Sub-structuring non-linear dynamic systems in the time domain

This paper presents a sub-structuring method which is simple and quite general, for modelling non-linear dynamic systems in the time domain. Hence ease of program writing and wide applicability are seen as the main advantages of the method. The method is based on the systems approach as used in vibration analysis type applications. It is particularly applicable to thermal type systems due to their diverse but modular nature. After developing the mathematical basis and the equations required, the method is applied to the simulation of a storage tank cool-down. The results are compared with those provided by first and fifth order numerical methods. In its present form, it is found to be nearly second order accurate.