Plastic Strength of Perforated Plates With Square Penetration Patterns

1975 ◽  
Vol 97 (3) ◽  
pp. 146-154 ◽  
Author(s):  
J. Porowski ◽  
W. J. O’Donnell
Keyword(s):  
Lower Bound ◽  
Entire Range ◽  
Solid Material ◽  
Biaxial Stress ◽  
Perforated Plates ◽  
Limit Loads ◽  
Plastic Strength ◽  
Circular Holes ◽  
Yield Surfaces

The sheet perforated with circular holes arranged in a square penetration pattern anp subjected to in-plane biaxial stress is investigated. Discontinuous fields of stress are used to obtain the lower-bound limit loads for the perforated material. The yield surfaces for the equivalent solid material are then derived and the effective plastic constants are given for the entire range of ligament efficiencies used in design.

Elastic Design Methods for Perforated Plates

1978 ◽  
Vol 100 (2) ◽  
pp. 356-362 ◽  
Author(s):  
J. S. Porowski ◽  
W. J. O’Donnell
Keyword(s):  
Finite Element ◽  
Thermal Loading ◽  
Solid Material ◽  
Perforated Plates ◽  
Finite Element Stress Analysis ◽  
Effective Elastic Constants ◽  
New Methods ◽  
Circular Holes ◽  
Elastic Design ◽  
Generalized Plane Strain

Methods for performing finite element stress analysis of perforated plates under pressure and complex thermal loading conditions are described. The concept of the equivalent solid material of anisotropic properties is employed to define the elasticity matrices to be used for axisymmetric analysis of plates containing triangular and square patterns of circular holes. Generalized plane strain effective elastic constants are used for better approximation of the overall plate behavior. New methods and curves for obtaining local ligament stresses from the nominal stresses in the equivalent solid material are given.

Bounded Elastic Moduli Multiplier Technique for Limit Loads: Part 2 - Case Studies

2021 ◽  
Author(s):  
Sathya Prasad Mangalaramanan
Keyword(s):  
Lower Bound ◽  
Case Studies ◽  
Power Law ◽  
Elastic Moduli ◽  
New Method ◽  
Stress Distributions ◽  
Limit Loads ◽  
Elastic Plastic ◽  
Thick Cylinder ◽  
Better Than

Abstract An accompanying paper provides the theoretical underpinnings of a new method to determine statically admissible stress distributions in a structure, called Bounded elastic moduli multiplier technique (BEMMT). It has been shown that, for textbook cases such as thick cylinder, beam, etc., the proposed method offers statically admissible stress distributions better than the power law and closer to elastic-plastic solutions. This paper offers several examples to demonstrate the robustness of this method. Upper and lower bound limit loads are calculated using iterative elastic analyses using both power law and BEMMT. These results are compared with the ones obtained from elastic-plastic FEA. Consistently BEMMT has outperformed power law when it comes to estimating lower bound limit loads.

scholarly journals Influence of Add-On Perforated Plates on the Protective Performance of Light-Weight Armour Systems

2018 ◽  
Vol 9 (1) ◽  
pp. 31-48
Author(s):  
Teresa FRAS ◽  
Norbert FADERL
Keyword(s):  
Hard Core ◽  
High Hardness ◽  
Steel Plates ◽  
Perforated Plates ◽  
Geometrical Properties ◽  
Impact Position ◽  
Circular Holes ◽  
Protective Performance ◽  
The Impact ◽  
Armour Steel

The presented experimental investigation, aimed at verification of defeat mechanisms against small-calibre projectiles, provided by 4-mm-thick perforated plates with different material- and geometrical properties, was performed. A regular pattern of punched holes in steel plates increases the possibility of asymmetrical contact between the plate and projectiles which may cause threat destabilization, rotation or fragmentation depending on the impact position. Three tested armour configurations comprise the super-bainitic high-hardness Pavise™ SBS 600P armour steel plates perforated by elongated holes of size 4  12 mm (the first configuration), the martensitic high-hardness Mars® 300P steel plates perforated by circular holes with a diameter of 5 mm (in the second configuration); and in the third configuration, the martensitic Mars® 300 plates perforated by oblong holes (4  10 mm) were used. The performed impact tests proved that the tested add-on plates assured high protection against the impact of 7.62  51 .308 Win P80 hard-core armour piercing (AP) projectiles. It was also observed that the plates caused similar mechanisms of bullet failure.

Accelerated Limit Loads Using Repeated Elastic Finite Element Analyses

2003 ◽  
Author(s):  
Prasad Mangalaramanan
Keyword(s):  
Finite Element ◽  
Lower Bound ◽  
Limit Load ◽  
Finite Element Analyses ◽  
Limit Loads ◽  
Bound Theorem

This paper demonstrates the limitations of repeated elastic finite element analyses (REFEA) based limit load determination that uses the classical lower bound theorem. The r-node method is prescribed as an alternative for obtaining better limit load estimates. Lower bound aspects pertaining to r-nodes are also discussed.

