static and dynamics

Question

The distance between two supports of leaf spring of a truck is 150 cm. Leaf spring set is subjected to 800 kg load.( σallow for spring= 300 MPa). (Height= 1 cm and width=5 cm) Determine the required number of spring for the system that has factor of safety 2?

Answer 1

Not including the (negligible) shear stress, the bending stress in the center of one leaf spring is 883N/m^2, so with a safety factor of 2 you would need six spring plates. This assumes that there is no friction between the plates, which is unrealistic. Also, typical leaf-spring packages do not use plates of the same length (and the given length is unusually long for a single axle). Lastly, I do not see a dynamic aspect to this problem.