Non-smooth evolutive laws in multisurface elastoplasticity with experimental evidence by infrared thermography. (1st June 2021) - De Angelis, Fabio
Abstract: Plastic and viscoplastic evolutive laws and the constitutive behaviour of materials represent a topic of interest for the mechanical modeling of many multisurface materials and structures. In the present paper non-smooth evolutive laws and constitutive relations for multisurface elastoplasticity are illustrated. This formulation is functional for modeling non-smooth elastoplastic problems as well as problems characterized by non-smooth yield criteria and non-differentiable functions. In this treatment the plastic dissipation is expressed by including the indicator function of the convex elastic domain in a form usually not reported in the literature. However, it is shown that this is a crucial aspect which enables for a regular extension of the rate-independent plastic formulation into a rate-dependent formulation. Accordingly, in the present work extended forms of non-smooth evolutive laws and constitutive relations are illustrated within the adopted mathematical framework which proves to be well-suited for multisurface structural problems. The connections between the proposed formulations and the classical forms are discussed by highlighting the advantages for the definition of extended forms of evolutive laws and constitutive relations in non-smooth multisurface elastoplasticity. Furthermore, the present treatment is complemented by experimental investigations. In order to give experimental evidence to the present constitutive modeling of multisurface elastoplasticity and to exemplify the illustrated formulation some elastoplastic evolutive processes are described by the application of infrared thermography. The reported experimental examples bear witness for the usefulness of infrared thermography to visualize elastoplastic and damage deformations and, accordingly, the capability to validate alternative approaches and extended formulations of evolutive laws and constitutive behaviour in non-smooth multisurface elastoplasticity.