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Dielectric elastomer transducers are often subject to large tensile stretches and are susceptible to rupture. Here we carry out an experimental study of the rupture behavior of membranes of an acrylic dielectric elastomer. Pure-shear test specimens are used to measure force-displacement curves, using samples with and without pre-cracks. We find that introducing a pre-crack into a membrane drastically reduces the stretch at rupture. Furthermore, we measure the stretch at rupture and fracture energy using samples of different heights at various stretch-rates. The stretch at rupture is found to decrease with sample height, and the fracture energy is found to increase with stretch-rate.

When electric current flows in a solder bump, electromigration generates stress, but creep relaxes it. After some time, the bump develops a steady-state stress field. We present a theory to show that the two processes — electromigration and creep — set an intrinsic length. When the intrinsic length is large compared to the height of the bump, electromigration is fast relative to creep and the steady-state stress field is linearly distributed in the bump. When the intrinsic length is small compared to the height of the bump, electromigration is slow relative to creep and the steady-state stress field nearly vanishes in the bump, except in a thin layer along the boundary of the bump. We further show that a critical electric current exists, below which the bump can sustain the steady-state stress field without forming voids. Theoretical predictions are compared with existing experimental observations.

Silicon can host a large amount of lithium, making it a promising electrode for high-capacity lithium-ion batteries. Upon absorbing lithium, silicon swells several times its volume; the deformation often induces large stresses and pulverizes silicon. Recent experiments, however, indicate that under certain conditions lithiation causes inelastic deformation. This paper models such an inelastic host of lithium by considering diffusion, elastic-plastic deformation, and fracture. The model shows that fracture is averted for a small and soft host—an inelastic host of a small feature size and low yield strength.

During charging or discharging of a lithium-ion battery, lithium is extracted from one electrode and inserted into the other. This extraction-insertion reaction causes the electrodes to deform. An electrode is often composed of small active particles in a matrix. If the battery is charged at a rate faster than lithium can homogenize in an active particle by diffusion, the inhomogeneous distribution of lithium results in stresses that may cause the particle to fracture. The distributions of lithium and stress in a LiCoO2 particle are calculated. The energy release rates are then calculated for the particle containing preexisting cracks. These calculations predict the critical rate of charging and size of the particle, below which fracture is averted.