CORRELATION BETWEEN THE COEFFICIENT-M AND COEFFICIENT-C OF THE PARIS RELATIONSHIP

Among the formulas used to represent the cracking speed with respect t o the stress amplitude, the Paris formula: da/dN = C Delta K-m is cert ainly the most widespread, Even though many studies have tried to find a relationship between the coefficients m and C of this equation, con troversies still exist. We show that this relation exists but does not have the general character given to it in the literature, and that it depends on the material, We then study the influence of various facto rs: temperature, heat treatments and the load factor, before trying to make a physical interpretation and to show the practical interest of this approach.