The Math FB can use data that is available at the output-connectors of other FBs.

You can use the Math FB to do:

Simple Algebra

For example: 2+3. The output will be 5, of course.

Parametric Constants

For example, connect the output of a Motion-Dimension FB of a Crank and the output of a Force-Data FB of the same Joint. You can use the Math FB to multiply the Torque(Nm) and the Velocity(rad/sec) values to give the Power(kW) as the output.

Top-Tip: Connect a Gearing FB to the input of a Math FB. You can edit the Gearing FB, so that it becomes a parametric-constant of an equation in the Math FB, for example, a Friction Coefficient.

Change the Units of a Variable

For example, change the units at the input-connector of a Math FB to different units at its output-connector - for example: mm to Newtons.

Add a Math FB:

The Math FB is now in the graphic-area

Open a Math FB dialog-box

The Math FB dialog-box is now open

The format of a variable in an equation is: Data-Channel (Wire-Number)

Three wires connected to the input of a Math FB

The image above shows three(3) Wires connected to input-connectors of a Math FB.

Wire-Numbers - IMPORTANT : Wire-Numbers start at 0

Data-Channel

Example Entries in an Equation:

By way of an example we will calculate Power :

P =  Ʈ . ω

Power (N.m./sec) = Torque(N.m.) × Angular Velocity (rad/sec)

Torque data and Angular-Velocity data are the inputs and Power is the output.

Thus, you need two input-connectors and one output-connector.

We get Torque data from a Force-Data FB.

We get Angular-Velocity data from a Motion-Dimension FB.

Prepare the model:

1.Add a Rocker - see Tutorial 1

2.Edit the CAD-Line of the Rocker, to open the CAD-Line dialog-box.

In Mass Properties tab > User Mass Properties .
Enter a value for the Mass

In Mass Properties tab > User Mass Properties .
Enter X and Y values to move the Mass from the start-Point of the CAD-Line.

We will not enter a value for the Inertia or Radius of Gyration. This makes the mass a Point Mass - the mass of the Rocker is reduced to a particle.

3.Add a Force-Data FB, open the Force-Data FB dialog-box, select the Pin-Joint, and select the Point in the Base-Part to find the Torque that acts-on the Base-Part.

See image above - the Wires and Data-Channels of the Force-Data FB and the Motion-Dimension FB

Prepare the Math FB:

1.Open the Math FB dialog-box:

2.Add two Input-Connectors with the Add-Input button

3.Select Power for the Output Data Type.

4.Click UPDATE button after we select the Output Data Type and before we add equations.

5.Enter the Equations to calculate Power.

The Math FB uses SI units for all data at its input-connectors

The equation in the Math FB is:

×

p(0)*v(1)

Wire-Number 0 (top), Channel 1 (p = Torque) × Wire-Number 1 (bottom wire), Channel 2 (v = Angular Velocity)

SYNTAX and VALID Equations:

Click the Update after you edit the equation to find if its syntax is correct or not correct.

For example, the syntax is not correct if it does not have the correct number of parentheses. The reason is given as a message in the Feedback-Area.

The at the left of each equation shows whether its syntax is correct.