DM312: Lecture 4 More on Bond Graphs

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32 Questions

What type of energy transformation occurs in the electric motor domain of the gyrator?

Electric to Mechanical rotation

Give an example of a domain that involves the transformation from hydraulic energy to mechanical rotation in a gyrator.

Wind turbine

What is the difference between a Transformer and a Gyrator?

Power transformation in a gyrator is irreversible

What are multi-port elements in Bond Graphs also known as?

Three-Port

What does the causal stroke indicate in the bond graph?

The direction in which the effort signal is directed

What do I elements in the bond graph receive and generate?

Receive effort and generate flow

What type of causal structure can resistive (or dissipative) R elements have?

Any type of causal structure

Define the term 'transformer ratio' as used in the context of Bond graphs.

The transformer ratio, denoted by 𝜆, represents the ratio of the primary and secondary voltages in a transformer.

What is the role of a gyrator in a Bond graph system? Explain using the gyrator ratio.

A gyrator in a Bond graph system helps to model a mechanical system element that behaves like an electrical network. The gyrator ratio, denoted by 𝑘, represents the ratio of mechanical effort variables to mechanical flow variables.

What are the key system variables mentioned in the context of the numerical solution of Bond graphs?

The key system variables mentioned are TF (transformer ratio), GY (gyrator ratio), R (resistive causality), and I (moment of inertia).

How does the model of the system using Bond graphs allow visualization of the system performance?

The model allows visualization of how variables are related and how the system performs.

Explain the difference between resistive causality and conductive causality in the context of Bond graphs.

Resistive causality represents the flow of effort (voltage or force) causing the flow of energy, while conductive causality represents the flow of energy causing the flow of effort.

How are junctions in the bond graphs described in terms of effort and flow transmission?

Junctions will transmit common effort and sum flow (0) or transmit common flow and sum effort (1).

What is the steady-state solution assumption for the system?

The steady-state solution assumes that I is unlimited by an 'ideal' source.

What are the key components of a two-port element bond graph?

Effort and flow

Explain the energy variable function in the context of bond graphs.

Energy variable function represents Effort (Se) and Flow (Sf) in the Energy Domain

What is the role of a transformer in the context of bond graphs?

Converts electrical power to desired voltage and current

Define the function of a gyrator in a bond graph system.

It transfers energy from one domain to another with inertia and friction losses, while also converting flow to effort.

Explain the causal structure of resistive (or dissipative) R elements in bond graphs.

Resistive elements have effort as the cause and flow as the effect

What is the steady-state solution assumption for the system?

The steady-state solution assumption for the system assumes that the input is unlimited by an 'ideal' source.

Explain the difference between resistive causality and conductive causality in the context of Bond graphs.

Resistive causality represents a cause-and-effect relationship between effort and flow, while conductive causality represents a cause-and-effect relationship between flow and effort.

What are the key system variables mentioned in the context of the numerical solution of Bond graphs?

The key system variables mentioned are TF (transformer ratio), GY (gyrator ratio), R (resistance), and I (inertia).

What are 5 examples of gyrators?

Electric motor, Generator (diesel) Electric Centrifugal pump, Wind turbine, Piston pump

In 0 junctions, what does the effort equal, and what does the flow equal

• Equality of effort: e1 = e2 = e3 = e4 • Flow sums to zero: f1 + f2 + f3 + f4 = 0

In 1 junctions, what does the effort equal, and what does the flow equal

Equality of flow: f1 = f2 = f3 = f4 • Effort sums to zero: e1 + e2 + e3 + e4 = 0

In junctions, describe the notation of arrows

• + / - sign depends on direction of arrow • + means arrow pointing to port • - means arrow pointing away from port

Explain what causality means in bond graphs

• Establishes cause and effect relationships between factors of power. • The inputs are characterised by the causal stroke. • Causal stroke indicates the direction in which the effort signal is directed. • Flow directed in opposite direction to causal stroke

Explain causality for flow and how its represented

Flow is the output of system A and effort is the output of system B. This is represented by a half arrow on the top with a vertical black bar at the base of the arrow.

Explain causality for effort and how its represented

Effort is the output of system A and flow is the output of system B. This is represented by a half arrow on the top with a vertical black bar at the tip of the arrow.

Explain causality for I elements

I elements are storage elements. They Receives effort (cause) and generates flow (effect)

Explain causality for C elements

C element (storage element) Receives flow and generates effort

Explain causality for R elements

• Resistive (or dissipative) R elements can have any type of causal structure

Study Notes

  • The text discusses the use of gyrators in different energy domains and the comparison between gyrators and transformers.
  • Gyrators are two-port elements that conserve power and are reversible. They are used to transfer energy between different domains.
  • In the electric motor domain, gyrators are used for electric to mechanical rotation, such as in a wind turbine.
  • In the hydraulic domain, gyrators are used for hydraulic to mechanical rotation, like in a hydrostatic pump.
  • The difference between gyrators and transformers lies in their power transformation, which is irreversible in transformers but not in gyrators.
  • Bond graphs are used to represent and analyze systems with multiple energy domains.
  • Multi-port elements, including gyrators and transformers, can have different causal structures.
  • Bond graph equations define the relationships between variables and elements in a system.
  • The text provides examples of bond graph representations for various energy systems, including a gear box and a hydro-electric power plant.
  • The text also discusses the importance of understanding causality in bond graph analysis and the numerical solution of bond graphs.
  • The text is from a lecture on bond graph guided functional design bond graph theory and applications in mechatronic systems.
  • The lecture covers topics such as two-port elements, bond graphs, causality, and numerical solution of bond graphs.
  • The text includes recaps from previous weeks on hydraulic and electrical systems and their energy variables and functions.
  • The text provides descriptions of energy variables and their functions in different energy domains, including hydraulic, mechanical, and electrical domains.
  • Transformers are mentioned as an example of two-port elements in different energy domains, with their symbols and equations defined.
  • The text discusses the importance of understanding the causality of energy variables in bond graph analysis and the equations that define bond graph elements.
  • The text includes examples of bond graph representations for different energy systems, such as a gear box and a hydro-electric power plant.
  • The text discusses the importance of understanding the numerical solution of bond graphs to determine the system's performance and provides examples of numerical solutions for different systems.
  • The text mentions a tutorial on defining bond graphs for mechatronic systems and the importance of self-study and revision of the material covered in the previous weeks.

Test your knowledge of bond graph system equations, resistive and conductive causality, and numerical solutions. This quiz covers the definitions and relationships of bond graph elements, such as transformers and gyrators.

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