CN-122024869-A - Simulation method for generation of microparticles on asphalt pavement based on molecular dynamics

Abstract

The invention provides a simulation method for generating microparticles on an asphalt pavement based on molecular dynamics, belongs to the technical field of road traffic environment, and solves the problems that the prior art cannot analyze the interaction behavior of tires and the asphalt pavement from a molecular level and reveal the microscopic mechanism generated by the microparticles in the friction process. The invention firstly builds a modified asphalt molecule, a tire rubber molecule and an aggregate substrate model by means of a molecular dynamics simulation method, builds a three-layer interface contact model after verifying rationality, carries out friction simulation through Confined Shear tasks under a set working condition after energy optimization, and reveals a microscopic mechanism generated by microparticles by analyzing the conditions of system energy change, atomic motion trail, chemical bond fracture and the like. The invention breaks through the limitation of the traditional macroscopic test, reveals the generation mechanism of the microparticles from the microscopic angle, and provides a theoretical basis for developing environment-friendly low-abrasion asphalt pavement materials and tires and controlling the pollution of pavement microplastic from the source.

Inventors

• XU TAO
• XING JIWEI
• XIA WENJING
• LIU SONG

Assignees

• 南京林业大学

Dates

Publication Date

20260512

Application Date

20260109

Claims (1)

1. 1. A simulation method for generating microparticles on an asphalt pavement based on molecular dynamics is characterized by comprising the following specific steps: (1) According to the selected typical road section pavement asphalt types, an asphaltene, colloid, aromatic component, saturation component and modifier molecular model is built in a Visualizer module of MATERIALS STUDIO software, four asphalt component molecules and modifier molecules are mixed according to the actual mass proportion of the main components of the modified asphalt by using a Amorphous Cell module, and are placed in the same unit cell, and reasonable density is set to build a modified asphalt molecular model; (2) Carrying out structural optimization and annealing treatment on the modified asphalt molecular model at normal temperature to minimize the energy of the model, carrying out molecular dynamics simulation on the model, and calculating a simulation density value to be compared with a density value measured by a modified asphalt test so as to verify the rationality of the modified asphalt molecular dynamics model; (3) According to the main components of the tire, a polyisoprene and styrene-butadiene copolymer molecular chain model is built in a Visualizer module, the polymerization degree is set to be 60, a disulfide and trisulfide molecular model is built at the same time, a AmorphousCell module is used, the two molecular chain models, disulfide and trisulfide molecular model are mixed according to the actual mass proportion of the main components of the tire, the two molecular chain models are placed in the same unit cell, reasonable density values are set, chemical reactions between disulfide, trisulfide and two molecular chains are simulated through a crosslinking script to form a crosslinking network structure, then structural optimization and annealing treatment are carried out on the tire rubber molecular model, the lowest energy state of a molecular system is ensured, and the rationality of the tire rubber molecular dynamic model is verified through molecular dynamic simulation; (4) Introducing a SiO 2 molecular model from MATERIALS STUDIO structural library, cutting a crystal face by using a Cleave Surfaces tool in Build, expanding the model into a plate-shaped model with a certain thickness by using a Build Vacuum Slab tool, and setting a sufficient vacuum layer to accommodate the modified asphalt molecules and the tire rubber molecular model above to construct an aggregate base model; (5) Adding a tire rubber molecular model as a first layer interface, a modified asphalt molecular model as a second layer interface and an aggregate substrate model as a third layer interface in the building Layers function to construct a tire and asphalt pavement interface contact model, performing structural optimization and annealing treatment on the interface model, and selecting the interface model with the lowest energy as an initial model of molecular dynamics simulation; (6) Using Confined Shear task of Forcite module to fix all atoms at the bottom of aggregate substrate, and simulating the movement friction behavior of the tire on asphalt pavement by applying shear load and a movement speed along x-axis direction to the first layer of tire rubber molecular model; (7) The Analysis function of Forcite modules is utilized to obtain the total energy, kinetic energy and potential energy of a system in the simulation process and the non-bond interaction energy between modified asphalt molecules and tire rubber molecules, the friction coefficient is calculated through the shearing stress and the normal stress of the system in the moving direction, the fracture and stripping processes of the modified asphalt molecules and the tire rubber molecules and the formation of microparticles are directly observed according to the atomic motion trail on an interface, the fracture number of chemical bonds in the friction process is counted by using a MATERIALS STUDIO Analysis tool, the atomic motion trail and the change of molecular conformation are analyzed, and therefore the specific position and mode of interface contact abrasion are determined, and the generation mechanism of the microparticles on an asphalt pavement is revealed.

