Impact Of Material Properties Research Articles

Material properties in fine grinding

The impact of material properties in grinding processes is twofold: • the objective of the comminution process is the production of well-defined product properties, • particles' transport to the stressing zone and particles' reaction to applied stresses depend on their inherent mechanical material properties. In order to understand the influence of material properties at various length scales, we draw a multiscale picture of comminution. At the most detailed level MD simulations may open insights into the otherwise not accessible zone directly at the crack tip. In continuum approaches, the energy flux from the elastically stressed specimen and the stress distribution around the crack can be modelled. Breakage probability obtained from particle stressing experiments or inversion of milling models can be described by a single master curve comprising two new material parameters. These results are used in mill models by clearly separating machine and material functions. In wet grinding, additional material parameters reflecting the particle–particle interactions are introduced, which control suspension rheology and particle stability. The paper concludes with some remarks on product engineering, i.e. concepts on how to optimise product quality.

Basic Approach to a Prediction System for Burr Formation in Face Milling

Geometric parameters and material properties are the two major categories of factors affecting burr formation in the milling process. Geometric parameters such as tool geometry, workpiece geometry, or process condition influence workpiece edge quality at the tool-chip interface. This study identifies a unified criterion to analyze burr formation for different tool engagements. The criterion exploits the exit order of cutting edges of the tool along the workpiece edge, which essentially includes the 3-D nature of the process. The criterion correlates the cutting mechanism and burr formation using the exit order sequence (EOS) as an approximation of chip flow angle. The impact of different possible exit order sequences on burr formation is analyzed. Previously observed phenomena are explained based on the EOS. Also, experiments are done with three different materials (with different ductilities) to analyze the impact of material properties on burr formation for a given EOS. Although burr sizes are different quantitatively with different material, the ranking of burr size for different EOS remained the same. An algorithm for the prediction of burr formation in face milling based on EOS is developed and tested and validated on two different profiles of an automotive part.

Interface corner stress states: plasticity effects

When a butt joint fails, failure often initiates in the region where the interface intersects the stress-free edge. Asymptotic solutions for the stress field found at this type of interface corner are presented for an idealized butt joint with rigid adherends and a thin, essentially semi-infinite, adhesive bond. Linear elastic, power law hardening, and perfectly plastic adhesive models are considered. A stress singularity of type σ∼Krδ(δ<0) exists when the adhesive is either linear elastic or power law hardening. The impact of material properties on the order of the stress singularity δ and the effect of load level and bond thickness on the value of the interface corner stress intensity factor K are detailed. Slip theory is used to determined the asymptotic, interface corner stress field for a perfectly plastic adhesive. This solution indicates that there is a high level of hydrostatic tension, equal to 1.5 δy, in the yielded material along the interface. The three asymptotic solutions are used to construct interface normal stress distributions that closely approximate full, finite element results for an idealization butt joint when small scale yielding conditions apply.