基于圆筒剪切模式的磁流变脂流变学特性检测方法与装置

针对现有测试装置剪切率低且难以使磁流变脂达到磁饱和的问题,提出了一种基于同心圆筒双边剪切模式的磁流变脂流变学特性检测方法,分析了剪切通道中磁流变脂在转子作用下的剪切流动特性与剪切应力分布,建立了磁流变脂传递力矩与剪切应力的理论关系,得出了由传递力矩导出标称剪切应力的近似算法;通过建立剪切率与剪切应力之间的函数关系,利用剪切通道中磁流变脂的平衡微分方程和流动边界条件,得出了由转子角速度导出磁流变脂标称剪切率近似算法;通过实验方法研究了剪切通道平均磁通密度与励磁电流的关系;设计与制作了磁流变脂检测装置,并利用磁流变脂检测装置完成了某典型磁流变脂检测,使磁流变脂的剪切率达到2000s~(-1)、磁通密度超过0.6T,测试结果与其它检测装置检测结果能较好吻合.

Test Method and Device for Rheological Behaviors of Magneto-rheological Greases Based on Coaxial Cylinder Shear Mode

A test method for rheological behaviors of MR greases based on double rotational coaxial cylinder shear mode is presented to obtain high shear strain rate and magnetic flux density. Both flow velocity profiles and shear stress profiles of MR greases in shear channels are analyzed. The theory relationship between shear stress acted on MR greases and transmission torques is established, the approximate algorithm is put forwarded to acquire nominal shear stresses of MR greases via transmission torques parameters. The relationship between shear strain rate and shear stresses is comprehensively established. On the basis of differential equation and its rational boundary conditions from stress equilibrium of MR greases micro-unit, the approximate algorithm is developed for nominal shear strain rates via rotor angular velocities. The relationship between average value of magnetic flux density in annular channels and excitation electrical currents are experimentally obtained. Based on the test method above, a rheometer is fabricated and modulated in Chongqing University, in which, torque sensor, angular velocity sensor and amperemeter are respectively used to test transmission torque, angular velocity and electrical current. Rheological parameters of certain MR grease by the rheometer, whose shear rate is more than 2000s~(-1) and magnetic flux density acting on MR greases exceed 0.6T, are in good agreement with those from the test with commercial rheometers.