A simple model of dynamic cleavage under longitudinal shear deformation is analyzed as an attempt to understand how ancient lapidaries might have produced smooth cleaved surfaces. Attention is concentrated on the time signature of the load applied to the specimen in order to maintain a constant stress intensity factor (or energy release rate) at the crack tip as it propagates away from the loca...

By partitioning the total stresses in a damaged composite into either mechanical and residual stresses or into initial and perturbation stresses, it was possible to derive several exact results for the energy release rate due to crack growth. These general results automatically include the effects of residual stresses, traction-loaded cracks, and imperfect interfaces. By considering approximate...

The dynamic steady-state propagation of two parallel semi-infinite, mode III cracks is considered for a general, infinite, homogeneous, and isotropic linearly viscoelastic body. A Barenblatt type failure zone is introduced in order to cancel the singular stress and a formula for the energy release rate is derived which provides immediate comparisons with the corresponding single crack problem. ...

        Controlled release swellable tablets of phenobarbital were prepared by a simple direct compression process using hydroxypropyl methylcellulose (HPMC) as the matrix former. The effects of the viscosity grades of HPMC and HPMC/lactose ratio and ethylcellulose (EC)/sodium carboxymethylcellulose (NaCMC) and their concentrations on the release behavior of phenobarbital from HPMC matrices wer...

A finite-element-based toolset has been developed to simulate arbitrary evolution of 3-D, geometrically explicit, interlaminar delaminations in composite structures. A new energy-based growth formulation uses the virtual crack extension (VCE) method to predict point-by-point growth along the delamination front. The VCE method offers an accurate and computationally efficient means to extract bot...

the purpose of this study was to prepare and characterize nimodipine loaded microspheres using ethyl cellulose (ec) as a carrier polymer through an emulsion solvent evaporation method. these evaluations characterized the pattern of drug release from prepared microspheres. nimodipin loaded microspheres were prepared using an emulsification solvent evaporation method. the effect of process variab...

the aim of this study was to develop an extended-release tablet formulation using a new in situ cross-linking method. the effects of polyvalent cations on theophylline release from tablets made with the polyanionic polymers sodium alginate and sodium carboxymethylcellulose, were investigated. different miliequivalents of the di and tri-valent cation, ca2+ and al3+, were added to tablet formulat...

Temperature determines the energy release rate of secondary high explosives. Thus, it is critical to know temperature applied an explosive predict its response impulse. However, measuring internal a heterogenous solid undergoing in detonation has many technical challenges. We will discuss several measurement techniques, their strengths, and limitations, propose alternative route assessing effec...