Below we have listed physical properties for both our E-Glass/Epoxy and Carbon/Epoxy battens.
At the bottom of the chart there is a brief discussion on the EI numbers, how we derived them and how they can help you in proper and exact batten selection for your sails.
PLEASE CLICK ON EACH TAB FOR INFO!
For weight (or mass) we use grams. (One gram equals 0.0022 lb., 1000 g or 1 Kg = 2.205 lb.)
For stiffness we use two expressions; Spring Rate and EI-Beam Theory numbers.
“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.
SR = Bending stiffness (ratio weight over deflection) (lbs/inches)
E = E-modulus (N/m^2 = Pa)
I = Moment of inertia (m^4)
EI = Bending stiffness (product of E and I) (Nm^2) (or more commonly Nm^2)
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.
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, …)