An Investigation into Metal-Based Energy Absorption Systems for Usage on Rotorcraft Landing Skids: Addressing Hard Landings and Repeated Impact Scenarios

The usage of energy absorption systems on rotorcraft is widespread and commonly centered around fluid-based designs. However, damping systems that rely on fluids are not feasible for applications in extreme and cryogenic conditions. With the rise in autonomous rotorcraft that fly on planets other than earth, a new energy absorption system must be developed that can meet the challenges these types of environments present. These designs must also be simple and require virtually no maintenance, as they will be isolated in space. The Ingenuity Helicopter employed an innovative energy absorption mechanism using two conjoined metallic spring-like disks—one made of titanium and the other of aluminum. Upon landing, the aluminum disk underwent plastic deformation to absorb impact energy, while the titanium disk provided a restoring force for repeated use. Our team conducted a series of physical tests to study the system implemented on the ingenuity rotorcraft. We began by machining several test articles to use in physical tension tests. We fabricated aluminum and titanium pillars along with two blocks to secure them together and to our test machine, an MTS Criterion. Our team performed four separate tension tests. The first two tests were with aluminum and titanium pillars alone and were meant to obtain a stress/strain curve for each material. We then performed two tests with the aluminum and titanium pillars side by side, secured together with the blocks. This setup replicated the mechanism found on the Ingenuity Helicopter. The first test had a strain gauge on the aluminum pillar, and the second identical test had a strain gauge on the titanium pillar. Therefore, by performing these four tests, we were able to obtain stress/strain curves of the pillars independently and fastened together with the block. This system was also replicated in FEA with the physical tests serving as validation. This paper seeks to investigate Ingenuity’s mechanism and determine if it may be suitable for other applications such as the NASA and Johns Hopkins Applied Physics Laboratory's Dragonfly.