Modelling of shear lag effect for piezo-elstodynamic structure for electro-mechanical imedance technique
27 Mar 2015-Proceedings of SPIE (International Society for Optics and Photonics)-Vol. 9435, pp 743-754
TL;DR: In this paper, the authors review the existing shear lag models and discuss the recent advances in impedance based coupled piezo-structural impedance model considering the shear delay effect with all responsible piezoelectric parameters.
Abstract: The impedance based structural health monitoring (SHM) techniques have utilized the electro-mechanical coupling
property of piezoelectric materials (piezo-impedance transducers), due to their self-sensing nature (ability to act both as
actuators and sensors), and its diminutive in shape and size, cost effectiveness and ease of installation. The adhesive
bond acts as an elastic medium which facilitates the transfer of stresses and strains developed due to piezo displacement
and also couples the impedance of PZT patch with that of the host structure. The sensitivity of the electro-mechanical
impedance (EMI) technique can be enhanced by understanding shear mechanism phenomena of the adhesive layer. This
paper reviews the existing shear lag models and discuss the recent advances in impedance based coupled piezo-structural
model duly considering the shear lag effect with all responsible piezo-mechanical parameters.
Citations
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TL;DR: A literature review of electromechanical impedance spectroscopy for structural health monitoring, with emphasis in adhesively bonded joints, is presented in this article, where the concept behind electromechanica...
Abstract: The article presents a literature review of electromechanical impedance spectroscopy for structural health monitoring, with emphasis in adhesively bonded joints. The concept behind electromechanica...
33 citations
TL;DR: In this article , a flexible strain sensor tape framework is designed and developed using poly (vinylidene chloride - co- vinyl chloride) (PVDC - co - VC) and polystyrene sulfonate functionalized carbon nanotube (PSS-CNT) polymer nanocomposite with underneath adhesive coating and a copper contact pad atop the sensor.
Abstract: In the emerging flexible electronics field, flexible and wearable sensors play a crucial role. Though many reports focused on developing flexible sensors with novel materials, translational research is scarce. This work focuses on a design framework for flexible strain sensors considering the design scalability, packaging feasibility, and end users’ issues along with the performance. To be specific, a flexible strain sensor tape framework is designed and developed using poly (vinylidene chloride - co - vinyl chloride) (PVDC - co - VC) and polystyrene sulfonate functionalized carbon nanotube (PSS-CNT) polymer nanocomposite with underneath adhesive coating and a copper contact pad atop the sensor. At the outset, numerical simulation is also carried out to understand the impact of uneven adhesive thickness profile on the sensor performance and emphasis the necessity of uniform adhesive coating underneath the sensor. Further, the PVDC - co - VC/PSS-CNT polymer nanocomposite is systematically optimized to find its percolation threshold to achieve its maximum performance. Later, the scaled-up long flexible strain sensor tape is developed and validated by measuring the gauge factor (GF) in multiple positions along the length of the sensor tape; it shows the uniform GF value of 15.2 ± 0.8 which ensures the sensor’s repeatability and reproducibility. As a testimony, the developed flexible strain sensor is demonstrated for wearable electronics applications with an indigenously developed Internet of Things (IOT)-enabled portable interface device. The present flexible strain sensor tape design framework supports scalability and packaging feasibility and solves end users’ installation issues.
TL;DR: The main contribution of this work is focused on finding the maximum coupling load that a piezoelectric sensor can read before being debonded based on the minimum size constraint of the sensor.
Abstract: In this study, piezoelectric sensors design adhesively bonded on truss elements is treated in the framework of mathematical programming. A numerical formulation based on the strength capacity of set structure, adhesive and piezoelectric sensor is proposed. Inside the formulations maximum strength capacity of the adhesive is considered as a limit value in the design. Two formulations are established to obtain the maximum strength of the set; the first one is built on the basis of finite differences and the other one on a formulation of finite elements both based on an admissible static field. The lower bound method applied to limit analysis is extended in this research to analyze trusses with sensors including the adhesive interface. Four examples are designed to assess the numerical methodologies in which the results are compared with other known data. The main contribution of this work is focused on finding the maximum coupling load that a piezoelectric sensor can read before being debonded based on the minimum size constraint of the sensor.
References
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TL;DR: In this paper, a scaling analysis is performed to demonstrate that the effectiveness of actuators is independent of the size of the structure and evaluate various piezoelectric materials based on their effectiveness in transmitting strain to the substructure.
Abstract: This work presents the analytic and experimental development of piezoelectric actuators as elements of intelligent structures, i.e., structures with highly distributed actuators, sensors, and processing networks. Static and dynamic analytic models are derived for segmented piezoelectric actuators that are either bonded to an elastic substructure or embedded in a laminated composite. These models lead to the ability to predict, a priori, the response of the structural member to a command voltage applied to the piezoelectric and give guidance as to the optimal location for actuator placement. A scaling analysis is performed to demonstrate that the effectiveness of piezoelectric actuators is independent of the size of the structure and to evaluate various piezoelectric materials based on their effectiveness in transmitting strain to the substructure. Three test specimens of cantilevered beams were constructed: an aluminum beam with surface-bonded actuators, a glass/epoxy beam with embedded actuators, and a graphite/epoxy beam with embedded actuators. The actuators were used to excite steady-state resonant vibrations in the cantilevered beams. The response of the specimens compared well with those predicted by the analytic models. Static tensile tests performed on glass/epoxy laminates indicated that the embedded actuator reduced the ultimate strength of the laminate by 20%, while not significantly affecting the global elastic modulus of the specimen.
2,719 citations
"Modelling of shear lag effect for p..." refers background or methods in this paper
...Crawley and Anderson (1990) [7] further analyzed the previous strain transfer mode [6] (Crawley and De Luis, 1987) based on Euler–Bernoulli beam theory....
