Diffusion akantu (bugfixes/46-bug-in-strain-energy-split-and-missing-constraint-in-phasefield) Change
rAKA/extra_packages/extra-materials/src/material_viscoelastic/material_stiffness_proportional.cc
rAKA/extra_packages/extra-materials/src/material_viscoelastic/material_stiffness_proportional.cc