Optimization of the Effective Shear Properties of a Bidirectionally Corrugated Sandwich Core Structure

2012 ◽  
Vol 80 (1) ◽  
Author(s):  
Camille C. Besse ◽  
Dirk Mohr
Keyword(s):  
Transverse Shear ◽  
Shear Stiffness ◽  
Element Model ◽  
Core Structure ◽  
Tool Geometry ◽  
Width Ratio ◽  
Four Point Bending ◽  
Representative Unit Cell ◽  
Sandwich Core ◽  
Dome Shape

The transverse shear stiffness of a newly-developed all-metal sandwich core structure is determined experimentally and numerically. The core structure is composed of a periodic array of domes which are introduced into an initially flat sheet through stamping. A finite element model of the stamping process is built and validated experimentally. A parametric study is performed to choose the stamping tool geometry such that the resulting core structure provides maximum shear stiffness for a given relative density. It is found that the optimal geometries for relative densities ranging from 0.2 to 0.35 all feature the same dome shape with the same height-to-width ratio. The simulation results also show that the estimated transverse shear strength of the proposed core structure is the same as that of hexagonal honeycombs of the same weight for high relative densities (greater than 0.35), but up to 30% smaller for low relative densities (lower than 0.2). In addition to numerical simulations of a representative unit cell, four-point bending experiments are performed on brazed prototype sandwich beams to validate the computational model.

scholarly journals Estimation of the Compressive Strength of Corrugated Cardboard Boxes with Various Perforations

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1095
Author(s):  
Tomasz Garbowski ◽  
Tomasz Gajewski ◽  
Jakub Krzysztof Grabski
Keyword(s):  
Compressive Strength ◽  
Estimation Error ◽  
Analytical Formula ◽  
Shear Stiffness ◽  
Element Model ◽  
Numerical Approach ◽  
Analytical Framework ◽  
Width Ratio ◽  
Corrugated Board ◽  
Corrugated Cardboard

This paper presents a modified analytical formula for estimating the static top-to-bottom compressive strength of corrugated board packaging with different perforations. The analytical framework is based here on Heimerl’s assumption with an extension from a single panel to a full box, enhanced with a numerically calculated critical load. In the proposed method, the torsional and shear stiffness of corrugated cardboard, as well as the panel depth-to-width ratio is implemented in the finite element model used for buckling analysis. The new approach is compared with the successful though the simplified McKee formula and is also verified with the experimental results of various packaging designs made of corrugated cardboard. The obtained results indicate that for boxes containing specific perforations, simplified methods give much larger estimation error than the analytical–numerical approach proposed in the article. To the best knowledge of the authors, the influence of the perforations has never been considered before in the analytical or analytical–numerical approach for estimation of the compressive strength of boxes made of corrugated paperboard. The novelty of this paper is to adopt the method presented to include perforation influence on the box compressive strength estimation.

A SIMPLIFIED ANALYTICAL PROCEDURE FOR SEISMIC ANALYSIS OF TIMBER LIGHT-FRAME SHEAR WALLS

2019 ◽  
Vol 3 (Special Issue on First SACEE'19) ◽  
pp. 173-180
Author(s):  
Giorgia Di Gangi ◽  
Giorgio Monti ◽  
Giuseppe Quaranta ◽  
Marco Vailati ◽  
Cristoforo Demartino
Keyword(s):  
Analytical Procedure ◽  
Seismic Analysis ◽  
Shear Walls ◽  
Element Model ◽  
Sensitivity Analyses ◽  
Width Ratio ◽  
Damping Factor ◽  
Equivalent Viscous Damping ◽  
Design Variables ◽  
Depth Analysis

The seismic performance of timber light-frame shear walls is investigated in this paper with a focus on energy dissipation and ductility ensured by sheathing-to-framing connections. An original parametric finite element model has been developed in order to perform sensitivity analyses. The model considers the design variables affecting the racking load-carrying capacity of the wall. These variables include aspect ratio (height-to-width ratio), fastener spacing, number of vertical studs and framing elements cross-section size. A failure criterion has been defined based on the observation of both the global behaviour of the wall and local behaviour of fasteners in order to identify the ultimate displacement of the wall. The equivalent viscous damping has been numerically assessed by estimating the damping factor which is in use in the capacity spectrum method. Finally, an in-depth analysis of the results obtained from the sensitivity analyses led to the development of a simplified analytical procedure which is able to predict the capacity curve of a timber light-frame shear wall.

