The BondLib library

The BondLib library is designed as a graphical library for modeling physical systems using the bond graph metaphor, including electriacal, hydraulical, and thermal systems. BondLib implements the methodology of modeling physical systems using bond graphs, a technique that had been developed 1960 at M.I.T. by Henry Paynter.

Bond graphs describe the power flows through a physical system. Since the concepts of energy conservation and power flow continuity are valid for all physical systems, bond graphs may be employed for modeling any and all physical phenomena.

Bond graphs form an intuitively attractive modeling tool that enables its user to understand and explain the dynamics of physical processes clearly and succinctly. For this reason, bond graphs are suitable both as a didactic and also as a highly practical tool for modeling physical systems.

About the bond graph modeling

Bond graphs are described in terms of four basic variables:

1. efforts (e),
2. flows (f),
3. generalized momentums (p), and
4. generalized positions (q).

The four variables are related to each other in the following fashion:

Power is always the product of effort and flow:

P = e*f

The three basic OnePort elements of the bond graph methodology are:

1. resistors (R): e = R(f),
2. capacitors (C): e = C(q), and
3. inductors (I): f = I(p),

where R, C, and I can be arbitrarily non-linear functions operating in the first and third quadrants only.

Bond graphs are domain independent. The four basic variables of a number of physical domains are summarized below:

	Effort	Flow	Generalized Momentum	Generalized Position
	e	f	p	q
Electrical	Voltage u (V)	Current i (A)	Magnetic Flux Φ (Vs)	Charge q (As)
Translational	Force F (N)	Velocity v (m/s)	Momentum M (Ns)	Postion x (m)
Rotational	Torque T (Nm)	Angular Velocity ω (rad/s)	Torsion T (Nm/s)	Angle φ (rad)
Hydraulic	Pressure p (N/m2)	Volume Flow q (m3/s)	Pressure Momentum Γ (Ns/m2)	Volume V (m3)
Chemical	Chem Potential μ (J/mol)	Molar Flow ν (mol/s)	-	Number of Moles n (mol)
Thermodynamic	Temperature T (K)	Entropy Flow S' (W/K)	-	Entropy S (J/K)

Important publications

1. Cellier, F.E. (1991), " Continuous System Modeling", Springer-Verlag, New York, ISBN: 0-387-97502-0, 755p.
2. Cellier, F.E. (1992), " Hierarchical Non-linear Bond Graphs: A Unified Methodology for Modeling Complex Physical Systems", Simulation, 58(4), pp. 230-248.
3. Cellier, F.E. (1995), " Bond Graphs: The Right Choice for Educating Students in Modeling Continuous-time Physical Systems", Simulation, 64(3), pp. 154-159.
4. Cellier, F.E. and R.T. McBride (2003), " Object-oriented Modeling of Complex Physical Systems Using the Dymola Bond-graph Library", Proc. ICBGM'03, 6^th SCS Intl. Conf. on Bond Graph Modeling and Simulation, Orlando, Florida, pp. 157-162.
5. Cellier, F.E. and A. Nebot (2005), " The Modelica Bond Graph Library", Proc. 4^th Modelica Conference, Hamburg, Germany.

Main author

Prof. Dr. François E. Cellier Institut für Computational Science ETH Zürich ETH Zentrum HRS H28 CH-8092 Zürich Switzerland

Phone: +41(1)632-7474 Fax: +41(1)632-1374 Email: FCellier@Inf.ETHZ.CH

License conditions

The BondLib package is free software; it can be redistributed and/or modified under the terms of the Modelica license, see the license conditions and the accompanying disclaimer.

Copyright (C) 2005, François E. Cellier.

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Version 2.2