A computer simulation model for the blow-blow forming process of glass containers

In glass container manufacturing (e.g. production of glass bottles and jars) an important process step is the blowing of the final product. This process is fast and is characterized by large deformations and the interaction of a hot glass fluid that gets into contact with a colder metal, the mould. The objective of this paper is to extend and further develop our finite element model [1] to be used for industrial purposes. To achieve this both steps of the forming of glass containers, namely blow-blow needs to be simulated and tested against real industrial problems. The model should be able to correctly represent the flow of glass, the energy exchange during the process and provide the final thickness of the final product. For tracking the geometry of the deforming inner and outer interface of glass, the level set technique is applied on a fixed mesh. At each time step the coupled problem of flow and energy exchange is solved by the model. Here the flow problem is only solved for the domain enclosed by the mould, whereas in the energy calculations, the mould domain is also taken into account. A non uniform temperature distribution is considered for the blowing of the preform. For all the calculations the material parameters (like viscosity) are based on the glass position, i.e. the position of the level sets. The velocity distribution, as found from this solution procedure, is then used to update the two level sets by means of solving a convection equation. A fast marching re-initialization algorithm is applied after each time step in order to let the level sets re-attain the property of being a signed distance function. The model is validated by several examples focusing on both the overall behavior (such as conservation of mass and energy) and the local behavior of the flow (such as glass-mould contact) and temperature distributions

Modelling stretch blow moulding of polymer containers using level set methods

Stretch blow moulding is a widely used technique e.g. for the production of PET bottles. In a stretch blow moulding process a hot preform of polymer is simultaneously stretched and blown into a mould shape. The process takes place at a fast rate and is characterised by large deformations and temperature gradients. In this paper a computer simulation model for stretch blow moulding is presented. The model is based on finite element methods and uses a level set method to track the interfaces between air, polymer and stretch rod. The PET behaviour is modelled as a non-newtonian, isothermal fluid flow, based on a viscoplastic material model. An application presented is the stretch blow moulding of a realistic PET water bottle. The model is validated by verifying volume conservation

Development of a Numerical Optimisation Method for Blowing Glass Parison Shapes

Industrial glass blowing is an essential stage of manufacturing glass containers, i.e. bottles or jars. An initial glass preform is brought into a mould and subsequently blown into the mould shape. Over the last few decades, a wide range of numerical models for forward glass blow process simulation have been developed. A considerable challenge is the inverse problem: to determine an optimal preform from the desired container shape. A simulation model for blowing glass containers based on finite element methods has previously been developed [14,15]. This model uses level set methods to track the glass-air interfaces. The model described in a previous paper of the authors showed how to perform the forward computation of a final bottle from the given initial preform without using optimisation. This paper introduces a method to optimise the shape of the preform combined with the existing simulation model. In particular, the new optimisation method presented aims at minimising the error in the level set representing the glass-air interfaces of the desired container. The number of parameters used for the optimisation is restricted to a number of control points for describing the interfaces of the preform by parametric curves, from which the preform level set function can be reconstructed. Numerical applications used for the preform optimisation method presented are the blowing of an axi-symmetrical ellipsoidal container and an axi-symmetrical jar

Modelling stretch blow moulding of polymer containers using level set methods

Stretch blow moulding is a widely used technique e.g. for the production of PET bottles. In a stretch blow moulding process a hot preform of polymer is simultaneously stretched and blown into a mould shape. The process takes place at a fast rate and is characterised by large deformations and temperature gradients. In this paper a computer simulation model for stretch blow moulding is presented. The model is based on finite element methods and uses a level set method to track the interfaces between air, polymer and stretch rod. The PET behaviour is modelled as a non-newtonian, isothermal fluid flow, based on a viscoplastic material model. An application presented is the stretch blow moulding of a realistic PET water bottle. The model is validated by verifying volume conservation

Development of a blood flow model including hypergravity and validation against an analytical model

Fluid structure interaction (FSI) appears in many areas of engineering, e.g. biomechanics, aerospace, medicine and other areas and is often motivated by the need to understand arterial blood flow. FSI plays a crucial role and cannot be neglected when the deformation of a solid boundary affects the fluid behavior and vice versa. This interaction plays an important role in the wave propagation in liquid filled flexible vessels. Additionally, the effect of hyper gravity under certain circumstances should be taken into account, since such exposure can cause alterations in the wave propagation underexposed. Typical examples in which hyper gravity occurs are rollercoaster rides and aircraft or spacecraft flights. This paper presents the development of an arterial blood flow model including hyper gravity. This model has been developed using the finite element method along with the ALE method. This method is used to couple the fluid and structure. In this paper straight and tapered aortic analogues are included. The obtained computational data for the pressure is compared with analytical data available

On the derivation of SPH schemes for shocks through inhomogeneous media

Smoothed Particle Hydrodynamics (SPH) is typically used for the simulation of shock propagation through solid media, commonly observed during hypervelocity impacts. Although schemes for impacts into monolithic structures have been studied using SPH, problems occur when multimaterial structures are considered. This study begins from a variational framework and builds schemes for multiphase compressible problems, coming from different density estimates. Algorithmic details are discussed and results are compared upon three one-dimensional Riemann problems of known behavior.</p

On the derivation of SPH schemes for shocks through inhomogeneous media

Smoothed Particle Hydrodynamics (SPH) is typically used for the simulation of shock propagation through solid media, commonly observed during hypervelocity impacts. Although schemes for impacts into monolithic structures have been studied using SPH, problems occur when multimaterial structures are considered. This study begins from a variational framework and builds schemes for multiphase compressible problems, coming from different density estimates. Algorithmic details are discussed and results are compared upon three one-dimensional Riemann problems of known behavior.</p