4 Bar Linkage

4 Bar Linkage Study

This exercise in mechanisms demonstrates the capabilities of a SOLIDWORKS Motion Study using a simple 4 bar linkage. Using the course guidelines to assemble the mechanism and modifying the mates to perfectly define it to one degree of freedom, the software helps analyze the motion of different points on the assembly and graph the torque and power of the crank arm motor.

Optimization of Mechanism

After assembling the model, the SOLIDWORKS Motion Study tools evaluated this mechanism and determined that with the given mates, the model is overconstrained. Following the guidelines of the course, the overdefining mates were carefully modified to improve the degrees of freedom (using the Gruebler Count) until there was a single positive degree of freedom in the model - which would become the motor.

Max Value of Motor Torque: -18 Newton-mm

Angle of Crank at Max Torque: 0° (to the horizontal)

The negative values of torque represent when there is torque being applied to the motor in the direction opposite to it's rotational motion. In this case, the weight of the crank, rocker, and extension are acting upon the motor and resisting it's motion, and their combination of weight happens to be the strongest at the crank's horizontal position between the two bearings. On the other hand, the weight can also push the motor in it's direction of rotation, which is the case at other peaks in the graph that display positive torque, such as when the rocker begins to tip and push the extension so that the crank is being pushed counterclockwise (it's original direction of travel)

Tracing the path of specific points in the simulation also allows us to export the graph as CSV values to gather and process further data from.

Max Vertical Force on Bearing: 0.3 Newtons

Max Vertical Force on NewBearing: 0.2 Newtons

Motor Power

The minimum power to rotate the crank at 20 RPM is 0.02 Watts, given that the max power exerted by the motor during it's rotation is when the max torque is applied to the motor, and this rotation is at a constant speed of 20 RPM. This graph tells us that the minimum power of the motor to maintain constant rotational speed must be enough to continue constant rotation during the mechanisms maximum torque in it's cycle. At 600 RPM, the power consumption shows us that the max positive power exerted by the motor is 370.32 Watts (the positive values are power exerted by the motor)