This paper summarizes recent studies on solid-state sintering with the goal of developing constitutive equations for use in finite element simulations of the sintering process. The assumed transport mechanisms are grain boundary diffusion and surface diffusion. Separate models are described for the three sintering stages - (1) initial neck formatio...
This paper summarizes recent studies on solid-state sintering with the goal of developing constitutive equations for use in finite element simulations of the sintering process. The assumed transport mechanisms are grain boundary diffusion and surface diffusion. Separate models are described for the three sintering stages - (1) initial neck formatio...
Ceramics are usually produced by pressing the powder in a die and sintering the resulting green body. A homogeneous density distribution after pressing is an important prerequisite to obtain equal shrinkage resulting in a final product which meets low tolerance limits. In this paper constitutive equations from micromechanical models are developed a...
The intermediate stage of sintering is characterized by equilibrium surfaces of the open pore space between the grains. These doubly curved surfaces are determined numerically for the three cubic arrangements of grains (simple cubic, b.c.c. and f.c.c). The numerical program constructs surfaces of constant mean curvature connected via the dihedral a...
Constitutive equations for the intermediate and late stages of sintering are derived assuming grain boundary diffusion to be the controlling transport mechanism. The surface of the pore space is assumed to be in equilibrium. Numerical results for the shape of equilibrium surfaces are taken from a companion paper (J. Svoboda, H. Riedel and H. Zipse,...
This paper presents a combined experimental-computational study of the impact of steel spheres on thin armor plates at an oblique angle of 70 deg. The plates were nominally 6 mm thick, rolled homogeneous armor. Two types of spheres were used, a hard steel and a soft iron. In all cases the velocity was around 1500 m/s. This combination of velocity a...
The penetration behavior of tungsten alloy, long-rod penetrators into high-hard steel is investigated at two impact velocities; 1.25 km/s and 1.70 km/s. The positions of the nose and tail of the projectile were measured by means of 600 kV flash X-ray system at different times during penetration. The wavecode CTH was used to numerically simulate the...
Da die einzelnen Bruchvorgänge schwierig zu quantifizieren sind und viele mikromechanische Erscheinungen, wie zum Beispiel der Einfluß einer zweiten Population von kleineren Hohlräumen, von mikromechanischen Modellen nicht beschrieben werden, können diese Modelle nur als phänomenologische Modelle betrachtet werden. Die materialspezifischen Paramete...
The ballistic performance of 17 penetrator materials, representing 5 distinct steel alloys treated to various hardnesses along with one tungsten alloy, has been investigated. Residual lengths and velocities, as well as the ballistic limit velocities, were determined experimentally for each of the alloy types for L/D 10 projectiles against finite-th...
