Component Characterization of an eVTOL Reference Model for Crashworthiness Studies

Researchers at the National Aeronautics and Space Administration (NASA) Langley Research Center (LaRC) have
conducted a series of structural component and seat level tests to improve finite element model (FEM) characterization of
a representative vertical take-off and landing (eVTOL) test article developed by NASA. A full-scale dynamic test was
conducted on the representative eVTOL test article in November of 2022. The test article represented a high wing, six
passenger eVTOL design concept and is referred to as the lift plus cruise (LPC) test article. The full-scale test identified
limitations in the analytical models used to predict aircraft structural response, in particular the composite material models
did not effectively capture brittle failure of the structure which were measured during dynamic loading. To better understand
the mechanism behind the composite material failure mechanisms observed and to improve the FEM, intact sample
specimens of the composite airframe structure were recovered from the test article post-test and used in material
characterization testing. In addition, the seat configurations used in the LPC test article were further studied using isolated
seat and anthropomorphic test device (ATD) drop tower testing.

Dynamic compression tests and three-point bend tests, conducted at varied impact speeds, were performed on the recovered
frame section specimens. Additional testing was conducted to characterize the material properties of the forming foam,
which remained in the frames after fabrication. These tests were used to improve characterization of the damage and failure
parameters of the composite material model used in the FE model of the LPC test article. Seat level tests were
conducted on the seats used in the LPC test article using acceleration pulses inclusive of current general aviation and
rotorcraft certification load levels as well as conditions representative of those measured at the seat base during the LPC
test.

The structural material models and seat environment models of the LPC test article FEM were calibrated using the generated
component test data. The updates made to these models were then integrated into the LPC FEM and simulated in the full-scale test condition. Results demonstrated the effectiveness of component testing to improve predictive capability of
composite aerospace structural models within the crash and dynamic loading environments. Demonstration of the LPC FEM
response across an accumulation of coupon, component, seat environment, and full-scale test levels provides confidence in
the predictive capability of this model for future use in the study of occupant safety within eVTOL relevant crash
environments.