Stress Analysis (24-262) Group 16
Stress Analysis (24-262) Group 16
David Chou, Conor Fitzgerald, Megan Tienjaroonkul

Mechanism


Our mechanism has a vertical rectangular prism for a base on which supports can be attached to the vertical walls. Two ends of this shape were clamped into the table to provide a secure connection for attachment. A long I-beam was attached via four supports to the base so that the far end of the beam is quite close to the weight. The motor was attached to that end of the beam and had a lever arm with a hook on it so that the weight only displaced in the vertical direction. A large counterweight was put on the other end of the lever arm so that the lift was not too much for the motor.

Servo Analysis


Length arm: 4 inches
Length Counterweight: 8 inches
Mass Counterweight: 4 ounces

Torque Counterweight: 0.1667 lb*ft
Torque weight: 0.333 lb*ft
Net torque required by motor: 0.1667 lb*ft

Motor Torque: 1.25 N*m+- 0.25
*Assume lower value= 1 N*m=0.7376 lb*ft
Proportion of Motor Torque used: (0.1667 lb*ft)/(0.7376 lb*ft)=0.226

Angle of Servo Rotation: Pi/2 (Approximately from –Pi/4 to Pi/4)
Y-Distance of lift: Sqrt(2)* Length arm=5.657 inches

Interesting Concepts


In original iterations of the design we had difficulties designing supports that acted outside of the horizontal and vertical planes which remained rigid. For design three we designed supports which were able to rigidly attach to two perpendicular planes. This was accomplished by overlapping cutting and bending L-channels and bolting the overlapped material together. By doing this the support became more rigid where bends were made and were more able to support the I-beam.