The quantitative predictive capabilities of a recently developed plastic-distortion-based micromorphic approach are rigorously assessed through analysis, finite element simulations, and systematic comparison with experimental observations and discrete dislocation dynamics (DDD) predictions. This approach is based on multiple series decompositions of higher-order kinematic terms, and provides flexible control of the scaling effects via a penalty parameter constraining the micromorphic variable. A comprehensive analytical investigation is first conducted using an idealized constrained shear layer problem to elucidate scaling effects associated with both energetic and dissipative higher-order effects. The approach is subsequently applied to predict the orientation-dependent response of thin metallic layers under confined compression. In agreement with experimental observations from the literature, finite element simulations reveal pronounced size effects for layers oriented perpendicular to the loading direction, arising from both first-order and higher-order contributions, whereas negligible size effects are observed for the 45° inclination. The formulation is further employed to capture the size effects in L-beam single-crystal specimens subjected to bending-torsion loading. Both energetic and dissipative higher-order contributions are incorporated, leading to good quantitative agreement with the experimentally observed responses, with a numerically predicted scaling exponent of 0.36 against the experimental value of 0.38. Finally, the model is applied to reproduce complex size-dependent responses obtained by DDD, under cyclic shear loading conditions. Good quantitative agreement is obtained, with a predicted scaling exponent of 0.26, fully consistent with the range 0 . 2 , 0 . 3 reported in recent DDD studies. The results obtained in this work demonstrate the strong predictive capabilities of the employed formulation across diverse loading conditions and specimen geometries, highlighting the effectiveness of the relaxed micromorphic implementation for the quantitative modeling of size effects in small-scale crystalline materials. • Quantitative assessment of size effects for realistic scaling prediction. • Micromorphic approach with energetic and dissipative higher-order effects is studied. • Orientation-dependent size effect in micropillar compression is reproduced. • Size-dependent scaling in single-crystal L-beam bending-torsion is predicted. • DDD simulation is reproduced with least-squares-based parameter identification.
Mukherjee et al. (Sat,) studied this question.