Abstract
Bar shaped specimens were prepared from iron powder. The specimens possessed a quasilayered distribution of porosity with porous outer regions and more dense core. For such specimens, the effective flexural moduli determined by means of flexural vibration parallel to the quasilayers were systematically higher than those determined from vibrations perpendicular to the quasilayers. When the more porous surface regions were more or less removed by grinding, the difference between “parallel” and “perpendicular” moduli decreased or even vanished. Such effect of surface regions of less stiffness was also confirmed theoretically by calculating the relevant moduli for model bars with quasilayered distribution of porosity.

Key words
sintered iron, heterogeneous distribution of porosity, effective flexural modulus

Full text (3727 KB)