| dc.description.abstract | In injection molding, the application of mold flow analysis has become more and more popular. In mold flow analysis, a computer aided design (CAD) model must be converted into sloid meshes so that the solver can perform the required analysis. Thin-shell plastic parts are very common in injection molding. A thin shell part generally involves a thin shell and protrusion features on its inside. Tetrahedral meshes are conventionally used for thin-shell parts owing to the ease for automatic generation and applicability for complex models. Recently, with the increasing on the accuracy requirement, it is getting popular to employ prismatic and hexahedral meshes in mold flow analysis. However, generating prismatic and hexahedral meshes requires the generation of assistant planes and the splitting of the model, which are typically done manually. The purpose of this study is to develop feature recognition and feature decomposition algorithms for thin-shell plastic parts for automating the construction of prismatic and hexahedral meshes. The proposed recognition algorithm includes hole and protrusion recognition. The protrusion features can be divided into the following types: rib, tube, column and symmetric extrusion. In the proposed algorithm, firstly, some pre-processing data and basic features (such as fillet and loop) must be computed. Then, holes and protrusion features are recognized by using the pre-processing data, fillets and loop data. In feature decomposition, feature regions are computed by using the data from various types of protrusion features. A feature region is essentially composed of multiple closed contours. An individual decomposition algorithm is developed for each type of protrusion features to yield the closed contours corresponding to each feature region. The primary contributions of this study are: firstly, various types of features are recognized, including hole, rib, tube, column and symmetrical feature. The composition faces, boundary conditions and related features for each of them are recorded. Secondly, several decomposition algorithms are developed to decompose protrusion features into feature regions, each of which is regular in shape and can be meshed with structured-type mesh. Multiple closed contours of each feature region and the topological data of these contours on the CAD model are also recorded. | en_US |