Automotive steel wheel as a critical component in

2.3. Cylindrical decomposition of damage
In Eq. (13), A0 TGX-221 the original cross-sectional area and Af0 is the cross-sectional area after fracture at the neck at atmospheric pressure [20]. The uniaxial tension tests under confining pressure for different alloys were carried out by Bridgman. The relation between the fracture strain and the confining pressure were presented in his work [44]. The pressure dependence function for the (X-W) damage plasticity model is the result of the Bridgman uniaxial tension tests under pressure loading. In the present study, a logarithmic form of the pressure dependence function is defined as follow [20]:equation(14)μp(p)=(1-qLn(1-σh/plim)),σh?plim[1-exp(1/q)]0σh<plim[1-exp(1/q)]
The effect of the Lode angle dependence function on the shape of the fracture envelope in the octahedral plane of the principal stress state is stop codon different and can be expressed as a function of the Lode angle (or other parameters of the same meaning). The method for determining Lode angle dependence function in (X-W) model is directly related to the method used by Wilikins et al. [34]. In other words, the Lode angle dependence function in (X-W) model is the result of its definition in Wilikins et al. model [20] and [34]. The stress asymmetry A in the Lode angle function of (W) model is related to the ratio of the principal deviatoric stresses as follow:equation(15)A=1-2χ1+X0?X?0.52χ-12-χ0.5?X?1