Recent content by Lesolee

Oh, I see what you mean now! No, the shaft didn't break, the "pivot" did. The pivot is not a simple bearing, it is a flexure. I didn't want to over-complicate the problem with unnecessary detail. The accelerometer is a way of quantifying the operating stress on the flexure, although to be fair...

The end-stops are actually pieces of foam, it is just pretty rigid foam. The lever arms are very rigid. I plan on putting an accelerometer on the drive coil, C, and then using the known inertia to calculate the shear force.

Considering 'M' (in the earlier diagram, "C" in the diagram below) to be a pivot means an infinite force as it decelerates instantaneously. A moving "5M" mass does not give a force. Only a decelerating "5M" can give a force and since the deceleration is again instantaneous the force is infinite...

Yes, in principle the load on the pivot would be zero. Practically it would be difficult to tolerance the end-stops so they hit at exactly the same angle. The real problem is that the angle of the end stop is toleranced by a distance. This is much easier further from the pivot. The 5M mass is so...

I would have thought the function needed would be a sine, so that at 45° you would get 4000lb x 4ft x sin(45) = 16,000 x 0.707 Alternatively, the weight is 4000lb and if only 4000 ft.lb is available the angle would be such as to make the offset from the axle 1 foot. 4ft x sin(th) = 1ft th =...

I guess that having reduced the problem to its essentials, the solution was closer to the surface. Another problem, the one with a bar and a force applied at one end, helped. The deceleration of the mass M (and the rest of the armature) requires a force. The pivot has to exert an equal and...

I have simplified the problem down to something like a physics textbook question, although this is a practical problem where the pivot on my rotary actuator has been damaged by a faulty driver which caused the armature to ram into the endstop. Obviously this needs better protection. My problem...