scholarly journals Kinematic Approach for a Global-Local Coupling: Compressive Behaviour of a Delaminated Panel

2011 ◽  
Vol 20 (6) ◽  
pp. 096369351102000 ◽  
Author(s):  
R. Borrelli ◽  
F. Caputo ◽  
A. Riccio ◽  
F. Scaramuzzino ◽  
A. Sellitto
Keyword(s):  
Three Dimensional ◽  
Composite Panel ◽  
Stiffened Panel ◽  
Good Prediction ◽  
Local Approach ◽  
Numerical Application ◽  
Delamination Growth ◽  
Growth Phenomenon ◽  
Local Coupling ◽  
Kinematic Approach

A kinematic approach to global/local coupling has been applied to investigate the behaviour of a delaminated stiffened composite panel, by using an in-house finite element based procedure. The delamination growth phenomenon has been simulated by employing fracture elements implemented in the B2000++® code, which are based on the Modified Virtual Crack Closure Technique (MVCCT); this technique is able to compute the energy release rate on the delamination front for each fracture mode. A very fine three-dimensional mesh in the delaminated region has been considered in order to obtain a good prediction of the delamination growth. The rest of the structure has been modelled by means of shell elements. A global/local approach based on point-wise multipoint constraint has been implemented in the in-house-code and used to connect shell meshes to solid ones. A numerical application on a delaminated composite stiffened panel taken from literature has been introduced. Models characterized by different levels of complexity, i.e. without delamination, with delamination, with delamination growth have been considered and compared to understand the effectiveness of the introduced kinematic approach.

Buckling analysis of a delaminated panel by using a kinematic global-local coupling approach

2014 ◽  
Vol 5 (4) ◽  
pp. 262-278
Author(s):  
A. Sellitto ◽  
R. Borrelli ◽  
F. Caputo ◽  
A. Riccio ◽  
F. Scaramuzzino
Keyword(s):  
Design Methodology ◽  
Three Dimensional ◽  
Matrix Cracking ◽  
Composite Panel ◽  
Stiffened Panel ◽  
Local Approach ◽  
Content Type ◽  
Kinematic Coupling ◽  
Coupling Approach ◽  
Delamination Front

Purpose – The purpose of this paper is to investigate on the behaviour of a delaminated stiffened panel; the delamination growth is simulated via fracture elements implemented in B2000++® code based on the Modified Virtual Crack Closure Technique (MVCCT), matrix cracking and fibre failure have been also taken into account. Design/methodology/approach – In order to correctly apply the MVCCT on the delamination front a very fine three-dimensional (3D) mesh is required very close to the delaminated area, while a 2D-shell model has been employed for the areas of minor interest. In order to couple the shell domain to the solid one, shell-to-solid coupling elements based on kinematic constraints have been used. Findings – Results obtained with the global/local approach are in good correlation with those obtained with experimental results. Originality/value – The global/local approach based on kinematic coupling elements in conjunction with fracture elements allows to investigate and predict the behaviour of a stiffened delaminated composite panel in an efficient and effective way.

Numerical Analysis of Delamination Growth in Laminated Composites under Buckling Behavior

2012 ◽  
Vol 433-440 ◽  
pp. 379-384
Author(s):  
Mohammad Kazem Ramezani ◽  
S M Mohseni Shakib ◽  
H Soltani
Keyword(s):  
Three Dimensional ◽  
Local Buckling ◽  
Element Model ◽  
Failure Criteria ◽  
Composite Panel ◽  
Delamination Growth ◽  
Buckling Behavior ◽  
Proposed Model ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

In this paper, a delamination growth analysis on composite panel containing embedded delamination has been performed using a three-dimensional finite element model. The effects of the delamination on the local buckling load and delamination growth are studied by using Hashin’s 3D failure criteria via UMAT user’s subroutine of ABAQUS FE program. A new proposed model shows enhancement of the accuracy of the results which showed a good agreement with available experimental data.

Stress Analysis of a Flange Stiffened FRP Composite Panel with Varying Stacking Sequence

2020 ◽  
Vol 847 ◽  
pp. 9-14
Author(s):  
Nabam Teyi ◽  
Santosh Kumar Tamang
Keyword(s):  
Stress Analysis ◽  
Structural Integrity ◽  
Three Dimensional ◽  
Composite Panel ◽  
Stiffened Panel ◽  
Stacking Sequence ◽  
Element Analysis ◽  
Frp Composite ◽  
Gfrp Composite ◽  
The Finite Element Analysis

