PubMed Health⌕ Search

Biomedical subjects

RC Ball

Publications and source records attributed to RC Ball.

At least 19 recordsLinked to original sources

Effects of nonlocal stress on the determination of shear banding flow

We analyze the steady planar shear flow of the modified Johnson-Segalman model, which has an added nonlocal term. We find that the new term allows for unambiguous selection of the stress at which two "phases" coexist, in contrast to the original model. For general differential constitutive models we show the singular nature of stress selection in terms of a saddle connection between fixed points in the equivalent dynamical system. The result means that stress selection is unique under most conditions for space nonlocal models. Finally, illustrated by simple models, we show that stress selection generally depends on the form of the nonlocal terms (weak universality).

Journal Article↗

Dynamical weight functions for a planar crack

The stress intensity factors are evaluated for a moving planar crack for loadings which vary arbitrarily in time and three dimensions of space. We exploit the adjoint elasticity equation obeyed by the corresponding weight functions, and a new and more universal Wiener-Hopf factorization of the Rayleigh function, this being the central difficulty in such calculations. For the mode II weight function we give further asymptotic results crucial to a subsequent calculation of crack stability with respect to out-of-plane perturbations.

Journal Article↗