HELP! Fully reversed load - definition?!! Application!?!?

Question

Hey,

What does it mean when the force is fully reversed?! Will the force/torque applied on the bike pedal/crank considered fully reversed?! I know it is, but I don't know why. In my analysis, I used weight of the rider as the only force applied to the pedal as it rotates, and that force is fully reversed to calculate factors of safety in the pedal/crank-arm.

How would I explain the logic behind that in the report?! Any ideas?

Thanks!

Answer 1

In fatigue testing an expected static or unidirectional cyclic load is applied in nominal and reversed polarities to accelerate failure and often to reveal the possibility of "low-cycle" (i.e., fewer high-load cycles rather than more low-load cycles) failures. Portions of the structure normally expected to sustain compressive loading are thus also subjected to tensile loading and vice versa. (Note that some bike riders occasionally stand on both pedals with the cranks horizontal, which applies reverse loading to the hindmost crank.) The ref. contains some interesting discussion of fully reversed load testing.

Answer 2

Definition Of Reversed

Answer 3

Loading Definition