Residual Stress and Warpage Models for Complex Injection Molded Parts
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W.-B. Young
Abstract
In the postfilling stage of an injection molding process, thermal induced residual stress usually develops during the solidification of the melt with non-uniform through thickness temperature distribution. Furthermore, the packing pressure is applied through the gate, and will be different in different locations. Since the local melt pressure varies with time due to the change of melt viscosity, the material solidifies under different frozen-in pressure. The stress relaxation behavior of the plastic materials also complicates the stress field. This study uses a simple thermoviscoelastic model to calculate the residual stress developed in the postfilling stage and a elastic model to determine the warpage after demolding for three dimensional complex parts. Based on the calculation of the injection molding process, the temperature and pressure histories in the postfilling stage can be determined, and used to calculate the developed stress field. The model divides the thickness into two regions, liquid and solid phases. Residual stress calculation is applied in the solid region, while the liquid region is kept at the melt pressure without any strain. The resulted in-mold stress fields are used to calculate the part warpage after demolding.
© 2002, Carl Hanser Verlag, Munich
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- Editorial
- Touchstones of Polymer Processing
- Twin Screw Extrusion and Compounding
- Residence Time Distribution Curves of Screw Elements in Twin-Srew Extruder
- Rheological Effect of Zinc Surfactant on the TESPT-Silica Mixture in NR and S-SBR Compounds
- Optimization of Processing Conditions for Polymer Twin-Screw Extrusion
- Fibers and Film
- The Prediction of Sharkskin Instability Observed during Film Blowing
- Tensile Strength Characteristics of Polymer Melts
- Biaxially Oriented PP Films Using the Double Bubble Process
- Fiber and Film
- Crystallization and Orientation Development in Melt Spinning Isotactic PP of Varying Tacticity
- Extrusion Coating
- Extrusion Coating with Metallocene-Catalysed Polyethylenes
- Injection Molding
- Design Sensitivity Analysis Applied to Injection Molding for Optimization of Gate Location and Injection Pressure
- Three-dimensional Numerical Modeling of Co-injection Molding
- Residual Stress and Warpage Models for Complex Injection Molded Parts
- Blow Molding
- Investigation of Design Parameters and Novel Design of Petaloid PET Bottles
Articles in the same Issue
- Editorial
- Touchstones of Polymer Processing
- Twin Screw Extrusion and Compounding
- Residence Time Distribution Curves of Screw Elements in Twin-Srew Extruder
- Rheological Effect of Zinc Surfactant on the TESPT-Silica Mixture in NR and S-SBR Compounds
- Optimization of Processing Conditions for Polymer Twin-Screw Extrusion
- Fibers and Film
- The Prediction of Sharkskin Instability Observed during Film Blowing
- Tensile Strength Characteristics of Polymer Melts
- Biaxially Oriented PP Films Using the Double Bubble Process
- Fiber and Film
- Crystallization and Orientation Development in Melt Spinning Isotactic PP of Varying Tacticity
- Extrusion Coating
- Extrusion Coating with Metallocene-Catalysed Polyethylenes
- Injection Molding
- Design Sensitivity Analysis Applied to Injection Molding for Optimization of Gate Location and Injection Pressure
- Three-dimensional Numerical Modeling of Co-injection Molding
- Residual Stress and Warpage Models for Complex Injection Molded Parts
- Blow Molding
- Investigation of Design Parameters and Novel Design of Petaloid PET Bottles
