JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 66

KNOW-HOW Mechanical design g…/… Stress concentration factors replacing (3) and (9) in (8), the efforts in the plate can be calculated. A laminate is symmetric if layers of the same material, thickness and orientation are symmetrically located with respect to the middle surface of the laminate. Symmetric laminates are among the most commonly used, because they do not present extensional/flexural coupling, and so do not bend during the curing process. All the laminates used in this work were of the type S-glass/epoxy, and symmetric. Some of them were also balanced. In a balanced laminate, for every layer at +φ , there is another at -φ with the same thickness and material; and for each 0º layer, there is a 90º layer, also of the same thickness and material. Fig. 6: Symetric angle-ply laminates Cross-ply laminates A cross-ply laminate has only layers oriented at 0° and 90°. To calculate the stress concentration factor, the stress in equation (7) corresponds to the tensile stress at the edge of the notch over the regular diameter, in the direction of the effort. Figure 5 shows the stress concentration factor variation as a function of the d/H relation. for these laminates are shown in Figure 6. The curves for the [30/-30]s, [45/-45]s and [60/-60]s angle-ply laminates are shown in Figure 6. As in the case of cross-ply laminates, the angle-ply laminates that repeat these sequences share the same curves, so the graphics were not included in this work. Even though the stresses are different in each layer, the stress concentration factor is the same. Conclusions This investigation showed that the subject of stress concentration is very complex, and that the results depend on the kind of material used, so it is not convenient to extrapolate the results obtained in one to another. The analysis of the results obtained here, along with the literature consulted, indicate that the stress concentration factor in composite materials depends on the geometry of the part, but that the type of laminate is also important. Acknowledgements: The authors would like to thank the Engineering Department and the Science and Technology Department of the Universidad Nacional del Sur for the support given for the development of these investigations. Contact: nfortega@criba.edu.ar References Fig. 5: Stress Concentration Factor in Cross-Ply symmetric laminates In the cross-ply laminates studied here, it can be observed that the stress concentration factor increases with the d/H relation and that all the configurations are kept in the interval, including the curves corresponding to single ply of 0º and that of 90º. The balanced laminates such as [0/90]s, [0/90/0/90]s all have the same curve, located among the ones mentioned above, while the non-balanced symmetric laminates are nearer to one or the other, depending on their respective number of layers. For example, [0/90/0] is near the 0º curve, but [90/0/90] is near the 90º curve. Besides, it can be seen that all the laminates that repeat a sequence such as [90/0/90] and [0/90/0]s, for example, share the same curve. All the curves in Figure 5 belong to the tension stress concentration factor, which is the same for the different layers. Though, the stresses are obviously different. [1] S. G. Lekhnitskii. Anisotropic Plates. Gordon and Breach Science Publishers, 1968. [2] S. Maiz, R. Rossi, P Laura, D. Bambill. Efectos de la Ortotropía sobre el Factor de . Concentración de Tensiones, ENIEF 2004, Mecánica Computacional, 23, 673-692, 2004. [3] M. Sánchez, N. Troyani. Factor teórico de concentración de esfuerzos en piezas cortas de materiales anisótropos, ENIEF 2003, Mecánica Computacional, 22, 2135-2144, 2003. [4] FlexPDE v.2.20. A Flexible Solution System for Partial Differential Equations, PDE Solutions Inc., 2001. [5] ALGOR v.15 Professional Mech/VE, Linear Stress and Dynamics. Reference Division, Pittsburg, 2002. Angle-ply laminates Angle-ply laminates are built with pairs of layers of the same + material and thickness, oriented at - φ . These laminates are balanced. If they are symmetric, the equations are the same as those for cross-ply symmetric laminates. The stress concentration factor was calculated at the maximum tension stress. The results obtained [6] E. J. Barbero. CADEC. Computer Aided Design Environment for Composites, 1999. [7] E. J. Barbero. Introduction to Composite Materials Design. Taylor and Francis, Inc., 1999. [8] R. M. Jones. Mechanics of Composite Materials. Taylor and Francis, Inc., 1999. [9] T. K. Paul, K. M. Rao. Finite Element Stress Analysis of Laminated Composite Plates Containing Two Circular Holes Under Transverse Loading. Computers & Structures, 54(4), 1995. JEC Composites Magazine / No37 December 2007

JEC COMPOSITES MAGAZINE - Issue #37 - December 2007

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #37 - December 2007

Cover
Edito
CONTENTS
NEWS WORLDWIDE
- Companies
- Agenda of events
- Innovations
BUSINESS
- Trends
- Market survey: China
- Initiative
- Niche markets
- Human capital
FEATURE - BIOCOMPOSITES
- Properties
- Materials
- Applications
USERS’ PLATFORM
- Composites in the world
- Applications
- Successful partners
- Impact analysis
KNOW-HOW
- Thermoplastic fabric
- Control
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - Cover
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 2
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - Edito
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 4
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 5
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - CONTENTS
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 7
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - - Companies
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 9
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 10
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 11
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - - Agenda of events
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 13
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - - Innovations
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 15
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 16
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 17
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - - Trends
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 19
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - - Market survey: China
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 21
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 22
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 23
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 24
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 25
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 26
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 27
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - - Initiative
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 29
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - - Niche markets
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 31
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - - Human capital
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 33
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - - Properties
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 35
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 36
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - - Materials
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 38
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 39
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 40
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 41
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - - Applications
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 43
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 44
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 45
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 46
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 47
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 48
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 49
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - - Composites in the world
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 51
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - - Applications
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 53
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - - Successful partners
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 55
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - KNOW-HOW
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 57
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 58
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - - Thermoplastic fabric
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 60
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 61
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - - Control
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 63
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 64
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 65
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 66
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 67
JEC COMPOSITES MAGAZINE - Issue #37 - December 2007 - 68
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