tongqing.lu's blog

In the past decade, the development of theory has deeply revealed the electromechanical coupling deformation mechanism of dielectric elastomer (DE). Many theoretical predictions on highly nonlinear deformation of dielectric elastomer have been verified by experiments. With the guidance of theory, the voltage-induced areal strain of dielectric elastomer has been increased from 100% in the pioneering work to the current record of 2200% and the energy density of a dielectric elastomer generator has reached 780 mJ/g.

Hydrogel 3D printing with the capacitor edge effect

Recent decades have seen intense developments of hydrogel applications for cell cultures, tissue engineering, soft robotics, and ionic devices. Advanced fabrication techniques for hydrogel structures are being developed to meet user-specified requirements. Existing hydrogel 3D printing techniques place substantial constraints on the physical and chemical properties of hydrogel precursors as well as the printed hydrogel structures. This study proposes a novel method for patterning liquids with a resolution of 100 μm by using the capacitor edge effect.

When a clamped membrane of elastomer is subject to a lateral pressure, it bulges into a hemispherical balloon. However, for a clamped membrane of dielectric elastomer (DE) under a lateral pressure as well as a voltage through the thickness, it may bulge into a regular hemispherical balloon or an irregular shape. This work focuses on the anomalous bulging behaviors (i.e. the irregular bulging shape) of a DE balloon under electromechanical coupling loading.

A transducer is a system that couples two loads. For example, an electromechanical transducer couples a mechanical force and an electrical voltage. A two-load, nonlinear system can exhibit rich behavior of bifurcation, which can be displayed in a three-dimensional space, with the horizontal plane representing the two loads, and the vertical axis representing the state of the system. In this three-dimensional space, a state of equilibrium at fixed loads corresponds to a point on a surface.

This paper explores the critical and post-bulging bifurcation of a cylindrical dielectric elastomer (DE) tube undergoing finite deformation under electro-mechanical coupling loading. Explicit expressions for the critical conditions of electro-mechanical bifurcation are derived by using a simplified mathematical method. The post-bifurcation path is comprehensively investigated by specifying the material model as ideal dielectric elastomer.

A highly deformable capacitor made of a soft dielectric and two conformal

electrodes can switch between two states discontinuously, by a first-order transition, as the total

charge varies gradually. When the total charge is small, it spreads evenly over the area of the

capacitor, and the capacitor deforms homogeneously. When the total charge is large, it localizes in

a small region of the capacitor, and this region thins down preferentially. The capacitor will

Bulge test is an effective technique to measure the mechanical properties of thin films. As the membrane size decreases to nano-scale, the surface effect plays a significant role in determining the mechanical behavior of the membrane, and the techniques commonly used to measure the bulk materials properties are not applicable. We explore the surface effect on the nano-scale bulge test using combined continuum theories and atomistic simulations. We formulate the load-deflection relation by incorporating the surface effect and analyze its size-dependent behavior. The present theoretical model is in quantitative agreement with the molecular dynamics simulations.

Postdoctoral position in the theory of materials

Materials Department
University of California, Santa Barbara

Gurtin–Murdoch continuum surface elasticity model is employed to study the buckling
delamination of ultra thin film–substrate system. The effects of surface deformation and
residual stress on the large deflection of ultra thin film are considered in analysis. A
concept of effective bending rigidity (EBR) for ultra thin plate is proposed on the basis of
Gurtin–Murdoch continuum theory and the principle of minimum potential energy. The
governing equations with EBR are formally consistent with the classical plate theory,