Numerical prediction of stress evolution during cooling of glass containers using the Narayanaswamy Model, by Benoît DEBBAU and M.Thierry MARCHAL (Ansys)


“Glass blowing is a high temperature process for the production of objects, such as bottles. Object shaping occurs in the liquid state. Cooling is actually an important stage; in particular, cooling speed and thus temperature history affects the glassy structure of the part and the development of residual deformations and stresses. In addition to this, structural relaxation also occurs.
Structural relaxation is well predicted with the Narayanaswamy model, which describes the transition between liquid and glassy states of the glass. This model combined with non-isothermal solid viscoelastic constitutive equations enables a reliable prediction of residual deformation and stresses.
In this paper, the influence of post-forming cooling conditions on the development of residual stresses and deformations in glass containers is examined. Here, we use the POLYFLOW software, developed by ANSYS Inc., and perform numerical simulations of cooling stress evolution under various conditions. The analysis of results allows detecting possible geometric and stress defects.”

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