Strain energy

Through characterizing the interaction of normal/shear stress–strain behavior on material planes of TC4 alloys, a new strain energy critical plane model describing mean stress effects is proposed for life prediction under tension–compression, pure torsion, and tension–torsion loadings. Moreover, a modified Ince–Glinka model is elaborated through considering crack surface close to the maximum shear strain plane. Three simple solutions are presented to determine cracking failure mode using the concepts of life, damage, and strain. Comparing with lifing models of Liu, Smith–Watson–Topper, and modified Ince–Glinka, the proposed model provides more accurate life predictions for TC4 and a compressor turbine disc by full-scale fatigue testing