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A self-powered, and self-actuating lithium ion battery (LIB) has the potential to achieve large deformation while still maintaining actuation force. The energy storage capability allows for continual actuation without an external power source once charged. Reshaping the actuator requires a nonuniform distribution of charge and/or bending stiffness. Spatially varying the state of charge and bending stiffness along the length of a segmented unimorph configuration have the effect of improving the tailorability of the deformed actuator. In this paper, an analytical model is developed to predict the actuation properties of the segmented unimorph beam to determine its usefulness as an actuator. The model predicts the free deflection, blocked deflection, and blocked force at the tip as a function of spatially varying state of charge and bending stiffness. The main contribution of the paper is the development of blocked deflection over the length of the segmented unimorph, which has not yet been considered in the literature. The model is verified using experimental data and commercial finite element analysis.
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Analytical modeling of a magnetoactive elastomer unimorph
Abstract Magnetoactive elastomers (MAEs) are capable of large deformation, shape programming, and moderately large actuation forces when driven by an external magnetic field. These capabilities enable applications such as soft grippers, biomedical devices, and actuators. To facilitate complex shape deformation and enhanced range of motion, a unimorph can be designed with varying geometries, behave spatially varying multi-material properties, and be actuated with a non-uniform external magnetic field. To predict actuation performance under these complex conditions, an analytical model of a segmented MAE unimorph is developed based on beam theory with large deformation. The effect of the spatially-varying magnetic field is approximated using a segment-wise effective torque. The model accommodates spatially varying concentrations of magnetic particles and differentiates between the actuation mechanisms of hard and soft magnetic particles by accommodating different assumptions concerning the magnitude and direction of induced magnetization under a magnetic field. To validate the accuracy of the model predictions, four case studies are considered with various magnetic particles and matrix materials. Actuation performance is measured experimentally to validate the model for the case studies. The results show good agreement between experimental measurements and model predictions. A further parametric study is conducted to investigate the effects of the magnetic properties of particles and external magnetic fields on the free deflection. In addition, complex shape programming of the unimorph actuator is demonstrated by locally altering the geometric and material properties.
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- PAR ID:
- 10440397
- Publisher / Repository:
- IOP Publishing
- Date Published:
- Journal Name:
- Smart Materials and Structures
- Volume:
- 32
- Issue:
- 9
- ISSN:
- 0964-1726
- Page Range / eLocation ID:
- Article No. 095021
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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