Fatigue ductility coefficient

Here As/2 = total strain amplitude, Ase/2 = elastic strain amplitude = a/(IE), Asp/2 = plastic strain amplitude = As/2 - AsJ2 = Ae/2 - a/(2E), Si = fatigue ductility coefficient (related to fracture strain in a monotonic tensile test), and cTf = fatigue strength coefficient (related to fracture stress in a mono tonic tensile test). 

For the fatigue ductility coefficient ej, the true fracture strain in tensile loading can be used as a good approximation. The fatigue ductility exponent b depends on the hardening of the material. Typical values for b are in the range of 0.4 to 0.73 [113,130]. 

Strain hardening exponent of the material n is needed together with the fatigue strength coefficient a f and the fatigue ductility coefficient f. these last two coefficient have been already calculated in sample problem 1. of Sect. 5.3 and are... 

Mechanical property n. Any property of a material that defines its response to a particular mode of stress or strain. Such properties include elastic moduli, strength, and ultimate strain in several modes, impact strength, abrasion resistance, creep, ductility, coefficient of friction, hardness, cychc fatigue strength, tear strength, and ma-chinability. Many ASTM tests in Section 08 are devoted to the mechanical properties of plastics. 

Mechanical properties include ultimate tensile strength, yield strength, ductility, fatigue endurance, creep resistance and stress rupture strength. Metallurgical properties refer to the physical and chemical characteristics of metallic elements and alloys, such as the alloy microstracture and chemical composition. Physical properties usually refer to the inherent characteristics of a material (i.e. density, melting temperature, heat transfer coefficient, specific heat, electrical conductivity, etc.). 

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