Effect of viscosity on cavity growth in ductile damage

• The experimentally evolution of damage is compared to the usual Huang law for 3 different steels.
• It is shown that this usual model need to be modified to reproduce the results.
• This change is shown to follow the Budiansky law (taking into account the influence of viscosity).
• This conclusion is checked by FE simulation looking at the cavity growth according to the viscosity.
• The calculations validate Budiansky model and give a better insight of the experimental results.

In this paper the Budiansky approach is used in order to reproduce the void growth measured experimentally by 3D tomography in metals. It permits to avoid the non physical fitting of the alpha coefficient in Huang’s law. This model considers the viscoplasticity of the material to account for the interaction between the voids. It is shown that strain rate sensitivity of the material is playing a key role on growth of cavity and thus on damage of materials. Moreover finite elements calculations are carried out to check the influence of geometrical parameters (fraction of porosity, distance between voids) on the damage behaviour. The results are in agreement with the Budiansky model.