超声珩磨时空化泡溃灭对固壁面的冲击作用研究

发布时间：2018-03-31 21:10

本文选题：超声珩磨　切入点：空化泡溃灭　出处：《中北大学》2017年硕士论文

【摘要】：超声珩磨时近壁面附近的空化泡在经过一系列膨胀-收缩-溃灭的泡壁运动后,会对壁面产生高温高压的空蚀作用。壁面的空蚀效果主要是受到由空化泡溃灭而产生冲击波和微射流的冲击影响。而壁面材料的形变也可能是受到空化泡溃灭压力场的作用。本论文以超声珩磨时磨削液中产生的空化泡作为研究对象,应用空化泡动力学、冲击波的界面传播和材料失效准则等理论,分析超声珩磨参数以及空化泡初始半径对空化泡溃灭压力场和冲击波的影响,并对材料失效所需冲击波和微射流的阈值进行计算。最后通过超声振动试验研究不同条件下工件材料表面受到空化泡溃灭冲击作用的表面质量变化情况。这为进一步研究超声珩磨时空化泡溃灭对固壁面的冲击作用提供了理论和试验基础。本论文的主要工作和结论如下:(1)建立了热-力耦合超声珩磨单磨粒磨削有限元模型,仿真结果表明:磨粒刃圆半径处于0.1μm和10μm左右,一定磨削深度下的磨粒刃口处切屑发生塑性去除,且磨削热效应对其具有促进作用;而磨粒刃圆半径处于1μm左右,磨粒刃口处切屑几乎没有塑性流动的现象,磨削热效应亦不明显。(2)在超声珩磨磨削区环境压力下,推导出空化泡溃灭时泡外压力场分布的数学模型,并分析空化泡体积比对最大压强的数值和位置的影响。分析得到:超声珩磨磨削区空化泡溃灭压力场对大多数壁面金属材料的影响属于弹性变形,其对壁面的空蚀作用没有直接的影响。(3)以超声珩磨时磨削液中产生的空化泡为研究对象,考虑液体表面张力,推导出空化泡最大半径的理论模型,计算得到空化泡最大半径在归一化时间为0.751时取得最大值。该数值随着声压振幅和空化泡初始半径的增加而增大,而随着珩磨压力的增大而减小。空化泡初始半径越小,其最大半径相对于其初始半径的放大倍数越大。(4)理论推导得到超声珩磨磨削区单空化泡泡能模型,并分析在一个超声周期内三个特征时刻点处,泡能受到声压振幅、珩磨压力和空化泡初始半径的影响。结果发现:对于以上三种参数均在归一化时间为0.249周围,空化泡泡能达到最大;相对于声压振幅和珩磨压力,空化泡初始半径对泡能的变化起主要的影响。结合强爆炸理论给出的爆炸能与引起的冲击波传播速度和压强的关系,在其它条件恒定不变的情况下,得到空化泡溃灭冲击波和泡能受到以上三种参数的作用趋势相同,且相应的也是空化泡初始半径对其溃灭冲击波的影响最大。(5)理论计算得到,当到达壁面时的空化泡溃灭冲击波强度大于203.77MPa时,就能使固壁面材料2024Al发生塑性变形;对应的壁面材料发生塑性变形下,需要到达固壁面的微射流速度大于262.59m/s。(6)搭建超声振动的冲击试验平台,试验发现:随着试验时间的增加,工件表面的粗糙度和维氏硬度都增加,并经过一定的快速增长后分别在不同的时间点进入缓慢递增阶段;随着超声振幅的增加,工件表面的粗糙度和维氏硬度先快速增长,在10.8μm左右达到最大值;工件表面的粗糙度与试验溶液粘滞系数的变化趋势相反,并且实验前后的工件表面的粗糙度和维氏硬度有一定的正相关性。超声振动空化泡溃灭对固壁面的冲击试验对研究超声珩磨磨削区空化泡溃灭对固壁面的冲击效果具有一定的指导意义。
[Abstract]:Ultrasonic honing of the cavitation bubble near the wall after a series of expansion and contraction - collapse of bubble wall motion, cavitation will produce high temperature and high pressure on the wall. The wall of the cavitation effect is mainly affected by the shock wave and cavitation bubble collapses by micro jet impact and wall deformation. The material may also be affected by cavitation bubble collapses. The pressure field generated in the ultrasonic grinding liquid honing of cavitation bubble as the research object, the application of cavitation bubble dynamics, the theory of wave propagation and the impact of the interface material failure criteria, analysis of Ultrasonic Honing Parameters and the initial radius of cavitation bubbles on the influence of cavitation bubble collapse pressure field and shock wave, and the failure of materials required for shock wave and micro jet threshold were calculated. Finally through the experimental study on ultrasonic vibration under different conditions of the workpiece surface by the impact of the cavitation bubble collapse The change of surface quality. It is of bubble collapse provides a theoretical and experimental basis for further research on the impact of solid wall ultrasonic honing space. The main work and conclusions are as follows: (1) the establishment of the thermo mechanical coupling of ultrasonic honing single grinding finite element model, the simulation results show that: the grain edge the radius of the circle is 0.1 M and 10 m, the abrasive grinding depth under certain edge at the mouth of the chip plastic removal and grinding, thermal effect has a promoting effect on it; and the abrasive edge radius is about 1 m, abrasive cutting edge cutting almost no plastic flow the phenomenon of grinding heat effect is not obvious. (2) in the environmental pressure grinding zone of ultrasonic