Thermo-Mechanical Metamaterials: Towards

Stimuli Responsive Micro-Robotics

1

26/05/2020

Besançon, France

Q. X. Ji, J. Moughames, J.Y. Qu, C. Clevy, Rabenorosoa, V. Laude,

M. Kadic

4D Printing & Meta Materials Conference

Material A

Material B

The bilayer beam expands (shrinks) and bends upon heating (cooling) due to the

difference in thermal expansion.

This thermal-mechanical process can be used as the deformation initiator, e.g.

thermal actuators for soft micro-robots.

Deformation mechanism of a bi-material beam

2

1 Introduction

Mechanism:

A real robot arm ( Images from: https://www.google.com/search )

Controlling principle of robot arms made

on thermo-mechanical blocks

3

1 Introduction

We design metamaterial blocks that each can translate and rotate in one

axis direction by thermal-stimuli. 2

1 We build a three-axis setup to complete 3D movement.

Pick-and-place task:

Working principle

1

(b)

A single cell and its operating principle: (a) undeformed and (b) deformed.

The high (low) expansion material is depicted in red (blue).

The bi-material beam bends upon heating, resulting in overall upwards translation

of the single cell.

Translation blocks

z

x y

2(a) 1<2

0 1.4 Displacement (mm)

ΔT=40K

4

2 Thermal-mechanical design

Deformed manner of the five-layer translation lattice

The top end moves upwards by d =6.54 mm. (1=8e-5 1/K, 2=5e-5 1/K, L=50 mm,

t=1 mm).

For clarity, the deformation is up-scaled by 10 times.

0

6.6

Tra

nsla

tio

n d

isp

lace

me

nt (μ

m)

d

L

z

x y

Parameters from: Qu, SCI REP, 2016

ΔT=40K

5

2 Thermal-mechanical design

Displacements against built parameters for the built five-layer translation

lattice (ΔT=40K)

Linear relation is observed between d and L (d and Δ Δ).

In Fig.(b), we fix 1 and increase 2 to get different D

(b) (a)

6

2 Thermal-mechanical design

Simulations

We investigate the actuation force that can be used to move objects by placing a

load on top of the extended lattice.

Deformed Undeformed

0 Displacement (mm)

ΔT=40K

7

2 Thermal-mechanical design

7

Actuation force

Simulated displacement of a single translation

cell with the change of force

Geometrical nonlinearity was considered.

The amplitude d increases linearly with the number of layers.

This Photo by Unknown Author is licensed under CC BY-SA-NC

8

2 Thermal-mechanical design

d

Spring-mass model

(ΔT=40K)

( Images from: https://www.google.com/search )

x

z y

(b)

A rotation cell : (a) undeformed and (b) deformed by 20 times.

(a)

The high (low) expansion material is depicted in red (blue).

The bi-material beam bends upon heating, resulting in overall rotation of

the single cell.

Rotation blocks

0 4 Displacement (mm)

ΔT=40K 2

1<2 1

9

2 Thermal-mechanical design

A rotation lattice and its deformed manner ( ΔT=40K)

The top end rotates by q =15.9° (1=8e-5 1/K, 2=5e-5 1/K, L=100 mm, t=1

mm)。

The angle q increases with more layers.

0

65

Ro

tati

on

dis

pla

cem

en

t (μ

m)

x z

y

q

10

2 Thermal-mechanical design

Simulations

Amplitudes against built parameters for a rotation cell (ΔT=40K)

Linear relation is observed between q and L (q and Δ).

In Fig.(b), we fix 1 and increase 2 to get different D.

(b) (a)

11

2 Thermal-mechanical design

Simulations

Actuation capacity for a rotation cell

M0

r F

The loading mass M0 is normalized to mass of the cell.

The amplitude q increases linearly with number of layers built.

The built cell (L/t=80) can move a normalized mass up to a order of 104.

q

12

2 Thermal-mechanical design

Pully-mass model

The two materials are written using same polymers with different laser power.

They resemble each other but are different in thermal expansion.

Pre-bending of the bi-material beam is observed. 13

3 Fabrication and experiments

Material A (laser power 35%)

Material A (laser power 55%)

Direct Laser Writting

14

3 Fabrication and experiments

Optical image

SEM image

Unit cell Lattice

Top view Side view

15

3 Fabrication and experiments

q

Experimental and simulation results

Errors mainly from

• Thermal expansion measurement

• Heating temperature

• Manufacture imperfections

16

3 Fabrication and experiments

Translation

blocks

17

Thanks for your attention!

Muamer Kadic Vincent Laude

Main researches

Metamaterials

Plasmonics

Electromagnetism

Mechanical Metamaterials

Topology

Acoustics

FEMTO-ST, MN2S Group