Description

Simulation method for generation of microparticles on asphalt pavement based on molecular dynamics Technical Field The invention relates to a simulation method for generating microparticles on an asphalt pavement based on molecular dynamics, and belongs to the technical field of road traffic environments. Background In recent years, road traffic environmental pollution is a serious challenge faced by countries around the world, and researches and statistics are carried out to count that the total pollution amount accounts for more than 1/4 of the environmental pollution. Road traffic pollution is divided into exhaust emission pollution and non-exhaust emission pollution, and the exhaust emission pollution is greatly reduced, but the non-exhaust emission pollution is still serious along with the improvement of automobile exhaust emission standards and purification technologies of various countries and the popularization of new energy automobiles at present. Wherein the micro particles formed by the abrasion of the tire and the road surface are one of the important parts in the non-exhaust emission. Asphalt pavement is currently widely used as a main road paving material due to its excellent characteristics in terms of construction, road performance and maintenance. However, asphalt pavement is subjected to friction from vehicle tires during long-term use, which can cause the asphalt film and tire surface on the asphalt pavement to be worn, thereby forming tiny asphalt microparticles and tire wear microparticles. Asphalt microparticles and tire wear microparticles completely accord with the definition of microplastic due to the material characteristics and the tiny particle size, and are one of the main sources of pavement microplastic. Asphalt microparticles and tire wear microparticles, after formation, are deposited primarily on roads and surrounding areas, one part of which is transported to soil or nearby water bodies with surface runoff, and the other part of which is suspended and migrates in the atmosphere. The tire wear microparticles generally comprise rubber additives, vulcanization accelerators, polycyclic aromatic hydrocarbons, zinc, cadmium and other heavy metals, and the asphalt is derived from petroleum refining residues, and the microparticles contain hydrocarbon compounds, sulfides and various metal elements adsorbed on the surfaces of the hydrocarbon compounds and sulfides with higher stability. Because of its broad environmental distribution, complex chemical composition, and high durability, these microparticles may enter the human body through respiratory exposure pathways or accumulate in the ecosystem through water migration, eventually being transmitted through the food chain, forming a potential threat to human health. Many studies on tire wear microparticles are currently carried out, and a great deal of information is available on the aspects of the emission factors, particle size distribution, physicochemical properties, influence on biology and environment and the like. The generation condition of tire wear microparticles under the condition that a vehicle runs on a road surface is simulated by a learner through a simulation device for preparing the friction between the tire and the simulated road surface, so that the tire wear microparticles are obtained in a laboratory. The influence of various factors on the tire wear micro-particles is determined by obtaining the characteristics of the tire such as the micro-morphology of the tire wear micro-particles generated on simulated roads with different speeds, tire pressures and different materials. In addition, partial scholars obtain samples of the tire wear micro-particles through a method of collecting the micro-particles on different roads, analyze the particle size and chemical composition, and calculate the emission factors of the tire wear micro-particles in partial areas through combining the distribution conditions of the tire wear micro-particles at different sampling points with the road surface type and traffic flow information. However, studies on asphalt microparticles generated by asphalt abrasion on asphalt pavement are relatively weak. Researchers obtain pavement micro-particle samples through a mode of in-situ sampling, obtain enriched tire wear micro-particles and asphalt micro-particles through density separation, and analyze the morphological characteristics and chemical components of the micro-particles by adopting a plurality of modern analysis technologies such as a scanning electron microscope-energy spectrometer, a micro Fourier transform infrared spectrometer and the like. At present, the research on asphalt microparticles is mostly to conduct macroscopic quantification or physicochemical property analysis of single particles, and the research on the generation mechanism of asphalt microparticles is almost blank. At present, molecular dynamics simulation technology is widely applied to researches in fields