Finite element bending analysis of symmetric and non-symmetric functionally graded sandwich beams using a novel parabolic shear deformation theory

2021 ◽  
pp. 146442072110050
Author(s):  
Mohamed-Ouejdi Belarbi ◽  
Abdelhak Khechai ◽  
Aicha Bessaim ◽  
Mohammed-Sid-Ahmed Houari ◽  
Aman Garg ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Shear Deformation ◽  
Transverse Shear ◽  
Deformation Theory ◽  
Shear Deformation Theory ◽  
Element Model ◽  
Beam Element ◽  
Functionally Graded ◽  
Sandwich Beams

In this paper, the bending behavior of functionally graded single-layered, symmetric and non-symmetric sandwich beams is investigated according to a new higher order shear deformation theory. Based on this theory, a novel parabolic shear deformation function is developed and applied to investigate the bending response of sandwich beams with homogeneous hardcore and softcore. The present theory provides an accurate parabolic distribution of transverse shear stress across the thickness and satisfies the zero traction boundary conditions on the top and bottom surfaces of the functionally graded sandwich beam without using any shear correction factors. The governing equations derived herein are solved by employing the finite element method using a two-node beam element, developed for this purpose. The material properties of functionally graded sandwich beams are graded through the thickness according to the power-law distribution. The predictive capability of the proposed finite element model is demonstrated through illustrative examples. Four types of beam support, i.e. simply-simply, clamped-free, clamped–clamped, and clamped-simply, are used to study how the beam deflection and both axial and transverse shear stresses are affected by the variation of volume fraction index and beam length-to-height ratio. Results of the numerical analysis have been reported and compared with those available in the open literature to evaluate the accuracy and robustness of the proposed finite element model. The comparisons with other higher order shear deformation theories verify that the proposed beam element is accurate, presents fast rate of convergence to the reference results and it is also valid for both thin and thick functionally graded sandwich beams. Further, some new results are reported in the current study, which will serve as a benchmark for future research.

scholarly journals Determination of Transverse Shear Stiffness of Sandwich Panels with a Corrugated Core by Numerical Homogenization

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1976
Author(s):  
Tomasz Garbowski ◽  
Tomasz Gajewski
Keyword(s):  
Transverse Shear ◽  
Shear Stiffness ◽  
The Finite Element Method ◽  
Homogenization Procedure ◽  
Plate Structures ◽  
Corrugated Board ◽  
Energy Equivalence ◽  
The Stability ◽  
Global Stiffness Matrix

Knowing the material properties of individual layers of the corrugated plate structures and the geometry of its cross-section, the effective material parameters of the equivalent plate can be calculated. This can be problematic, especially if the transverse shear stiffness is also necessary for the correct description of the equivalent plate performance. In this work, the method proposed by Biancolini is extended to include the possibility of determining, apart from the tensile and flexural stiffnesses, also the transverse shear stiffness of the homogenized corrugated board. The method is based on the strain energy equivalence between the full numerical 3D model of the corrugated board and its Reissner-Mindlin flat plate representation. Shell finite elements were used in this study to accurately reflect the geometry of the corrugated board. In the method presented here, the finite element method is only used to compose the initial global stiffness matrix, which is then condensed and directly used in the homogenization procedure. The stability of the proposed method was tested for different variants of the selected representative volume elements. The obtained results are consistent with other technique already presented in the literature.

