Mechanical design of stimuli-responsive flexible rotary joint using liquid crystal elastomers

doi:10.1007/s10483-025-3328-7

摘要/Abstract

Abstract:

Conventional rotary actuators mainly rely on electric or hydraulic/pneumatic motors to convert energy into mechanical motion, making them one of the most widely used actuation methods in industrial manufacturing, robotics, and automation control. However, these traditional actuators often suffer from limitations in operability and applicability due to their complex structures, bulky systems, high energy consumption, and severe mechanical wear. Liquid crystal elastomers (LCEs) have been increasingly used for programmable actuation applications, owing to their ability to undergo large, reversible, and anisotropic deformations in response to external stimuli. In this work, we propose a compact flexible rotary joint (FRJ) based on LCEs. To describe the thermo-mechanical coupled behaviors, a constitutive model is developed and further implemented for finite element analysis (FEA). Through combining experiments and simulations, we quantify the dynamic rotational behavior of the rotor rotating relative to the base driven by the induced strain of the FRJ under cyclic thermal stimuli. The proposed rotary joint features a simple structure, lightweight design, low energy consumption, and easy control. These characteristics endow it with significant potential for miniaturization and integration in the field of soft actuation and robotics.

Key words: liquid crystal elastomer (LCE), rotary actuator, flexible rotary joint (FRJ), programmable actuation, reversible cyclic motion

中图分类号:

. [J]. Applied Mathematics and Mechanics (English Edition), 2025, 46(12): 2221-2240.

Weicong ZHANG, Zengting XU, Baihong CHEN, Xiangren KONG, Rui XIAO, Jin QIAN. Mechanical design of stimuli-responsive flexible rotary joint using liquid crystal elastomers[J]. Applied Mathematics and Mechanics (English Edition), 2025, 46(12): 2221-2240.

图/表 19

Number of connection points	$R$ /mm	$α / (∘)$
2	17	30
3	17	20
4	17	10

Joint	Drive method	Size/mm	Weight/g	Power/W
Electromotor^[48]	Electric	35	80	4.5
RV reducer^[49]	Electric	$> 40$	4 700	1 700
Maxon EC90 motor^[50]	Electric	22	600	90
Rotating pneumatic clutch^[51]	Pneumatic	50	450	–
Double-blade rotating cylinder^[52]	Hydraulic	500	4 300	–
Hydraulic rotary joint^[53]	Hydraulic	172	1 000	–
Hydraforce PV70	Hydraulic	–	$> 190$	50–60
Bucher hydraulics	Hydraulic	–	$> 500$	$> 30$
DVP vacuum	Pneumatic	$> 60$	$> 250$	10–30
Maxon EC-max 16	Electric	16	20	5–10
Oriental motor PKP223	Electric	28	110	1–5
Present work	Thermal	34	3.2	~10

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Training detail	Value
Hidden layers	{36, 36}
Training size	1 000
Training error/%	0.3
Validation error/%	2.7
Optimal parameter prediction error/%	0.6