Novel stitch-bonded sandwich composite structures

Potluri, Prasad; Kusak, E; Reddy, T.Y.

doi:10.1016/s0263-8223(02)00087-9

Cited by 133 publications

(75 citation statements)

References 7 publications

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“…As no damage detections are available for sandwiches with laminated faces, except for a stitched one (see Potluri et al (2003)), the comparison with experiments is limited to the contact force time history. Modelling of stitching (Icardi and Sola (2013)) could be applied, but as it represents an uncertainty source that could prevent from the assessments of (i)-(iv), it is left to a future study.…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

Impact Damage Analysis with Stress Continuity Constraints Fulfilment at Damaged-Undamaged Regions and at Layer Interfaces

Icardi

Urraci

2017

Lat. Am. j. solids struct.

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Low-velocity impacts have a relevant importance for safety of laminated and sandwich composite structures, because they are highly susceptible to damage. In this paper, a 3D cost effective zig-zag model is developed in order to efficiently simulate such impacts. It a priori fulfills the continuity of out-of-plane stresses at layer interfaces, the continuity of stresses under in-plane variation of properties across undamaged and damaged regions and it is suitable for general boundary conditions. Its main advantage is its capability to accurately predict stresses from constitutive equations at a low cost, along with being refined across the thickness keeping fixed the number of unknowns. A modified Hertzian contact law that forces the target to conform to the shape of the impactor and the Newmark's implicit time integration scheme are used for computing the contact force time history. The progressive damage analysis is carried out using stress-based criteria. Non-classical feature, a continuum damage mesomechanic model is employed that accounts for the effects of local failures in homogenized form by modifying the strain energy expression. Fiber, matrix and delamination failures are predicted using stress-based criteria, and then the modified strain energy expression is employed for computing stresses. Such modeling options enable to account for the residual properties as they are in the reality, as shown by the comparison with the damage experimentally detected. As shown by the comparison with experiments, a closed-form solution by the Galerkin's method, obtained as a series expansion of trial displacement functions, accurately simulates the contact force and the damage progressively accumulated. The results show the importance of in-plane stress continuity for obtaining accurate predictions.Keywords Impact-induced damage; 3D variable-kinematics zig-zag model; undamaged/damaged stress continuity; interlayer stress continuity; fixed d.o.f; mesomechanic damage model.

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Section: Numerical Results and Discussionmentioning

confidence: 99%

Impact Damage Analysis with Stress Continuity Constraints Fulfilment at Damaged-Undamaged Regions and at Layer Interfaces

Icardi

Urraci

2017

Lat. Am. j. solids struct.

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“…[7,8] reviewed the thermal effects on various experimental and theoretical studies done by authors in hydrodynamic bearings. [9,10,11,12] stated that during steady state condition of rotor bearing, at whirling motion of shaft, the hydrodynamic forces rise above the external loads and the shaft obtains a circular orbit. [13,14] conducted a non-linear transient analysis on rotor-bearing system.…”

Section: Hydrodynamic Lubricated Bearingsmentioning

confidence: 99%

Analysis on Circular Journal Bearing with the effect of Eccentricity Ratio

Hussain¹,

Bhaskar²,

Prasad³

et al. 2016

JAMES

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Bearings are used to support loads of other machine elements. Hydrodynamic journal bearings have been widely used for heavy duty. Circular journal bearings are provided with clearance to accommodate the lubricants and remove the heat during relative motion between journal and bearing. In this paper plain journal bearings are considered to analyse the effect of eccentricity ratio during motion. The pressure developed due to variation of eccentricity ratio has been determined using finite difference technique. A program has been in written in MATLAB to determine the pressure, and effect of eccentricity and attitude angles. Fluent analysis has been done to determine the variation of pressure developed during motion. The contours of pressure has been plotted and compared with the numerical analysis results. It is observed that the pressure increased with increase in eccentricity ratio and the Sommerfeld number decreased with increase in eccentricity ratio.

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“…As final example, the sandwich panel with foam core analysed by Potluri et al [52] is considered. The panel is square with a 300 mm side and it is clamped on all the sides.…”

Section: Foamed Core Sandwichesmentioning

confidence: 99%

Indentation of Sandwiches Using a Refined Zig-Zag Model and a Mesoscale Damage Model

Icardi¹,

Sola²

2014

ujme

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An accurate and cost effective zig-zag plate model with variable kinematics and fixed degrees of freedom recently developed by the authors, which a priori fulfills the stress and displacement continuity requirements, is applied to study indentation of sandwiches with honeycomb/foam core. The variable elastic properties of the core during crushing are evaluated apart and once at a time through a 3D finite element analysis. Shell elements with elastic-plastic isotropic properties are adopted to discretize honeycomb cores and faces, instead solid elements with nonlinear material behavior are used for foam cores. To keep low the computational burden, the structural response is computed in closed form by the zig-zag model using these elastic properties. The damage analysis is carried out through a mesoscale model that determines the degraded properties of failed regions in a physically consistent way. A good agreement with experiments taken from the literature being shown, the present simulation procedure with a low computational effort is proven to be an efficient alternative to the ones currently employed.

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Novel stitch-bonded sandwich composite structures

Cited by 133 publications

References 7 publications

Impact Damage Analysis with Stress Continuity Constraints Fulfilment at Damaged-Undamaged Regions and at Layer Interfaces

Impact Damage Analysis with Stress Continuity Constraints Fulfilment at Damaged-Undamaged Regions and at Layer Interfaces

Analysis on Circular Journal Bearing with the effect of Eccentricity Ratio

Indentation of Sandwiches Using a Refined Zig-Zag Model and a Mesoscale Damage Model

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