Computer modeling of engineering systems with a large number of interconnected multi degree of freedom (DOF) subsystems requires flexible modeling tools. Flexible modeling tools with arbitrary input-output structure formulate equations to fit the input-output structure of specific engineering systems at the cost of globally reformulating equations with every model change. Each equation formulation requires performance verification. This can be particularly cumbersome in large models. In previous work Byam and Radcliffe  designed modular modeling, a flexible modeling method that eliminates equation reformulation and enhances experimental model performance verification in large models. A fixed input-output structure for all multi DOF modular modeling elements eliminates equation reformulation. The cost is a connector to assemble elements adding complexity to the global model. Modular modeling analysis is a systematic realization of compatible standardized modular elements and connectors. Structural and automotive examples are given.