Large panel structures made of composites are common building units in aerospace industries. In order to increase the stiffness of such structures, the panel or skin is adhered to a flange and supported by a web. Such a stiffened panel is modeled as an arrangement of web, flange and panel with an interface between the flange and the panel. In this paper, three dimensional stress analysis of one such stiffened panel has been carried out using the finite element analysis. The geometric non-linearity has been assumed in the analysis. The effect of material anisotropy and the laminate stacking sequence on the stress components has been studied. Material Graphite Fiber Reinforced Polymeric (GFRP) composite has been used and, two different configurations were considered while the unidirectional prepregs were laid up in quasi-isotropic [0/0/0/0]2 and cross-ply [0/90/90/0]2. Subsequently, the coupled stress failure criterion has been used to predict the critical location of damage onset. When component damage indicator attained the value of 1.0, the component was considered to lose stiffness and structural integrity.

scholarly journals A Novel (2, 3)-Threshold Reversible Secret Image Sharing Scheme Based on Optimized Crystal-Lattice Matrix

Symmetry ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2063
Author(s):  
Jiang-Yi Lin ◽  
Ji-Hwei Horng ◽  
Chin-Chen Chang
Keyword(s):  
Crystal Lattice ◽  
Three Dimensional ◽  
Lattice Models ◽  
Cover Image ◽  
Secret Image Sharing ◽  
Secret Data ◽  
Secret Image ◽  
Image Sharing ◽  
Sharing Scheme ◽  
Growth Phenomenon

The (k, n)-threshold reversible secret image sharing (RSIS) is technology that conceals the secret data in a cover image and produces n shadow versions. While k (kn) or more shadows are gathered, the embedded secret data and the cover image can be retrieved without any error. This article proposes an optimal (2, 3) RSIS algorithm based on a crystal-lattice matrix. Sized by the assigned embedding capacity, a crystal-lattice model is first generated by simulating the crystal growth phenomenon with a greedy algorithm. A three-dimensional (3D) reference matrix based on translationally symmetric alignment of crystal-lattice models is constructed to guide production of the three secret image shadows. Any two of the three different shares can cooperate to restore the secret data and the cover image. When all three image shares are available, the third share can be applied to authenticate the obtained image shares. Experimental results prove that the proposed scheme can produce secret image shares with a better visual quality than other related works.

Finite Element Analysis of Top-Hat–Stiffened Panels of Fiber-Reinforced–Plastic Boat Structures

2007 ◽  
Vol 44 (01) ◽  
pp. 16-26
Author(s):  
Ömer Eksik ◽  
R. Ajit Shenoi ◽  
Stuart S. J. Moy ◽  
Han Koo Jeong
Keyword(s):  
Finite Element ◽  
Lateral Pressure ◽  
Three Dimensional ◽  
Element Model ◽  
Stiffened Panel ◽  
Element Analysis ◽  
Stiffened Panels ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastic ◽  
Experimental Findings

This paper describes the development of a finite element model in order to assess the static response of a top-hat-stiffened panel under uniform lateral pressure. Systematic calculations were performed for deflection, strain, and stress using the developed model based on the ANSYS three-dimensional solid element (SOLID45). The numerical modeling results were compared to the experimental findings for validation and to further understand an internal stress pattern within the different constituents of the panel for explaining the likely causes of the panel failure. Good correlation between experimental and numerical strains and displacements was achieved.

scholarly journals Supervised Learning of Natural-Terrain Traversability with Synthetic 3D Laser Scans

2020 ◽  
Vol 10 (3) ◽  
pp. 1140 ◽  
Author(s):  
Jorge L. Martínez ◽  
Mariano Morán ◽  
Jesús Morales ◽  
Alfredo Robles ◽  
Manuel Sánchez
Keyword(s):  
Supervised Learning ◽  
Autonomous Navigation ◽  
Three Dimensional ◽  
Point Clouds ◽  
Natural Environments ◽  
Good Prediction ◽  
Ground Vehicles ◽  
3D Point Clouds ◽  
Natural Terrain ◽  
Robotic Simulator

Autonomous navigation of ground vehicles on natural environments requires looking for traversable terrain continuously. This paper develops traversability classifiers for the three-dimensional (3D) point clouds acquired by the mobile robot Andabata on non-slippery solid ground. To this end, different supervised learning techniques from the Python library Scikit-learn are employed. Training and validation are performed with synthetic 3D laser scans that were labelled point by point automatically with the robotic simulator Gazebo. Good prediction results are obtained for most of the developed classifiers, which have also been tested successfully on real 3D laser scans acquired by Andabata in motion.

