Finite element evaluation of thermal stresses during the solidification of a glass pour

Abstract

The purpose of this thesis is to determine the temperature history, thermal stress history, and the susceptibility to fracture of glass (borosilicate) as it is poured (in a liquid state) into a canister and allowed to cool into a solid state. The general purpose finite element code ABAQUS was utilized to simulate the glass pour problem. The thermomechanical problem was solved using an axisymmetric geometry and with proper boundary conditions.

Three specific problems were addressed: (1) determination of temperature history in the glass pour as it was being poured into a stainless steel canister; (2) determination of the thermal stress history in the glass as it solidifies and cools to room temperature; and (3) assessment of potential for fracture in the solidified glass as a result of the induced thermal stresses. Phase change effects were not considered in the model.

In determining the temperature history of the glass pour, heat loss due to natural convection and radiation from various surfaces were considered. Once the canister was full, the temperature history was recorded. The recorded temperature history was then used to determine the thermal stress history in the glass pour. Based on the determined thermal stress history, the principal stresses were calculated and compared with the yield strength of glass to determine the potential for crack formation. When determining the thermal stress history in glass, two different sets of boundary conditions were used. The first boundary condition assumes that glass remains in contact vdth the canister wall as it cools down. The second boundary condition allows the glass to separate from the canister wall as it contracts.

The fracture analysis results showed that both cases have potential for crack formation. However, the second set of boundary conditions (the set that allows the glass to separate from the canister wall) seems to simulate more realistically the possibility and location of the cracks that may form.