A heavy-lift drone suffered a catastrophic fracture in its chassis during a delivery mission. Subsequent 3D forensic analysis, supported by volumetric meshes and projected ultrasounds, revealed internal delaminations in the carbon fiber. The main cause was a critical error in the fiber orientation during the automated lamination process, a defect invisible to the naked eye that compromised the structural integrity of the part.
Mapping delaminations with Ansys Composite PrepPost and GOM Inspect 🛠️
The engineering team used GOM Inspect to digitize the fractured geometry and generate a high-precision 3D mesh. On this mesh, data from an ultrasonic scan was projected, allowing the identification of areas of separation between layers. Using Ansys Composite PrepPost, the actual laminate model was recreated and the stress state prior to failure was simulated. The simulation confirmed that a deviation of just 5 degrees in the fiber orientation in a critical layer generated stress concentrations that exceeded the material's fatigue limit, causing the in-flight fracture.
Predictive simulation as a barrier against silent failures 🔍
This case demonstrates that fatigue in composite materials is not always visible. Internal delaminations act as silent cracks that grow under cyclic loading until collapse. Integrating tools like Rhino for geometric modeling and KeyShot for damage visualization allows analysts to communicate complex findings. Predictive simulation, validated with ultrasound data, becomes the only viable defense to ensure safety in critical components of unmanned aircraft.
Is it possible for a carbon fiber laminate to pass all standard fatigue tests in the lab and still suffer a catastrophic in-flight fracture due to a failure mode not detected by 3D ultrasound?
(PS: Material fatigue is like yours after 10 hours of simulation.)