Technical note | C-27J NASTRAN Global Finite Element Model User Manual C27J-DST-v3.0

Abstract

The Royal Australian Air Force (RAAF) has commenced a fleet acquisition of C-27J aircraft (AIR8000 Phase 2) to support RAAF tactical airlift capability requirements. As part of the Structural Substantiation Program, a global Finite Element Model (FEM) of the C-27J airframe was obtained from the original equipment manufacturer Alenia Aeronautica. A global airframe FEM is an important supplementary tool in support of current and future RAAF C-27J structural integrity management. In the present user manual, detailed descriptions of the various sub-models constituent to the global model, including guidelines on their use are provided. Pending experimental validation, the enhanced and verified C-27J Global FEM is a linear elastic internal loads model that will be a useful tool in providing global loads results such as wing tip displacements, field stresses, running loads, connection forces, and other potential uses as described within the body of this document. The user manual provides important information on how to use and update the model, and the limitations associated with it.

Executive Summary

The Royal Australian Air Force (RAAF) has commenced a fleet acquisition of C-27J aircraft (AIR8000 Phase 2) to support RAAF tactical airlift capability requirements. As part of the Structural Substantiation Program, a global Finite Element Model (FEM) of the C-27J airframe was obtained from the Original Equipment Manufacturer (OEM) Alenia Aeronautica. In 2013, DST Group completed a preliminary review of the C-27J Global FEM and recommended several areas of model enhancement, including specific C-27J FEM verification and validation activities. The objectives of these enhancements were: alignment with DST Group model orientation norms, improved useability, alignment with design baseline data, and a reduction of potential usage errors.

 A global airframe FEM is an important supplementary tool in support of current and future RAAF C-27J structural integrity management. Previously, no comprehensive FEM user manual or model verification process existed. Hence, in the present user manual, detailed descriptions of the various sub-models constituent to the global model, including guidelines on their use, are provided. Each sub-model is allocated a particular numbering regime, with space for additional nodes and elements, thereby allowing sub-model modification and augmentation that can be easily spliced into the global FEM. Pending experimental validation, the enhanced and verified C-27J Global FEM is a linear elastic internal loads model that will be a useful tool in providing global loads results such as wing tip displacements, field stresses, running loads, and connection forces, as well as providing a foundation for more detailed stress analysis. However, assessment has also identified some remaining limitations associated with legacy modelling constructs which are also discussed within this manual.

 This user manual provides critical information on how to use and update the C-27J Global FEM. The limitations associated with this model require focussed consideration by users; it is vital that all users of the C-27J Global FEM are familiar with this manual before working with the model.