Aerospace & Defense Technology - June 2021 - 6

Military Aerospace Technology
part complexity, time available, cost,
and the level of safety needed.
Relatively new to the field of composite
inspection is X-Ray Tomography
or Computed Tomography (CT).
This inspection approach, propelled
forward by significant advances in CT
analysis software, can look deeply into
materials of almost any kind, from
resin-fiber panels to aerospace aluminum.
Revealing characteristics that
cannot be captured and visualized
with any other technology, these
three-dimensional inspections are the
foundation for trust in high-performance,
high-safety aerospace parts
and assemblies.
Why is this software technology
particularly important now? Aside
from the intense economic pressures
on the aerospace industry for efficiency
and fast, early-stage successes,
both in design and production, new
material and manufacturing strategies
need to be fully quantified and
understood. More than ever, the tools
are ready to provide validation of designs
to their manufactured versions
at the end of (and increasingly even
during) production lines, as well as to
help predict the behavior of materials
and construction strategies in the
R&D stage.
State of Computed Tomography (CT)
Today's CT analysis software has benefited
from giant leaps made in highperformance
computing and corresponding
development of powerful al go -
r ithms and user-interfaces. Technical
challenges are much more easily
solved than even a few years ago. For
example, leading scan-data analysis
software can now peer into very complex
or dense materials to create highresolution,
dimensionally accurate,
3D volume (voxel) images and numerical
analyses that address pressing engineering
questions.
Together, the numerical outputs and
color-coded, 3D images derived from
analysis software expose the microstructure
of composites, offering As-Designed
and As-Manufactured comparisons critical
to quality, closed-loop inspections
and the archiving of digital twin representations
at each point of creation.
6
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Figure 2. (Left) Orientation analysis carried out on a glass-fiber-reinforced sheet-molding compound
(SMC). Each direction is coded by a certain color. This orientation data can be used to obtain fiber orientation
distributions over the thickness to validate flow simulations and to provide reliable data for the
structural simulation. Image courtesy of IAM-WK / KIT (Institute for Applied Materials/ Karlsruhe Institute
of Technology), Germany. (Right) Local orientation histograms of a woven fabric are shown in yellow. Using
the principal orientations of these histograms allows engineers to measure the local shear angle of the
material after the draping process. (Image courtesy of Volume Graphics)
Figure 3. Porosity (upper left and top images) and fiber orientation (upper right image) can be visualized
and quantified using a single CT-scan. Both results can be mapped onto a FE-Mesh (bottom-center image)
to be used locally as inputs for the material modelling for structural analyses or in order to validate
process simulations. (Image courtesy of Volume Graphics)
Programs exist as standalones or in a
turnkey package that will analyze material
density, orientation of reinforcement
structures, internal defects (adhesive failure,
delamination, cracking, etc.) originating
from design and manufacturing flaws
or overload, and strain patterns calculated
from multiple scans of different states of a
sample using digital volume correlation.
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ToC
Any type of structure can be captured
and characterized against its design intent-from
autoclave to additively manufactured
hybrid composites. Templates
can be created to rapidly and repeatedly
analyze part features and problems automatically.
This includes porosity analysis
(e.g., the pore volume and distance
from the surface); fiber and resin analyAerospace
& Defense Technology, June 2021

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Aerospace & Defense Technology - June 2021

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