| Titre : | Contribution to the Modeling of Structures with Complex Geometries with and without Stiffeners |
| Auteurs : | oussama Tamami, Auteur ; Djamal Hamadi, Directeur de thèse ; Ayoub ASHRAF, Directeur de thèse |
| Type de document : | Monographie imprimée |
| Editeur : | Biskra [Algerie] : Université Mohamed Kheider, 2017 |
| Format : | 150.P / Ill / 30/20 cm |
| Accompagnement : | CD |
| Langues: | Français |
| Mots-clés: | Complex Structures,Cylindrical Shell Model,Numerical Modeling,Stiffeners,Experimental work. |
| Résumé : |
In practice, the complex structures such as thin shells, where the structure covers a
large area with a very complex geometry and sometimes supporting heavy loads, can cause very large displacements. This fact often requires the addition of stiffeners to increase the rigidity and to minimize the deformation. These complex structures can be analyzed through modeling by the finite element method. In general, joints or connections between the stiffeners and shell structures are difficult to model. The proposed tasks to resolve this problem is through proper modeling of the stiffened shell structures along with validation using experimentally tested representative specimens. In this thesis, several experimental and numerical investigations regarding the behavior of a cylindrical shell model are conducted. The behavior of cylindrical shell models under a concentrated load, with and without stiffeners and edge beam are studied. Numerical modeling using a flat shell element developed recently and two ABAQUS elements are used. The results obtained experimentally and numerically are compared and commented upon |
| Sommaire : |
Abstract ............................................................................................................................ i
.................................................................................................................................. iiملخص Contents ............................................................................................................................. iii Figure Captions ............................................................................................................ viii Table Captions .............................................................................................................. xi Notation ........................................................................................................................ xv Chapter 1 General Introduction 1.1 Introduction ............................................................................................................. 2 1.2 Advantages of the Finite Element Method ............................................................... 3 1.3 Modeling the structure ........................................................................................... 4 1.4 Discretisation ........................................................................................................... 5 1.5 Objective of the thesis ............................................................................................. 6 Chapter 2 Shell Structures: Design And Analysis 2.1 Introduction ............................................................................................................ 9 2.2 Shells Theory .......................................................................................................... 10 2.2.1 Membrane Behaviour .................................................................................. 10 2.2.2 Bending Behaviour ..................................................................................... 11 2.3 Review of the Assumptions and Numerical Modeling of Shell structures ........... 12 2.3.1 Modeling Approach used for Shell Structures by Flat Shell Finite Elements .................................................................................................... 15 2.3.2 Flat Shell Finite Element Formulation ....................................................... 18 2.4 Analysis of stiffened shell Structures ..................................................................... 19 2.4.1 General description .................................................................................... 19 2.4.2 Review of Stiffened Shells and finite element modeling ......................... 20 2.4.3 Various studies on stiffened shells ............................................................ 21 iv 2.4.3.1 Ring-Stiffened Cylindrical Shells ............................................... 21 2.4.3.2 Stringer-Stiffened Cylindrical Shells ........................................... 23 2.4.3.3 Gabled Hyperbolic Paraboloid Shell .......................................... 24 2.5 Conclusion ............................................................................................................. 27 Chapter 3 Description Of The Experimental Work and The Numerical Analysis 3.1 Introduction ........................................................................................................... 29 3.2 Experimental work ........................................................................................... 30 3.2.1 system set-up ............................................................................................. 30 3.2.1.1 Test 1 (Cylindrical shell with no end diaphragms and No Stiffeners, t=2mm, CNDNS2) ................................................... 30 3.2.1.2 Test 2 (Cylindrical shell with No end diaphragms and No Stiffeners, t=1.2mm, CNDNS) .................................................. 31 3.2.1.3 Test 3 (Cylindrical shell with two end rigid Diaphragms and No Stiffeners, t=1.2mm, CDNS) ............................................... 31 3.2.1.4 Test 4 (Cylindrical shell with No end Diaphragms and two Stiffeners, t=1.2mm, CNDS) ................................................... 32 3.2.1.5 Test 5 (Cylindrical shell with two end Diaphragms and two Stiffeners, t=1.2mm, CDS) ....................................................... 34 3.2.1.6 Test 6 (Cylindrical shell with two end Diaphragms and two Stiffeners resting on longitudinal beams "Stringers", t=1.2mm, CDSS) ...................................................................................... 34 3.2.1.7 Stiffeners characteristics ............................................................ 34 3.2.1.8 Boundary conditions ................................................................ 35 3.2.2 Apparatus used ........................................................................................... 36 3.2.3 Measurements ........................................................................................... 37 3.2.4 Applied loads ............................................................................................ 39 3.3 Numerical Analysis ................................................................................................ 39 3.3.1 ABAQUS Code ........................................................................................ 39 3.3.1.1 Introduction .............................................................................. 39 3.3.2 Type of ABAQUS element used for analysis in this thesis ....................... 40 3.3.2.1 S4R Element ............................................................................. 40 v 3.3.2.2 C3D8IH Element ...................................................................... 