3 Creating Custom Modeling Components - MapleSim Help

Online Help

All Products    Maple    MapleSim


Home : Support : Online Help : MapleSim : User's Guide : MapleSimUserGuide/Chapter03

Contents     Previous     Next     Index

3 Creating Custom Modeling Components

In this chapter:

• 

Understanding Custom Components

• 

Creating Custom Components with Signal-Flow Behavior

• 

Creating Custom Components with Physical Connections

• 

Working with Custom Components in MapleSim

• 

Example: Creating a Nonlinear Spring-Damper Custom Component

3.3 Creating Custom Components with Physical Connections

When you create custom components based on physical connections, each connection port has two variables associated with it: the across variable and the through variable. The through variable represents a flow of a conserved quantity (such as heat, mass, current, force or torque) and the across variable represents the driving force in a system (temperature difference, pressure difference, voltage drop, velocity or relative angular velocity).

 

Table 3.3: Characteristics of Through and Across Variables

Characteristics of Through Variables

Characteristics of Across Variables

Conserved quantity (like heat or mass)

Has a direction of flow

Satisfies the relationship input = output + accumulation

Uniform across a domain

Drives the flow of the conserved quantity

Is a scalar

Defined as the difference between two points within a physical domain

 

Table 3.4 shows the mathematical relationships defining the connection between various across and through variables.

 

Table 3.4: Through and Across Variable Mathematical Relationship

Domain

Governing Equation

Through Variable

Across Variable

Ohm’s Law

Electrical Domain

I=VR 

I

V

Hagen–Poiseuille equation

Hydraulic Domain

ⅆmⅆ t=πD4ρ128 L μP

ⅆmⅆ t

P

Fourier's law

Thermal Domain

ⅆQⅆ t=hA T

ⅆQⅆ t

T

Deriving the System Equations for a Resistor

Table 3.5 shows a model of a simple resistor with several variables and one parameter.

 

Table 3.5: Resistor Variables and Parameters

Variable

Parameter

Description

i(t)

 

Current

v(t)

 

Voltage difference

vLeft(t)

 

Voltage on the left port

vRight(t)

 

Voltage on the right port

 

R

Resistance

Ohm’s Law defines the relationship between the voltage and the current as

vt=VrighttVleftt

 

vt=it R

 

Figure 3.9 shows the equations mapped to the custom component ports.

Figure 3.9: Resistor Port Mapping

 

The current i(t) on the right port has a negative sign, representing flow out of the resistor. The current on the left port is positive, representing flow into the resistor. The resistance (R) is defined as a parameter available in the Propeties tab ( ).

 

Contents     Previous     Next     Index


Download Help Document

Was this information helpful?



Please add your Comment (Optional)
E-mail Address (Optional)
What is ? This question helps us to combat spam