Satyajit Panda

Flank wear prediction in drilling using back propagation neural network and radial basis function network

In the present work, two different types of artificial neural network (ANN) architectures viz. back propagation neural network (BPNN) and radial basis function network (RBFN) have been used in an attempt to predict flank wear in drills. Flank wear in drill depends upon speed, feed rate, drill diameter and hence these parameters along with other derived parameters such as thrust force, torque and vibration have been used to predict flank wear using ANN. Effect of using increasing number of sensors in the efficacy of predicting drill wear by using ANN has been studied. It has been observed that inclusion of vibration signal along with thrust force and torque leads to better prediction of drill wear. The results obtained from the two different ANN architectures have been compared and some useful conclusions have been made.

Piezo-viscoelastically damped nonlinear frequency response of functionally graded plates with a heated plate-surface

A geometrically nonlinear frequency-domain analysis of functionally graded plates integrated with an active constrained layer damping (ACLD) arrangement is performed by developing an incremental nonlinear closed-loop dynamic finite element model of the overall plate. The active constraining layer is made of piezoelectric fiber reinforced composite (PFRC) and a heated substrate-plate surface is considered. The analysis is mainly for investigating the effect of temperature on the nonlinear vibration characteristics of the overall plate in the frequency domain and also, on the corresponding control authority of the PFRC constraining layer. A negative velocity feedback control strategy is utilized to achieve active damping. The temperature dependent material properties of the substrate plate are graded in the thickness direction according to a power law, and expressed in terms of the power law exponent and the constituent material (metal and ceramic) properties. Using the Golla-Hughes-McTavish method for modeling the viscoelastic material, the incremental nonlinear finite element equations of motion are derived in the frequency domain assuming periodic motion of the overall plate. An arc-length extrapolation solution technique is used in combination with a new strategy for determination of incremental arc-length. The numerical illustrations show a potential use of PFRC actuator in the ACLD arrangement and suggest an optimal thickness of viscoelastic layer for more effective use of PFRC. The analysis reveals the significant effects of initial thermal bending of the overall smart plate on its nonlinear dynamic behavior in the frequency domain. The effects of temperature, metal-volume fraction in substrate, fiber volume fraction in PFRC and the fiber orientation angle in the PFRC on the control authority of the ACLD layer are presented. For the use of the ACLD layer in the form of a patch, a new numerical strategy for determining its optimal location and optimal size for effective control is presented.

Harmonically exited nonlinear vibration of heated functionally graded plates integrated with piezoelectric composite actuator

A nonlinear frequency response analysis of a smart functionally graded plate operating under a heated substrate plate surface is presented. The analysis is mainly for investigating the effect of temperature on the harmonically exited nonlinear vibration characteristics of smart functionally graded plates and also on the corresponding control authority of piezoelectric fiber–reinforced composite actuator bonded to the substrate plate surface. A negative velocity feedback control strategy is utilized so as to achieve smart damping. The temperature-dependent material properties of the ceramic metal–based functionally graded plate are graded in the thickness direction. Based on the von Karman nonlinear strain–displacement relations and assuming periodic motion, a nonlinear dynamic incremental finite element model of the overall smart functionally graded plate is developed. An arc-length extrapolation technique with a new strategy for determining the arc length is used for numerical solutions. The analysis reveals significant effects of temperature and metal volume fraction in substrate on the structural dynamic behavior of the overall plate. The analysis also reveals the effects of temperature, metal volume fraction in substrate, fiber volume fraction in piezoelectric fiber–reinforced composite, and fiber orientation in piezoelectric fiber–reinforced composite on the smart damping. For using the piezoelectric fiber–reinforced composite actuator in the form of a patch, its optimal location and size are numerically determined.