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...Crawley and de Luis (1987) [6] modelled the elastic bonding layer as a finite thickness between the PZT patch and structural beam, where patch was employed only as actuators....
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...For the static case, the shear lag effect was quantified in static analysis in terms of shear lag ratio [6,8] (Crawely and de Luis, 1987; Sirohi and Chopra, 2000a, b)....
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TL;DR: In this paper, techniques for modeling induced strain actuation of beam-like components of intelligent structures are developed, including two analytical models and one numerical model describing the detailed mechanics of induced strain actuators bonded to and embedded in one-dimensional structures.
Abstract: In this paper, techniques for modeling induced strain actuation of beam-like components of intelligent structures are developed. Two analytical models and one numer ical model describing the detailed mechanics of induced strain actuators bonded to and embedded in one-dimensional structures are presented. The models illustrate the exten sion, bending, and localized shearing deformations induced. The range of parameters for which the simpler analytic models are valid is also established. The specific characteris tics of one type of induced strain actuator, piezoceramic materials, are discussed, and im plications for practical use of piezoceramic actuators are outlined. Experimental results are used to validate the beam actuation models presented.
585 citations
03 Apr 1989
TL;DR: In this paper, techniques for modeling induced strain actuation of beam-like components of intelligent structures are developed, including two analytical models and one numerical model describing the detailed mechanics of induced strain actuators bonded to and embedded in one-dimensional structures.
Abstract: In this paper, techniques for modeling induced strain actuation of beam-like components of intelligent structures are developed. Two analytical models and one numer ical model describing the detailed mechanics of induced strain actuators bonded to and embedded in one-dimensional structures are presented. The models illustrate the exten sion, bending, and localized shearing deformations induced. The range of parameters for which the simpler analytic models are valid is also established. The specific characteris tics of one type of induced strain actuator, piezoceramic materials, are discussed, and im plications for practical use of piezoceramic actuators are outlined. Experimental results are used to validate the beam actuation models presented.
303 citations
"Modelling of shear lag effect for p..." refers methods in this paper
...Crawley and Anderson (1990) [7] further analyzed the previous strain transfer mode [6] (Crawley and De Luis, 1987) based on Euler–Bernoulli beam theory....
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TL;DR: In this paper, an orthotropic angle-ply laminate with an embedded piezoceramic patch is presented to show the coupling of bending and extension, and a comparison between the current work and that of Dimitriadis et al. is given.
Abstract: Classical laminated plate theory (CLPT) is applied to a laminate plate with induced strain actuators, such as piezoceramic patch, bonded to its surface or embedded within the laminate to develop an induced strain actuation theory that allows for the actuator patch to be spatially distributed. When piezoceramic patches are subjected to voltage fields, the equivalent external forces induced by piezoceramic patches can be determined upon the assumption of free constraint for the expansion or contraction of piezoceramic patches. This assumption is generally done in thermal expansion problem. Several examples, including pure bending and pure extension, are illustrated. For the case of pure bending, a comparison between the current work and that of Dimitriadis et al. (1989) is given. In addition, an orthotropic angle-ply laminate with an embedded piezoceramic patch is presented to show the coupling of bending and extension.
292 citations
"Modelling of shear lag effect for p..." refers background in this paper
...Since the adhesive does not change the material properties of adherents, attaching the PZT patches with adhesives has a broad range of applications than other bonding method [1] (Wang and Zeng, 2008)....
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TL;DR: In this paper, the authors analyzed the mechanism of force transfer through the bond layer and presented a step-by-step derivation to integrate the shear lag effect into impedance formulations, both one-dimensional and two-dimensional.
Abstract: The electromechanical impedance (EMI) technique for structural health monitoring (SHM) and nondestructive evaluation (NDE) employs piezoelectric-ceramic (PZT) patches, which are surface bonded to the monitored structures using adhesives. The adhesive forms a finitely thick, permanent interfacial layer between the host structure and the patch. Hence, the force transmission between the structure and the patch occurs through the bond layer, via shear mechanism, invariably causing shear lag. However, the impedance models developed so far ignore the associated shear lag and idealize the force transfer to occur at the ends of the patch. This paper analyses the mechanism of force transfer through the bond layer and presents a step-by-step derivation to integrate the shear lag effect into impedance formulations, both one-dimensional and two-dimensional. Further, using the integrated model, the influence of various parameters (associated with the bond layer) on the electromechanical admittance response is studied by means of a parametric study. It is found that the bond layer can significantly modify the measured electromechanical admittance if not carefully controlled during the installation of the PZT patch.
205 citations
"Modelling of shear lag effect for p..." refers background or methods or result in this paper
...For 2D case, the piezoelectric constitutive equations can be reduced to (Bhalla and Soh, 2004a)[3] ( ) 3 33 3 31 1 2 T D E d T T = + + ε (20)...
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...(2006) [3] experimentally studied the effect of both the thickness adhesive as well as the type of adhesive layer used to bond the patch to the host structure....
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...…the inertia term, the impedance modification factor (ξ ), which was only ‘qualitatively’ described by Xu and Liu (2002) [9], was rigorously derived by Bhalla and Soh (2004c) [3] and for a square PZT patch as 0 0 1 11 eff u P u ζ = ⎛ ⎞′ + ⎜ ⎟⎜ ⎟ ⎝ ⎠ (6) where p is defined as s s s wGp Z h jω =…...
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...It was found that the both the adhesive composition and the thickness could considerably affect the measured EMI signature, the observation closely matching those of Bhalla and Soh 2004c [3]....
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...The governing dynamic shear lag equation (Bhalla and Soh, 2004c) [3] for a structural element shown in Fig....
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