The version available on the official website supports mfront (windows version; http://www.dhondt.de/calculix_2.19_4win.zip), you only need to have mfront libraries and reference in the .inp file (like): Using MFront Mazars Material Model
The version available on the official website supports mfront (windows version; http://www.dhondt.de/calculix_2.19_4win.zip), you only need to have mfront libraries and reference in the .inp file (like): Using MFront Mazars Material Model