Structural Health Monitoring: Precise Data as a fundament for Structural Integrity
Structural Integrity, as an engineering discipline exists to ensure the
structure or a component of a structure is fit for purpose and can continue to
be so. Meaning it can support the basic features it was designed to carry –
carrying its weight, the weight added onto it, the mechanical load on it,
without prediction of potential deformation, cracks, catastrophic
The Necessity for Structural Health Monitoring (SHM) and basic definition of
The shift from simple experimental observation of complex structure to its Structural Health
Monitoring as a serious discipline has been driven by two factors:
the degradation and deterioration of construction materials (as well as lack
of economic efficiency while integrating these materials into larger
the availability of less expensive, yet more durable and efficient tools and
instruments as well as software-boosted systems, that in combination may help
accomplish the data collection/signal processing tasks necessary to maintain
longer structural integrity.
SHM is fundamentally the intelligent combination of traditional theoretical
structural mechanics, material science, electronics, with innovative data
acquisition, and software automated technologies.
The general aim of applications in this discipline is to achieve structures
that have safety and reliability characteristics that vastly differ from
traditional ones, in a positive manner.
Initially, the traditional means of
monitoring of I.e aircraft was based on the hours of flight or cycles of
landing it had performed. This made it necessary to retire these aircraft in a
pre-defined number of hours. With the development of systems connected to load
cycles and fatigue, the science boosted the possibilities: fatigue meters were
developed which counted of divergence of the present(positive and negative)
g-levels during use. Further down the line of course, much more advanced systems
came along such as Flight Data Recorder (FDR), Electro-Mechanical Mission
Computer (EMMC), etc.
The Aircraft Structural
Health Monitoring was not the only SHM focus area neither. In the early
days, non-destructive testing (NDT) methodologies were brought to civil
engineering through the ’40s. It was brought by the increasing necessity of
the engineers to perform in-situ determination of homogeneity and
strength(especially the compressive strength) of fresh concrete (i.e. for
The techniques of I.e. rebound hammer, pull-out test, etc. are systematized
and based on surface hardness measurements. The ageing of structures increased
the need for systems and tools that would allow detection of hidden,
under-surface defects, as well as estimation of changes in mechanical properties
in the materials.
Structural Health and Integrity are of course supposed to be
considered before the construction has started, and after the
construction is done – there should be relevant warranties of proper
condition, and maintenance strategies suggested for the structure.
One of the main no-brainers is that a structure requires periodical
maintenance checks to ensure its integrity to continue being used with the same
load, help predict the upcoming requirements for Maintenance and the means to
prevent Structural Health decline.
determination of the specific location of the damage;
calibration of the volume of the damage intensity;
prediction of the Remaining Structure Life in accordance with the
Depending on the method of the SHM used, and more specifically the kind of
sensors used to carry the above-listed tasks – there are different possible
outcomes, with different success rates. We tried to identify the most commonly
used ones, and identify the trends connected to these.
Structural health monitoring is commonly performed in two main ways –
passive and active. Passive SHM mostly measures various
operational parameters and then uses those as evidence to determine the state of
a structure. As useful as this method is, it does not directly detect and focus
on the essence of the issues.
As opposed to the passive SHM, the active SHM is focused on
directly assessing structural health through structural damage detection
This active SHM way combines especially the non-destructive
evaluation (NDE) methodologies, by taking them to the next level.
Instead of just performing non-destructive tests once in a while, the active SHM
aims to develop damage detection infrastructures, powered by sensors that can be
permanently installed on the structure and provide on-demand data on Structural
Over the years NDT methods have gained vast interest from the industry due to
the generally positive outcome they provide for the SHM. The most
commonly used NDT performed today are surface tests like dye
penetrants or magnetic particle technologies. In power generation, oil and gas,
manufacturing, and other industries, Eddy Current testing is a famous one as it
is a rather accurate way to inspect tubing, bolt holes, bars, etc. (it is
capable of detecting both surface and subsurface defects). However, current
conventionally used methods also have some downsides to them according to
scientific records and claims of professionals like;
Coin tapping – simple but time-consuming, predominantly
Vibration analysis – real-time possibility, but it is
hard to determine damage severity.
Thermography – non-contact, fast detection, needs a
Optical – limited by the information from the surface
and/or dusty environment.
Radiography methods – high resolution, expensive,
Eddy Current testing – limited penetration depth, the
surface must be accessible.
An unprecedented approach as a Structural Health Monitoring method
RVmagnetics strives to utilize an active SHM methodology
through a unique MicroWire
sensing system that provides on-demand, data (pressure, temperature,
vibrations, tensile, compression torque forces, etc.) with no physical contact
or wiring necessary, which can be collected and used to make the Predictive
Maintenance AI smarter as time goes by.
The cornerstone of the technology is the MicroWire. It is the
world’s smallest passive sensor. One of the main added values it provides is
the possibility to have it integrated into essential structural components.The
MicroWire is thin (3–70 µm) and flexible, so it does not increase an
additional weight or cause any physical deformation on an application
The data these sensors provide is extremely accurate even though no physical
contact or wiring is necessary in the vicinity of up to 10 cm distance from
them. The signal is processed through Magnetic field (only a few
mA necessary to generate).
Eventually, the system enables NDT in real-time, thus enabling the on-demand
data acquisition discussed if we have the active SHM methods. This, on top of
the safety-critical necessity to perform SHM, also adds a component of
stratification of the structures in question.
Whether it is reinforced concrete, petal or steel sheets, bearings or even
screws – this solution can equip the application with temperature, stress,
vibration, and other measurements. In addition to this, the two especially
productized spheres are the Monitoring of Colled rolled steel
Sheets and Monitoring of Composite Materials as such.