Smart composite solution for real-time NDT and predictive maintenance
If a composite material can be defined as a combination of two or more
distinct materials to attain new properties that can not be achieved by those of
individual components acting alone", then it is only natural that production
errors and material flaws will occur, as in every other manufacturing process.
These composite material flaws can have a butterfly effect on the whole
structure, which not only can bring tragic outcomes in the safety-critical
applications but can also damage the economic health of the composite
manufacturer and subsequently assembly companies.
Composite materials are fundamentally distinguished by polymer science
between thermoset and thermoplastic composites. Thermoplastics are softened when
heated and can be later re-melted and reúformed, whereas thermosets are put
through a chemical reaction when heated which is commonly called curing, and is
irreversible. Both are important for their application demands and requirements
and open up different yet exciting opportunities!
Based on this distinguishing method of the composite materials we can also
clarify their manufacturing methods
Thermoset Composites Manufacturing Methods:
Hand layup – resin coat is applied on a material
surface, after which i.e. a fabric reinforced material is placed
Vacuum bag – laminate layup is covered with an airtight
bag, after which the air is removed and the material is cured (20–40 degree)
under 1 bar pressure Autoclave – similar to the method above this process
also is in a vacuum. A material layup (i.e. the mould, prepreg, peel ply,
vacuum bag) is placed in an autoclave where vacuum, temperature and pressure on
the material can be controlled
Resin injection – In this method the mould usually
consists of top and bottom parts, and the space in between has the design and
thickness of the desired final product. Reinforced materials (fabrics, mats,
etc.) are placed in between the two moulds in dry plates. The resin is then
injected and cured in 25–40 degree celsius under 1 bar pressure.
Pultrusion – In this method a material is pulled through
a die (resin).
Filament winding – Dry spulls / creel of the material is
pulled through a comb, after which the material goes through resin bath and nip
rollers, and winded on a rotating mandrel on a desired shape.
High and low temperature compression moulding – similar
to resin injection this method requires moulds that consist of upper and lawyer
halves and have the desired shape of a final product – when a resin is
injected from the lawyer half, a staple is placed – pressure then shapes the
desired form of the final material
Thermoplastic Manufacturing methods:
Automated Tape Laying (ATL) – loaded roller system lais
unidirectional tapes on a mould. This helps change and control the degrees of
articulation depending of the complexity of the desired final product
Automated Fibre Placement (AFP) – significant strength
is used with a machine to place multi-layered composite products, usually
Melt impregnation techniques – usually used to
manufacture laminates of sandwich assembly. Fibre from the reel goes through
heating, polymer impregnation, calendering, water bath and finally pulled onto
Super plastic forming – argon gas is injected onto the
laminate which presses on a mould (the mould also has a die on the
Autoclave technique – the above mentioned autoclave
technique is also commonly used to produce flat laminates
Filament winding – to produce components with regular
geometric cross sections.
Types of damages
Composite materials also undergo a variety of damages and material behaviour,
which can also be specific per their type. To list the examples – common types of material behaviour
and damages of carbon composites include debonding, delamination,
deformation, solidification, wrinkling, matrix failure, crazing, broken
Manufacturing of anomaly detection methods are often inherent in composites,
naturally, the introduction of composites into large scale production directly
depends on the successful application of non-destructive testing
Even though some of the current NDT methods are better in certain
environments than the others, so far there isn’t introduced any “golden
mean” technology, whether using the coin tapping, vibration analysis,
thermography, optical, ultrasound, radiography methods or eddy current
testing – various limitations occur – limited accuracy, limited
penetration depth, composite surface accessibility, methods being cost-intensive
or time-consuming, limited use in a dusty industrial environment, need of a
vibration-free environment or being unable to determine damage severity, etc. In
general – only a few of them allow real-time measurements.
