Knowledge intensive engineering aims at flexible applications of a variety of product life cycle knowledge, such as design, manufacturing, operations, maintenance, and recycling. Many engineering domain theories are organized and embedded within CAD and CAE tools and engineering activities can be formalized as modeling operations to them. Since most of domain theories deal with the physical world and can be associated with physical concepts, a physical concept ontology can form a common ontology to integrate engineering models that are formed based on domain theories. This paper reports a physical ontology-based support system for knowledge intensive engineering called Knowledge Intensive Engineering Framework (KIEF) to integrate multiple engineering models and to allow more flexible use of them. First, the paper describes the physical ontology as the core of KIEF and an ontology-based reasoning system, called a pluggable metamodel mechanism, to integrate and maintain relationships am...