CN113506597B - Analysis method for adsorption performance of organic antifriction agent based on molecular dynamics - Google Patents
Analysis method for adsorption performance of organic antifriction agent based on molecular dynamics Download PDFInfo
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- 238000001179 sorption measurement Methods 0.000 title claims abstract description 57
- 239000003831 antifriction material Substances 0.000 title claims abstract description 40
- 238000000329 molecular dynamics simulation Methods 0.000 title claims abstract description 22
- 238000004458 analytical method Methods 0.000 title abstract description 10
- 239000002199 base oil Substances 0.000 claims abstract description 38
- 238000000034 method Methods 0.000 claims abstract description 33
- 238000005461 lubrication Methods 0.000 claims abstract description 27
- 239000000463 material Substances 0.000 claims abstract description 22
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- 238000010008 shearing Methods 0.000 claims abstract description 11
- 238000006073 displacement reaction Methods 0.000 claims abstract description 10
- 206010034719 Personality change Diseases 0.000 claims abstract description 7
- 230000001050 lubricating effect Effects 0.000 claims abstract description 7
- 235000021355 Stearic acid Nutrition 0.000 claims description 38
- QIQXTHQIDYTFRH-UHFFFAOYSA-N octadecanoic acid Chemical compound CCCCCCCCCCCCCCCCCC(O)=O QIQXTHQIDYTFRH-UHFFFAOYSA-N 0.000 claims description 38
- OQCDKBAXFALNLD-UHFFFAOYSA-N octadecanoic acid Natural products CCCCCCCC(C)CCCCCCCCC(O)=O OQCDKBAXFALNLD-UHFFFAOYSA-N 0.000 claims description 38
- 239000008117 stearic acid Substances 0.000 claims description 38
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 27
- 239000010687 lubricating oil Substances 0.000 claims description 24
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- RZJRJXONCZWCBN-UHFFFAOYSA-N octadecane Chemical compound CCCCCCCCCCCCCCCCCC RZJRJXONCZWCBN-UHFFFAOYSA-N 0.000 claims description 18
- 238000004364 calculation method Methods 0.000 claims description 17
- 229910052742 iron Inorganic materials 0.000 claims description 10
- -1 3, 5-diethyl tetradecane Chemical compound 0.000 claims description 9
- ISQLYZNRIXBHCG-UHFFFAOYSA-N 2,4-dimethylhexadecane Chemical compound CCCCCCCCCCCCC(C)CC(C)C ISQLYZNRIXBHCG-UHFFFAOYSA-N 0.000 claims description 8
- 239000013078 crystal Substances 0.000 claims description 6
- 229910052799 carbon Inorganic materials 0.000 claims description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 4
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- 229940038384 octadecane Drugs 0.000 description 1
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Abstract
The invention relates to an analysis method of adsorption performance of an organic antifriction agent based on molecular dynamics. Firstly, constructing a lubricating model in a nano gap by utilizing molecular dynamics software, wherein the base oil contains an organic antifriction agent; secondly, adopting a DREIDING force field, and simulating adsorption and shearing by using Materials Studio and lamMPS software; and finally, according to the position change of the antifriction agent molecules in the adsorption process, acquiring the relation of the attitude change, time and displacement of the antifriction agent molecules and the density distribution of the base oil molecules, and analyzing the friction factor and the absorption performance of the antifriction agent. The method overcomes the defect that the existing physical test cannot be measured on line, quantitatively predicts the molecular distribution, density, diffusion coefficient and adsorption energy of the lubricant from the atomic scale; dynamically and timely displaying the movement and lubrication condition of the molecules. The method is simple and flexible, provides reliable basis for the practical application of the organic antifriction agent, and has wide application prospect and guiding value.
Description
Technical Field
The invention belongs to the technical field of molecular dynamics simulation, and particularly relates to an analysis method of adsorption performance of an organic antifriction agent based on molecular dynamics.
Background
In order to avoid direct contact between friction pairs, the application of lubricating oil is one of the most important means. The lubricating oil film under the nano-gap lubrication condition is easy to break, so that the friction pairs are in direct contact, and friction and abrasion are increased. Therefore, lubricating oil additives capable of reducing frictional wear under nanogap lubrication conditions are becoming increasingly important. While considering the environmental pollution problem caused by lubricant additives, an environmentally friendly Organic friction reducer (Organic FrictionModifiers, OFMs) containing only C, H, O and N has received widespread attention from the whole society.
