H 2 STORAGE “WITH VERY BIG STRUCTURES, THE CURING CAN TAKE SEVERAL DAYS” 1 Elisabeth Gleis, research associate, TU Munich Chair of Carbon Composites 2 3 1. Cevotec’s fully automated fiber patch placement process can be combined with any existing wet or towpreg winding equipment 2 & 3. The 2025 Honda CR-V e:FCEV powertrain consists of a single 174hp motor that drives the front wheels. Two hydrogen tanks are mounted underneath and behind the back seat; the fuel cell system and drive unit are under the hood are always some issues during the curing process, and the curing can take several days.” For example, during the curing of a thermosetting tank an exothermic reaction takes place, which requires the parameters of the curing oven to be varied to prevent excess heat buildup. This is not the case with thermoplastics. However, the thermoplastic approach does have some significant downsides: it is far slower than filament winding and the materials are considerably more expensive than even towpregs. There is also work underway to develop new processes for tank construction that combine techniques to reduce the amount of material used. For example, one project in Munich is looking to mix towpreg winding with robotized placement of fiber patches, a process developed by Munich-based Cevotec and deployed by the university in its research. The most highly stressed parts of a tank are the domed sections at either end; when using traditional winding construction, the material thickness at these points dictates the overall thickness. By adding localized reinforcement, the material thickness elsewhere can be reduced, saving weight and cost. Gleis and her team are developing this approach a step further, working on the application of ‘tufting’, where a loop of materials is pulled out of the tows to interface with the layer above. “This gives a reinforcement in the thickness direction, and you can also vary the angle of the tufting to place it in line with the pressure vessel surface. The simulations and work we have undertaken so far indicate that we should be able to save even more material and increase efficiency further.” 48 www.automotivepowertraintechnologyinternational.com / March 2024