磁流变液微观结构的数值模拟

摘要

2-D numerical simulation for chain and shear processes of magnetorheological fluid (MFR) was carried out based on the analysis of forces acting on solid particles in the MFR by use of the velocity Verlet algorithm. The main factors for chain process and shear mechanical behavior were studied. The results indicate that some almost parallel chains in the simulation district are generated at the end of the simulation. The variety process of the particle chain is first quick and then slow. The whole time for the process is about 2-3 milliseconds. The larger the volume percentage of the particles, the more the number of whole chain. When the MFR is sheared under the low velocity, the split of old chains and the form of new chains are almost in a state of dynamic balance. On the contrary, the particles incline to the shear direction, but the number of the whole chains decreases, and the speed of the form of new chains is lower than that of the split of old chains obviously. The shear strength of the single chain first increases and then decreases. The yield shear stress of the MRF increases with the increase of the intensity of magneto field and the volume percentage of particles.%通过分析磁流变液中固体颗粒的受力,利用分子动力学中的速度Verlet算法,对磁流变液链化过程和剪切过程进行了二维数值模拟,并对影响链化和剪切的主要因素进行了研究.研究结果表明:粒子的运动最终会在模拟区域内形成若干条几乎平行的链;颗粒链化时的变化过程先快后慢;整个链化过程所耗费的时间在2～3 ms之间;颗粒体积百分率越大,模拟时所成通链越多;磁流变液受到剪切荷载作用时,低剪切速率下,旧链的断裂和新链的生成基本上达到动态平衡的状态,高剪切速率下,粒子向剪切方向的倾斜程度变大,但是通链减少,新链的生成速度明显跟不上旧链的断裂速度;单链的剪切强度先增大后减小;磁流变液的剪切屈服应力随磁感应强度和颗粒体积百分率的增大而增大.