Chaitali Ray

Comparative perspective of various shear deformation theories with experimental verification for modal analysis of hybrid laminates

The present paper deals with the free vibration modal analysis of hybrid laminates using a finite element model based on the third order shear deformation theory (TSDT) and the first order shear deformation theory (FSDT). A computer code has been developed using MATLAB, 2013. The experimental investigation on the free vibration of hybrid laminates made of carbon and glass fibres has been conducted. The hybrid laminate is prepared by placing carbon fibres in the outermost laminae and glass fibres in the rest of the laminate. The bi-directional glass and carbon fabrics and the epoxy resin are used for the preparation of laminates in the laboratory. The experimental models of laminates have been prepared by the resin infusion process using vacuum bagging technique. The natural frequencies of hybrid laminates for different modes are determined and the mode shapes are plotted for the corresponding frequencies by experiment and numerical procedure. The finite element formulations based on TSDT and FSDT for the composite laminates predict the natural frequencies and are validated by comparing with the experimental results.

Thermal Stress Analysis of Laminated Composite Plates Using Third Order Shear Deformation Theory

The strength properties of FRP collectively make up one of the primary reasons for which civil engineers select for the construction of structures. The higher order shear deformation theory accounts not only for transverse shear strains of laminated composites but also for a parabolic distribution of the distribution of the transverse strains through the thickness of the plate. Consequently, no shear correction factor is needed. The laminated composite plates have been analysed under thermal load using third order shear deformation theory. The plate is subjected to constant temperature over the surface. The finite element modeling of the plate has been generated using an eight node isoparametric plate bending element with seven degrees of freedom per node. The results in terms of deflection and stresses has been validated by formulating the laminated composite plates using ANSYS 14.0 based on the first order shear deformation theory. The results compare very well. The 2 × 2 gauss integration procedure has been adopted. The stresses have been calculated at the gauss points and the nodal stresses have been computed by extrapolating the stresses at the gauss points. The transverse stresses developed due to the thermal load have been computed and plotted in the present study.

Experimental and Numerical Modal Analysis of Laminated Composite Plates with GFRP

Fibre reinforced polymer composites have gradually gained wide acceptance in civil engineering applications. Many possibilities of using FRP in the strengthening and construction of concrete structures have been explored. The present paper deals with the modal analysis of glass fibre reinforced laminated composite with epoxy resin. The numerical as well as experimental investigations on the laminated composite plates have been carried out. The finite element formulation for the composite plates using first order and higher order shear deformation theories has been developed using MATLAB. The finite element formulation has also been carried out using the software package ANSYS 14.0. The numerical results have also been validated by conducting experimental investigation. The glass-epoxy laminated composite plates have been manufactured in the laboratory by vacuum infusion method using the vacmobile system. The dynamic analysis has been conducted by using B&K impact hammer, unidirectional piezoelectric CCLD accelerometer (B&K type-4507), photon plus data acquisition system and the modal analysis software (Pulse). The comparison between the numerical and the experimental results is satisfactory.

Bending of FRP Bridge Deck Under the Combined Effect of Thermal and Vehicle Load

Fibre reinforced plastics (FRP) composite materials have been introduced in bridge engineering as it offers easy installation, lightweight and corrosion resistance. In the present investigation, FRP bridge deck has been modeled using the ANSYS 14.0 software package. A finite element computer code has also been developed for the analysis of the bridge deck. The deck has been formulated as a laminated composite plate stiffened with closely spaced laminated stiffeners having box configuration. The first order shear deformation theory has been applied. The box stiffener induces a considerable amount of torsional rigidity due to its closed attachment with the plate. Therefore, the torsional rigidity of the stiffener has been calculated by considering the stiffener cross section as a hollow box configuration. The bridge deck model has been developed as one plate at top and another plate at bottom with vertical blade stiffeners placed between the horizontal plates using ANSYS 14.0. The temperature gradient between the top and the bottom surfaces of the FRP bridge deck is developed due to low thermal conductivity of FRP materials and hollow section which gives rise to a very high thermal stress. The thermal load on the deck has been considered to be varying linearly through the depth of the deck. The combined effect of vehicle load and temperature gradient through the thickness on the bending behaviour of the FRP deck has been studied in the present analysis. The present formulation has been validated by comparing the obtained results with those available in the published literature.