An efficient finite element formulation based on a first-order shear deformation theory (FSDT) is presented for the active control of functionally gradient material (FGM) plates with integrated piezoelectric sensor/actuator layers subjected to a thermal gradient; this is accomplished using both static and dynamic piezothermoelastic analyses. The formulation based on FSDT can be applied to a range of relatively thin-to-moderately thick plates. A constant displacement-cum-velocity feedback control algorithm coupling the direct and inverse piezoelectric effects is applied to provide active feedback control of the integrated FGM plate in a self-monitoring and self-controlling system. Numerical results for the control of bending and torsional deflections and/or vibrations are presented for a FGM plate comprising zirconia and aluminium. The effects of constituent volume fraction and the influence of feedback control gain on the static and dynamic responses of the FGM plates are examined in detail. Copyright © 2001 John Wiley & Sons, Ltd.

Active control of FGM plates subjected to a temperature gradient: Modelling via finite element method based on FSDT

Active constrained layer damping treatments promise to be an effective means of vibration suppression in structures. Basically, the concept consists in either replacing or augmenting the constraining layer of a constrained viscoelastic material with piezoceramic actuators in an attempt to improve vibration suppression properties by capitalizing on both passive and active damping techniques. An important issue in such configurations is the concept that the actuation ability of the piezoceramic is reduced by the viscoelastic layer, rather than enhanced. On the other hand, an active constraining layer increases the shear in the viscoelastic and thus forms an effective means of enhancing the damping mechanism. Some design considerations for pure passive, pure active control, and active constrained layer damping are discussed here. Several authors have reported comparisons and formulations of active constrained layer damping techniques. The approach presented here differs in that it employs an energy principle for the equations of a beam with partial active/passive constrained layer damping treatments. To simulate a realistic design problem, the optimal sizing, length, and thickness of treatments subject to a total thickness restriction is studied for cases of active constrained layer, passive constrained layer, and pure active control. The results show that the active constrained layer damping treatment provides better vibration suppression than passive damping treatments, and it even out-performs pure active control for low-gain applications.

https://iopscience.iop.org/article/10.1088/0964-1726/5/3/008/pdf

Some design considerations for active and passive constrained layer damping treatments

A study on the damping characteristics of laminated composites with integral viscoelastic layers

In this paper we present a layerwise finite element model for the analysis of sandwich laminated plates with a viscoelastic core and laminated anisotropic face layers. The stiffness and mass matrices of the element are obtained by Carrera’s Unified Formulation (CUF). The dynamic problem is solved in the frequency domain with viscoelastic frequency-dependent material properties for the core. The dynamic behaviour of the model is compared with solutions found in the literature, including experimental data.

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A finite element model using a unified formulation for the analysis of viscoelastic sandwich laminates

This paper describes the formulation of a theory for the prediction of damping and natural frequencies of laminated composite beams with multiple viscoelastic damping layers. The damping layers are constrained (or sandwiched) by anisotropic laminates. The in-plane shear strains of the damping layers and the constraining layers are included in the model. Closed-form solutions for the resonance frequencies and modal loss factors of the composite beam system under simple supports are derived using the energy and Ritz method. A parametric study has been conducted to study the variation of dynamic stiffness and modal loss factor of the system with structural parameters (e.g., the ply orientations of laminas, thickness of the damping layers and the laminates), operating temperature, and damping material properties. The design of composite beams for maximizing the damping capacity is also presented in this paper which includes the determination of operating temperature range corresponding to given structural parameters and finding optimal structural parameters corresponding to given temperature range. Finally, some experimental results are compared with theory for the cases of single and double damping layer beam systems that show good agreement between predicted and measured natural frequencies.

Dynamic Analysis and Design of Laminated Composite Beams with Multiple Damping Layers

This paper presents a dynamic model for the transverse vibration analysis of an adhesively bonded composite double‐strap joint. The differential equations of motion of the joint system are derived using the energy method and Hamilton’s principle. It is assumed that the energy dissipated by the joint system is contributed by both the shear and longitudinal deformation of the adhesive layers. The combination of natural boundary conditions, forced boundary conditions, and continuity conditions yields the frequency equations to predict the system resonance frequencies and modal loss factors. The effects of structural parameters and material properties of the adhesive layer on the system modal loss factors and resonance frequencies are also studied.

Analysis of natural frequencies and modal loss factors of simply supported beams with adhesively bonded double‐strap joints

Damping of laminated composite beams with multiple viscoelastic layers

This paper proposes new prefabricated autoclaved lightweight concrete (ALC) connectors which allow limited sliding. The seismic performance of the proposed connectors and a traditional connector (L-hooked bolt) were investigated in depth. Three specimens of full-scale steel frames with ALC panel and connectors were subjected to horizontal low-cyclic loading. The failure modes, hysteretic behavior, strength and deterioration of stiffness and energy-dissipating performance of all specimens were analyzed and discussed. The experimental results indicated that the frames of the new connectors were more reliable than the traditional connector. The energy-dissipating capacity of the specimen frames with new connectors increased by 23.0% and 24.4%, and deterioration of stiffness increased by 10.6% and 13.0%. The new ALC panel connectors not only increased elastic stiffness in the early stage, but also provided some stiffness in the elastoplastic and plastic stages. Using relevant construction measures, the frames with new connectors displayed good cooperative behavior and safety reliability. To summarize, the new ALC connectors tested showed excellent performance in resisting seismic loading and had good assembly efficiency and could provide a basis for the development and application of a new type of ALC steel frame connector.

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Seismic Performance of Panel Connectors with Steel Frame Based on Autoclaved Lightweight Concrete (ALC)

Abstract As a critical component for steel beam and concrete slab to work together, the strength of the shear connector affects the flexural load capacity and stiffness of the composite beam. Connectors were generally studied for longitudinal shear resistance. However, transverse shear needs to be considered when the main beam is far away and the transverse connection is weak. In this paper, an angle connector pre-embedded in the precast slab was proposed, and its pre-embedded position makes it exhibit better transverse shear resistance. To assess the strength, stiffness, and slip capacity of the angle connector, two groups of composite beam with precast slabs negative moment flexural were tested, then several finite element groups were simulated in push-out test. The test variable was the existence of angle connectors, and the variables simulated were the yield strength of the angle connector and its flange thickness. The results showed that the composite beam with angle connectors has greater stiffness than ordinary ones, with little difference in flexural strength capacity and less slippage. The results show that angle connectors can replace extending rebars in precast slabs, which will reduce construction costs. In addition, a new design equation was proposed, including the yield strength of the connector and the thickness of its flange which are not unified in the current equations. The simulations determined the strength of the angle connectors in relation to the yield strength of the angle connector and its web thickness. 

https://doi.org/10.1186/s40069-022-00507-x

Shulin He

Papers

Dynamic Analysis and Design of Laminated Composite Beams with Multiple Damping Layers

Analysis of natural frequencies and modal loss factors of simply supported beams with adhesively bonded double‐strap joints

Damping of laminated composite beams with multiple viscoelastic layers

Seismic Performance of Panel Connectors with Steel Frame Based on Autoclaved Lightweight Concrete (ALC)

Research on Angle Connector in Composite Beam