Case Study: Boeing achieves improved thermal stability and reduced coating‑crack risk in composite lightning‑strike protection with COMSOL Multiphysics

Boeing Simulates Thermal Expansion in Composites with Expanded Metal Foil for Lightning Protection of Aircraft Structures

Boeing faced the challenge of protecting the carbon-fiber composite structure of the 787 Dreamliner from lightning strikes by adding expanded metal foil (EMF) without inducing thermal-stress cracking in the protective coatings during flight thermal cycles. To evaluate coating failure risk and optimize EMF design, Boeing researchers used Comsol’s COMSOL Multiphysics to simulate thermal expansion and stress in a multi-layer composite layup representative of aircraft skin.

Using COMSOL Multiphysics’ Thermal Stress interface, Boeing built a coefficient-of-thermal-expansion (CTE) model that coupled heat transfer and solid mechanics, inputting custom material properties and varying EMF parameters (material, height, width, aspect ratio). Comsol simulations quantified layer stresses and displacements and showed key effects—e.g., increasing EMF height by 4× raised displacement by ~60%, mesh aspect-ratio changes reduced displacement by ~2%, and mesh-width changes altered displacement by ~3%—and predicted higher displacements and cracking risk for aluminum EMF versus copper. Experimental tests validated the Comsol results (copper layups showed no cracks; aluminum did), guiding Boeing to favor copper EMF and specific mesh design trade-offs to reduce crack risk and maintenance.

Boeing

Jeffrey Morgan

Project Lead