The OFMs additive molecule is an amphiphilic surfactant molecule consisting of an alkyl chain and terminal polar groups. Polar groups are adsorbed on the metal surface by virtue of Van der Waals force between molecules or atoms to form an adsorption film of a monolayer or a multi-molecular layer. The structural stability of the adsorption film has important significance for reducing friction and protecting the friction pair surface. Organic friction reducers are most common and widely studied in the long history of friction modifiers, but their exact mechanism of low friction is still a pending problem. Meanwhile, since physical or chemical change of the monolayer film at the time of the test is a very rapid process, which makes it difficult to observe the initial adsorption process, the formation process of the molecular adsorption film has not been known.
The molecular dynamics simulation method not only can dynamically and timely display the distribution rule of molecules and density in the lubricating oil layer and overcome the defect that the initial stage atomic motion cannot be measured in the test, but also can flexibly and accurately establish various molecular structure models, thereby overcoming the defect that the test method cannot detect and research the novel lubricating oil which is not developed yet. Molecular dynamics simulation is adopted to provide theoretical basis and technical support for the adsorption mechanism of the organic antifriction agent between the nanogaps.
Disclosure of Invention
The invention aims to provide an analysis method for the adsorption performance of an organic antifriction agent based on molecular dynamics, which realizes the shearing simulation under the conditions of different surface nano roughness and different lubricant compositions, observes the position change of the organic antifriction agent molecules in the adsorption process from an atomic scale, acquires the relation of the attitude change, time and displacement of the organic antifriction agent molecules and the density distribution of base oil molecules at different moments, examines the change of friction factors, and explores the adsorption mechanism of the organic antifriction agent under different conditions.
In order to achieve the above purpose, the technical scheme of the invention is as follows: an analysis method of adsorption performance of an organic antifriction agent based on molecular dynamics comprises the following steps:
step S1, establishing a molecular dynamics simulation model: building a rough wall surface model of crystal orientation [100] metallic iron by utilizing LAMMPS software, building a lubricating oil model by utilizing material Studio software, and combining the wall surface model and the lubricating oil model into a nano-gap lubricating model;
s2, performing adsorption simulation and shearing simulation on the nano gap lubrication model by using a full atomic force field DREIDING and using Materials Studio software and lamMPS software to obtain a simulation result, and storing the result in an output file;
and S3, visually expressing the simulation result, acquiring the relation of the attitude change, time and displacement of the organic antifriction agent molecules at different moments and the density distribution of the base oil molecules according to the position change of the organic antifriction agent molecules in the adsorption process, and analyzing the adsorption performance of the organic antifriction agent under different conditions.
In an embodiment of the present invention, the step S1 specifically includes:
s11, constructing a rough wall model of metal iron by utilizing LAMMPS software, and selecting alpha-Fe with a lattice constant of
The crystal orientation is [100]]Setting different wall surface roughness, wherein the upper wall surface roughness and the lower wall surface roughness are the same; stearic acid is selected as an organic antifriction agent, n-octadecane, 2, 4-dimethyl hexadecane and 3, 5-diethyl tetradecane which have the same carbon content but different structures are selected as base oil, a lubricating oil model is constructed by utilizing an Amorphos Cell module in material Studio software, and the space structure of the constructed lubricating oil model is optimized by a formite module;
step S12, establishing a nano gap lubrication model of an upper wall surface, an oil film and a lower wall surface, and combining the wall surface model and the lubricating oil model into the nano gap lubrication model by utilizing a Build module in material Studio software; the upper and lower wall surfaces are divided into 6 layers: the outer layer is a rigid layer for applying the nano-gap condition, the middle is a constant temperature layer for providing environmental influence factors, and the inner layer is a free deformation layer for extracting mechanical properties;
step S13, setting a nanogap condition of a nanogap lubrication model, setting periodic nanogap conditions in the x and y directions, and setting shrinkage nanogap conditions in the z direction;
and S14, selecting potential functions of corresponding materials, and selecting a full-atomic force field DREIDING potential to describe the action between iron atoms and iron atoms, between iron atoms and stearic acid molecules, between iron atoms and base oil molecules, between stearic acid molecules and stearic acid molecules, between base oil molecules and base oil molecules, and between stearic acid molecules and base oil molecules.
