INTRODUCTION

Resin Transfer Molding (RTM)
* Resin is injected into the preform through gate(s).
Fill time is directly affected by gate locations.

Multiple gates are needed to reduce fill time

EXHAUSTIVE SEARCH METHOD

Exhaustive search for the minimum fill time scenario is impractical for multiple gate injections
• Liquid Injection Molding Simulation (LIMS) as FE tool
• FE mesh node(s) as the potential gate(s)
• Too many scenarios to be simulated

DISTANCE BASED FILL TIME ESTIMATION

• Fill time is estimated by calculating the distance between gate(s) to the edges of the part

• Euclidean distance cannot be used to estimate fill time for complex geometries. Geodesic distance between two points on the surface is needed.

Geodesic Distance Calculation on the Curved Surface

• Dijkstra’s algorithm used to find the shortest path in a graph is implemented on the FE mesh

DISTANCE DISTRIBUTION v/s RESIN FLOW ARRIVAL TIMES

• Single gate injection for the cut-out plate

• Two-gate injection for the orthotic leg

TWO-GATE INJECTION OPTIMIZATION FOR THE OTHOTIC LEG

• The longest distance for each of the scenario is calculated.
• Theses distances are sorted in increasing order.
• Only the scenarios with smallest distances are selected to perform mold filling simulations in LIMS

CONCLUSIONS

• Distance based method can reflect the flow pattern and the fill time.
• Such fast methods can act as preliminary search method so that a large number of unwanted scenarios can be excluded from the number of cases to be explored.
• The savings are significant when multiple gates are needed in a mold to reduce the filling time.

ACKNOWLEDGEMENTS

This work is supported by the Defense Advanced Research Projects Agency (DARPA) through the Composite Orthotics program.