The Study of Soft Electrohydraulic (SEH) Actuation via Dimensional Analysis*
*For a more in-depth explanation, see "Actuation Behavior of Hydraulically Amplified Self-Healing Electrostatic (HASEL) Actuator via Dimensional Analysis" published in Actuators.
All figures and data are from: Washington, A., Su, J., & Kim, K. J. (2023). Actuation Behavior of Hydraulically Amplified Self-Healing Electrostatic (HASEL) Actuator via Dimensional Analysis. Actuators 2023, 12(5), 208; https://doi.org/10.3390/act12050208
Project Objective
Develop knowledge of soft electrohydraulic (SEH) actuators, like the HASEL actuator, using dimensional analysis concepts.
Further the understanding of the SEH actuation mechanism and develop mathematical relationship for the electro-mechano-hydraulic actuator mechanism.
Methodology
Initially, an analytical equation is derived based on:
The mechanical deformation
The fluid dynamics
The electrostatic force component
The Buckingham Pi method of dimensional analysis is applied to the analytical equation.
Results
12 different parameters were considered in the analysis with 4 being chosen as the repeating parameters:
Young's Modulus (mechanical)
Fluid density (hydraulic)
Fluid viscosity (hydraulic)
Applied voltage (electrostatic)
Eight dimensionless Π groups were developed that relates the various parameters to each other.
From this analysis, the Washington-Kim (WK) Group was developed which describes the electro-mechano-hydraulic connection.
The Washington-Kim Group
Where:
ε is the permittivity of the dielectric materials
V is the applied voltage
ρ is the fluid density
μ is the dynamic viscosity of the fluid
Y is the Young's modulus.
Model and Experimental Results
Experimental testing was done to compare the results of the analysis to the performance of the actuator.
The calculated displacement from the WK was compared to the experimental displacement (strong correlation (p < 0.05) with 62.3% of variance).