Allows more flex or spring.
why 1/4?Bending stiffness is equivalent to the modulus of elasticity and the moment of inertia. In the case of the flat bar which is the actual cross section of each cultivator shank at any point, the moment of inertia is width x thickness cubed / 12 (English measures). If it was a single beam for example 1 inch by 1 inch for easy calculations, I = (1 x 1)/12 or 1/12. In this case you have 2 beams each 0.5 thick. The cube of 0.5 is 0.125 so each beam has a moment of inertia of .125/12, but you have 2 independent beams stacked so it is additive or 0.25/12. The formula is M=EIk where M is the bending moment, E is the modulus of elasticity for the material being used, and I is the area moment of inertia. k is the resulting curvature. Two thicknesses stacked together are 1/4 as rigid as 1 single thickness unless they are completely fused for the entire length.
Bending stiffness is equivalent to the modulus of elasticity and the moment of inertia. In the case of the flat bar which is the actual cross section of each cultivator shank at any point, the moment of inertia is width x thickness cubed / 12 (English measures). If it was a single beam for example 1 inch by 1 inch for easy calculations, I = (1 x 1)/12 or 1/12. In this case you have 2 beams each 0.5 thick. The cube of 0.5 is 0.125 so each beam has a moment of inertia of .125/12, but you have 2 independent beams stacked so it is additive or 0.25/12. The formula is M=EIk where M is the bending moment, E is the modulus of elasticity for the material being used, and I is the area moment of inertia. k is the resulting curvature. Two thicknesses stacked together are 1/4 as rigid as 1 single thickness unless they are completely fused for the entire length.