Batten material properties above are explained in terms of weight and stiffness.

Battens are used to stabilize sail shape, and are used primarily for their rigidity or stiffness.

"Spring Rate" numbers and "EI" numbers are values used to quantify this flexural rigidity or bending stiffness property of a batten due to the material properties combined with the geometry or shape and size of the batten.

"Spring Rate" is the ratio of the weight in lb. over the deflection in inches using a constant beam span (1 m). For the same beam geometry, and when using a constant beam span of 1 meter, the correlation factor between Spring Rate and EI is 3.65 (EI = 3.65 X SR).

According to Beam Theory, the bending stiffness of a beam, E.I, is defined as the product of the modulus of elasticity (E) (also called Young's Modulus) and the moment of inertia (I) (also called mass moment of inertia). Metric units are in kilograms and meters (Kgf = 9.807 N)

EI-Beam Theory values were all measured and calculated using standard engineering calculations that give a bending stiffness value in Nm^2. The deflection (d) is measured at the center of the beam length, and is related as d = PL^3/48IE. We note that it is proportional to the load P, to the cube of the span L, and inversely proportional to the flexural rigidity IE. Solving for EI = PL^3/48d. For this calculation, any span and load can be used, making sure that the deflection doesn't excessively sag the batten and change the measured length of the batten.
Feel free to email us with any questions or discussions.

Most of the deflections were measured using a 10 lb. weight for the deflection. Values preceded with a "*" were measured at the lower weights indicated, yielding higher accuracy.

Ps
Visco-elastic properties affecting dynamic batten response are not reflected by the E.I values, as they are more material property related (E-Glass, Carbon, Epoxy, interfacial adhesion, …)