【作者】 陈曦；

【导师】 周里群；

【作者基本信息】 湘潭大学 ， 工程硕士（机械工程领域）（专业学位）， 2019， 硕士

【摘要】 目前国内自行研制的路面铣刨机和国外的同类型产品相比依然存在很大的差距,工作寿命较短,工作状况不稳定从而导致路面铣削质量不稳定。种种因素让国产铣刨机丧失了很大一部分竞争力,因此进一步提升国产路面铣刨机的技术水平已经迫在眉睫。对于路面铣刨机而言,其相关技术研究的重点和关键是分析沥青混合料复杂的细观力学性能、粗细集料和沥青砂浆之间的相互作用以及建立铣刨刀具工作过程的有限元模型。本文利用有限元仿真软件ABAQUS针对沥青混凝土各组分的物理性质构建贴近沥青混凝土实际性质的细观力学本构模型,建立沥青混凝土和铣刨刀具相互作用的有限元模型来获得切削过程的切削力;在细观力学条件下求出刀具所受摩擦阻力平均值;尤其是刀具和集料颗粒接触时的力学情况变化规律。本文主要研究工作有:(1)明确刀具在切削过程中的运动轨迹和受力情况,进而求出刀尖的轨迹方程和摩擦阻力f计算公式;明确摩擦阻力f与工作参数之间的关系。(2)从细观力学的角度对沥青混凝土内部组分进一步细化,在对沥青混凝土试件建模的过程中分别建立沥青砂浆和集料颗粒的细观模型并采用Johnson-Cook模型分别设置集料颗粒和沥青砂浆的力学性能;利用Python软件结合蒙特卡罗算法完成集料颗粒在沥青混凝土试件中的随机投料工作;网格划分过程中分别采用四边形网格和三边形网格对集料颗粒和沥青砂浆进行网格划分以表示两种不同的细观材料,其中切削区的集料颗粒和沥青砂浆采用细网格,其他区域则采用普通网格从而在保证计算精度的同时尽可能的减少计算量;利用有限元分析软件ABAQUS对刀具在不同工作参数下的工作状态进行动力学分析,从而得到刀具在沿进给方向和垂直于进给方向的切削力;将仿真结果导入MATLAB中生成刀具摩擦阻力的变化曲线,从而得到其随各种因素变化的规律,并根据以上规律总结出铣刨机最佳工作参数组合。(3)在金属切削加工过程中常采用将刀具表面覆盖涂层的方式来减小刀具的磨损,尝试将同样的方式应用到铣刨机刀具上。其中沥青砂浆和集料颗粒的建模方法与常规切削相同,涂层刀具则是在刀具刀头的外表面覆盖一层厚度为4?m的涂层,再分别设置了涂层的刀具基体的材料参数后将涂层和刀具的接触面定义为第一和第二表面,将沥青砂浆和集料上的质点集分别定义为第一和第二表面,将刀具涂层外表面和沥青砂浆和集料上的质点集分别定义为第一、第二和第三表面;由于刀具基体和涂层是两种不同的材料,故采用两种不同的网格分别进行划分,刀具基体采用四边形网格,涂层采用三边形网格;完成以上步骤之后即可提交运算。更多还原

【Abstract】 At present,there is still a big gap between the domestically developed road surface milling and planing machine and the same type of foreign products.All kinds of factors make the domestic road milling and planing machine lose a lot of competitiveness,so it is urgent to further improve the technical level of the domestic road milling and planing machine.As for the pavement milling machine,the key of its related technology research is to analyze the complex micromechanical properties of asphalt mixture,the interaction between coarse and fine aggregate and asphalt mortar,and to establish the finite element model of the working process of the milling cutter.In this paper,the finite element simulation software ABAQUS is used to build a micromechanical constitutive model close to the actual properties of asphalt concrete according to the physical properties of each component,and the finite element model of the interaction between asphalt concrete and milling cutter is established to obtain the resistance of the milling process.Under the condition of micromechanics,the average value of friction resistance is obtained.Especially when the cutter and aggregate particles contact the mechanical changes in the law.The main research contents of this paper are as follows:determine the tool’s motion path and force during cutting,and then find the path equation of tool tip and the calculation formula of frictional resistance f;Furthermore,the relationship between friction resistance f and parameters such as feed speed v,cutting depth h and rotation speed n of milling planer was obtained.(1)Determine the movement path and force of the cutting tool in the cutting process,and then work out the trajectory equation of the tool tip and the calculation formula of friction resistance f;The relationship between the working parameters of friction resistance f is clarified.(2)From the perspective of micromechanics,the internal components of asphalt concrete are further refined.In the process of asphalt concrete specimen modeling,the micromechanics models of asphalt mortar and aggregate particles are respectively established,and the mechanical properties of aggregate particles and asphalt mortar are respectively set by Johnson-Cook model.The random feeding of aggregate particles in asphalt concrete samples was completed by using Python software and monte-carlo algorithm.Meshing process respectively using quadrilateral mesh and trilateral grid meshing of aggregate and asphalt mortar to represent two different mesoscopic material,including cutting material particles and asphalt mortar with fine grid,in other areas are using commongrid so as to ensure calculation precision at the same time as far as possible to reduce amount of calculation;Using the finite element analysis software ABAQUS to analyze the dynamics of the cutting tool under different working parameters,the cutting resistance along the feed direction and perpendicular to the feed direction can be obtained.The simulation results are imported into MATLAB to generate the change curve of tool friction resistance,so as to obtain the rule of its change with various factors,and according to the above rule,summarize the best working parameter combination of the milling and planing machine.(3)In the metal cutting process often use the tool surface coating method to reduce tool wear,try to apply the same way to the milling machine tool.Of asphalt mortar and aggregate particles of modeling method and conventional cutting is the same,coated tools is on the outer surface of the cutter head covering a layer of coating thickness is 4 ?m,then the coating knife base material parameters were set up after the coating and interface is defined as the first and second surface of a tool,the set of particles on asphalt mortar and aggregate respectively defined as the first and second surface,the coating on the outer surface and asphalt mortar and aggregate particle sets was defined as the surface of the first,second and third respectively;Because the tool matrix and coating are two different materials,so the use of two different grid division,respectively,the tool matrix using quadrilateral grid,coating using trihedral grid;You can submit the operation after completing the above steps.更多还原