The objective of the research work is to develop a product model which is applicable to represent shapes, structures and attributes of mechanical assemblies based on the STEP. In particular, emphasis is given to establishment of a data structure to represent hierarchical relations and connecting relations among the assemblies, sub-assemblies and parts.
A data structure of the product model was proposed to describe the mechanical assemblies. The data structure developed here consists of the entities defined in the STEP and the entities newly proposed to represent the hierarchical relations and the connecting relations among the mechanical assemblies. A prototype of the product modeling system has been developed to input the product model data and to transfer the product model data to the model data for dynamic kinematic analysis.