FDTD TECHNIQUES TO SIMULATE COMPOSITE AIR …...• FDTD is able to handle COMPLEX 3D (Dispersive,...

Salvador G. Garcia, UGR

FDTD TECHNIQUES TO SIMULATE COMPOSITE AIR

VEHICLES FOR EMC• Luis D. Angulo – University of Granada• Sandra Greco – University of Rome La Sapienza• Miguel Ruiz Cabello – University of Granada• Salvador G. García – University of Granada• Maria Sabrina Sarto – University of Rome La Sapienza

Partially supported by:

Salvador G. Garcia, UGR

OUTLINE• MOTIVATION

• CEM in EMC: PROJECT

• CFRC COMPOSITES: EQUIVALENT MIBC• TIME DOMAIN: MIBC FOR FDTD• EXAMPLES• STABILITY, CAUSALITY AND PASSIVITY• MIBC FOR FEM: DGTD• CONCLUSIONS

Salvador G. Garcia, UGR

MotivationUSE OF COMPOSITES IN AIRCRAFTS

Salvador G. Garcia, UGR

CEM EMCNEED OF HIGH PERFORMANCE COMPUTER TOOLS

Full Wave Time Domain: BROADBAND

• FDTD is able to handle COMPLEX 3D (Dispersive, Anisotropic, Non-Linear, PML…)

• DGTD is a highly accurate alternative to FDTD

REQUIRE VOLUMIC MESHING ► HIGH CPU/MEMORY• SUBCELL MODELLING NECESSARY TO REDUCE

COMPUTATIONAL COSTS (THIN-XXXXX)– THIN-LAYERS, THIN-SLOTS, THIN-WIRES

44 EUROPEAN PARTNERS: SYNTHETIC FRAMEWORK

Salvador G. Garcia, UGR

CFRC LAMINATESEQUIVALENT LAYER MODEL

( ) ( ) ( ) ( )( ) ( ) ( ) ( )

front fr bkfront back front front

bk fr backfront back back back

Z Z HZ ZH H H

NORMAL INCIDENCE IN A MULTILAYER:

MIBC

Salvador G. Garcia, UGR

MIBC enables:- To model field penetration trough conducting

structures;- To predict diffusion of magnetic field in conducting

enclosures;- To predict redistribution effect of electromagnetic field in

conducting enclosures.

D'Amore, M.; Sarto, M.S.; , "Theoretical and experimental characterization of the EMP-interaction with composite-metallic enclosures," Electromagnetic Compatibility, IEEE Transactions on , vol.42, no.2, pp.152-163, May 2000

MIBC vs SIBC

Salvador G. Garcia, UGR

1 1

( ) ( ) ( ) ( )k

N Np tk

kk kk

RZ Z Z t Z t R e u tj p

( ) ( ) ( ) ( ) ( ') ( ') 't

E Z H E t Z t t H t dt

Frequency dispersion VECTOR-FITTED as the sum of complex-conjugate pole-residue pairs fractions

IMPEDANCE BOUNDARY CONDITIONS

FOR RESULTS IN THIS WORK THE CODE IS PROVIDED BY

CONVOLUTION

Salvador G. Garcia, UGR

FDTD EMC HIRF SOLVER• Yee Cell Structured mesh• Finite Difference in space.• Leap Frog in Time.

• Very simple explicit algorithm• MPI parallel• Locally conformal (with Dey-Mittra stabilization)

www.ugrfdtd.esUGR PARALLEL HPC

FDTD&

UGR HOLLAND-BERENGER MULTIWIRE

BUNDLE SOLVER+

URM MIBCTHIN-PANEL SOLVER

Salvador G. Garcia, UGR

M. S. Sarto, “A new model for the FDTD analysis of the shielding performances of thin composite structures,” IEEE Trans.Electromagn. Compat., vol. 41, no. 4, pp. 298–306, Nov. 1999.

e. g. carbon fiber composites, graphene ► anisotropy

,0 ,0 , ,00

,0 ,0 , ,00

, , ,

, ,

( )( )( )( )

( ) , ( )- ( )( )- ( )( )

ISO ANI ISO ANIy y y t y tzyANI ISO ANI ISOz z z t z tyz

ISO ANI Izdyd y t y t y d

ANI ISOydzd z t z t

Z Z Z ZHZ Z Z ZH

Z ZH Z Z ZH Z Z

,

, ,

SO ANIy d

ANI ISOz d z d

ZZ Z

0ANIZ

DISPERSIVE ANISOTROPIC MIBC

1/2,... 1/2,...n ni iHz Hz

TIME DOMAIN

NOT YEE’sYEE’s

1 11, 2, 3,

1

,N

n n n n n n nk k k k k k

K

E Z H q q H q H

CO-LOCATED IN TIME AND IN SPACE!

