Portable equipment for in situ health monitoring of material

The thermal effects at elevated temperatures mostly exist for pressure vessel and pipe (PVP) applications. The technologies for diagnosis and prognosis of PVP systems need to take the thermal effect into account and compensate it on sensing and monitoring of PVP structures. One of the extensively employed sensor technologies has been permanently installed piezoelectric wafer active sensor (PWAS) for in-situ continuous structural health monitoring (SHM). Using the transduction of ultrasonic elastic waves into voltage and vice versa, PWAS has been emerged as one of the major SHM sensing technologies. However, the dynamic characteristics of PWAS need to be explored prior its installation for in-situ SHM. Electro-mechanical impedance spectroscopy (EMIS) method has been utilized as a dynamic descriptor of PWAS and as a high frequency local modal sensing technique by applying standing waves to indicate the response of the PWAS resonator by determining the resonance and anti-resonance frequencies. Another SHM technology utilizing PWAS is guided wave propagation (GWP) as a far-field transient sensing technique by transducing the traveling guided ultrasonic waves (GUW) into substrate structure. The paper first presents EMIS method that qualifies and quantifies circular PWAS resonators under traction-free boundary condition and in an ambience with increasing temperature. The piezoelectric material degradation was investigated by introducing the temperature effects on the material parameters that are obtained from experimental observations as well as from related work in literature. GWP technique is also presented by inclusion of the thermal effects on the substrate material. The MATLAB GUI under the name of Wave Form Revealer (WFR) was adapted for prediction of the thermal effects on coupled guided waves and dynamic structural change in the substrate material at elevated temperature. The WFR software allows for the analysis of multimodal guided waves in the structure with affected material parameters in an ambience with elevated temperature.

Download Full-text

Diagnostics and monitoring of the longest span extradosed bridge in Europe

IABSE Congress, New York, New York 2019: The Evolving Metropolis ◽

10.2749/newyork.2019.0794 ◽

2019 ◽

Author(s):

Mikołaj Miśkiewicz ◽

Krzysztof Wilde

Keyword(s):

Health Monitoring ◽

Diagnostic Procedures ◽

Theoretical Assumptions ◽

Speed Up ◽

Internal Forces ◽

Post Tension ◽

Cantilever Construction ◽

Final Acceptance ◽

Acceptance Tests

<p>The article presents complex diagnostic procedures applied for the purpose of behavior analysis of the extradosed bridge with the longest span in Europe that was built in 2018 in Poland. The system of health monitoring was used to: register internal forces in temporary supports, monitor concrete bonding, perform in situ diagnostics and operation tests. The bridge is a continuous four‐span structure with spans theoretical lengths equaling: 132.5+206.0+206.0+132.5 m. During the construction of the bridge, two technical monitoring systems were used. As a consequence of their application, it was possible to carry out works with the lowest level of risk and therefore the work schedule was accelerated. The first of systems was designed to measure forces transferred to temporary supports during cantilever construction stages. The second system was designed to measure changes of the strength of curing concrete, after it was poured at the site, which allowed to speed up the removal of the scaffoldings and post‐tension of cross section with cables. When the bridge was finished, a Structural Health Monitoring (SHM) system was installed and final acceptance tests were launched. The obtained results were used to validate theoretical assumptions done at the stage of the bridge structural design and provided insight into the complex bridge behavior.</p>

Download Full-text

In-Situ Health Monitoring of Aerospace Structures via Dynamic Strain Measurements

AIAA Scitech 2019 Forum ◽

10.2514/6.2019-1758 ◽

2019 ◽

Cited By ~ 1

Author(s):

Benjamin L. Martins ◽

John B. Kosmatka

Keyword(s):

Health Monitoring ◽

Dynamic Strain ◽

Aerospace Structures ◽

Strain Measurements

Download Full-text

Comparative evaluation of in situ stress monitoring with Rayleigh waves

Structural Health Monitoring ◽

10.1177/1475921718798146 ◽

2018 ◽

Vol 18 (1) ◽

pp. 205-215 ◽

Cited By ~ 7

Author(s):

James Martin Hughes ◽

James Vidler ◽

Ching-Tai Ng ◽

Aditya Khanna ◽

Munawwar Mohabuth ◽

...

Keyword(s):

Rayleigh Wave ◽

Harmonic Generation ◽

Health Monitoring ◽

Rayleigh Waves ◽

Second Harmonic ◽

Monitoring Systems ◽

Stress Monitoring ◽

Bulk Waves ◽

Health Monitoring Systems

The in situ monitoring of stresses provides a crucial input for residual life prognosis and is an integral part of structural health monitoring systems. Stress monitoring is generally achieved by utilising the acoustoelastic effect, which relates the speed of elastic waves in a solid, typically longitudinal and shear waves, to the stress state. A major shortcoming of methods based on the acoustoelastic effect is their poor sensitivity. Another shortcoming of acoustoelastic methods is associated with the rapid attenuation of bulk waves in the propagation medium, requiring the use of dense sensor networks. The purpose of this article is twofold: to demonstrate the application of Rayleigh (guided) waves rather than bulk waves towards stress monitoring based on acoustoelasticity, and to propose a new method for stress monitoring based on the rate of accumulation of the second harmonic of large-amplitude Rayleigh waves. An experimental study is conducted using the cross-correlation signal processing technique to increase the accuracy of determining Rayleigh wave speeds when compared with traditional methods. This demonstrates the feasibility of Rayleigh wave–based acoustoelastic structural health monitoring systems, which could easily be integrated with existing sensor networks. Second harmonic generation is then investigated to demonstrate the sensitivity of higher order harmonics to stress-induced nonlinearities. The outcomes of this study demonstrate that the sensitivity of the new second harmonic generation method is several orders of magnitude greater than the acoustoelastic method, making the proposed method more suitable for development for online stress monitoring of in-service structures.

Download Full-text