Leaf spring maximum flex range?

Thinking installing airbag suspension over leaf springs on trailer. Primary to increase ground clearance when off-road.
Trying to find out how to calculate how much leaf spring can flex without damage.


So pressure from airbag will be flexing leaf spring in opposite direction. Increasing arch instead of decreasing, when normally for example when load in bed is added, spring will flex out.

So "C" in the picture in rest position is 4 inches. Airbag will put pressure in the center, push down, and will increase "C" gap to 12 inches. So the question is how to calculate what is maximum "C" chamber can be? Maximum arch increase?

Thank you guys.

 

^The spring stress and deflection equations still work, just you'll get negative values for dmax with negative values of F: https://www.engineersedge.com/material_science/leaf-spring-design.htm . Max stress is still meaningful whether positive or negative, since the leafs are in bending.

Max allowable stress depends on the leaf material. Divide by 1.5 (because bending) and look up the applicable spring material curves.