Requirement change management is a challenging issue in software development. One of the main objectives of the Intent-Defined Adaptive Software program is to verify the satisfaction of requirement changes during software development. In this paper, we develop an ontology-based method to detect inconsistencies in Systems Modeling Language (SysML) models with Object Constraint Language (OCL) constraints as a first step of requirement change management. Specifically, we map the SysML/OCL models to Web Ontology Language (OWL), so that the consistency of the corresponding ontology can be checked by OWL reasoners automatically. We propose a set of mapping rules to interpret the components of SysML state machine diagrams, along with OCL constraints, to OWL. Toward this objective, we demonstrate three consistency reasoning tasks over a state machine diagram using OWL reasoners. In each case, the result of reasoning is accompanied by an explanation of the logic behind the decision.