Pressurization test on CFRP liner-less tanks at liquefied nitrogen temperature

Two liner-less CFRP concept tanks were prepared for internal pressurization tests at liquefied nitrogen (LN₂) temperature. The tanks were designed in two patterns of eight-ply UD quasi-isotropic lay-up, in the shape as a cylinder of 600 mm in diameter and 1200 mm in length, covered with an aluminum flange at one end and with a CFRP hemisphere dome at the other. The maximum strain was applied as the damage onset condition so that the internal pressurization at LN₂ temperature did not damage them up to 1.1 MPa. Damage onsets, such as transverse cracking and leak path formation, were monitored during the tests using helium flow detection, acoustic emission, and pressure-strain monitoring. The CFRP concept tanks showed no damage in the 1.1 mm thick cylindrical gauge section under pressurization up to 1.1 MPa at LN ₂ temperature. The design was thus shown to be successful in keeping the CFRP tanks intact.