Numerical analysis of stereolithography processes using the finite element method

Int J Adv Manuf Technol

Lan

2005

The rapid prototyping (RP) process is the fastest and most feasible method for prototype construction. However, with the use of any material or build method the phenomenon of volume shrinkage is unavoidable. It is known that volume shrinkage and curl distortion are the major causes that lead to poor accuracy of the built prototype. Subsequently, in order to improve the precision of dimension and volume shrinkage, more expensive equipment is used on the market. Also, it is expensive and inefficient to obtain better process parameters through trail and error in the RP process. In order to improve the precision of dimension, reduce the processing cost and the frequency of trail and error, this study first induces the concept of computeraided engineering (CAE) into the processing of RP, which uses a dynamic finite element simulation code to simulate the photopolymerization process, so as to reduce the time for selecting the processing parameters and obtain the distortion data. Second, by means of reverse distortion compensation to obtain a new CAD model, then it is sent to a RP machine for the actual prototyping processes, so as to obtain a more accurate precision. Finally, in order to confirm this method and restriction in experimental equipment, the stereolithography process and simple laser scanning path are chosen as examples. The results of the simulation and experiment prove that the method proposed herein is effective. It not only can reduce the cost of equipment but also obtain a better precision of dimension on final-parts at the same time. Besides, it is believed that this research method can be promoted to other materials or build methods in RP fabrication.

Section: Introductionmentioning

confidence: 99%

Compensation of distortion in the bottom exposure of stereolithography process

Int J Adv Manuf Technol

Lan

2005

“…Wiedemann et al [6] showed how the interaction between reexposed solidified resin and curing resin can influence part distortion. To simulate the deformation of a built part, Bugeda et al [7] applied the finite element method to analyse the distortion that is caused by the shrinkage effect. They used a linear elastic model with a constant Young modulus and Poisson ratio.…”

Section: Introductionmentioning

confidence: 99%

Fundamental study and theoretical analysis in a constrained-surface stereolithography system

Int J Adv Manuf Technol

Kuriyama²,

Jiang

2004

Stereolithography (SL) technology can be classified into two types, free-surface and the constrainsurface SL systems. Constrain-surface stereolithography (SL) systems have the advantages of resin savings, reduced cost and better layer thickness control. However, the material properties of the curing process and the fabrication parameters need to be determined and optimal process parameters should be found using numerical analysis in order to eliminate trial and error. This paper reports some fundamental experiments that have been conducted in order to explore the curing properties of the resin NAF202 in an E-DARTS system. In addition, a theoretical analysis of the photopolymer curing process in the E-DARTS system has been proposed. A dynamic finite element simulation code with weight function was developed to model the point-bypoint curing process in a constraine-surface SL system. A simple implementation to evaluate the developed program is presented, indicating that the proposed program can simulate the shrinkage analysis in accordance with path planning.

“…In 1995, two three-dimensional finite element method (FEM) simulation computer programs [4,6] were developed. Both of them were based on the same mathematical model.…”

Section: Introductionmentioning

confidence: 99%

Curl Distortion Analysis During Photopolymerisation of Stereolithography Using Dynamic Finite Element Method

The International Journal of Advanced Manufacturing Technology

Jiang

2003

Stereolithography is one of the rapid prototyping processes which uses a photopolymer as the raw material to build prototypes. The photopolymer absorbs energy by selective laser exposure. The curing effect starts when the absorbing energy exceeds a critical value, and the process is called photopolymerisation. The photopolymerisation changes the phase from liquid to solid. The cured volume can expand and then shrink on cooling. The process parameters such as the scanning speed, scanning path, scanning pitch, and the slicing thickness, lead to different shrinkage and curl distortion, so, the photopolymerisation process is a dynamic material behaviour. In this study, a dynamic finite element simulation code has been developed to simulate the photopolymerisation process. The simulated result for a suspended beam which corresponds to the process parameters shows that a short raster causes less curl distortion than a long raster. The experimental result agrees very well with the simulated result.