TITLE:
Studies on Cold Workability Limits of Brass Using Machine Vision System and its Finite Element Analysis
AUTHORS:
J. Appa Rao, J. Babu Rao, Syed Kamaluddin, NRMR Bhargava
KEYWORDS:
Friction, Upsetting, Vision System, Finite Element Analysis
JOURNAL NAME:
Journal of Minerals and Materials Characterization and Engineering,
Vol.10 No.9,
July
20,
2011
ABSTRACT: Cold Workability limits of Brass were studied as a function of friction, aspect ratio and
specimen geometry. Five standard shapes of the axis symmetric specimens of cylindrical
with aspect ratios 1.0 and 1.5, ring, tapered and flanged were selected for the present
investigation. Specimens were deformed in compression between two flat platens to predict
the metal flow at room temperature. The longitudinal and oblique cracks were obtained as
the two major modes of surface fractures. Cylindrical and ring specimen shows the oblique
surface crack while the tapered and flanged shows the longitudinal crack. Machine Vision
system using PC based video recording with a CCD camera was used to analyze the
deformation of 4 X 4 mm square grid marked at mid plane of the specimen. The strain paths
obtained from different specimens exhibited nonlinearity from the beginning to the end of the
strain path. The circumferential stress component Os increasingly becomes tensile with continued deformation. On the other hand the axial stress Oz , increased in the very initial stages of deformation but started becoming less compressive immediately as barreling
develops. The nature of hydrostatic stress on the rim of the flanged specimen was found to be
tensile. Finite element software ANSYS has been applied for the analysis of the upset forming
process. When the stress values obtained from finite element analysis were compared to the
measurements of grids using Machine Vision system it was found that they were in close
proximity.