Composite Material and Structure

Fatigue Life is an Inverse proportion to applied strain range.The formula is given by: Where: Nf​ is the fatigue life of the composite laminate. A is a constant related to the material and loading conditions. Δε is the applied strain range during cyclic loading.

Fiber Orientation Angle is an Arctan of fiber orientation vector components.The formula is given by: Where: θ is the fiber orientation angle. X and Y are the respective components of the fiber orientation vector.  

Critical Fiber Volume Fraction is a Minimum fibers to prevent crack propagation.The formula is given by: Where: Vf∗​ is the critical fiber volume fraction. KIC​ is the fracture toughness of the composite material. σf​ is the tensile strength of the fibers. L is the characteristic length associated with crack growth.

Matrix Strength Efficiency Factor is a Composite matrix strength relative to individual.The formula is given by: Where: η is the matrix strength efficiency factor. σmatrix, composite​ is the strength of the matrix in the composite material. σmatrix, individual​ is the strength of the matrix material individually.

Strain Energy Release Rate is an Energy per unit area during crack propagation.The formula is given by: Where: G is the strain energy release rate. dW is the change in potential energy. dA is the change in crack area.

The efficiency of fiber strength in a composite compared to individual fibers.The formula is given by: Where: σfc  is a stress fiber composite. σfi  is a stress fiber individual.

Matrix Toughness is a Resistance to crack propagation in composite matrix.The formula is given by: Where: KIc​ is the fracture toughness of the matrix. σf​ is the ultimate tensile strength of the matrix material. c is a constant related to the crack geometry and specimen configuration.

Fiber Aspect Ratio is a Length relative to diameter for reinforcement. The formula is given by: Where: Aspect Ratio is the dimensionless ratio representing the fiber’s length-to-diameter ratio. Fiber Length is the length of the fiber. Fiber Diameter is the diameter of the fiber.

Interlaminar Shear Strength is a Resistance to shearing forces between laminate layers.The formula is given by: Where: τinterlaminar​ is the interlaminar shear strength. F is the applied force required to shear the material. A is the cross-sectional area over which the force is applied.

Hygrothermal Expansion is a Measures dimensional changes in composite laminates due to moisture and temperature.The formula is given by: Where: εtotal​ is the total strain. εthermal is the thermal strain. εmoisture​ is the moisture-induced strain.