Department of Civil Engineering

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Subject: search.filters.subject.Composite laminates

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Now showing 1 - 6 of 6
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    Non-Linear Stability and Failure of Laminated Composite Stiffened Cylindrical Panels Subjected to In-Plane Impulse Loading
    (Elsevier, 2021-02) Patel, S. N.; Kumar, Rajesh
    In this article, the non-linear dynamic buckling behavior and failure of laminated composite stiffened cylindrical (LCSC) panel is performed in the finite element framework when subjected to sinusoidal and rectangular in-plane pulse loading. Balanced symmetric cross-ply laminates and balanced symmetric angle ply laminates are considered in this study. The first ply failure load (FPFL) of the panel is evaluated and checked whether it occurs before the non-linear dynamic buckling phenomenon considering four different failure theories. Convergence and validation studies are carried out using the present mathematical formulation and compared with the results from the existing literatures. The effect of loading duration, loading function, aspect ratio of stiffener and the ply orientation of the skin and stiffener on the non-linear dynamic buckling of LCSC panel is studied in detail and the results are reported. It is observed that the non-linear dynamic buckling load (DBL) of balanced and symmetric angle ply (45°/−45°/−45°/45°) stiffened panel is lower than those of unstiffened composite cylindrical panel upto aspect ratio of the stiffener (ds/bs) equal to 8 when subjected to rectangular pulse load. In case of balanced and symmetric cross ply (0°/90°/90°/0°) stiffened panel the DBL of stiffened panel is lower than those of unstiffened panel when the aspect ratio of the stiffener is less than 4 with rectangular pulse load. Further, the free vibration, static buckling and static post-buckling analyses of the panels are carried out as and when required.
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    Non-Linear dynamic pulse buckling of laminated composite curved panels
    (TechnoPress, 2020-01) Patel, S. N.
     In this paper, non-linear dynamic buckling behaviour of laminated composite curved panels subjected to dynamic in-plane axial compressive loads is studied using finite element methods. The work is carried out using the finite element software ABAQUS. The curved panels are modelled with S4R element and the nonlinear dynamic equilibrium equations are solved using the ABAQUS/Explicit algorithm. The effect of aspect ratio, radius of curvature and thickness are studied. The importance of orientation of plies in the direction of loading is also reiterated in this study. Vol\'mir\'s criterion is used to calculate the dynamic buckling loads. The panels are subjected to rectangular pulse load of various amplitude and durations and the responses are observed. For particular loading amplitude, a critical value of loading duration is observed beyond which the variation of dynamic buckling load is insignificant. It is also observed that, the value of dynamic bucking load reduces as the loading duration is increased though the reduction is not much after a particular loading duration.
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    Effect of Cutout on the Stability and Failure of Laminated Composite Cylindrical Panels Subjected to In-Plane Pulse Loads
    (World Scientific, 2022) Patel, S. N.; Kumar, Rajesh
    In this investigation, the nonlinear dynamic buckling analysis and the failure analysis of laminated composite cylindrical (LCC) panel with different shapes of cutouts under the action of rectangular in-plane pulse loads are performed in the finite element framework. Cross-ply laminates which are balanced symmetric are considered in the investigation. The first ply failure load (FPFL) of the panel is evaluated and checked whether it occurs before the nonlinear dynamic buckling phenomenon considering Tsai–Wu failure criterion. Convergence and validation studies are undertaken, and the results are compared with those from the existing literature. The effects of loading duration, cutout area and cutout geometry on the panel are investigated in detail and results are reported. The results indicate that for the panel with cutout, its dynamic buckling load (DBL), in certain cases, compared to the static buckling load (SBL), can be lower even if the loading duration is half of its first natural period. Additionally, the vibration and the static buckling analyses of the panels are carried out as and when required.
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    Postbuckling Response and Failure of Symmetric Laminated Plates with Rectangular Cutouts under Uni-axial Compression
    (Korea Institute of Science and Technology Information, 2008) Singh, Shamsher Bahadur
    This paper deals with the buckling and postbuckling responses and the progressive failure of square symmetric laminates with rectangular cutouts under uniaxial compression. A detailed investigation is made to show the effects of cutout size and cutout aspect ratio on prebuckling and postbuckling responses, failure loads and failure characteristics of (+45/−45/0/90)2s, (+45/−45)4s and (0/90)4s laminates. The 3-D Tsai-Hill criterion is used to predict the failure of a lamina while the onset of delamination is predicted by the interlaminar failure criterion. In addition, the effects of boundary conditions on buckling load, failure loads, failure modes and maximum transverse deflection for a (+45/−45/0/90)2s laminate with and without cutout have also been presented. It is concluded that square laminates with small square cutouts have more postbuckling strength than without cutout, irrespective of boundary conditions.
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    Postbuckling response and failure of symmetric laminated plates with rectangular cutouts under in-plane shear
    (Techno Press, 2010-01-30) Singh, Shamsher Bahadur
    This paper deals with the buckling and postbuckling responses, and the progressive failure of square laminates of symmetric lay-up with a central rectangular cutout under in-plane shear load. A detailed investigation is made to show the effects of cutout size and cutout aspect ratio on the buckling and postbuckling responses, failure loads and failure characteristics of (+45/-45/0/90)2s, (+45/-45)4s and (0/90)4s laminates. The 3-D Tsai-Hill criterion is used to predict the failure of a lamina while the onset of delamination is predicted by the interlaminar failure criterion. In addition, the effects of boundary conditions on buckling loads, failure loads, failure modes, and maximum transverse deflection for a (+45/-45/0/90)2s laminate with and without a square cutout have been presented. It is concluded that because of early onset of delamination at the net section of cutouts before first-ply failure, total strength of the laminate with very small cutouts can not be utilized.
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    Cutout shape and size effects on response of quasi-isotropic composite laminate under uni-axial compression
    (Techno Press, 2010-06) Singh, Shamsher Bahadur
    Cutouts are often provided in structural and aircraft components for ventilation, for access, inspection, electric lines and fuel lines or sometimes to lighten the structure. This paper addresses the effects of cutout shape (i.e., circular, square, diamond, elliptical-vertical and elliptical-horizontal) and size on buckling and postbuckling response of quasi-isotropic (i.e., (+45/−45/0/90)2s) composite laminate under uni-axial compression. The finite element method is used to carry out the investigation. The formulation is based on first order shear deformation theory and von Karman