40 3.3.3 The shell element ACM-RSBE5 [Ham2015] .......................................... 41 Chapter 4 Experimental And Numerical Investigation Of The Behavior Of A Cylindrical Shell Model 4.1 Introduction ............................................................................................................ 44 4.2 Cylindrical shell with no end Diaphragms, t = 2 mm ........................................... 45 4.2.1 Vertical Displacements at point 1 ............................................................. 45 4.2.2 Vertical Displacements at point 2 ............................................................. 47 4.2.3 Vertical Displacements at point 3 .............................................................. 50 4.2.4 Vertical Displacements W (mm) Under Different Applied Loadings with numerical analysis (10x10) meshes, deflection for points 1,2 and 3 ........ 53 4.3 Cylindrical shell with no end Diaphragms, t = 1.2mm .......................................... 57 4.3.1 Vertical Displacements at point 3 .............................................................. 52 4.3.2 Vertical Displacements W (mm) Under Different Applied Loadings with numerical analysis (10x10) meshes, deflection for point 3 ....................... 60 4.4 Cylindrical shell with end Rigid Diaphragms, t =1.2mm ...................................... 61 4.4.1 Vertical Displacements at point 3 ............................................................. 61 4.4.2 Vertical Displacements W (mm) Under Different Applied Loads with numerical analysis (10x10) meshes, deflections for point 3 ..................... 63 4.5 Conclusion ............................................................................................................. 65 Chapter 5 Experimental And Numerical Investigation Of The Behavior Of The Cylindrical Shell Model With Stiffeners 5.1 Introduction ............................................................................................................ 67 5.2 Cylindrical shell with No end Diaphragms and two Stiffeners, t=1.2mm, CNDS... 68 5.2.1 Vertical Displacements W (mm) Under Different Applied Loadings with numerical analysis (10x10) meshes, deflection for point 3 ....................... 72 5.3 Cylindrical shell with two end Diaphragms and two Stiffeners, t=1.2mm, CDS ... 74 vi 5.3.1 Vertical Displacements W (mm) Under Different Applied Loadings with numerical analysis (45x25) meshes, deflection for point 3 ....................... 76 5.4 Cylindrical shell with two end Diaphragms and two Stiffeners resting on longitudinal beams "Stringers", t=1.2mm, CDSS ................................................. 79 5.4.1 Vertical Displacements W (mm) Under Different Applied Loadings with numerical analysis (45x25) meshes, deflection for point 3 ........................ 81 5.5 Conclusion ............................................................................................................. 84 Chapter 6 Effect Of Boundary Conditions And The Stiffeners On The Cylindrical Shells 6.1 Introduction ............................................................................................................ 87 6.2 Effectiveness of boundary conditions on the cylindrical shell ............................. 87 6.2.1 Cylindrical shell with No end Diaphragms and No Stiffeners CNDNS .... 88 6.2.2 Cylindrical shell with two end rigid Diaphragms and No Stiffeners CDNS 88 6.2.3 Comparison with the ACM-RSBE5 element results ............................... 89 6.2.4 Comparison with ABAQUS results ........................................................... 90 6.2.5 Comparison with the experimental results ................................................. 90 6.3 Effectiveness of boundary conditions on complex structures "cylindrical shell with stiffeners" .................................................................................................... 91 6.3.1 Cylindrical shell with no end diaphragms and two stiffeners, t=1.2mm .. 92 6.3.2 Cylindrical shell with two end diaphragms and two stiffeners, t=1.2mm 92 6.3.3 Comparison with the ABAQUS results .................................................... 93 6.3.4 Comparison with the Experimental results ............................................... 93 6.4 Effectiveness of stiffeners on complex structures "stiffened cylindrical shells" ... 94 6.4.1 First Comparison: Effect of ring stiffeners on the vertical displacement at the top of the cylinder "point 3" for the cylindrical shell reposed on 4 points ......................................................................................................... 95 6.4.1.1 Cylindrical shell with No end diaphragms and No Stiffeners, t = 1.2mm ................................................................................ 95 vii 6.4.1.2 Cylindrical shell with No end Diaphragms and two Stiffeners, t=1.2mm .................................................................................. 96 6.4.1.3 Comparison with the ABAQUS element results ..................... 96 6.4.1.4 Comparison with the Experimental results ............................ 97 6.4.1.5 Diminution Percentage of the horizontal displacements at point 6 using the experimental results ....................................... 97 6.4.2 Second Comparison: Effect of ring stiffeners on the vertical displacement at the top of the cylinder ..................................................... 98 6.4.2.1 Cylindrical shell with end Rigid Diaphragms, t =1.2mm ....... 98 6.4.2.2 Cylindrical shell with two end diaphragms and two stiffeners, t=1.2mm .................................................................................. 99 6.4.2.3 Comparison with the ABAQUS element results ..................... 100 6.4.2.4 Comparison with the Experimental results ............................. 100 6.4.3 Third Comparison: Effect of stringers on the vertical displacement at the top of cylinder and the horizontal displacement at the point 6 ................. 101 6.4.3.1 Cylindrical shell with two end diaphragms and two stiffeners, t=1.2mm ................................................................................. 101 6.4.3.2 Cylindrical shell with two end diaphragms and two stiffeners resting on longitudinal beams "stringers", t=1.2mm ............... 102 6.4.3.3 Comparison with the ABAQUS element results ..................... 102 6.4.3.4 Comparison with the Experimental results ............................. 103 6.4.3.5 Percentage of diminution of Horizontal Displacements at point 6 using the experimental results ..................................... 103 6.5 Conclusion ............................................................................................................ 104 General conclusion and recommendations for further work .......................................... 106 References ...................................................................................................................... 108 Appendix A ..................................................................................................................... 117 Appendix B ..................................................................................................................... 119 |
Disponibilité (1)
| Cote | Support | Localisation | Statut | Emplacement | |
|---|---|---|---|---|---|
| TH/0775 | Thèse de doctorat | BIB.FAC.ST. | Empruntable | Salle de mémoires et de théses |
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