Self-Sustained Euler Buckling of an Optically Responsive Rod with Different Boundary Constraints

Abstract

Self-sustained oscillations can directly absorb energy from the constant environment to maintain its periodic motion by self-regulating. As a classical mechanical instability phenomenon, the Euler compression rod can rapidly release elastic strain energy and undergo large displacement during buckling. In addition, its boundary configuration is usually easy to be modulated. In this paper, we develop a self-sustained Euler buckling system based on optically responsive liquid crystal elastomer (LCE) rod with different boundary constraints. The buckling of LCE rod results from the light-induced expansion and compressive force, and the self-buckling is maintained by the energy competition between the damping dissipation and the net work done by the effective elastic force. Based on the dynamic LCE model, the governing equations for dynamic Euler buckling of the LCE rod is formulated, and the approximate admissible trigonometric functions and Runge-Kutta method are used to solve the dynamic Euler buckling. Under different illumination parameters, there exists two motion modes of the Euler rod: the static mode and the self-buckling mode, including alternating and unilateral self-buckling modes. The triggering conditions, frequency, and amplitude of the self-sustained Euler buckling can be modulated by several system parameters and boundary constraints. Results indicate that strengthening the boundary constraint can increase the frequency and reduce the amplitude. It is anticipated that this system may open new avenues for energy harvesters, signal sensors, mechano-logistic devices, and autonomous robots.

A light-powered self-rotating liquid crystal elastomer drill

“…Based on stimuli-responsive materials, including liquid crystal elastomers (LCEs) [ 28 ], ionic gels [ 29 , 30 ], hydrogels [ 31 , 32 ], etc., diverse self-oscillating systems have been widely developed recently. Especially, there have been numerous attempts to construct a large number of self-sustained motion patterns, such as vibration [ 33 ], bending [ 34 , 35 ], rolling [ [36] , [37] , [38] ], spinning [ 39 ], torsion [ 40 ], shuttling [ 41 ], self-oscillating auxetic metamaterials [ 42 ], self-floating [ 43 ] and self-curling [ 44 ], shrinking [ 45 ], swimming [ 46 ], swinging [ 16 , 47 ], buckling [ 48 , 49 ], jumping [ 50 , 51 ], rotation [ 52 , 53 ], chaos [ 54 ] and even synchronized motion of coupled self-oscillators [ 55 ]. In these self-oscillating systems, some special mechanisms are generally required for absorbing energy from the external environment to compensate for the dissipation consumed by the system damping [ 1 ].…”

Self-Sustained Oscillation of Electrothermally Responsive Liquid Crystal Elastomer Film in Steady-State Circuits

“…A rich variety of Self-excited oscillation systems constructed based on active materials have been recently reported, such as hydrogels [20,21], dielectric elastomers, ionic gels [22,23], liquid crystal elastomers (LCEs) [24][25][26][27][28][29] and temperature-sensitive polymers [30][31][32][33]. At the same time, researchers have proposed and constructed different Self-excited oscillation patterns based on various types of active materials, such as bending [30][31][32], flexing, twisting [33,34], stretching and contracting [35], rolling [36], swimming, oscillating, vibrating [37][38][39], jumping [40][41][42], rotating [43], turning outward or reversing, and even the synchronized motion of several coupled Self-oscillators.…”

“…A rich variety of Self-excited oscillation systems constructed based on active materials have been recently reported, such as hydrogels [20,21], dielectric elastomers, ionic gels [22,23], liquid crystal elastomers (LCEs) [24][25][26][27][28][29] and temperature-sensitive polymers [30][31][32][33]. At the same time, researchers have proposed and constructed different Self-excited oscillation patterns based on various types of active materials, such as bending [30][31][32], flexing, twisting [33,34], stretching and contracting [35], rolling [36], swimming, oscillating, vibrating [37][38][39], jumping [40][41][42], rotating [43], turning outward or reversing, and even the synchronized motion of several coupled Self-oscillators. Owing to the damping effect of systems, Self-excited oscillation consumes energy during motion, so it usually originates from nonlinear feedback mechanisms that compensate for the damping consumption of a system through energy input [44][45][46], such as the Self-shadowing mechanism [36,47], the coupling mechanism of chemical reaction and large deformation [22], and the coupling motion mechanism of air expansion and liquid column [48,49].…”

Self-Sustained Chaotic Jumping of Liquid Crystal Elastomer Balloon under Steady Illumination

“…Furthermore, these materials have led to the engineering of diverse modes of self-sustained motion modes, each characterized by their own unique dynamics. These motion modes span from vibration [ 9 , 10 , 11 ], bending [ 12 , 13 , 14 , 15 ], rolling [ 16 , 17 ], torsion [ 18 , 19 ], stretching and contraction [ 20 , 21 ], to even swimming [ 22 ], oscillating [ 23 , 24 , 25 ], buckling [ 26 , 27 , 28 , 29 , 30 ], jumping [ 31 , 32 , 33 ], rotating [ 34 ], valving, or reversing [ 35 , 36 ]. Intricate nonlinear feedback mechanisms, including phenomena such as self-shading [ 26 ], the coupling of large deformations with chemical reactions [ 1 , 2 ], and the generation of photothermal surface tension gradients [ 37 , 38 ], make these self-sustained motion modes possible.…”