RecurDyn Virtual Lab 2: Simple Pendulum

Problem

AB is a uniform bar with a mass of 2 kg and a length of 450 mm. Bar AB swings in a vertical plane about the pivot at A. The angular velocity (theta dot) = 3 rad/s when theta = 30 degrees. Compute the force supported by the pin at A at that instant.

Theoretical Solution

Total reaction force is 14.4926 N.

If you want to know more information of this process.please reading the attachment file of this article.

RecurDyn Virtual Lab 1: Spring-Mass Model

Problem

A 10-kg cylinder is released from rest with x=1 m, where the spring is not stretched. Determine the following:

(a) Maximum velocity v of the cylinder and the corresponding value of x (a)

(b) Maximum value of x during the motion (b)

The stiffness of the spring is 450 N/m.

Theoretical Solution

(a) maximum v=1.4619 m/s occurring at x=1.2179 m

(b) maximum x=1.4358 m

RecurDyn Solution

To start RecurDyn and create a model:

1. 1. On your Desktop, double-click the RecurDyn tool.
2. 2. Create a new model:

• Units: mks
• Gravity: -Y

To create the cylinder part (10 kg):

1. 1. From the Toolkit bar, click the Cylinder tool.
2. 2. Select centers of the two ends of the cylinder as (0,0.9,0) and (0,1.1,0) so the center of the cylinder is exactly 1 m away from the origin in the –y direction.
3. 3. Double-click the cylinder to enter the Body edit mode. Then, right-click the cylinder and click Properties.
4. 4. Change the radius to 0.05 m.
5. 5. Exit Body edit mode.
6. 1. Right-click the cylinder and select Properties.
7. 2. Set Material Input Type to User Input.
8. 3. Change Mass to 10 kg. Because the cylinder will not be rotating, the moments of inertia can remain unchanged.
9. 1. From the Force menu, choose Spring.
10. 2. Using the default creation method (Point, Point), select the origin and then the center of the cylinder.

To change the mass to 10 kg:

To create a spring part (spring-damper, k=450 N/m, no damping):

1. 1. Right-click the spring and select Properties to set the spring constant and the damping coefficient as shown in the dialog box on the right.
2. 2. Click OK.
3. 1. From the Analysis menu, choose Dynamic/Kinematic.
4. 2. Turn off numerical damping by clicking the Parameters tab, and setting the numerical damping coefficient to 0.
5. 3. Click the General tab and change the Plot Multiplier Step Factor to 10.
6. 4. Run the simulation by clicking Simulate.

To run an analysis:

RecurDyn prompts you to save your file if you have not already done so.

To create plots and determine velocity and distance:

1. Enter the plotting environment by clicking the Plot Result tool.
2. In the Database window, expand Body1 and double-click Pos_TY and Vel_TY to plot the position and velocity in the y-direction.
3. Select the Trace Data tool to find the point at which the maximum velocity occurs (frame 347, 1.4622 m/s). Then, find the position that corresponds to that velocity (1.2175 m). You can also see that the maximum displacement is 1.4359 m.

If you would like to increase the precision of the plots, you can increase the number of steps, as well as the plot multiplier factor.

Comparison of Results

Results are summarized in the following table: