A Plane Stress Failure Criterion for Inorganically-Bound Core Materials

Abstract

Inorganically-bound core materials are used in foundries in high quantities. However, there is no validated mechanical failure criterion, which allows performing finite-element calculations on the core geometries, yet. With finite-element simulations, the cores could be optimised for various production processes from robotic core handling to the decoring process after the casting. To identify a failure criterion, we propose testing methods, that enable us to investigate the fracture behaviour of inorganically-bound core materials. These novel testing methods induce multiple bi-axial stress states into the specimens and are developed for cohesive frictional materials in general and for sand cores in particular. This allows validating failure criteria in principal stress space. We found that a Mohr-Coulomb model describes the fracture of inorganic core materials in a plane stress state quite accurately and adapted it to a failure criterion, which combines the Mohr-Coulomb model with the Weakest-Link theory in one consistent mechanical material model. This novel material model has been successfully utilised to predict the fracture force of a Brazilian test. This prediction is based on the stress fields of a finite element method (FEM) calculation.

Influence of Gating System Parameters of Die-Cast Molds on Properties of Al-Si Castings

“…Due to the facts mentioned above, directing the melt jet without hitting the cores appears more advantageous. Figure 9 shows the distribution of defects occurring in the cast body in the case where the melt jet hit the core [3,25].…”

“…In the simulation, the observed determining parameter of the design suitability was the ratio of shrinks in the cast body and the gating channels after solidification. Figure 10 shows a simulation of the gating system and distribution of defects after completion of the casting cycle [25]. The simulation and visual representation proved that the numerical design proposal of the gating system was not suitable.…”

Printing Parameter Requirements for 3D Printable Geopolymer Materials Prepared from Industrial Side Streams

“…Objects printed on a smaller scale can have similar strength properties compared to cast parts. According to Lechner et al [ 40 ], finite element method optimisation is preferable for testing the mechanical properties of cast objects, which is state-of-the-art for various materials used on industrial scale productions. Similarly, during the casting process, the evolving thermal fields can be detected through casting process simulation [ 41 ].…”

Characterization of Slurry-Cast Layer Compounds for 3D Printing of High Strength Casting Cores

“…Previous investigations of similar types of slurry showed an adjustability of the 3-point bending strength by slurry additives and sintering parameters up to 18 MPa [ 9 ]. Since the lost structures must be removable after casting, casting cores are intended to exhibit strengths sufficient to withstand the loads during handling and casting while assuring destructibility after casting [ 11 , 12 ].…”