In an embodiment of the present invention, the step S2 specifically includes:
s21, relaxing the system under the regular ensemble and the micro-regular ensemble, and relaxing the system by utilizing a Nose-Hoover hot bath method so as to enable an initial model of the system to reach an equilibrium state, simulating the density of the system, and verifying the rationality of a nano gap lubrication model;
s22, in the pressurizing stage, the regular ensemble during relaxation is relieved, the temperature of the constant temperature layer is set, the lower wall surface rigid layer is fixed, and pressure is applied to the upper wall surface rigid layer, so that the system is in a stable state;
step S23, in the shearing stage, the pressure is kept unchanged, and simultaneously, the two rigid layers respectively move along the x axis at the same speed and opposite direction;
and S24, data processing, namely performing molecular dynamics simulation calculation on the lubrication system by utilizing Materials Studio software and LAMMPS software, and counting calculation results to obtain related data of a simulation process and calculation results, outputting a file, wherein the output file contains variable parameters and change information of atomic coordinates.
In one embodiment of the invention, the dynamic modules in the Materials Studio software are utilized to simulate the adsorption process of the lubrication system, and the total energy of the system, the total energy of the lubricant molecules and the total energy of wall atoms are obtained through the force module.
In one embodiment of the invention, a self-written program file is subjected to molecular dynamics simulation calculation on the shearing process of the lubrication system through LAMMPS software.
In an embodiment of the invention, the time step of the molecular dynamics simulation has important influence on the simulation process and the simulation result, and the selected step is ensured to not only improve the calculation efficiency, but also obtain effective analysis data.
In an embodiment of the present invention, the step S3 specifically includes: the method comprises the steps of visually expressing an output file by using open source software OVITO, observing the position change of organic antifriction agent molecules in the adsorption process, acquiring the relation of the attitude change, time and displacement of the organic antifriction agent molecules and the density distribution of base oil molecules at different moments, examining the change of friction factors, and analyzing the adsorption performance of the organic antifriction agent under different conditions.
Compared with the prior art, the invention has the following beneficial effects: the invention overcomes the defects of high cost and insufficient precision of the existing test, deeply explores the adsorption mechanism of the organic antifriction agent between the nanogaps from the atomic level, and has great theoretical significance for further application and development of the novel organic antifriction agent.
Drawings
FIG. 1 is a flow chart of a method of an embodiment of the present invention.
Fig. 2 is a nanogap lubrication model in an embodiment of the invention.
FIG. 3 is an adsorption process of stearic acid in n-octadecane in examples of the present invention.
Fig. 4 is a comparison of adsorption time of stearic acid in different base oils under different roughness conditions in examples of the present invention.
FIG. 5 shows the adsorption energy of stearic acid molecules under different conditions in the examples of the present invention.
FIG. 6 is a comparison of diffusion coefficients of stearic acid molecules in examples of the present invention.
FIG. 7 is a comparison of friction coefficients under different conditions in examples of the present invention.
Detailed Description
The technical scheme of the invention is specifically described below with reference to the accompanying drawings.
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
The invention relates to an analysis method of adsorption performance of an organic antifriction agent based on molecular dynamics, which comprises the following steps:
step S1, establishing a molecular dynamics simulation model: building a rough wall surface model of crystal orientation [100] metallic iron by utilizing LAMMPS software, building a lubricating oil model by utilizing material Studio software, and combining the wall surface model and the lubricating oil model into a nano-gap lubricating model;
s2, performing adsorption simulation and shearing simulation on the nano gap lubrication model by using a full atomic force field DREIDING and using Materials Studio software and lamMPS software to obtain a simulation result, and storing the result in an output file;
and S3, visually expressing the simulation result, acquiring the relation of the attitude change, time and displacement of the organic antifriction agent molecules at different moments and the density distribution of the base oil molecules according to the position change of the organic antifriction agent molecules in the adsorption process, and analyzing the adsorption performance of the organic antifriction agent under different conditions.
The following is a specific embodiment of the present invention.
