Residual stresses in gas-assisted injection molding

Residual stresses are a major issue in the mechanical and optical behavior of injection-molded parts. In this study, we analyze their development in the case of gas-assisted injection molding (GAIM) of amorphous polymers. Flow-induced residual stresses are computed within a decoupled approach, in wh...

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Bibliographic Details
Published in:Rheologica acta 2010, Vol.49 (1), p.23-44
Main Authors: Custódio, Frederico J. M. F., Anderson, Patrick D., Peters, Gerrit W. M., Cunha, António M., Meijer, Han E. H.
Format: Article
Language:English
Subjects:
Applied sciences
Characterization and Evaluation of Materials
Chemistry and Materials Science
Complex Fluids and Microfluidics
Compressibility
Computational fluid dynamics
Exact sciences and technology
Finite element method
Food Science
Gas injection molding
Injection molding
Injection moulding
Kinematics
Machinery and processing
Materials Science
Mathematical models
Mechanical Engineering
Moulding
Original Contribution
Plastics
Polymer industry, paints, wood
Polymer Sciences
Residual stress
Soft and Granular Matter
Technology of polymers
Three dimensional models
Viscous flow
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Summary:Residual stresses are a major issue in the mechanical and optical behavior of injection-molded parts. In this study, we analyze their development in the case of gas-assisted injection molding (GAIM) of amorphous polymers. Flow-induced residual stresses are computed within a decoupled approach, in which elastic effects are neglected in the momentum balance, assuming a generalized Newtonian material behavior. In a staggered procedure, the computed viscous flow kinematics are used to calculate normal stresses employing a compressible version of the Rolie-Poly model. For the computation of thermally and pressure-induced residual stresses, a linear thermo-viscoelastic model is used. A 3-D finite element model for GAIM is employed, which is able to capture the kinematics of the flow front and whose capabilities to predict the thickness of the residual material layer have been validated by Haagh and Van de Vosse (Int J Numer Methods Fluids 28:1355–1369,  1998 ). In order to establish a clear comparison, the development of residual stresses is analyzed using standard injection molding and GAIM for a test geometry.
ISSN:0035-4511
1435-1528
DOI:10.1007/s00397-009-0392-6