A Simulation Methodology for Metallic Structure to Enable Smarter Testing
M. Chengalva, The Boeing CompanyThe ability to simulate structural behavior at all scales provides a significant competitive advantage in particular by enabling smarter physical testing. In the aerospace context, where extensive and expensive structural testing programs are the norm for new airplane programs, simulations hold the potential to save hundreds of millions of dollars if successfully implemented at appropriate levels as part of a smarter testing approach. Simulations enable rapid evaluations of structural configurations which in turn enable design optimization and trade studies to be performed at a fraction of the time and cost of physical testing.
The road to the successful implementation of reliable simulation methods consists of two sequential segments. The first of these is the development of modeling methodologies that are robust. The second segment is an extensive and rigorous validation exercise that evaluates the methods across the design space.
Within the Structural Methods & Allowables (SMA) group, part of the Boeing Commercial Airplanes Structures core organization, a generalized FEM-based modeling methodology for predicting the ultimate strength of composite and metallic structures has been developed. This approach differs from a conventional FEM approach because it involves the creation and implementation of user-defined material subroutines into the source code of the FEM solver. Known as ‘U-FEM’, this method has successfully predicted the ultimate strength of a variety of metallic structures and has also seen airplane-level application in the form of predicting the strength of critical components in support of airplane programs at Boeing.
For metallic structures the validation process has predominantly utilized test data derived from lugs, channel and angle tension tests. Materials utilized to manufacture these specimens have been characterized with standard simple tension and compression coupon tests and this data is used to construct the U-FEM material model. The U-FEM results are scrutinized and numerous convergence studies conducted to refine the modeling process. Parametric tools enable rapid correlations encompassing load-deflection, failure mode and ultimate strength data.
The successful completion of the above validation paves the way for use within Structures core to help develop design data for deployment via traditional methods. Additionally, it provides a key piece of the puzzle on the roadmap for future implementations with the end-goal of enabling smarter physical testing across the Boeing enterprise.