Transverse shear stiffness of structural core sandwich

1994 ◽  
Vol 27 (3) ◽  
pp. 317-329 ◽  
Author(s):  
Tomas Nordstrand ◽  
Leif A. Carlsson ◽  
Howard G. Allen
Keyword(s):  
Transverse Shear ◽  
Shear Stiffness

scholarly journals DIAGNOSIS PROCESSES FOR DESERT ROSE DOMES OF THE SOUF REGION IN ALGERIA

2019 ◽  
Vol XLII-2/W11 ◽  
pp. 115-119
Author(s):  
C. Azil ◽  
B. Djebri ◽  
L. Rovero
Keyword(s):  
Urban Landscape ◽  
Element Model ◽  
Structural Behavior ◽  
Structural Behaviour ◽  
Construction Technique ◽  
Architectural Elements ◽  
Vernacular Buildings ◽  
Dome Shape ◽  
Diagnostic Investigations

<p><strong>Abstract.</strong> In the Souf region of Algeria, all vernacular buildings are covered by domes, built with an unusual building material, the desert rose stone, peculiar to the region. These domes represent an element of identity of the region and describe a unique urban landscape that deserves to be protected and enhanced. Unfortunately, these architectural elements have suffered damage that devalues the urban landscape compromising their conservation. In particular, many domes have severe cracks and have collapsed in large areas.</p><p>Diagnostic investigations were carried out with the aim to understand the causes of the damages and to carry out guidelines for consolidation.</p><p>In particular, in situ surveys have allowed to analyze the employed construction technique, the collection of samples for the chemical-physical and mechanical investigations of the materials and a manual geometric survey of a typical building module. In addition, a Finite Element Model of a building module was realized with the aim of investigating structural behavior.</p><p>Considerations were made on the influence of the dome shape on structural behaviour and on the fractures pattern detected in many domes.</p>

Buckling of sandwich panels with transversely flexible core: Correction of the equivalent single-layer model using thick-faces effect

2018 ◽  
Vol 22 (5) ◽  
pp. 1612-1634 ◽  
Author(s):  
J Jelovica ◽  
J Romanoff
Keyword(s):  
Finite Element ◽  
Transverse Shear ◽  
Sandwich Panels ◽  
Shear Deformation Theory ◽  
Single Layer ◽  
Element Model ◽  
Layer Model ◽  
The Core ◽  
Truss Core ◽  
Single Layer Model

Modeling a periodic structure as a homogeneous continuum allows for an effective structural analysis. This approach represents a sandwich panel as a two-dimensional plate of equivalent stiffness. Known as the equivalent single-layer, the method is used here to analyze bifurcation buckling of three types of sandwich panels with unidirectional stiffeners in the core: truss-core, web-core and corrugated-core panels made of an isotropic material. The transverse shear stiffnesses of these panels can differ by several orders of magnitude, which cause incorrect buckling analysis when using the equivalent single-layer model with the first-order shear deformation theory. Analytical solution of the problem predicts critical buckling loads that feature infinite number of half-waves in the direction perpendicular to the stiffeners. Finite element model also predicts buckling modes that have non-physical, saw-tooth shape with infinite curvature at nodes. However, such unrealistic behavior is not observed when using detailed three-dimensional finite element models. The error in the prediction of the critical buckling load is up to 85% for the cases considered here. The correction of the equivalent single-layer model is proposed by modeling the thick-faces effect to ensure finite curvature. This is performed in the finite element setting by introducing an additional plate with tied deflections to the equivalent single-layer plate. The extra plate is represented with bending and transverse shear stiffness of the face plates. As a result, global buckling is predicted accurately. Guidelines are proposed to identify the sandwich panels where ordinary model is incorrect. Truss-core and web-core sandwich panels need the correction. Corrugated-core panels without a gap between plates in the core have smaller shear orthotropy and do not need the correction. Modeling the thick-faces effect ensures correct results for all cases considered in this study, and thus one should resort to this approach in case of uncertainty whether the ordinary equivalent single-layer model is valid.

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