Magnetorheological (MR) grease, which is a type of magneto-sensitive smart material, exhibits complex viscoelastic behavior under different magnetic fields. Storage and loss moduli from oscillatory test are commonly used to characterize such field-dependent viscoelastic behavior. However, they are not able to represent the higher harmonic nonlinearity appeared in oscillatory responses under large amplitude oscillatory (LAOS) shear. In this paper, an investigation is conducted on the characterization of the filed-dependent nonlinearity of MR grease under LAOS by utilizing of Fourier transform (FT)-Chebyshev analysis. To capture the higher harmonic nonlinearity for the modeling and analysis, a comprehensive test program has been conducted. Firstly, MR grease with 70% weight percentage of carbonyl iron particles (MRG-70) is prepared and the stress response of MRG-70 under the oscillatory shear from small to large strain amplitudes with different magnetic field are measured. Then the higher harmonics in stress response signal are used to detect the intercycle nonlinearity of MRG-70 and compare with the traditional analysis method of dynamic modulus. Further, the elastic and viscous measures from FT-Chebyshev analysis are obtained to capture the inter-/intracycle nonlinear behaviors, that is, strain stiffening/softening, shear thickening/thinning, of MRG-70 under LAOS. It is found that, in the presence of magnetic fields, the onset of the intercycle nonlinearities of MRG-70 is originated from shear thickening of MR grease. With the further increase of the shear strain, MRG-70 exhibits the nonlinearities with different combinations of strain stiffening/softening and shear thickening/thinning.

磁流变（MR）润滑脂是一种磁敏智能材料，在不同的磁场下表现出复杂的粘弹性行为。振荡测试的存储模量和损耗模量通常用于表征这种取决于现场的粘弹性行为。但是，它们不能代表在大振幅振荡（LAOS）剪切下的振荡响应中出现的较高的谐波非线性。本文利用傅立叶变换（FT）-Chebyshev分析法对LAOS下MR润滑脂的磁场依赖性非线性进行了研究。为了捕获高次谐波非线性以进行建模和分析，已进行了全面的测试程序。首先，制备了具有70％重量百分比的羰基铁颗粒（MRG-70）的MR润滑脂，并测量了MRG-70在不同磁场下从小到大应变振幅在振荡剪切下的应力响应。然后，应力响应信号中的高次谐波被用于检测MRG-70的周期间非线性，并与传统的动态模量分析方法进行比较。此外，通过FT-Chebyshev分析获得了弹性和粘性度量，以捕获LAOS下MRG-70的周期内/周期内非线性行为，即应变变硬/软化，剪切增稠/变薄。已经发现，在磁场的作用下，MRG-70的循环间非线性的发生是由于MR润滑脂的剪切增稠而引起的。随着剪切应变的进一步增加，