The Three-rod Linkage


 

tex2html_wrap_inline119 Statement of the problem

Linkage is a common mechanism used for connecting two bodies, usually two rods. In this problem, we use a three-rod linkage to illustrate the kinematics of the system. An interesting question for the linkage system is the velocities of different locations such as the pin-joint or mass center of a rod in the system. Also we are curious about the relative motion of different points in the system, therefore we designate different reference frame to observe the motion.

tex2html_wrap_inline119 Exercises

Reference on the Ground
  1. By moving the Slider or input a number in the box, set a value of angular velocity of rod AB, e.g. 200 rad/s.
  2.  Select a reference frame on the ground by clicking on one of the four buttons- Ground. If the system is out of the window, using the Scroll Bars on the left-hand side and bottom of the window to move it back.
  3.  Let the program Run for a while then stop it. Watching trajectories of different points. What do you find?
  4.  Click on Reset and Erase Track, then you can choose different reference frame let the program Run again.
Reference on A
  1. Select a reference frame on point A by clicking on the button- A. If the system is out of the window, using the Scroll Bars to move it back.
  2.  Let the program Run for a while then stop it. Now how is the motion of point C and E?
  3.  Click on Reset and Erase Track, choose different reference frame to Run the program again.
Reference on DE and C
  1. Following the same procedure, you can choose the center of rod DE or point C to Run the program. What do you find out?
  2.  Can you give a simple conclusion about the relative motion of different points by choosing different reference frame? Why are we interested in the relative motion of different points in the system?

tex2html_wrap_inline125 Think Twice

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