Fracture Statistics for Inorganically-Bound Core Materials

Abstract

In this article, we study the fracture characteristics of inorganically-bound foundry cores. It will be shown that the fracture stress of inorganic cores follows Weibull’s strength distribution function for brittle materials. Using three-point and four-point-bending experiments, the volume dependence of the bending fracture stress is analyzed and a Weibull model fitted. Furthermore, the fracture stress of arbitrary bending experiments can be calculated based on the Weibull parameters found.

A Plane Stress Failure Criterion for Inorganically-Bound Core Materials

“…Please note that in this section all experimental results are scaled to the effective volume of the three-point-bending experiment according to Weibullian statistics and the approach proposed by Lechner et al in an earlier article [ 31 ]. Furthermore, we only determined data points on one side of the hydrostatic axis in Figure 2 , due to the axial symmetry of the Drucker-Prager and the Mohr-Coulomb criteria.…”

“…With the experimental results in this article and previous literature [ 31 ], which show that IOB cores follow Weibull statistics and a Mohr-Coulomb failure criterion, we have to answer the question of how both findings can be merged to one consistent mechanical model.…”

“…Please note that the fracture of IOB cores is following a Weibull distribution. This makes a correction of the fracture stresses according to the effective volumes for each test setup necessary [ 31 ]. Comparing specimens with a shape factor m and different volumes V , the fracture stress follows: …”

“…The hardening of the binder results in binder bridges between the individual sand grains. The specimens were stored at 20 °C and 10% humidity after production [ 31 ].…”

Acoustical and Optical Determination of Mechanical Properties of Inorganically-Bound Foundry Core Materials

“…The first step of building such a mechanical simulation is to determine the basic material parameters, in order to build a material model. Lechner et al showed that inorganically-bound core materials behave like a brittle material [5]. For a brittle material, the basic material parameters for a simulation are Young's modulus, shear modulus, fracture stress and fracture strain.…”