The stability of the internal cavities of steel casting

The mechanism and causes of the formation of casting defects, manifested in the deviation of the geometry of the internal cavities from the «cylindrical», are investigated. It is shown that the causes of distortion of the geometric shape are associated with deformation of the casting rod during thermal and mechanical interaction with the melt. Using the possibilities of computer simulation in the MAGMASOFT package, the temperature distributions of the metal in the casting body during the casting and solidification were analyzed. Areas of distortion of the geometric shape of the inner part of the casting correspond to the area of the rod subjected to the highest and longest thermal loads. The characteristics of the temperature fields in the respective zones indicate overheating of individual areas of the rod to temperatures causing phase stresses in the structure of the core mixture, sufficient for the occurrence of deformations in it. To eliminate the defect under consideration, two approaches were used to reduce the magnitude of phase stresses in the casting rod and to adjust the design of the rod tooling.

Discrete element simulation studies of angles of repose and shear flow of wet, flexible fibers

The mechanics of wet and flexible fiber flows is better understood by analyzing agglomeration and solid phase stresses.

Simulation of Stress Distribution in a Thick- Walled Bushing Produced by Die-Casting

Metallographic investigations and a computer simulation of stresses in a gravity die-casting bushing were performed. Simulation of the casting process, solidification of the thick-walled bushing and calculations of the stress was performed using MAGMA5.3 software. The size variability of phases κII affecting the formation of phase stresses σf, depending on the location of the metallographic test area, was identified. The distribution of thermal σt and shrinkage stresses σs, depending on the location of the control point SC in the bushing's volume, was estimated. Probably the nature of these stresses will change slightly even after machining. This can cause variations in operating characteristics (friction coefficient, wear). Due to the strong inhomogeneity of the stress distribution in the bushing's casting, it is necessary to perform further tests of the possibility to conduct thermal treatment guaranteeing homogenization of the internal stresses in the casting, as well as to introduce changes in the bushing' s construction and the casting technology. The paper presents the continuation of the results of research aimed at identifying the causes of defects in the thick-walled bushing, die-casting made of CuAl10Fe5Ni5Cr aluminium bronze.

NUMERICAL STUDY ON THE INFLUENCE OF INFILTRATION ON SWASH HYDRODYNAMICS AND SEDIMENT TRANSPORT IN THE SWASH ZONE

Infiltration and exfiltration processes have a significant influence on the hydrodynamics of the swash zone. Such processes need to be taken into account in the modelling of cross-shore sediment transport and the prediction of beach profile evolution. This paper presents a numerical study of the swash hydrodynamics using a 2D Volume-Averaged Reynolds-Averaged Navier-Stokes model, which was calibrated and validated against new experimental data. The model was used to simulate wave run-up from regular waves over permeable and impermeable fixed slopes. Swash flow velocities and water depth data were obtained from the simulations and used to estimate bed shear stresses at three different locations on the beach slope. The results show that infiltration can have opposing effects on the bed shear stress when compared to equivalent swash on an impermeable slope. During the uprush phase, stresses are directly increased due to boundary layer thinning, whereas, during the backwash phase, there is a significant reduction of flow leading to a decrease in the bed shear stresses.