Assessment of cross-laminated timber panels by the state-space approach

2019 ◽  
Vol 22 (11) ◽  
pp. 2375-2391
Author(s):  
Asad S Albostami ◽  
Zhangjian Wu ◽  
Lee S Cunningham
Keyword(s):  
State Space ◽  
Three Dimensional ◽  
The State ◽  
Composite Panel ◽  
State Space Approach ◽  
Cross Laminated Timber ◽  
Practical Applications ◽  
The Cross ◽  
Analytical Approaches ◽  
Space Approach

In this article, cross-laminated timber panels are investigated as a novel engineering application of the state-space approach. As cross-laminated timber is a laminated composite panel, the three-dimensional analytical method provided by the state-space approach offers the potential for improved accuracy over existing common approaches to the analysis of cross-laminated timber. Before focusing on the specific application to cross-laminated timber, the general theory of the state-space approach is outlined. The method is then applied to describe the behaviour of a number of cross-laminated timber panel configurations previously examined experimentally and analytically. In order to demonstrate the capability of the state-space approach in this application, the results are compared with those from various two-dimensional and three-dimensional analytical approaches and finite element modelling briefly. With a view to design, different failure criteria are explored to assess the ultimate strength of the cross-laminated timber panels. The state-space approach demonstrates its superior capability in capturing the nonlinear distribution of the elastic stresses through the thickness of the cross-laminated timber panels over a range of span-to-thickness ratios common in practical applications.

Geometry Effects in Eulerian/Granular Simulation of a Turbulent FCC Riser with a (kg-?g)-KTGF Model

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Hamid Reza Nazif ◽  
Hassan Basirat Tabrizi ◽  
Farhad A Farhadpour
Keyword(s):  
Cross Section ◽  
Large Scale ◽  
Rectangular Cross Section ◽  
Three Dimensional ◽  
Circular Cross Section ◽  
Good Prediction ◽  
Model Predictions ◽  
Secondary Circulations ◽  
Sharp Corners ◽  
Granular Simulation

Three-dimensional, transient turbulent particulate flow in an FCC riser is modeled using an Eulerian/Granular approach. The turbulence in the gas phase is described by a modified realizable (kg-?g) closure model and the kinetic theory of granular flow (KTGF) is employed for the particulate phase. Separate simulations are conducted for a rectangular and a cylindrical riser with similar dimensions. The model predictions are validated against experimental data of Sommerfeld et al (2002) and also compared with the previously reported LES-KTGF simulations of Hansen et al (2003) for the rectangular riser. The (kg-?g)-KTGF model does not perform as well as the LES-KTGF model for the riser with a rectangular cross section. This is because, unlike the more elaborate LES-KTGF model, the simpler (kg-?g)-KTGF model cannot capture the large scale secondary circulations induced by anisotropic turbulence at the corners of the rectangular riser. In the cylindrical geometry, however, the (kg-?g)-KTGF model gives good prediction of the data and is a viable alternative to the more complex LES-KTGF model. This is not surprising as the circulations in the riser with a circular cross section are due to the curvature of the walls and not due to the presence of sharp corners.

scholarly journals Micromechanical Modeling of Brittle Fracture of French RPV Steel: A Comprehensive Study of Stress Triaxiality Effect

2008 ◽  
Author(s):  
Jean-Philippe Mathieu ◽  
Olivier Diard ◽  
Karim Inal ◽  
Sophie Berveiller
Keyword(s):  
Brittle Fracture ◽  
Low Temperatures ◽  
Mean Field ◽  
Three Dimensional ◽  
Stress Triaxiality ◽  
Micromechanical Modeling ◽  
Multiscale Approach ◽  
Local Approach ◽  
Rpv Steel ◽  
Probability Of Fracture

The present study describes a multiscale representation of mechanisms involved in brittle fracture of a french Reactor Pressure Vessel (RPV) steel (16MND5 equ. ASTM A508 Cl.3) at low temperatures. Attention will be focused on the representation of stress heterogeneities inside the ferritic matrix during plastic straining, which is considered as critical for further micromechanical approach of brittle fracture. This representation is tuned on experimental results [1]. Modeling involves micromechanical a description of plastic glide, a mean field (MF) model and a realistic three-dimensional aggregates Finite Element (FE) simulation, all put together inside a multiscale approach. Calibration is done on macroscopic stress-strain curves at different low temperatures, and modeling reproduces experimental stress heterogeneities. This modeling allows to apply a local micromechanical fracture criterion of crystallographic cleavage for triaxial loadings on the Representative Volume Element (RVE). Deterministic computations of time to fracture for different carbide sizes random selection provide a probability of fracture for an Elementary Volume (EV) consistant with the local approach. Results are in good agreement with hypothesis made by local approach to fracture. Hence, the main difference is that no phenomenological dependence on loading or microstructure is supposed for probability of fracture on the EV: this dependence is naturally introduced by the micromechanical description.

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