As shown in fig. 1, the embodiment provides a method for analyzing the adsorption performance of an organic antifriction agent based on molecular dynamics, in this example, the wall roughness is set to 0.8nm, the external load is 49.95Mpa, the wall temperature is 313.15K, and the shearing speed is 10m/s, so as to simulate the actual working condition, and the specific steps are as follows:
step S1, establishing a molecular dynamics simulation model, namely establishing a rough wall model of metallic iron by utilizing LAMMPS software, and selecting alpha-Fe with a lattice constant of
The crystal orientation is [100]]The roughness of the wall surface is 0.8nm, the roughness of the upper wall surface and the lower wall surface are the same, and the wall surface model is shown in figure 1. Stearic acid is selected as an organic friction reducer, n-octadecane, 2, 4-dimethyl hexadecane and 3, 5-diethyl tetradecane which have the same carbon content and different structures are respectively selected as base oil, a lubricating oil model is constructed by utilizing material Studio software, the lubricating oil model comprises 144 base oil molecules and 6 friction reducer molecules, and the space structure of the constructed model is optimized by a formite module; the wall model and the lubricating oil model are combined into a nano-gap lubricating model, as shown in fig. 2.
And S2, performing adsorption simulation and shearing simulation on the nano gap lubrication model by utilizing Materials Studio software and LAMMPS software, obtaining a simulation result, and storing the result in an output file.
And S3, visually expressing the simulation result, acquiring the relation of the posture change, time and displacement of the organic antifriction agent molecules at different moments and the density distribution of the base oil molecules according to the position change of the organic antifriction agent molecules in the adsorption process, and analyzing the adsorption mechanism of the organic antifriction agent under different conditions.
In this embodiment, in step S1, a lubricating oil model is constructed by using a Materials Studio software am orphos Cell module, and the space structure of the constructed model is optimized by a formite module.
In this embodiment, in step S1, the wall surface model and the lubricating oil model are combined into a nanogap lubricating model by using a Build module in Materials Studio software, and the upper and lower wall surfaces are divided into 6 layers: the outer layer is a rigid layer for applying the nanogap conditions, the middle is a constant temperature layer for providing environmental influence factors, and the inner layer is a free deformation layer for extracting mechanical properties.
In this embodiment, in step S1, the DREIDING potential is selected to describe the effect between the iron atom and the iron atom, the iron atom and the stearic acid molecule, the iron atom and the base oil molecule, the stearic acid molecule and the stearic acid molecule, the base oil molecule and the base oil molecule, and the stearic acid molecule and the base oil molecule.
In this embodiment, in the simulation process, in order to reduce the simulation time, the step length is selected to be 1fs, so that the calculation efficiency is improved, and effective analysis data can be obtained.
Further, a model constructed by the Materials Studio software is converted into a data file which can be identified by the LAMMPS through a msi2lmp tool of the LAMMPS.
In this embodiment, in step S2, the system is relaxed under the condition of regular ensemble and micro-regular ensemble, the system is relaxed by using the Nose-Hoover hot bath method at the temperature of 313.15K, the temperature damping coefficient is set to 100fs, so that the initial model of the system reaches an equilibrium state, and the sign that the system reaches a steady state is that the kinetic energy, potential energy and total energy of the system are all converged to a normal value.
In this embodiment, in step S2, after the system is fully relaxed, the regular ensemble during relaxation is released, the temperature of the constant temperature layer is set to 313.15K, the lower wall rigid layer is fixed, and the pressure of 49.95MPa is applied to the upper wall rigid layer, and the pressurizing time is 600ps, so that the system reaches a stable state.
In this embodiment, the adsorption process of the lubrication system is simulated by using a Dynamics module in Materials Studio software, and the total energy of the system, the total energy of the lubricant molecules and the total energy of wall atoms are obtained by a formite module.
In this embodiment, in step S2, the pressure during the pressurization phase is maintained constant while the two rigid layers are each
Positive and negative movement along x-axis at a speed of 5m/s, shear distance
In the embodiment, a self-written program file is subjected to molecular dynamics simulation calculation on the shearing process of the lubrication system through LAMMPS software.
In the present embodiment, the friction factor has a calculation formula of F L ＝μ(L 0 +F N )＝F 0 +μ·F N Wherein: f (F) L For friction force, L 0 For the deflection of friction force, F N For positive pressure, μ is the friction factor.