Performance of a short piezoelectric fiber–reinforced composite actuator in vibration control of functionally graded circular cylindrical shell

For improved flexibility and conformability of piezoelectric fiber–reinforced composite actuator, it is reconstructed in a recent study by the use of short piezoelectric fibers (short piezoelectric fiber–reinforced composite) instead of continuous fibers (continuous piezoelectric fiber–reinforced composite). This modification facilitates its application in short piezoelectric fiber–reinforced composite layer form instead of continuous piezoelectric fiber–reinforced composite patch form particularly in case of host structures with highly curved boundary surfaces. But the corresponding change in actuation capability is a major issue for potential application of short piezoelectric fiber–reinforced composite that is studied in this work through the control of vibration of a functionally graded circular cylindrical shell under thermal environment. First, an arrangement of continuous piezoelectric fiber–reinforced composite actuator patches over the host shell surface is presented with an objective of controlling all modes of vibration. Next, the use of short piezoelectric fiber–reinforced composite actuator layer for similar control activity is demonstrated through an arrangement of electrode patches over its surfaces. Subsequently, an electric potential function is assumed for the consideration of electrode patches and a geometrically nonlinear coupled thermo-electro-mechanical incremental finite element model of the harmonically excited overall functionally graded shell is developed. The numerical results reveal actuation capability of short piezoelectric fiber–reinforced composite actuator layer with reference to that of the existing continuous piezoelectric fiber–reinforced composite/monolithic piezoelectric actuator patches. The effects of temperature, size of electrode patches, properties of piezoelectric fiber–reinforced composite, and functionally graded properties on the control activity of short piezoelectric fiber–reinforced composite/continuous piezoelectric fiber–reinforced composite actuator are also presented.

Non-linear analysis of smart annular plates using cylindrically orthotropic piezoelectric fiber-reinforced composite

This article deals with geometrically non-linear finite element analysis of substrate annular plates integrated with the annular patches of the piezoelectric fiber reinforced composite (PFRC) material. The PFRC material is a cylindrically orthotropic smart composite material in which the piezoelectric fibers are circumferentially reinforced in the epoxy matrix material. The annular PFRC patches are activated by the externally applied voltage across their thickness and act as the distributed actuators for controlling the non-linear deformations of the substrate annular plates. Based on the first-order shear deformation theory and the von Karman non-linear strain–displacement relations, the non-linear governing finite element equations of equilibrium of this electro-elastic coupled problem are derived employing the principle of minimum potential energy. The governing non-linear finite element equations are then solved using direct iteration method. The numerical illustrations reveal the significant control authority of the cylindrically orthotropic annular PFRC patches in counteracting the non-linear deformations of the substrate annular plates. The numerical illustrations also reveal that for the constant circumferential stretch of the annular PFRC patches, if their radial span is less than that of the substrate annular plate, then the radial location of the annular patches attached to the top surface of the substrate plate plays an important role for their effective control authority. Along with this location, the minimum radial length of the annular PFRC patches is also assessed without affecting the performance of the overall smart plate significantly.

Augmented constrained layer damping in plates through the optimal design of a 0-3 viscoelastic composite layer

In this work, a new 0-3 viscoelastic composite (VEC) layer is presented for augmented constrained layer damping of plate vibration. The 0-3 VEC layer comprises a rectangular array of the thin rectangular graphite-wafers embedded within the viscoelastic matrix. The inclusions of graphite-wafers in the constrained 0-3 VEC layer confine the motion of the viscoelastic phase for its reasonable in-plane strains along with the enhanced transverse shear strains. This occurrence of coincidental shear and extensional strains within the viscoelastic phase is supposed to cause augmented damping capacity of the constrained layer, and it is investigated by integrating the constrained 0-3 VEC layer over the top surface of a substrate plate. A finite element (FE) model of the overall plate is developed based on the layer-wise shear deformation theory. Using this FE model, first, a bending analysis of the overall plate is performed to investigate the mechanisms of damping in the use of 0-3 VEC layer. Next, the damping in the overall plate is quantified for different sets of values of the geometrical parameters of the 0-3 VEC layer. These results reveal significant improvement of damping in the plate due to the inclusions of graphite-wafers within the constrained viscoelastic layer. But, the augmentation of damping indicatively depends on the geometrical parameters in the arrangement of the graphite-wafers. So, the 0-3 VEC layer is configured appropriately through an optimization algorithm, and finally, the forced frequency responses of the overall plate are evaluated to demonstrate the augmented attenuation of vibration-amplitude via the inclusions of graphite-wafers within the constrained viscoelastic layer in an optimal manner.

