Being able to showcase how different physics interact with each other in a single system is a difficult thing. Indeed, each sub-system representing a specific physics (hydraulic, pneumatic, mechanic, electrical, thermal, electromechanical,…) has different properties and inner specificities which make a dynamic & multi-physics behavior complex to understand. Nevertheless, by taking a step back, we can realize that all those physics share a common base which is – whatever the habits, conventions, notations, and units of measurement used – the energy/power balance & transfer between the constitutive elements of the system. Establishing analogies between those physics, from an energetic point of view, allow to unify the modeling approach as well the analysis for all of them, with a common language.
This is an existing approach known as the bond graph. It is a graphical tool for displaying multi-physics system interactions. This practical approach enables to model and understand the energy transfer between the inner components of the system, as well as the energy storage, dissipation and modulation leading to the dynamics of the system, whatever the underlying physics.
Several software, like Simcenter Amesim, are designed using the concepts of the bond graph, like the energy transfer/storage/dissipation core component definition, as well as the acausal and/or causal modeling approaches to further generate the equation set of the model for simulation.
In this article, we aim at walking you through the basics of that theory: chose to either go step by step, playing chapters one after the other or listen to the complete video version hereunder:
The basic definition of bond graph & Brush up about all concepts
The origins of bond graph and history
The six native elements in the bond graph representation, and example
The bond graph causality advanced concept
To find out references used by Julien Lagnier to build that podcast, as well as website useful link to go further into your learning practice, click on the attachment.
More about the author:
Julien Lagnier is product manager for the Vehicle System Dynamics solution in Simcenter Amesim at Siemens Digital Industries Software, recently graduated with a PhD in Mechatronics (2017) from the University of Lyon and INSA Lyon, in bond graph theory, modeling, controls, and vehicle dynamics.