Incorporation of Strain Hardening Effect Into Simplified Limit Analysis

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
P. S. Reddy Gudimetla ◽  
R. Adibi-Asl ◽  
R. Seshadri
Keyword(s):  
Lower Bound ◽  
Strain Hardening ◽  
Limit Load ◽  
Element Analysis ◽  
Active Volume ◽  
Limit Loads ◽  
Reference Volume ◽  
Perfectly Plastic ◽  
Tangent Method ◽  
Elastic Perfectly Plastic

In this paper, a method for determining limit loads in the components or structures by incorporating strain hardening effects is presented. This has been done by including a certain amount of the strain hardening into limit load analysis, which normally idealizes the material to be elastic perfectly plastic. Typical strain hardening curves such as bilinear hardening and Ramberg–Osgood material models are investigated. This paper also focuses on the plastic reference volume correction concept to determine the active volume participating in plastic collapse. The reference volume concept in combination with mα-tangent method is used to estimate lower-bound limit loads of different components. Lower-bound limit loads obtained compare well with the nonlinear finite element analysis results for several typical configurations with/without crack.

Integral Mean of Yield Criterion in Design and Fitness for Service Assessment

2008 ◽  
Author(s):  
R. Adibi-Asl ◽  
R. Seshadri
Keyword(s):  
Lower Bound ◽  
Variational Formulation ◽  
Yield Criterion ◽  
Hot Spot ◽  
Corrosion Damage ◽  
Limit Load ◽  
Assessment Procedure ◽  
Limit Loads ◽  
Reference Volume ◽  
Volume Method

Mura’s variational formulation for determining limit loads, originally developed as an alternative to classical methods, is extended further by allowing the pseudo-elastic distributions of stresses to lie outside the yield surface provided they satisfy the “integral mean of yield” criterion. Consequently, improved lower-bound and upper-bound values for limit loads are obtained. The mα estimation limit load method, reference volume method and the fitness for service assessment procedure (including corrosion damage and thermal hot spot damage), are all applications and extensions of the “integral mean of yield” criterion.

Effect of the Horizontal Perforated Plates on the Turbidity Removal Efficiency in Water Treatment Plant of Tikrit University

2019 ◽  
Vol 26 (4) ◽  
pp. 38-42
Author(s):  
Ahmed Ibrahim
Keyword(s):  
Treatment Plant ◽  
Water Treatment Plant ◽  
Water Turbidity ◽  
Turbidity Removal ◽  
Perforated Plates ◽  
Sedimentation Basin ◽  
Tigris River ◽  
Turbidity Level ◽  
Hydraulic Load ◽  
Circular Holes

The study aims to show effect of adding the circular perforated plates in sedimentation basin in horizontal position on the efficiency of the sedimentation basin as was the use of perforated panels with circular holes and placed inside the sedimentation basin and took two levels of turbidity of the water 125 and 150 NTU respectively in the Tigris river during the preparation of the study with variable hydraulic load and the efficiency was calculated at each case of plates in the basin where the variables that were adopted is the number of perforated panels so that the ratio of the area of holes/total area of panel is 20% , and also variation in water turbidity levels and the hydraulic load. The result showed a significant decrease in the output turbidity levels from sedimentation tank with the use of perforated panels at the raw water turbidity 150 NTU and hydraulic load between 0.9 and 1.2 m3/m2.hr were 95% higher efficiency when three panels were put and hydraulic load 0,9 m3/m2.hr, while there was fluctuation with some of hydraulic load levels at turbidity level of 125 NTU and same number of panels

Bounded Elastic Moduli Multiplier Technique for Limit Loads: Part 1 - Theory

2022 ◽  
Author(s):  
Sathya Prasad Mangalaramanan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Lower Bound ◽  
Power Law ◽  
Elastic Moduli ◽  
Stress Distributions ◽  
Finite Element Analyses ◽  
Element Analysis ◽  
Limit Loads ◽  
Reduced Modulus

Abstract Statically admissible stress distributions are necessary to evaluate lower bound limit loads. Over the last three decades, several methods have been postulated to obtain these distributions using iterative elastic finite element analyses. Some of the pioneering techniques are the reduced modulus, r-node, elastic compensation, and linear matching methods, to mention a few. A new method, called the Bounded Elastic Moduli Multiplier Technique (BEMMT), is proposed and the theoretical underpinnings thereof are explained in this paper. BEMMT demonstrates greater robustness, more generality, and better stress distributions, consistently leading to lower-bound limit loads that are closer to elastoplastic finite element analysis estimates. BEMMT also questions the validity of the prevailing power law based stationary stress distributions. An accompanying research offers several case studies to validate this claim.

Local Limit-Load Analysis Using the mβ Method

2006 ◽  
Vol 129 (2) ◽  
pp. 296-305 ◽  
Author(s):  
R. Adibi-Asl ◽  
R. Seshadri
Keyword(s):  
Lower Bound ◽  
Upper Bound ◽  
Local Limit ◽  
Limit Load ◽  
Element Analysis ◽  
Limit Loads ◽  
Linear Elastic ◽  
Reference Volume ◽  
Component Design ◽  
Load Analysis

Several upper-bound limit-load multipliers based on elastic modulus adjustment procedures converge to the lowest upper-bound value after several linear elastic iterations. However, pressure component design requires the use of lower-bound multipliers. Local limit loads are obtained in this paper by invoking the concept of “reference volume” in conjunction with the mβ multiplier method. The lower-bound limit loads obtained compare well to inelastic finite element analysis results for several pressure component configurations.

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