Tensile Modulus (chord modulus of the fiber)

E = B x (P2 - P1) x Ro / ((e2 – e1) × MUL) ----- ASTM D4018

where:

E = fiber chord modulus, GPa;

P2 = tensile load at upper strain limit, N (lb);

P1 = tensile load at lower strain limit, N (lb);

Ro = fiber density, g/cm³;

e2 = upper strain limit, microstrain;

e1 = lower strain limit, microstrain;

MUL = fiber mass unit length, g/m; and

B = unit conversion factor (10^-3 if load is in N).

My test results (resin-impregnated carbon tow):

Tensile load at upper strain limit, N (Pu) = 1190

Tensile load at lower strain limit, N (Pl) = 725

Fiber density, g/cm3 = 1.8

Elongation % = 1.51

Strain at Failure, micro-strain = 15120

Upper strain limit, micro-strain = 6000

Lower strain limit, micro-strain = 1000

Fiber mass unit length, g/m (MUL) = 0.813

Unit conversion factor (10−3 if load is in N) (B) = 0.001

Fiber chord modulus, GPa (E) = 0.000205904

Could you please help me understand why there is such a large discrepancy in the modulus of resin-impregnated carbon tow? The carbon tow modulus should be in the range of three digits before the decimal point.

Also, I have concerns about whether the equation provided in ASTM D4018 is correctly balanced in terms of units.