Finite Element Analysis of Solidification in Rapid Freeze Prototyping

Rapid freeze prototyping (RFP) can generate three-dimensional ice patterns from computer-aided design (CAD) models by depositing and solidifying water droplets layer by layer. One important issue of the RFP process is how to fabricate the ice pattern to desired accuracy in an acceptable short time. The waiting time between two successive layers is a critical factor. A waiting time that is too short will lead to unacceptable part accuracy, while a waiting time that is too long will lead to an excessive build time. Finite element analysis is employed in this study to predict the solidification time of a newly deposited water layer and to develop a better understanding of heat transfer during the RFP process. ANSYS Parametric Development Language (APDL) is utilized to develop software for the prediction of solidification time. The result is used to investigate the effect of various process parameters on the solidification time of an ice column and a vertical ice wall. These parameters include environment temperature, heat convection coefficient, initial water droplet temperature, layer thickness, and waiting time between two successive layers. Experiments are conducted and the measured results are shown to agree well with simulation results.

[1]  R. Kovacevic,et al.  Effect of Volume of Heat Sink on Process and Physical Properties of Parts Built by Welding Based SFF , 2002 .

[2]  Ming-Chuan Leu,et al.  Study of Part Geometric Features and Support Materials in Rapid Freeze Prototyping , 2003 .

[3]  Sun Sheng,et al.  Preform design in axisymmetric forging by a new FEM-UBET method , 1998 .

[4]  Kumar K. Tamma,et al.  Recent advances, trends and new perspectives via enthalpy-based finite element formulations for applications to solidification problems , 1990 .

[5]  Gabriel Bugeda Miguel Cervera,et al.  Numerical prediction of temperature and density distributions in selective laser sintering processes , 1999 .

[6]  F. Niebling,et al.  Analyzing the DMLS Process by a Macroscopic FE-Model , 2002 .

[7]  Cristina H. Amon,et al.  Molten droplet solidification and substrate remelting in microcasting Part II: Parametric study and effect of dissimilar materials , 1999 .

[8]  Cristina H. Amon,et al.  Successive Deposition of Metals in Solid Freeform Fabrication Processes, Part 1: Thermomechanical Models of Layers and Droplet Columns , 2001 .

[9]  Dimos Poulikakos,et al.  An Experimental Study of Molten Microdroplet Surface Deposition and Solidification: Transient Behavior and Wetting Angle Dynamics , 2000 .

[10]  Ming-Chuan Leu,et al.  Investigation of Layer Thickness and Surface Roughness in Rapid Freeze Prototyping , 2003 .

[11]  R. Kovacevic,et al.  Process Control of3D Welding as a Droplet-Based Rapid Prototyping Technique , 1998 .

[12]  Fritz B. Prinz,et al.  Numerical and Experimental Investigation of Interface Bonding Via Substrate Remelting of an Impinging Molten Metal Droplet , 1996 .

[13]  Von Richards,et al.  Dimensional accuracy and surface roughness of rapid freeze prototyping ice patterns and investment casting metal parts , 2004 .

[14]  Yang He,et al.  Coupled thermo-mechanical analysis of the high-speed hot-forging process , 1997 .

[15]  Ming C. Leu,et al.  Experimental study on the ice pattern fabrication for the investment casting by rapid freeze prototyping (RFP) , 2002, Comput. Ind..

[16]  M. B. Hsu,et al.  A Finite Element Model of Multi-Layered Laser Sintered Parts , 1991 .

[17]  Stephen C. Danforth,et al.  A Phenomenological Numerical Model For Fused Deposition Processing of Particle Filled Parts , 1995 .

[18]  T. C. Tszeng,et al.  Thermal analysis of solidification by the temperature recovery method , 1989 .

[19]  K. Osakada,et al.  Finite element analysis of melting and solidifying processes in laser rapid prototyping of metallic powders , 1999 .

[20]  K. Osakada,et al.  Finite element analysis of single layer forming on metallic powder bed in rapid prototyping by selective laser processing , 2002 .

[21]  S. Schiaffino,et al.  Molten droplet deposition and solidification at low Weber numbers , 1997 .

[22]  Minglei Sun,et al.  A Three Dimensional Model for Selective Laser Sintering , 1991 .

[23]  Cristina H. Amon,et al.  Successive Deposition of Metals in Solid Freeform Fabrication Processes, Part 2: Thermomechanical Models of Adjacent Droplets , 2001 .