A comparative study on the smart damping capabilities of cylindrically orthotropic piezoelectric fiber–reinforced composite actuators in vibration control of simply supported/fully clamped isotropic annular plate

For active control of vibration of plane structures of revolution, a cylindrically orthotropic piezoelectric fiber–reinforced composite actuator is addressed in a recent study. Some other available piezoelectric composites, which are originally constructed in Cartesian coordinate frame, can also be reconstructed in polar coordinate frame for similar application. Making use of all these piezoelectric composites in polar coordinate frame of an annular plate, a comparative study on their control capabilities is performed at present. All the piezoelectric composites are used in the form of patches which are optimally configured over the host plate surface and utilized as smart dampers. The geometrical and material properties of the piezoelectric composites are taken in uniform manner and the corresponding electric fields in function of applied voltage are evaluated for derivation of a closed-loop finite element model of the smart annular plate. First, the patches of every piezoelectric composite are optimally configured through the proposition of a new methodology. Next, the control/damping capabilities of the piezoelectric composites are evaluated for fundamental symmetric/asymmetric mode of vibration of the plate. The numerical results first illustrate the implementation and suitability of the present methodology for optimal size and locations of actuator patches. Subsequently, the results demonstrate damping capabilities of all the piezoelectric composites to label potential ones.

A design of active constrained layer damping treatment for vibration control of circular cylindrical shell structure

A new 1-3 viscoelastic composite material (VECM) layer is designed for improved active constrained layer damping (ACLD) treatment of vibration of a functionally graded (FG) circular cylindrical shell. Besides this improved active damping treatment, another objective of this study is to control all the modes of vibration of the shell effectively using the treatment (active constrained layer damping) in layer-form throughout the outer shell-surface. In this design of active constrained layer damping treatment in layer-form, its (active constrained layer damping) necessary conformability with the curved host shell-surface is ensured by the use of a vertically reinforced 1-3 piezoelectric composite (PZC) constraining layer, whereas the effective control of several modes of vibration of the shell is achieved by the use of electrode-patches over the surfaces of the constraining layer. A fruitful strategy in the arrangement of electrode-patches is proposed for effective control of several modes of vibration of the shell using one configuration of the electrode-patches. An electric potential function is assumed for this use of electrode-patches and a geometrically nonlinear coupled electro-visco-elastic incremental finite element model of the overall shell is developed for its analysis in the frequency-domain. The analysis reveals significant improvement of active damping characteristics of the active constrained layer damping layer for the use of the present 1-3 viscoelastic composite material layer instead of the traditional monolithic viscoelastic material (VEM) layer. The analysis also reveals the suitability of the present strategy of arrangement of electrode-patches for achieving aforesaid control-activity of the ACLD layer. The effects of temperature in the host functionally graded shell and different geometric parameters in the design of the 1-3 viscoelastic composite material layer on the damping characteristics of overall shell are also presented.

Design and Effective Properties of a Functionally Graded Unidirectional Fiber-Reinforced Composite

The present work deals with the design of a fiber-reinforced composite lamina with varying fiber-volume fraction (FVF) along its thickness direction. In the available elastic analyses of this kind of composite, the elastic properties are evaluated based on the assumptions like continuous variation of FVF and existence of decoupled representative volume element (RVE) at every point along the thickness direction. In order to predict the graded material properties without any of these assumptions at present, first a micro-structure of similar graded composite is designed for the variation of FVF according to a sigmoid function of thickness coordinate. Next, a continuum micro-mechanics finite element model of the corresponding representative volume (RV) is derived. The RV is basically composed of several micro-volumes of different FVFs and the classical homogenization treatment is implemented over these micro-volumes without decoupling them from the overall volume of RV. The importance of this coupled analysis is verified through a parallel decoupled analysis. The effect of the total number of micro-volumes within a specified thickness of lamina on its graded elastic properties is presented. The characteristics of graded elastic properties according to the sigmoid function are also discussed.Copyright