Showing papers by "Robert F. Singer published in 1984"

Improvement of the "young" fatty neck.

Abstract: The properly selected relatively young patient with good skin tone and an obtuse cervicomental angle can be aesthetically improved through just a submental incision, combined with an extensive submandibular defatting and medial platysmoplasty.

The effect of grain shape on stress rupture of the oxide dispersion strengthened superalloy inconel MA 6000

Abstract: Creep specimens of Inconel MA 6000 with different grain aspect ratios (GAR) ranging from about 4 to 60 were tested at 950\" C at a stress of 230 MPa. The resulting rupture times show a pronounced dependence on the GAR below a value of about 20, where fracture is mainly intergranular. At higher GAR values, the rupture time becomes less sensitive to grain shape, and fracture is predominantly transgranular. These results are interpreted in the light of the hypothesis that sliding of the elongated grains along longitudinal grain boundaries, which is a necessary accommodation mechanism, controls the rate of creep damage accumulation on boundaries perpendicular to the applied stress. A quantitative model for the coupling between the two processes is presented. If it is assumed that the oxide dispersoid introduces a threshold stress for sliding, then the transition in the fracture mode with increasing GAR can be explained quantitatively: The reason is that, above a critical GAR of about 20, the damage-induced shear stress in the longitudinal boundaries lies below the threshold, and sliding and damage accumulation on transverse boundaries are suppressed. This approach results in a quantitative description of the beneficial interaction between elongated grain shape, boundary waviness and oxide dispersion.