Integration of cabin environment into the aircraft crashworthiness assessment process

Kurzfassung

The German Aerospace Center (DLR) has established a sophisticated process chain for aircraft design, resulting from the aggregation of multidisciplinary expertise of various DLR institutes. Such a collaborative process employs the Common Parametric Aircraft Configuration Schema (CPACS) data format to exchange the aircraft description and analysis results. The PANDORA design environment (Parametric Numerical Design and Optimization Routines for Aircraft) is an established tool within the DLR process chain developed at the Institute of Structures and Design (BT) for the automatic generation of global and detailed Finite Element (FE) structural models subsequently used for static and dynamic (crash) analyses and structural sizing. Within the DLR project ARCADIA (Automated and Reconfigurable Cabin Development Process in Aircraft design), PANDORA is extended to achieve a higher level of detail in the FE modelling for cabin crashworthiness analysis, by integrating secondary structures and advanced Anthropomorphic Test Devices (ATDs) to represent the passengers. As a result, the automatic generation of a cabin based on CPACS geometric and structural data is now achieved in a matter of minutes, rather than hours of manual work, paving the way to fully parametrized crashworthiness studies of full aircraft models including injury risk assessment. Aeronautic crashworthiness is increasingly important, due to the fast growth of the sector and the interest in new greener configurations, involving new safety problems to explore. The aforementioned integrated process chain is necessary as the certification authorities are starting to change the regulations shifting from prescriptive to performance-based requirements, by considering the crash performance of seats and airframe in a combined approach. This may lead to expensive and complex full-scale testing, strengthening the importance of validated simulations. For disruptive aircraft or cabin design, the crash load mitigation may influence the overall fuselage design and hence it should be considered in an early phase of the design chain. In this paper, two main topics are addressed for the ATD integration. First, the capability to create structural LS-DYNA models, on a wide range from low complexity to high fidelity, was implemented in PANDORA and validated through numerical benchmarks and comparisons with previous well-established reference models. Secondly, the methodology to model ATDs, belts, and seats is defined and validated in a parallel study and a build-in library for different ATD types is created. These basic library models are then combined to simulate the CPACS-defined seat configurations. Finally, the cabin model with ATDs is integrated into the structural model. A preliminary simulation is presented as a result of the integration methodology. The implemented process shall accelerate the development of innovative aircraft concepts, while aiding designers to improve aircraft safety, by considering crashworthiness from early predesign phases. In particular, the emphasis is on addressing the safety challenges of novel designs such as zero-emission configurations and high-density cabin layouts in which the design space is yet to be explored, and parametric analysis is of fundamental importance.