PIECEWISE LINEAR RECURSIVE CONVOLUTION

DUPLICATED UNKNOWNS

Salvador G. Garcia, UGR

EXPLICIT SCHEME

Salvador G. Garcia, UGR

Prepreg copper mesh 10 POLES VF

SIMULATIONANALYTICAL

RESULTS: ISOTROPIC

Salvador G. Garcia, UGR

RESULTS: ISOTROPIC

SIMULATION (Gaussian pulse derived)ANALYTICALSIMULATION (Gaussian pulse)

CFC (0.5 mm, 0º) + WOOD (5 mm) + CFC (0.5 mm, 90º)20 POLES VF

Salvador G. Garcia, UGR

Aluminum foil (0.3 mm) Measurements in a dual reverberating chamber

RESULTS: ISOTROPIC

Salvador G. Garcia, UGR

COPPER MESH4 POLES VF

RESULTS: ANISOTROPIC

TE SIMULATIONTM SIMULATIONTE ANALYTICALTM ANALYTICAL

Salvador G. Garcia, UGR

SENSITIVITYANISOTROPIC MESHED MODEL

Freq

SE

(dB

)

PBC

PBC

PBC

PBC PBC PBC

PBC

PBC

Salvador G. Garcia, UGR

LATE-TIME INSTABILITIES!

ENSURE• STABILITY• CAUSALITY• PASSIVITY

STABILITY Boundedness

( ) analytic 0 iffZ -1

lim Z(t)

Z(t) =Fourier ( )t

Z

Trivial!

CAUSALITY Response AFTER excitation

1

( ) ( ) ( )N

kr i

k k

RZ Z Z j Zj p

( )lim 0

( )1( ) ''

( )1( ) ''

ir Cauchy

ri Cauchy

Z

ZZ P d

ZZ P d

KRAMER-KRONIG

Automatic! Re 0kp

Salvador G. Garcia, UGR

PASSIVITY

( ) 0 , ( )=Eigenvalues ( ) ( ) Reals HZ Z

( ) 0 , 0 , 1...4iiZ i

NOT AUTOMATIC IN VECTOR-FITTING!

WORKAROUND IN LEAP-FROG:

• Tune number-of-poles, band fitting• Stable time-step GREATER than maximum

Nyquist period for non-passive behavior

• Other conditions for Runge-Kutta | ( ) 0 COURANTt t

Min

Salvador G. Garcia, UGR

ACCURATE ALTERNATIVE TO FDTD : DGTDThe field is allowed to be DISCONTINUOUS at the boundaries

• COMMUNICATE ADJACENT ELEMENTS THROUGH NUMERICAL FLUXES• QUASI-EXPLICIT • DOES ANYTHING FDTD DOES! (DISPERSIVE, SIBC, etc.)

DISCONTINUOUS GALERKIN FEM

Size ~ q2 ,q=Basis order Flux terms

Salvador G. Garcia, UGR

MIBC MMT FOR DGTD

MODIFY the flux conditions for PEC:

with

PEC, PMC FLUX CONDITIONS

PLRC TIME DOMAIN

Salvador G. Garcia, UGR

SIBC MMT FOR DGTD

VALIDATION: ISOTROPIC CASE

Salvador G. Garcia, UGR

REAL AIRCRAFT

FDTD:cells: 703.704.332d.o.f: 4.394.792.584 DGTD:elements: 8.845.279d.o.f: 966.682.616

freq (MHz)

Cur

rent

inca

ble

(A)/

Ein

(V/m

)

100 101 102 10310-5

10-4

10-3

10-2

FDTDDGTD

freq (MHz)

Hto

tal/

Hin

100 101 102 10310-3

10-2

10-1

100

101

FDTDDGTD

Salvador G. Garcia, UGR

MECHANICAL MODEL

MESH/REPAIR

INPUT/OUTPUT FILE (HIRF-SE STANDARD)

MTLN CRIPTE+MPI HPC PARALLEL SOLVERS: EMC, RCS, ANTENNAS, etc.

CONCLUSIONSVALIDATED TOOL FOR HIRF-SE CERTIFICATION OF METALIC AND COMPOSITE AIRCRAFTS

Salvador G. Garcia, UGRTHANK YOU!

UPCOMING:

+

Salvador G. Garcia, UGR

UGRFDTD• Periodic BC, PEC, PMC, CPMPL ABCs• Uneven mesh spaced grid• N-pole/residues nth order frequency dependent materials Sub-cell single-

conductor cable model and junctions (multiconductor ongoing) • Resistive loading of cables • Lossy anisotropic materials • Thin Slots • Bi-anisotropic, periodic, DNG media (ongoing)• Excitations: plane wave, dipoles, cable voltage sourceMixed MPI

paralellization/OpenMP• Portable: Tested in Cray-PGI, Sunstudio Fortran, Intel Fortran, GNU fortran• GUI: GiD (ongoing), interim: CADFIX.

• Coupled with CRIPTE cable bundle solver (ongoing through )• Coupled with IELF and FSV (through )