This application will calculate stiffness coefficient using B. Hunt's method taken
from INAV... It may also be used for density calculations of individual sheets
The calculations are based on the following formula:
The formula for the buckling load is ...
buckling load = pi^2*e*bb*bd^3/(12*bl^2)
e = youngs modulus of elasticity.
So we can calculate youngs modulus from the buckling load and the sheet dimensions...
bb = balsa breath (width)
bd = balsa depth (thickness)
bl = balsa length in inches
bw = balsa weight in grams
load = load in grams
The formula becomes:
youngs modulus e = 0.188*bl^2*(load-bw)/(bb*bd^3) in gcm^-2
With this, we can then calculate density and stiffness coefficient.
density = 3.8*bw/(bl*bb*bd) in lb/ft^3
SC = e *2500/(density^2*13000000)
SC < 90 is poor, 90-100 is average, 110 is good and > 120 is super.