A slightly technical question asked in a non technical way

When the cranks are turning and the crank arm/pedal is at a given position between 12 0' clock and 6 o'clock, where is the most stress placed and at what position (12-1-2-3-4-5 or 6 0' clock) etc?

I ask this as I had a few chainring bolts come loose and actually lost one completely on a recent ride and wondered at what position the most stress/power occurs. Would the most stress be on the chairing bolt above the crankarm (trailing/pulling) or below the crankarm (leading/pushing) at a certain position as this is where I either lost the bolt or where the most loose bolt was.

TIA