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Innovation & Technologie Angebot

Remote structural health monitoring of civil infrastructure

Country of Origin: Italy
Reference Number: TOIT20181016004
Publication Date: 16 October 2018

Summary

An Italian research center offers a patented technique based on mid infrared digital holography, enabling real-time remote monitoring of displacements/deformations/vibrations of large size structures. It provides a precise estimate of the amplitude and frequency of the natural oscillation of the structure, establishing its functionality and health status.
A company to turn the prototype into a product and bring it to the market is searched, offering manufacturing and technology agreement.

Description

The dynamic characterization of a large size structure (building, wall, bridge, …) implies the knowledge of its fundamental oscillation modes and provides crucial information on the elastic response of the structure to seismic events, environmental stress (wind, rain and natural calamities) or anthropogenic activities (rail or vehicular traffic, underground works, etc.). Currently, such a characterization is obtained by means of seismometers, synthetic aperture radar or laser doppler vibrometers. Such devices, however, have serious drawbacks which prevent their application at a large scale. 

The Italian research center proposes a method which overcomes these critical issues and paves the way to systematic seismic vulnerability experimental assessment.



The system relates to a technology based on Mid Infrared Digital Holography (MIR DH), an interferometric imaging technique providing amplitude and phase information on the wavefront scattered by an object irradiated with IR coherent radiation. In DH, the interferometric pattern (hologram) resulting from the superposition of the radiation scattered by the target and an appropriate reference beam is recorded on a suitable digital recording device so that it can be numerically processed to extract the wave-front information. The phase information, in particular, is related to the optical path length of the laser and, consequently, to the target displacements. With respect to visible DH, Infrared DH inherently benefits from wavelength scaling of both mechanical stability requirements and linear field of view, thus proving to be perfectly suited for large size structures monitoring.



The system has been patented, filing an Italian Patent and an International Patent. The two applicants are the Italian research centre and an important  Italian University.



A prototype employing a compact radiofrequency CO2 laser at 10.6 μm, a thermal focal plane array, IR optics and electronic/software components for device control and data processing was developed. Such a semi-portable device was positively tested in the laboratory and in the field to measure the oscillation modes of a four-story building. The comparison with seismometric measurements has provided very promising results for the use of the holographic method in the framework of structural monitoring. 



The research center is looking for an industrial partner that, with their assistance, will develop an engineered and certified commercial device (equipped with user friendly software and dedicated electronic circuitry) with the same technical specifications as the advanced prototype but optimized for its compactness, robustness and functionality.

The commercial device will be sold/rent to Engineering Societies dedicated to seismic vulnerability assessment or industrial vibration monitoring.

A manufacturing agreement and a technical cooperation agreement will be defined to develop a "commercial" product based on the offered technology.

Advantages and Innovations

The infrared holographic technique allows to measure the amplitude and frequency of the oscillation modes of the structures from remote, in an extremely short time (few minutes), with a limited use of human resources and with a sensitivity of the order of the tenth of a micron in the determination of the oscillation amplitude.

This simplified measurement procedure reflects directly into a drastic reduction in costs and measurement times thus making it possible to monitor all buildings and bridges in entire urban areas. 

The holographic technique also has clear advantages when it is necessary to evaluate the conditions of damaged structures as it allows to carry out surveys without accessing the structure and, therefore, in absolute safety. 

With this technique it is also possible to simultaneously investigate extended surfaces of the structure, obtaining a real map of the deformations/displacements of the surface under examination. 

Finally, the technique is also able to follow drift motions of the examined structure.



No real competitor is currently present on the market.



The IP and know-how could be easily transferred to a third part with minimum expertise in the field of optical measurement/imaging.

Stage Of Development

Field tested/evaluated

Requested partner

A small or medium company with optical, mechanical and electronic expertise is sought to realize the final engineered and certified commercial device.