1. Lab 6 Kinematics & Constraints

2. Make 2 and 3-D models Work as individuals but refer to lab partners
Read Doug Blanding’s booklet for ideas
Start with 2-D models out of manila folders
Punch works well for making holes for joints
Stick pins for grounded joints
Thumbtacks for free joints

3. Statically Deterministic
Introduction
Statically Deterministic
Force
Moment
Two force member
Degree of Freedom
Kinematic constraint

4. Suggested models – single constraint
One grounded joint – only rotation
One swivel joint – rotation and translation

5. Dual in-line constraints
Ground joints 1 & 4 and make 2 & 3 a little long
What happens? Toggle or oil can effect

6. Dual constraints – not parallel – virtual pivot

7. Dual constraints - parallel
Instantaneous center of rotation is at infinity
But translational modes constrained
Add second set of parallel constraints

8. Cascading constraints
Practical application – Drafting machine – parallel motion in 2-D

9. Exact 2-D constraints
Design a “tangent bar” constraint for a circular disk
This is often used for the radial constraint of a telescope mirror

10. Practical examples of 2-D exact constraints

11. 2-D exact constraint table

12. 3-D exact constraint table

13. Build 3-D constraint systems
Use swab sticks, capplugs and hot glue gun to make models
Careful with the glue gun – the glue can burn if it is still hot

14. Make some compound connections
Use manila folder sheet material and glue gun

15. Investigate stiffening sheets

16. 2-D Trusses

17. Rigid 3-D structures

18. Tangent Arm

19. Tangent Arm

20. Example of Kinematic Constraint

21. Example of Virtual Pivot

22. Example of Vee

23. Example of “Canoe Ball”
Large contact surface radius to reduce Hertzian contact stress

24. Example of mechanical 3D constraint

25. Example of 3D Constraint

26. Example of 3D Constraint