15.5:
Relative Motion Analysis – Velocity
A stroke engine has a slider-crank mechanism that converts rotational motion from the crank into linear motion of the slider or vice versa.
As the crank rotates due to external force, it causes the connecting rod to move, resulting in a general planar motion.
Point A from the connecting rod and point B from the crank undergo translational motion. Furthermore, point B also undergoes rotational motion with respect to point A.
The absolute translational motion of points A and B can be studied using a fixed frame.
Similarly, the rotational motion of point B, with respect to point A, can be analyzed using a translating x'y' frame attached to point A.
The absolute linear velocity of point B is then expressed as the vector sum of the absolute linear velocity of point A and the relative velocity of point B with respect to point A.
Here, the last term represents the relative velocity of point B due to the rotational motion having the direction perpendicular to the segment AB.
15.5:
Relative Motion Analysis – Velocity
A stroke engine has a slider-crank mechanism that converts rotational motion from the crank into linear motion of the slider or vice versa. This mechanism consists of three main parts: the crank, the connecting rod, and the slider.
When an external force is exerted, it sets the crank into a rotational movement. This, in turn, instigates the motion of the connecting rod, leading to what is referred to as a general plane motion. This process involves two key points – point A on the connecting rod and point B on the crank. Both these points experience translational motion. In addition to this, point B also experiences a rotational motion in relation to point A. This dual motion at point B adds complexity to the mechanics of the stroke engine.
To understand the movements of points A and B, different frames of reference can be used. The absolute translational motion of both points can be examined using a stationary or fixed frame, while the rotational motion of point B relative to point A can be studied with a translating x'y' frame attached to point A.
The absolute linear velocity of point B can then be calculated as the vector sum of two components – the absolute linear velocity of point A and the relative velocity of point B with respect to point A. The latter term signifies the relative velocity of point B due to its rotational motion. This motion's direction is always perpendicular to segment AB, which connects points A and B.