NextGen Stress & Fracture for Lightweight Structures

The dream in stress and fracture analysis has always been to be able to simulate cracks initiating and then propagating in a stress field in a metal or composite structure. To date, the engineer is only able to see a stress plot that identifies highly stressed problematic areas. Only a stress and fracture expert may be able to accurately figure out where cracks will initiate and in which direction it will propagate. The latest tools now give this ability but have not been widely used or accepted in aerospace. This effort would benchmark the latest tools with accepted standards in aerospace and seek to develop appropriate techniques to develop highly visual simulations of cracks initiating and propagating. These techniques will help us to engineer far more robust aerospace structures mitigating risk to the mission and crew. This is critical for a Mars mission where reliability of hardware is paramount.

NASGRO (NASA Crack Growth Software) is the globally used (Boeing, Lockheed, NASA, ESA, Airbus, Bombardier, Embraer,..) aerospace standard for fracture analysis. It uses an extensive test data base to develop predictive crack growth models. Finite element models of these crack cases will be built and analyzed using Marc's new powerful crack initiation and propagation features. These will be compared to NASGRO results and techniques will be developed to ensure greatest correlation. These techniques will be applied to complex geometry with the final goal of making a crack, when it occurs, grow in a benign direction. These techniques and results will be published enabling the aerospace industry to develop far more reliable structural components. Marc also simulates delamination in composites very visually.

A report detailing the crack cases studied, correlations between NASGRO and Marc FEA, videos showing how the cracks grow. For complex geometries, the video showing how the cracks grow will be very educational in designing such crack arresting features. Crack growth rates and growth directions may be studied for different applied loads. The Marc analysis settings that will give the best correlations will be documented.