Composites can be manufactured using either resin transfer ...

Figure 6.5. FFT spectrum based on Abaqus results comparing the frequency response
of a [06/904/06]T orientation undamaged coupon and a coupon with an embedded crack
in the middle four plies. ...........................................................................................................52
Figure 6.6. Enlarged view of a FFT spectrum at frequencies near 976.6 Hz showing less
than 2% difference between the frequency response of a [06/904/06]T orientation
undamaged coupon and a coupon with an embedded crack in the middle four plies. .............52
Figure 6.7. Complete FFT spectrum for [016]T composite coupons comparing the
frequency response of undamaged to damaged coupons that is provided by varying the
depth of a surface crack. ..........................................................................................................53
Figure 6.8. An enlarged view of FFT spectrum for an [016]T undamaged composite
coupon and coupons with a surface crack of various depths for frequencies near: a)
976.6 Hz and b) 7.617 kHz. ....................................................................................................54
Figure 6.9. A graphical representation of RMS deviation between a [016]T undamaged
coupon and coupons with a surface crack of various depths as a function of crack depth. .....55
Figure 6.10. Complete FFT spectrum for [016]T composite coupons comparing the
frequency response of an undamaged coupon to coupons with a four ply deep crack at
various depths. .........................................................................................................................56
Figure 6.11. An enlarged view of a FFT spectrum for an [016]T undamaged composite
coupon and coupons with a four ply deep surface crack at various depths at frequencies
near: a) 976.6 Hz and b) 7.617 kHz. ........................................................................................56
Figure 6.12. A graphical representation of RMS deviation between a [016]T undamaged
composite coupon and coupons with a four ply deep crack at various depths as a
function of crack location. .......................................................................................................57
Figure 6.13. Complete FFT spectrum for [016]T composite coupons comparing the
frequency response of undamaged coupon to coupons with a four ply deep surface
crack at various locations across the coupon. ..........................................................................58
Figure 6.14. Enlarged view of FFT spectrum for an [016]T undamaged composite
coupon and coupons with a four ply deep surface crack at various locations at
frequencies near: a) 976.6 Hz and b) 7.617 kHz. ....................................................................59
Figure 6.15. A graphical representation of RMS deviation between an [016]T undamaged
composite coupon and coupons with a four ply deep surface crack at various locations
across the coupon. ....................................................................................................................60
Figure 7.1. A flow chart demonstrating the interface between MATLAB and Abaqus
that used for generating data set for sensor placement optimization (where count is the
iteration number). .....................................................................................................................62
Figure 7.2. A FE representation of longitudinal strain component contour plot observed
on the top surface of a composite coupon with an embedded crack in the middle. .................63
xiii