A Comparison of MAFIA / Microwave Studio Calculations with Experimental Results for Indirect Lightning Effects on Carbon Composite Structures

A study of indirect lightning effects on carbon composite structures with internal tubing is performed using the ‘ab initio’ Maxwell equation codes MAFIA and Microwave Studio (MWS). The modeling is performed both in the time and frequency domain by a finite difference method that can accommodate anisotropic media. Both time and frequency domains are used to better reflect the actual testing performed on aircraft. Solutions in frequency domain also help to overcome limitations of the time domain calculations. Time calculations cannot be performed for pulses longer than 100–200 μs due to the Courant condition and computer time limitations and hence, low frequency resonances of the system could be missed. Three dimensional frequency domain calculations are available with MAFIA and MWS, while time domain results are available in MAFIA, MWS and EMA3D. The results of the time domain calculations are compared with experiments in the frequency domain by taking the Fourier transforms of the results. The driving current input pulse is given, the currents densities and voltage distribution are computed throughout the entire structure. Boundary conditions are chosen to closely replicate the ones present in the experiment. The current distribution on the external wing skin and internal components is compared to experimental values. From the computed field distributions the voltages between critical points can be determined to ascertain breakdown conditions.