For any sector professional, it’s no secret that we are living in a world
where many composite-based structures are serving beyond the lifetime they were
designed for and they are likely to remain in service for even longer. Many
composite structures are in need of immediate attention. Their repair,
maintenance, or replacement will cost millions of dollars, however, it still
needs to take place.
New solutions for the composite industry
We at RVmagnetics believe – that the composite industry
needs to take a new road and develop smart self-monitored composites that can
provide significant added value on top of the traditional NDT methods. How?
MicroWires – miniaturized, magnetic, contactless microsensors of physical
quantities (sensing temperature, pressure, and magnetic field directly and pull,
axial stress, mechanical stress, torsion, bending, vibration, etc.
The MicroWires are composite materials themselves, they consist of metallic
nucleus and glass coating. MicroWire is a passive, unpowered element. To
“power” it – enable sensing and obtain real-time live data – a set of
coils (powered, active element) and electronics are placed within the range of
10cm and allow contactless sensing. Without causing any material flows, or
adding almost no additional weight MicroWires can be easily introducedinto composites such as
carbon fiber composites, glass fiber, ceramic composites, plastic
They can simply be embedded between composite layers in the production
process which, naturally gives you control over:
each part of the production process (e.g. measure temperature locally not
only on the surface but also in between the layers)
random inspections and defect detections
real-time live data about the current state of the composite (up to ten
thousand times per second resolution) through the lifetime the composite
Solution provides a real opportunity to create self-monitored composites that
reduce the likelihood of material failure, optimizes the production process to
manage composite properties minimizing material and production costs,
accelerating processes (composite decking, bonding, etc.) without
risking cracks or other failures. In a nutshell – increasing quality level
while decreasing material waste.
Combining AI with live data brings the opportunity to increase safety
drastically, provide data on remaining useful lifetime
(RUL) for the structure. The financial gain lays in reducing the frequency
of maintenance tasks, transforming the preventive and reactive maintenance into
Simply, a maintenance timetable can be created on the go.
While current structural health monitoring methods are valuable in detecting
and preventing potential damages in the production process or
post-production we strive for safety, real-time measurements and industry
transformation towards digital. MicroWire sensing technology provides a gateway
to real-time data from places that have been impossible to access thus far.
A few of the specific use cases are, for example:
Resin flow monitoring – where MicroWIres can be placed within the mold
layers and, as they can sense few microns of change in a physical space – the
resin flow can be clearly detected at each part where the wire is placed,
moreover, during the curing process and after, during the solidification
process, the MicroWire can provide real-time temperature and pressure data to
confirm if the composite has been cured properly, and weather the resin is
Filament Winding – MicroWire can be supplied on a spuul as well, and be
windied into the final product with the composite fibres. This gives the
opportunity to have a smart sensor within a composite material and detect
potential delaminations, shocks, misalignments, or – to receive data from
different depth of the material – to see the distribution of stress and
temperature within the depth of i.e. carbon fiber pressure vessels for hydrogen,
composite rebars, etc.
Curing – a composite material needs to be cured (i.e in autoclave) within
specific temperatures, length of curing and pressures applied onto the
material – our sensors give the unique advantage to do the monitoring of this
process directly from within, in real-time.
Wrinkling – there are limits and thresholds to certain levels of wrinkles,
bubbles, that can occur within the surface of a composite material (under the
fibres) – there hasn’t yet been clarified a process or system that can
properly identify the wrinkles, notify the manufacturing unit and confirm the
level of the error. MicroWire finds their application in a unique way here as
well – by detecting the position/pressure changes when wrinkles start to
With a B2B sales & marketing background in INGO & Foreign Investments in government sectors, Tigran is now responsible for extensive industry research in RVmagnetics focused on marketing the company both in R&D and Business spaces. Tigran is up to date with trends in deep tech, sensors, and innovative startups in need of niche growth. He shares the knowledge with RVmagnetics communities via blogs, publications, and news releases, while also using his experience to Manage RVmagnetics' Key Partners' accounts.