Numerical analysis of softening materials: some often overlooked aspects

Techniques ranging from high-resolution electron to atomic-force microscopy enable the examination of very low scales and provide an unprecedented possibility to link the micro-structure with the macroscopic properties of materials. Regrettably, while the significance of micro-scale softening mechanisms in influencing macro-scale material behaviours is nowadays largely recognized in continuum damage mechanics and many efforts are being spent to forge the link between micro and macro, micro-scale damage modelling is often addressed numerically too naively. The talk will highlight some topical aspects that have been up to now overlooked or dealt with too superficially by comparing the performances of different numerical algorithms in solving KARUSH-KUHN-TUCKER conditions for a simple softening spring. It is concluded that even such a primitive model might require numerical analysis to face unexpected challenges.