Enhanced Polymer Nanocomposites for Condition Assessment of Wind Turbine Blades

Damages in composite components of wind turbine blades and large-scale structures can lead to increase in maintenance and repair costs, inoperability, and structural failure. The vast majority of condition assessment of composite structures is conducted by visual inspection and non-destructive evaluation (NDE) techniques. NDE techniques are temporally limited, and may be further impeded by the anisotropy of the composite materials, conductivity of the fibers, and the insulating properties of the matrix. In previous work, the authors have proposed a novel soft elastomeric capacitor (SEC) sensor for monitoring of large surfaces, applicable to composite materials. This soft capacitor is fabricated using a highly sensitive elastomer sandwiched between electrodes. It transduces strain into changes in capacitance. Here, we present a fabrication method for fabricating the SEC. Different surface treatment techniques for the nanoparticles are investigated and the effects on the mechanical and the electrical properties of the produced film are studied. Results show that using melt mixing fabrication method was successful at dispersing the nanoparticles without using any surface treatment, including coating the particles with PDMS oil or the use of Si-69 coupling agent. Yet, treating the surface would result in increasing the stiffness of the matrix as well as improving the interaction between the filler particles and the matri

Large-scale surface strain gauge for health monitoring of civil structures

Health monitoring of civil structures is a process that aims at diagnosing and localizing structural damages. It is typically conducted by visual inspections, therefore relying vastly on the monitoring frequency and individual judgement of the inspectors. The automation of the monitoring process would be greatly beneficial by increasing life expectancy of civil structures via timely maintenance, thus improving their sustainability. In this paper, we present a sensing method for automatically localizing strain over large surfaces. The sensor consists of several soft capacitors arranged in a matrix form, which can be applied over large areas. Local strains are converted into changes in capacitance among a soft capacitors matrix, permitting damage localization. The proposed sensing method has the fundamental advantage of being inexpensive to apply over large-scale surfaces. which allows local monitoring over large regions, analogous to a biological skin. In addition, its installation is simple, necessitating only limited surface preparation and deployable utilizing off-the-shelf epoxy. Here, we demonstrate the performance of the sensor at measuring static and dynamic strain, and discuss preliminary results from an application on a bridge located in Ames, IA. Results show that the proposed sensor is a promising health monitoring method for diagnosing and localizing strain on a large-scale surface

Dynamic characterization of a soft elastomeric capacitor for structural health monitoring applications

A novel thin film sensor consisting of a soft elastomeric capacitor (SEC) for meso-scale monitoring has been developed by the authors. Each SEC transduces surface strain into a measurable change in capacitance. In previous work, the authors have shown that the performance of the SEC compares well with conventional resistive strain gauges, providing a resolution of 25 με using an inexpensive off-the-shelf data acquisition system for capacitance measurements. Here, we further the understanding of the thin film sensor by characterizing its dynamic behavior. The SEC is subjected to dynamic loads in bending mode. The study of Fourier and wavelet transforms indicates that the sensor can be used to identify dynamic inputs. Overall results demonstrate the promising capabilities of the thin film sensor at dynamic monitoring of civil structures.This proceeding is published as Hussam Saleem, Simon Laflamme, Filippo Ubertini, "Dynamic characterization of a soft elastomeric capacitor for structural health monitoring applications", Proc. SPIE 9061, Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2014, 906115 (8 March 2014); doi: 10.1117/12.2045324. Posted with permission.</p

Enhanced Polymer Nanocomposites for Condition Assessment of Wind Turbine Blades

Damages in composite components of wind turbine blades and large-scale structures can lead to increase in maintenance and repair costs, inoperability, and structural failure. The vast majority of condition assessment of composite structures is conducted by visual inspection and non-destructive evaluation (NDE) techniques. NDE techniques are temporally limited, and may be further impeded by the anisotropy of the composite materials, conductivity of the fibers, and the insulating properties of the matrix. In previous work, the authors have proposed a novel soft elastomeric capacitor (SEC) sensor for monitoring of large surfaces, applicable to composite materials. This soft capacitor is fabricated using a highly sensitive elastomer sandwiched between electrodes. It transduces strain into changes in capacitance. Here, we present a fabrication method for fabricating the SEC. Different surface treatment techniques for the nanoparticles are investigated and the effects on the mechanical and the electrical properties of the produced film are studied. Results show that using melt mixing fabrication method was successful at dispersing the nanoparticles without using any surface treatment, including coating the particles with PDMS oil or the use of Si-69 coupling agent. Yet, treating the surface would result in increasing the stiffness of the matrix as well as improving the interaction between the filler particles and the matrixThis proceeding is published as Saleem, H., M. Thunga, M. Kollosche, M. Kessler, and Simon Laflamme. "Enhanced polymer nanocomposites for condition assessment of wind turbine blades." In Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2013, vol. 8694, p. 86940A. International Society for Optics and Photonics, 2013. DOI: 10.1117/12.2009856. Posted with permission.</p

Large-scale surface strain gauge for health monitoring of civil structures

Health monitoring of civil structures is a process that aims at diagnosing and localizing structural damages. It is typically conducted by visual inspections, therefore relying vastly on the monitoring frequency and individual judgement of the inspectors. The automation of the monitoring process would be greatly beneficial by increasing life expectancy of civil structures via timely maintenance, thus improving their sustainability. In this paper, we present a sensing method for automatically localizing strain over large surfaces. The sensor consists of several soft capacitors arranged in a matrix form, which can be applied over large areas. Local strains are converted into changes in capacitance among a soft capacitors matrix, permitting damage localization. The proposed sensing method has the fundamental advantage of being inexpensive to apply over large-scale surfaces. which allows local monitoring over large regions, analogous to a biological skin. In addition, its installation is simple, necessitating only limited surface preparation and deployable utilizing off-the-shelf epoxy. Here, we demonstrate the performance of the sensor at measuring static and dynamic strain, and discuss preliminary results from an application on a bridge located in Ames, IA. Results show that the proposed sensor is a promising health monitoring method for diagnosing and localizing strain on a large-scale surface.This proceeding is published as Simon Laflamme, Matthais Kollosche, Venkata D. Kollipara, Hussam S. Saleem, Guggi Kofod, "Large-scale surface strain gauge for health monitoring of civil structures", Proc. SPIE 8347, Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2012, 83471P (5 April 2012); doi: 10.1117/12.913187. Posted with permission.</p

Soft Elastomeric Capacitor Network for Strain Sensing Over Large Surfaces

Field applications of existing sensing solutions to structural health monitoring (SHM) of civil structures are limited. This is due to economical and/or technical challenges in deploying existing sensing solutions to monitor geometrically large systems. To realize the full potential of SHM solutions, it is imperative to develop scalable cost-effective sensing strategies. We present a novel sensor network specifically designed for strain sensing over large surfaces. The network consists of soft elastomeric capacitors (SECs) deployed in an array form. Each SEC acts as a surface strain gage transducing local strain into changes in capacitance. Results show that the sensor network can track strain history above levels of 25 με using an inexpensive off-the-shelf data acquisition system. Tests at large strains show that the sensor's sensitivity is almost linear over strain levels of 0-20%. We demonstrate that it is possible to reconstruct deflection shapes for a simply supported beam subjected to quasi-static loads, with accuracy comparable to resistive strain gages.This is an author's manuscript of an article from IEEE/ASME Transactions on Mechatronics 18 (2013): 1647–1654, doi.10.1109/TMECH.2013.2283365. Posted with permission.</p