In this embodiment, the positive pressure and friction of the nanogap lubrication system are mainly the forces of the lubricating oil film on the free deformation layer.
And performing molecular dynamics simulation calculation on the self-written program file by using the LAMMPS software, and counting calculation results to obtain an output log file and dump file of the related data of the simulation process and the calculation results.
In this example, the initial adsorption process of stearic acid in n-octadecane when the wall roughness is 0.8nm is shown in fig. 3, wherein the main chain of stearic acid molecule is represented by bright green, oxygen atom is represented by red, and at t=170 ps, stearic acid molecule is adsorbed on the solid wall after passing through the adsorption layer by virtue of long Cheng Kulun force between self-COOH polar group and solid wall atom.
In this example, the adsorption time of stearic acid (the time it takes for the first stearic acid molecule to adsorb to the wall surface) under different base oils and different roughness conditions is shown in fig. 4, and it can be seen that the adsorption time of stearic acid under different roughness conditions in three base oils with the same carbon content is ordered as follows: 3, 5-diethyl tetradecane < n-octadecane <2, 4-dimethyl hexadecane.
In this example, the adsorption energy is used to measure the adsorption strength of the lubricant on the solid surface, and in order to compare the stability of the adsorption film formed by the lubricant under different conditions, the adsorption energy E between stearic acid molecules and the nano-sized rough Fe wall surface is calculated adsorp : the calculation formula is E adsorp ＝E total -E 1 -E 2 +E 3 Wherein E is adsorp For the adsorption energy of stearic acid molecules and Fe surface, E total To simulate the total energy of the lubrication system, E 1 Energy of lubricating system without stearic acid molecule, E 2 E is the sum of the energies of the base oil molecules and the stearic acid molecules 3 Is the energy of the base oil molecule. E (E) adsorp Negative values of (c) indicate attraction between molecules and interfaces, positive values indicate repulsion, and absolute values are used to indicate adsorption energy of stearic acid molecules to Fe surfaces during analysis for ease of understanding.
In this example, the adsorption energy of stearic acid under different wall roughness and different base oil conditions is shown in fig. 5, from which it can be seen that the adsorption energy of stearic acid molecules is always minimal in 3, 5-diethyltetradecane base oil with long chain branches, compared to the other two base oils, when the roughness is in the range of 0.0-0.8 nm; in a lubrication system taking n-octadecane, 2, 4-dimethyl hexadecane and 3, 5-diethyl tetradecane as base oil, the adsorption energy of stearic acid molecules is maximum when the roughness is 0.2 nm; with the increase of the wall roughness, the adsorption energy of stearic acid molecules in three lubrication systems is gradually reduced.
In this example, the diffusion coefficientIs calculated according to the movement time and the root mean square displacement of the selected molecule, and the calculation formula is
Wherein E (integer, 1.ltoreq.E.ltoreq.3) is the system dimension when calculating the diffusion coefficient, r (τ) represents the position of the particle at τ, and M (τ) is the average displacement of all atoms.
The diffusion coefficients of stearic acid under the conditions of different wall surface roughness and different base oils are shown in fig. 6, and it can be seen that the magnitude relation of the diffusion coefficients of stearic acid molecules in three base oils is as follows: 3, 5-diethyl tetradecane < n-octadecane <2, 4-dimethyl hexadecane, along with the increase of the wall roughness, the diffusion coefficient of stearic acid molecules in three base oils after stable diffusion gradually increases, which indicates that more stearic acid molecules are dissociated in a lubricating oil film at this time, so that the adsorption energy is reduced, and a stable adsorption film cannot be formed.
In this example, the average friction force F obtained for lubrication systems under different conditions L And average positive pressure F N The friction factor μ calculation formula is used: f (F) L ＝μ·F N And calculating to obtain the friction factors under all the states. As can be seen from fig. 7, the friction factor of n-octadecane is in the range of 0.068 to 0.095; the friction factor of 2,4 dimethyl hexadecane is in the range of 0.090-0.101; the friction factor of 3,5 diethyl tetradecane is in the range of 0.100-0.122; under the same roughness condition, the magnitude relation of the friction factors is as follows: mu (mu) N-octadecane <μ 2,4 dimethyl hexadecane <μ 3,5 Diethyltetradecane 。
The above is a preferred embodiment of the present invention, and all changes made according to the technical solution of the present invention belong to the protection scope of the present invention when the generated functional effects do not exceed the scope of the technical solution of the present invention.
