Patent ID: 8515688

Claim:
A system to predict a fatigue life of an aluminum alloy under cyclic multiaxial loading, the system comprising: an information input configured to receive at least one of information relating to the aluminum alloy and information relating to a stress state present in the aluminum alloy and microstructure characteristics and thermophysical and mechanical properties of the aluminum alloy; an information output configured to convey information relating to the aluminum alloy; a processing unit; and a computer-readable medium cooperative with at least one micromechanics-based fatigue life model program which is stored thereon, wherein the fatigue life model predicts the fatigue life of the aluminum alloy by processing the received information, the received information comprising: a hardening factor of the aluminum alloy, the hardening factor defined by at least one of a plurality of uniaxial cyclic hardening factor parameters comprising a fatigue strength coefficient, a fatigue ductility coefficient, a fatigue strength exponent, and a fatigue ductility exponent, wherein the uniaxial cyclic hardening factor parameters are related to probabilistics of defects and microstructure characteristics in the aluminum alloy, an additional hardening factor due to dislocation interactions in multiple slip systems, the additional hardening factor defined by at least one of an additional hardening coefficient, a hardening exponent of torsion, and a non-proportionality value, wherein at least one of the additional hardening coefficient, the hardening exponent of torsion, and the non-proportionality value is related to probabilistics of microstructure and dislocation structures in the aluminum alloy, and at least one of: a critical shear plane of the aluminum alloy where a shear strain amplitude is at its maximum value, a damage factor of the aluminum alloy, the damage factor defined by at least one of a plurality of damage factor parameters comprising a maximum shear strain amplitude, a normal strain amplitude, a maximum normal strain amplitude, a shear stress amplitude, and a normal stress amplitude, a microstructure characteristic and thermophysical and mechanical properties of the aluminum alloy defined by at least one of a defect size, a volume fraction of the defects, secondary dendrite arm spacing (SDAS), a grain size, a size of the second phase particle, an aspect ratio of the second phase particle, a volume fraction of the second phase particle, a shear modulus value, a Poisson ratio, and a Young's modulus value and; wherein size distributions of casting defects or microstructure characteristics are determined by an extreme value statistics (EVS) with a cumulative distribution function expressed as: F ⁡ ( x ) = exp ⁡ ( - exp ⁡ ( - x - ζ δ ) ) where x is a characteristic parameter of casting defects or microstructure characteristics and ζ and δ are extreme value statistical distribution parameters.