Problem: Using MD ADAMS, Find the initial force supported by the pin at A for a bar that swings in a vertical plane, given the initial angular displacement and initial angular velocity. Also, find the pendulum frequency. Note: If you need assistance on a step, just click on it for more information. Note: Click on images to enlarge.

1) Click on Create a new model.

2) Under Start in, browse to the folder where you want to save your model.

3) Type the name of the new Model name as pendulum and click OK.

4) Make sure that the Gravity is set to Earth Normal (-Global Y) and the Units is set to MMKS - mm,kg,N,s,deg.

1) From the ribbon Bodies select the RigidBody: Link icon.

2) Then select New Part and under Length, enter 450 mm, under Width, enter 20 mm, and under Depth, enter 27.5 mm. Make sure the Length, Width, and Depth boxes are checked.

3) Click on the origin on the working grid to place the pendulum at 0,0,0.

4) Right-click anywhere on the working grid and a small window will appear in the bottom left corner of the window, this is called the Location Event window. In the Location Event window, enter 450,0,0 as the other endpoint and click Apply.

1) From the ribbon Bodies select the RigidBody: Sphere icon.

2) Make sure Add To Part is selected and enter 25 mm for the Radius.

3) Then select PART_2, the link, as the part you are going to add the sphere to.

4) Then, in the Location Event window enter 450,0,0 as the center of the sphere and click Apply .

1) Right-click on the link and point to Part:PART_2 and then select Rename.

2) In the New Name text box, enter .pendulum.pendulum, and then click OK.

1) Right-click on the stone and go to Part: pendulum and then select Modify.

2) Set Define Mass by to User Input and in the Mass text box, enter 2.0. In the Inertia text boxes (Ix, Iyy, Izz), enter 0.

3) Then, right-click the Center of Mass Marker text box, and go to pendulum.pendulum.cm and then go to Modify.

4) In the Location box, enter 450,0,0, then click OK and OK. If you get a warning message about the change in position of your center of mass marker, simply ignore it and click Close.

1) From the ribbon Connectors select Create a Revolute Joint.

2) In the container, select 2 Bod-1 Loc and Normal to Grid.

3) Select the pendulum as the first body.

4) The ground as the second body.

5) Then select 0,0,0 as the location in the Location Event Window and click Apply.

6) Right-click on the joint and go to Joint:JOINT_1 and then select Rename.

7) In the New Name text box, enter .pendulum.pivot, and then click Apply and OK.

1) Right-click on the pivot joint, and go to Joint:pivot, and then select Measure.

2) In the box, where it says Measure Name, enter pivot_force_x. Set Characteristic to Force, and select X as the Component. Make sure .pendulum.MARKER_5 and Create Strip Chart are selected, and click Apply and Cancel.

3) Again in the box, where it says Measure Name, enter pivot_force_y. Set Characteristic to Force, and select Y as the Component. Make sure .pendulum.MARKER_5 and Create Strip Chart are selected, and click Apply and Cancel.

1) From the ribbon Bodies select Construction Geometry: Marker.

2) Make sure Add to Ground and Global XY are selected, and using the mouse or Location Event select 450,0,0 as the marker location.

3) With the marker selected, go to Edit and select Rename.

4) In the New Name text box, enter .pendulum.ground.angle_ref, and then click Apply and OK.

1) From the Design Exploration menu, go to Measure and then go to Angle and select New.

2) In the Measure Name text box, enter pend_angle.

3) Then, right-click the First Marker text box, and go to Marker, and then go to Pick.

4) Go to the working grid, and pick a marker that is on the pendulum, which is also located at its end, for example, select the cm marker.

5) Right-click the Middle Marker text box, go to Marker, and then go to Pick.

6) Then, pick a marker that is at the location of the pivot.

7) Right-click the Last Marker text box, go to Marker, and then go to Pick.

8) Pick the marker that is on the ground and at the end of the pendulum, the marker that you just created in the previous step, .pendulum.ground.angle_ref. Then click Apply and Cancel.

1) Right-click on the pivot joint, and go to Joint:pivot, and then go to Modify.

2) Go to Initial Conditions and in the Joint Initial Conditions dialog box, select Rot. Displ and enter -30 in the text box. Select Rot.Velo and enter -300 in the text box. Then click OK and OK.

1) From the Status bar right-click the Information tool stack and click on the Verify tool. Close the window once your model has been verified.

2) Simulate your model for 2 seconds with 100 steps using the Simulation tool.

1) Right-click the blank area inside the pend_angle graph, and go to Plot: scht1 and then go to Transfer to Full Plot.

2) You should now be in the ADAMS/PostProcessor. Now, select the Plot Tracking tool.

3) To determine the Global Components, move the cursor over the plot to where t=0 and make note of the value of Y.

4) In the dashboard, go to Clear Plot.

5) Set the source to Measures, and from the Measure list, select pivot_force_x and select Surf.

6) Move the cursor over the plot where t=0, and make note of the value of Y.

7) From the Measure list, select pivot_force_y.

8) Move the cursor over the plot where t=0, and make note of the value of Y.

9) To determine the frequency, from the Measure list, select pend_angle.

10) Estimate the period of the curve, then find the reciprocal of the period to determine the frequency.

• The Horizontal Force supported by the pivot A is equal to -Ancos30.
• The Vertical Force supported by the pivot A is equal to -Ansin30.