Efficient calculation of trapped volumes in the layered manufacturing process

Prototypes of a design are always needed for the purposes of visualisation and evaluation for manufacturability, functionality, and aesthetic appearan ce. Since the prototyping process requires a significant amount of cost and time, various rapid prototyping processes have recently been introduced. H owever, it is usually necessary for a part built up by a rapid prototyping system to be finished by a post-processing process, in which the stair step s on the surfaces, the support structures (if they exist), and the unproces sed material are eliminated. This post-processing is usually done manually and is a time-consuming task. Eliminating the trapped volumes (the volume o f the unprocessed material entrapped by the solidified portion) is sometime s impossible in some processes. this study provides a designer with a tool to detect the existence of trapp ed volumes and to calculate the quantity in a given build-up direction, so that a suitable build-up direction is chosen or the part is built in pieces to avoid the problems caused by the trapped volumes. Since the proposed al gorithm can efficiently calculate the amount of the trapped volumes in any build-up direction, it has the potential for such applications as optimisin g the build-up direction to minimise the trapped volumes.