Design and Optimization of Defense Hole System for Shear Loaded Laminates

2011 ◽  
pp. 161-170
Author(s):  
Mohammad Al-Husban ◽  
Salih N. Akour ◽  
Jamal F. Nayfeh
Keyword(s):  
Principal Stress ◽  
Fiber Orientation ◽  
Stacking Sequence ◽  
Stress Concentrations ◽  
Principal Stress Direction ◽  
Design And Optimization ◽  
Stress Direction ◽  
The Matrix ◽  
Circular Holes

Stress concentrations associated with circular holes in pure biaxial shear-loaded laminates can be reduced by up to 20.56%. This significant reduction is made possible by introducing elliptical auxiliary holes along the principal stress direction. The effect of the stacking sequence, the fiber orientation, and the stiffness of both the fiber and the matrix are investigated.

Design and Optimization of Defense Hole System for Uniaxially Loaded Laminates

2011 ◽  
pp. 129-150
Author(s):  
Salih N. Akour ◽  
Mohammad Al-Husban ◽  
Musa O. Abdalla
Keyword(s):  
Principal Stress ◽  
Fiber Orientation ◽  
Stress Concentrations ◽  
Principal Stress Direction ◽  
Design And Optimization ◽  
Stress Direction ◽  
The Matrix ◽  
Circular Holes

Stress concentrations associated with circular holes in pure Uniaxial-loaded laminates can be reduced by up to 24.64%. This significant reduction is made possible by introducing elliptical auxiliary holes along the principal stress direction. The best reduction is achieved when four elliptical defense holes are introduced in the vicinity of the main hole. The effect of the fiber orientation, as well as the stiffness of both the fiber and the matrix are investigated.

Design and Optimization of Defense Hole System for Hybrid Loaded Laminates

2011 ◽  
pp. 151-160
Author(s):  
Salih N. Akour ◽  
Mohammad Al-Husban ◽  
Jamal F. Nayfeh
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fiber Orientation ◽  
Stacking Sequence ◽  
Element Analysis ◽  
Principal Stress Direction ◽  
Design And Optimization ◽  
Maximum Reduction ◽  
The Matrix ◽  
Circular Holes

Stress concentration associated with circular holes in hybrid loading (i.e., tension-compression ratios of 0.25, 0.50, and 0.75) achieved maximum reduction of 31.7%. This reduction is obtained by introducing elliptical defense holes along the principal stress direction. Finite element analysis is used to optimize the size and location for defense hole system. The effect of the stacking sequence, the fiber orientation, and the stiffness of both the fiber and the matrix are investigated.

Fatigue Design Criteria as Function of the Principal Stress Direction Relative to the Weld Toe

2008 ◽  
Author(s):  
Inge Lotsberg
Keyword(s):  
Principal Stress ◽  
Hot Spot ◽  
Stress Conditions ◽  
Design Criteria ◽  
International Institute ◽  
Proportional Loading ◽  
Principal Stress Direction ◽  
Fatigue Design ◽  
Stress Direction ◽  
Weld Toe

For fatigue design it is necessary to provide guidelines on how to calculate fatigue damage at weld toes based on S-N data when the principal stress direction is different from that of the normal direction to the weld toe. Such stress conditions are found at details in different types of plated structures. Some different fatigue criteria for these stress conditions are presented in design standards on fatigue design. Criteria used by the International Institute of Welding (IIW), Eurocode, British Standard and in the DNV standards have been assessed against some relevant fatigue test data presented in the literature. Only proportional loading conditions have been considered here. (By proportional loading is understood that the principal stress direction is kept constant during a load cycle). An alternative equation for calculation of an equivalent or effective stress range based on stress normal to the weld toe and shear stress at the weld toe has been proposed. The proposed methodology can be used for nominal S-N curves and it can be used together with a hot spot stress S-N curve with stresses read out from finite element analysis. The different design criteria are presented in this paper together with recommendations on analysis procedure.

Powder strength after changes in principal stress direction

1994 ◽  
Vol 81 (1) ◽  
pp. 31-40 ◽  
Author(s):  
T. Dunstan ◽  
M. Jamebozorgi ◽  
S. Akbarian-Miandouab
Keyword(s):  
Principal Stress ◽  
Principal Stress Direction ◽  
Stress Direction

Comparison of Strain Rate Calculation Methods for Environmental Fatigue Correction Evaluation

2012 ◽  
Author(s):  
Seiji Asada
Keyword(s):  
Strain Rate ◽  
Principal Stress ◽  
Evaluation Method ◽  
Calculation Methods ◽  
Sample Problem ◽  
Nuclear Facility ◽  
Principal Stress Direction ◽  
Stress Direction ◽  
Rate Calculation ◽  
Fatigue Evaluation

A Code Case for procedure to determine strain rate and Fen for environmental fatigue evaluation is under preparation in the ASME BPV Committee on Construction of Nuclear Facility Components (III). The draft Code Case is to incorporate two methods for strain rate calculation. One is based on NB-3216.1 “Constant Principal Stress Direction” that comes from the JSME Environmental Fatigue Evaluation Method. The other is based on NB-3216.2 “Varying Principal Stress Direction” that was proposed by M. Gray et al. In this paper, both methods are explained and compared by using a sample problem.

Design of a defence hole system for a shear-loaded plate

2003 ◽  
Vol 38 (6) ◽  
pp. 507-517 ◽  
Author(s):  
S. N Akour ◽  
J. F Nayfeh ◽  
D. W Nicholson
Keyword(s):  
Finite Element Analysis ◽  
Principal Stress ◽  
Pure Shear ◽  
Optimization Method ◽  
Optimum Size ◽  
Stress Concentrations ◽  
Element Analysis ◽  
Search Optimization ◽  
Stress Directions ◽  
Circular Holes

Stress concentrations associated with circular holes in pure shear-loaded plates can be reduced by up to 13.5 per cent by introducing elliptical auxiliary holes along the principal stress directions. These holes are introduced in the areas of low stresses near the main circular hole in order to smooth the principal stress trajectories. A systematic study based on univariate search optimization method is undertaken by using finite element analysis (FEA) to determine the optimum size and location for an auxiliary defence hole system. The results are validated using RGB (red-green-blue) photoelasticity.

Sign in / Sign up

Export Citation Format

Share Document