Temperature-dependent anisotropic material modeling of the sheet metal component within the polymer injection forming process
In the course of this work, an extended material model for a carbon steel sheet metal has been developed based on Hill’48 yield criterion, considering temperature-dependent plastic anisotropy coefficients. This material model is applied on a polymer injection forming process in which the sheet metal heats up to a critical forming temperature through the contact with the plastic melt. At this temperature range blue brittleness occurs. The elastic properties, the yield stress as well as the plastic anisotropy coefficients of the sheet material become significantly different compared to those at room temperature. It should be emphasized that especially temperature-dependent anisotropy coefficients are not yet considered in most common material models. With the help of the presented modelling approach a more precise modelling of the temperature-dependent carbon steel material behavior can be realised.
Polymer Injection Forming: A New Age Technology for Manufacturing Polymer-Metal Hybrids
.................................................................................................................................................. ii DEDICATIONS .............................................................................................................................................. v ACKNOWLEDGMENTS ................................................................................................................................ vi LIST OF TABLES ............................................................................................................................................ x LIST OF FIGURES ......................................................................................................................................... xi 1. MOTIVATION AND INTRODUCTION ........................................................................... 1 1.1 Multi‐material design and hybrid components .................................................................... 1 1.2 Metal‐polymer hybrid technology ...................................................................................... 4 1.3 Introduction of Polymer Injection Forming (PIF) as a hybrid manufacturing system ............. 8 2. LITERATURE REVIEW AND RESEARCH GAPS ...................................................... 12 2.1 Similar processes .............................................................................................................. 12 2.2 Experimental investigations .............................................................................................. 17 2.3 Approaches to modeling of PIF ......................................................................................... 19 2.4 Practical challenges ahead of industrial application .......................................................... 22 2.5 Summary of research gaps ................................................................................................ 24 3. AIMS AND ORGANIZATION OF THE WORK ........................................................... 26 4. EXPERIMENTAL CONFIGURATION TO STUDY PIF PROCESS .......................... 29 4.1 Experimental setup .......................................................................................................... 29 4.2 Processed Materials ......................................................................................................... 36 4.3. Specimens preparation and measurement ....................................................................... 39 5. INVESTIGATION ON THE EFFECT OF BLANK HOLDER FORCE AND ITS INTERACTION WITH INJECTION RATE ...................................................................... 43
New Linearized Relation for the Universal Viscosity−Temperature Behavior of Polymer Melts
The temperature dependence of zero-shear viscosity (η) or terminal flow relaxation time (τ) is one of the most fundamental properties of polymer melts.1 Generally, the viscosity-temperature behavior is divided in two regions, although Ngai and Plazek2 have proposed four groups of relaxation mechanisms above the glass transition temperature Tg in the coupling model. Each region is described by semiempirical functions involving two or three adjustable parameters (whose physical significance is not always clear). The first region is located at temperatures well above Tg, i.e., Tg + 100 °C or ∼ 1.3Tg, and follows a simple Arrhenius equation: