# A Unidirectional Soft Dielectric Elastomer Actuator Enabled by Built-In Honeycomb Metastructures

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## Abstract

**:**

## 1. Introduction

## 2. Materials and Fabrication

#### 2.1. Materials Selection

#### 2.2. Fabrication

## 3. Model and Simulation

#### 3.1. Modeling of DEs

#### 3.2. Finite Element Analysis

#### 3.2.1. Setting

#### 3.2.2. Effect of Prestretches: ${\lambda}_{1}$ and ${\lambda}_{2}$

#### 3.2.3. Effect of Honeycomb Angle $\theta $

#### 3.3. Final Design for Prototyping

## 4. Experimental Section

#### 4.1. Setup

#### 4.2. Results

#### 4.3. Discussion

## 5. Conclusions and Future Outlook

## Supplementary Materials

## Author Contributions

## Funding

## Conflicts of Interest

## References

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**Figure 1.**Schematic of a DE membrane coupled with honeycomb metastructures. When a high voltage is applied, the actuator outputs a unidirectional motion. The two insets illustrate the sections of the DE membrane sandwiched between metastructures and between electrodes, respectively.

**Figure 3.**(

**a**) Print metastructures on a DE membrane with an FDM printer. (

**b**) Release the actuator prototype from the substrate membrane and connect copper tapes to it.

**Figure 4.**The CAD model in ABAQUS: (

**a**) assembly of the DE membrane and honeycombs; (

**b**) the geometry parameters of each honeycomb cell.

**Figure 5.**Voltage-induced axial strains ${\epsilon}_{x}$ and ${\epsilon}_{y}$ with different $\theta $ under ${\lambda}_{1}=4.0$, ${\lambda}_{2}=2.5$.

**Figure 8.**The actuation strains ${\epsilon}_{x}$ and ${\epsilon}_{y}$ vary with the trapezoid input voltage.

**Figure 9.**The actuator configurations: (

**a**) the released state before activation and (

**b**) the most deformed state at 7.5 kV. The scale bar is 8 mm.

Original Thickness | Shear Modulus | Dielectric Constant | Breakdown Strength |
---|---|---|---|

1 mm | 45 kPa | $4.0\times {10}^{-11}$ F/m | ∼100 MV/m |

Flexural Modulus | Poisson’s Ratio | Beam Length L | Beam Width w | Beam Height h |
---|---|---|---|---|

78 MPa | 0.36 | 8 mm | 0.8 mm | 2 mm |

**Table 3.**The actuation strains with different prestretches for $\theta ={90}^{\circ},\mathsf{\Phi}$ = 7.5 kV.

Case | ${\mathit{\lambda}}_{1}$ | ${\mathit{\lambda}}_{2}$ | ${\mathit{\epsilon}}_{\mathit{x}}$ (%) | ${\mathit{\epsilon}}_{\mathit{y}}$ (%) |
---|---|---|---|---|

1 | 4.0 | 2.5 | 7.02 | 1.09 |

2 | 4.0 | 2.0 | 5.57 | 1.13 |

3 | 3.2 | 3.2 | 5.71 | 0.66 |

4 | 3.0 | 3.0 | 4.87 | 0.58 |

5 | 2.5 | 4.0 | 8.40 | 0.69 |

6 | 2.0 | 4.0 | 7.56 | 0.58 |

**Table 4.**The actuation strains with different prestretches for $\theta ={150}^{\circ},\mathsf{\Phi}$ = 7.5 kV.

Case | ${\mathit{\lambda}}_{1}$ | ${\mathit{\lambda}}_{2}$ | ${\mathit{\epsilon}}_{\mathit{x}}$ (%) | ${\mathit{\epsilon}}_{\mathit{y}}$ (%) |
---|---|---|---|---|

1 | 4.0 | 2.5 | −3.32 | 31.41 |

2 | 4.0 | 2.0 | −3.28 | 23.77 |

3 | 3.2 | 3.2 | −1.71 | 30.97 |

4 | 3.0 | 3.0 | −1.44 | 26.59 |

5 | 2.5 | 4.0 | −0.62 | 23.27 |

6 | 2.0 | 4.0 | −0.27 | 14.45 |

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## Share and Cite

**MDPI and ACS Style**

Liu, K.; Chen, S.; Chen, F.; Zhu, X.
A Unidirectional Soft Dielectric Elastomer Actuator Enabled by Built-In Honeycomb Metastructures. *Polymers* **2020**, *12*, 619.
https://doi.org/10.3390/polym12030619

**AMA Style**

Liu K, Chen S, Chen F, Zhu X.
A Unidirectional Soft Dielectric Elastomer Actuator Enabled by Built-In Honeycomb Metastructures. *Polymers*. 2020; 12(3):619.
https://doi.org/10.3390/polym12030619

**Chicago/Turabian Style**

Liu, Kun, Shitong Chen, Feifei Chen, and Xiangyang Zhu.
2020. "A Unidirectional Soft Dielectric Elastomer Actuator Enabled by Built-In Honeycomb Metastructures" *Polymers* 12, no. 3: 619.
https://doi.org/10.3390/polym12030619