A containment case includes a fan assembly including a hub having a plurality of fan blades extending radially outward between radially inward blade roots and radially outward blade tips. Containment case includes a radially outer shell circumscribing fan assembly and having a first radially inner surface and a radially outer surface, an inner structure having a second radially inner surface extending along first radially inner surface, and a trench extending circumferentially along second radially inner surface into inner structure from second radially inner surface. The trench is approximately axially aligned with the fan assembly. The containment case also includes, within the trench, a trench filler layer configured to dissipate impact energy from a released fan blade and having a plurality of sheets including a fibrous composite material having a plurality of fibers fabricated within each sheet, where the sheets are coupled together into a repeating pattern of hollow units.