1,721,038 research outputs found
Non-probabilistic analysis of laminated composites based on fuzzy uncertainty quantification
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Effect of size-dependent properties on electromechanical behaviour of composite structures
No full textDue to its electromechanical applications in the form of nanodevices such as distributors, actuators, and sensors, the electromechanical behavior of piezocomposite structures becomes a new avenue for research. This article presents the derivation of an exact analytical solution of the composite plate based on theory of Kirchhoff’s plate and extended theory of piezoelectricity. The electromechanical behavior of piezocomposite structures accounting the influence of size-dependent properties such as piezoelectric and surface effect is investigated. In addition to this, the parametric analysis is carried out using the different parameters such as aspect ratio and thickness on the electromechanical response of composite structures. The consequences of the present study explore that the influence of size-dependent properties on the electromechanical behavior of composite structures is noteworthy with respect to the size of structures and can be ignored at bulk sizes. The electromechanical behavior including dynamic response (resonant frequency) of composite plates shows significant enhancement as compared to the conventional composite plate. This current study offers pathways for developing novel composite materials with enhanced control authority and offer guideline for the application and design of nanodevices in energy harvesting. It also highlights the opportunity to evolve high-performance and lightweight micro/nano-electro-mechanical system (M-/NEMS)
Surface elasticity based nonlocal vibration analysis of bidirectional functionally graded tapered nanobeam
No full textThe present paper proposes the impact of the mutual interplay of nonuniform geometry with surface and nonlocal stresses on the vibration characteristics of bi-directional functionally graded tapered nanobeam with surface layers. The material composition of nanobeam is assumed to follow a power-law distribution along the thickness and exponential along the length. The nonuniformity in the geometry of nanobeam arises due to the linear variation of thickness along its length. The considered nanobeam is modeled as a Timoshenko nanobeam with surface layers of negligible thickness. The nonlocal and surface effects are incorporated using Eringen's nonlocal theory with Gurtin-Murdoch's surface elasticity theory. Hamilton's energy principle is employed to derive the nonlocal equations of motion with boundary conditions. The differential quadrature method is exploited to obtain the natural frequencies and the convergence of the method is demonstrated. A parametric study is introduced to investigate the influence of critical parameters such as taper parameter, surface parameter and nonlocal parameter on the vibration characteristics of bi-directionally graded nanobeam. This work explains that the nonuniformity in the geometry of nanobeam significantly influences the frequency range of tapered nanobeam with surface layers. These results will serve as a benchmark for future work on nonuniform nanostructures
Metal-wire-based twin one-dimensional orthogonal array configuration of PZT patches for damage assessment of two-dimensional structures
No full textThis article presents a new field-deployable algorithm harnessing the metal-wire-based variant of the electro-mechanical impedance technique, warranting drastically lesser number of piezo sensors, for damage detection and localization on large two-dimensional structures such as plates. The metal-wire-based approach is a new variant of the electro-mechanical impedance technique. Although less sensitive than the conventional electro-mechanical impedance technique, it is a panacea in situations where direct bonding of lead zirconate titanate (PZT) patches on the host structure is not possible, such as inaccessible structural locations, parts under continuous impact from external loads, brittle materials (triggering signatures without any peaks) or high-temperature locations. This article first reports detailed experimental investigations into the practical aspects of the metal-wire-based electro-mechanical impedance technique. These cover the effect of various associated parameters, such as the wire cross-section, shape, discontinuity and other related issues. Repeatability of signature is also investigated along with the effect of possible breakage in the wire and inadvertent bending. The technique is further adapted by replacing the wire by a thin foil, which is found to improve the damage sensitivity substantially. The proposed algorithm for damage localization on two-dimensional structures uses the PZT patches in the metal-wire-based orthogonal twin-array configuration. The metal-wire-based electro-mechanical impedance technique is first simulated through finite element method, coupled with the basic impedance model, to test the algorithm on the numerical model of a mild steel plate, 1200 mm×970 mm×8 mm in size. The algorithm is then validated through full-scale test on the actual plate, covering damage at various locations. The developments of this article shall pave way for practical application of the metal-wire-based electro-mechanical impedance technique on large two-dimensional structures with minimum number of sensors, especially in situations where the direct electro-mechanical impedance technique is not feasible to be used.</p
Experimental investigations of metal wire based EMI technique for steel structures
No full textInfrastructure construction is the second largest economic activity in India after agriculture and it is growing rapidly. Structural Health Monitoring (SHM) aims to provide new solutions for easy and swift inspection of engineered structures. Electromechanical impedance (EMI) technique is a relatively new useful and convenient technique in the area of SHM. Though this technique shows promising results in the area of SHM, the main disadvantage of this technique is the brittleness of the piezo-electric (PZT) material. To overcome this problem, a new variant has recently emerged wherein a metal wire is coupled with the PZT patch and then attached with the host structure. This paper primarily focuses on evaluating the metal wire based EMI technique for damage assessment of 2D structure. Test results show that the technique can effectively identify and locate damage on a 2D structure
Random field based approach for quantifying the spatial variability in composite laminates
No full textInvestigation into metal wire based variant of EMI technique for structural health monitoring
No full textElectro mechanical impedance method (EMI) is a newly non-destructive evaluation method which is becoming very famous in the field of structural health monitoring. In this article a new approach is being proposed to effectively detect the initiation and progression of structural damage by the global dynamic electro-mechanical impedance (EMI) techniques. In this context the PZT patches are being used to determine the natural frequency and the strain mode shapes and the electro mechanical admittance signature to facilitate an improved damage assessment. Nowadays the safety issues for the case of composite building materials are getting more importance. The main problem of using EMI method is its brittleness so to overcome from this problem we are using this method by coupling a metal wire with a PZT element. In this method we created progressive damages and deterioration scenarios and we evaluated with the application of the proposed metal wire EMI method
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