Nonlinear Dynamic Model of M-EHA Considering Fluid Bulk Modulus Variation

Abstract

：In order to accurately predict the dynamic output characteristics of M-EHA, a nonlinear dynamics model considering fluid bulk modulus and density variation is proposed. The intrinsic nonlinearity of giant magnetostrictive materials is described by the Jiles-Atherton model. The overall fluid transmission characteristics are modeled by coupling the valve vibration equation, the flow equation, the fluid lines pressure drop equation and the hydraulic cylinder dynamic equation. In order to study the effects of modulus and density variation during high-pressure fluid transmission, the fluid equivalent modulus is treated as a function of pressure, and the effects of fluid compressibility, inertia and viscosity on the output characteristics of M-EHA are studied based on electro-hydraulic analogies theory. Finally, the nonlinear dynamic model of the whole actuation system is established. The model is iteratively solved by the fourth-order Runge-Kutta method. Combined with the experimental comparison, the relationship between driving frequency, bias pressure, load and output performance of the operating system is studied. The results show that the output performance of the actuation system varies bimodally with the driving frequency, and as the biase pressure increases, the peak frequency rises and the optimal output level is reached at 2.6 MPa bias. It lays a theoretical foundation for the design development and optimization of high-performance M-EHA.

Structure design of torque sensor based on inverse magnetostriction effect

“…The structural optimization analysis of Galfenol torque sensor involves magnetic mechanical coupling [10][11], and it is simulated and optimized using Comsol Multiphysics finite element software. As shown in Figure 1, import the model into Comsol software and set the basic material properties and physical fields.…”