potential energy, position and speed of each atom in the system according to the selected potential function, and carrying out balance constraint on the pressure head and the matrix atoms so as to enable the initial model of the system to reach a balance state; and after the system relaxation is completed, carrying out internal equilibrium state evolution on the system under the micro regular ensemble (NVE) to enable the system to reach an equilibrium state.
3. The method for constructing the simulated dynamic model of the motion molecular dynamics of the simulated flutter environment hinge mechanism, which is characterized by comprising the following steps of: in the step 1, a crystal model with a matrix of nonmetallic silicon is constructed by utilizing LAMMPS software, the crystal lattice structure of the silicon is a diamond structure, the lattice constant a is 0.543nm, the model corresponds to crystal directions [100], [010] and [001] in the X, Y and Z directions respectively, and the sizes of the directions are 50a multiplied by 16a multiplied by 25a, and 162416 silicon atoms are contained; the pressure head is cylindrical with the radius of 8a, and the material is diamond.
4. The method for constructing the simulated dynamic model of the motion molecular dynamics of the hinge mechanism in the simulated flutter environment according to claim 3, wherein the method comprises the following steps of: the upper half atoms of the pressure head are removed, only the cylindrical structure of the half part is remained in calculation, and the pressure head contains 30679 carbon atoms after removal.
5. The method for constructing the simulated dynamic model of the motion molecular dynamics of the simulated flutter environment hinge mechanism, which is characterized by comprising the following steps of: in the step 3, three interaction potentials are included: si-Si atoms, C-C atoms, and C-Si atoms.
6. The method for constructing the simulated dynamic model of the motion molecular dynamics of the simulated flutter environment hinge mechanism, which is characterized in that: the interactions between the Si-Si atoms are fitted by a Tersof multi-body potential function; the interaction between the diamond indenter and the silicon substrate atoms is described using a Morse potential.
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