honing, deduces the cavitation bubble broken mathematical model of pressure field distribution, and analyzes the influence value and position of cavitation bubble volume ratio on the maximum pressure. Results: the ultrasonic honing grinding area Of bubble collapse pressure field effect on most wall metal material is elastic deformation, which has no direct effect on the wall surface of the cavitation effect. (3) in ultrasonic honing when grinding fluid cavitation bubble as the research object, considering the surface tension of the liquid, a theoretical model derived from the maximum radius of the cavitation bubble, calculated the maximum radius of cavitation bubble in the normalized time 0.751 gets the maximum value. The value increases with the increase of initial radius of cavitation bubble and the sound pressure amplitude, and decreases with increasing pressure. Honing the initial radius of cavitation bubbles is smaller, the maximum radius relative to the initial radius of the greater the magnification (4) deduced from the theory. The ultrasonic honing grinding zone single bubbles model, and analyze the three characteristics of time points in a cycle of bubble by ultrasonic, sound pressure amplitude, initial radius of cavitation bubble and honing pressure. The influence of the Now, for the above three parameters were normalized in time for 0.249 around, bubbles can reach the maximum; relative to the pressure amplitude and honing pressure. The influence of the initial radius of cavitation bubble mainly on global energy changes. With the strong explosion theory gives explosion caused by the shock and the relationship between wave velocity and pressure, constant at other conditions are constant, by shock wave and cavitation bubble collapses bubble can be above three parameters of the same trend, and is also the largest initial radius of cavitation bubble collapse shock wave effect. (5) the theoretical calculation, when reaching the wall when the shock wave intensity is greater than the cavitation bubble collapses 203.77MPa, can make the solid wall material of 2024Al plastic deformation occurred; corresponding wall materials under plastic deformation, need to reach solid wall surface of the micro jet velocity is greater than 262.59m/s. (6) to build the impact of ultrasonic vibration The test platform, the test showed that: with the increase of test time, workpiece surface roughness and hardness are increased after Vivtorinox, and the rapid growth of certain respectively at different time points into the slowly increasing stage; with the increase of ultrasonic amplitude, surface roughness and hardness of the first Vivtorinox rapid growth, reaching a maximum at 10.8 m; the change trend of workpiece surface roughness and test solution viscosity contrast, and surface roughness of the workpiece before and after the experiment and Vivtorinox hardness had a positive correlation. The ultrasonic vibration cavitation bubble collapse on the solid wall surface of the impact test for the study of ultrasonic cavitation bubble collapse honing grinding zone has certain guiding significance to the solid the wall of the impact.

【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG663;TG580.67

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