Claims (1)
1. The method for analyzing the adsorption performance of the organic antifriction agent based on molecular dynamics is characterized by comprising the following steps of:
step S1, establishing a molecular dynamics simulation model: building a rough wall surface model of crystal orientation [100] metallic iron by utilizing LAMMPS software, building a lubricating oil model by utilizing material Studio software, and combining the wall surface model and the lubricating oil model into a nano-gap lubricating model;
s2, performing adsorption simulation and shearing simulation on the nano gap lubrication model by using a full atomic force field DREIDING and using Materials Studio software and lamMPS software to obtain a simulation result, and storing the result in an output file;
s3, visually expressing an simulation result, acquiring the relation of the attitude change, time and displacement of the organic antifriction agent molecules and the density distribution of the base oil molecules at different moments according to the position change of the organic antifriction agent molecules in the adsorption process, and analyzing the adsorption performance of the organic antifriction agent under different conditions;
wherein,,
the step S1 specifically comprises the following steps:
s11, constructing a rough wall model of metal iron by utilizing LAMMPS software, selecting alpha-Fe with a lattice constant of 2.87A and a crystal orientation of [100], and setting different wall roughness, wherein the upper wall roughness and the lower wall roughness are the same; stearic acid is selected as an organic antifriction agent, n-octadecane, 2, 4-dimethyl hexadecane and 3, 5-diethyl tetradecane which have the same carbon content but different structures are selected as base oil, a lubricating oil model is constructed by utilizing an Amorphos Cell module in material Studio software, and the space structure of the constructed lubricating oil model is optimized by a formite module;
step S12, establishing a nano gap lubrication model of an upper wall surface, an oil film and a lower wall surface, and combining the wall surface model and the lubricating oil model into the nano gap lubrication model by utilizing a Build module in material Studio software; the upper and lower wall surfaces are divided into 6 layers: the outer layer is a rigid layer for applying the nano-gap condition, the middle is a constant temperature layer for providing environmental influence factors, and the inner layer is a free deformation layer for extracting mechanical properties;
step S13, setting a nanogap condition of a nanogap lubrication model, setting periodic nanogap conditions in the x and y directions, and setting shrinkage nanogap conditions in the z direction;
step S14, selecting potential functions of corresponding materials, and selecting full-atomic force field DREIDING potential to describe the action between iron atoms and iron atoms, iron atoms and stearic acid molecules, iron atoms and base oil molecules, stearic acid molecules and stearic acid molecules, base oil molecules and base oil molecules, stearic acid molecules and base oil molecules;
the step S2 specifically comprises the following steps:
s21, relaxing the system under the regular ensemble and the micro-regular ensemble, and relaxing the system by utilizing a Nose-Hoover hot bath method so as to enable an initial model of the system to reach an equilibrium state, simulating the density of the system, and verifying the rationality of a nano gap lubrication model;
s22, in the pressurizing stage, the regular ensemble during relaxation is relieved, the temperature of the constant temperature layer is set, the lower wall surface rigid layer is fixed, and pressure is applied to the upper wall surface rigid layer, so that the system is in a stable state;
step S23, in the shearing stage, the pressure is kept unchanged, and simultaneously, the two rigid layers respectively move along the x axis at the same speed and opposite direction;
s24, data processing, namely performing molecular dynamics simulation calculation on the lubrication system by utilizing Materials Studio software and LAMMPS software, and counting calculation results to obtain relevant data of a simulation process and calculation results, outputting a file, wherein the output file contains variable parameters and change information of atomic coordinates;
the step S3 specifically comprises the following steps:
the method comprises the steps of visually expressing output files by using open source software OVITO, observing the position change of organic antifriction agent molecules in the adsorption process, obtaining the relation of the attitude change, time and displacement of the organic antifriction agent molecules at different moments and the density distribution of base oil molecules, examining the change of friction factors, and analyzing the roughness of different wall surfaces and the adsorption performance of the organic antifriction agent under different base oil conditions.
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