Calculation (mechanical properties)

Tensile modulus, Shear modulus and Poisson’s ratio of unidirectional composites

These important properties can be estimated by Chamis’s equation that I’ve been referring for years. It seems there are several version of the equation but I applied the most reliable equation that I believe is theoretically makes sense.

CF modulus (L direction) (GPa)
CF modulus (T direction) (GPa)
CF shear modulus(LT)
CF shear (T direction) (TZ)
CF Poisson’s ratio (LT)
CF Poisson’s ratio (TZ)
Resin modulus (GPa)
Resin Poisson’s ratio
Vf (%)
E L-direction
E T-direction
G LT-direction
G TZ-direction
Poisson’s ratio (LT)
Poisson’s ratio (TZ)

Estimation of base material properties

Sometimes base material properties such as transverse tensile modulus and poisson’s ratio of the carbon fiber. In those cases, if the composite properties are provided, the base material properties can be estimated.

Tensile modulus of carbon fiber in transverse direction

Tensile modulus of UD material (T direction) (GPa)
Resin modulus (GPa)
Vf (%)
CF modulus T-direction

Summary comments

In this article, I introduced several methods to calculate mechanical properties for unidirectional composites or carbon fiber. However, the calculated values are theoretical values (just for estimation) and not exact value in materials. You may need to think carefully how to use the calculated value.