Stress Concentration Factors in Auxetic Rods and Plates

2013 ◽  
Vol 394 ◽  
pp. 134-139 ◽  
Author(s):  
Teik Cheng Lim
Keyword(s):  
Stress Concentration ◽  
Circumferential Stress ◽  
Axial Direction ◽  
Thin Plates ◽  
Auxetic Materials ◽  
Circular Holes ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Future Work ◽  
Poissons Ratio

Auxetic materials are solids that possess negative Poissons ratio. Although rare, such materials do occur naturally and also have been artificially produced. Due to their unique properties, auxetic materials have been extensively investigated for load bearing applications including in biomedical engineering and aircraft structures. This paper considers the effect of Poissons ratio on the stress concentration factors on rods with hyperbolic groove and large thin plates with circular holes and rigid inclusions. Results reveal that the use of auxetic materials is useful for reducing stress concentration in the maximum circumferential stress of the rods with grooves, and in plates with circular holes and rigid inclusions. However, the use of auxetic materials increases the stress concentration in the axial direction of the rod. Therefore a procedure to accurately select and/or design materials with precise negative Poissons ratio for optimal design is suggested for future work.

The Stress Concentration Factors in Cylindrical Tubes with Transverse Circular Holes

1959 ◽  
Vol 10 (4) ◽  
pp. 326-344 ◽  
Author(s):  
H. T. Jessop ◽  
C. Snell ◽  
I. M. Allison
Keyword(s):  
Stress Concentration ◽  
Maximum Stress ◽  
Stress System ◽  
Complete Knowledge ◽  
Geometrical Shapes ◽  
Cylindrical Tubes ◽  
Circular Holes ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Better Than

The “frozen stress” techniques of photoelasticity can give a complete knowledge of the stress, system in a solid body, but the examination of the stresses requires more time and care than in corresponding flat plate tests. In tests on tubes with transverse circular holes, sponsored by The Royal Aeronautical Society, all practicable geometrical shapes are examined and the maximum stress is measured in tension, bending and torsion. The results are comprehensive and show the inadequacy of previous results. In all cases the maximum stress occurs inside the bore of the hole. The accuracy of all the graphs of stress concentration factors is better than five per cent.

Investigation of Pressure Stress Concentration Factors for Intersecting Elliptic Bores With Circular Bores in Blocks

2009 ◽  
Author(s):  
Elie A. Badr ◽  
Nataly Yousef
Keyword(s):  
Regression Analysis ◽  
Stress Concentration ◽  
Tilt Angle ◽  
Hoop Stress ◽  
Elliptic Hole ◽  
Lower Stress ◽  
Circular Holes ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Pressure Stress

Stress concentration factors due to intersecting elliptic bores as well as circular bores in blocks have been thoroughly investigated by Badr [1] and Sorem et al [2]. Results of these investigations indicated that intersecting elliptic crossbores generate lower stress concentration factors than those due to intersecting circular crossbores. In this study, we investigate stress concentration factors for crossbores in blocks (cubical and rectangular) emanating from intersecting elliptic with circular holes. Comparing these results with those generated by Badr [1] for elliptic hole intersections; it was found that crossbores due to intersecting elliptic with circular bores generate higher hoop stress concentration factors. A regression analysis was also performed to determine a relationship between the stress concentration factors, the bore ratio (a2/a1) and the tilt angle θ.

Howland’s isotropic Kts curve for plates with circular holes as a master curve for Kts in orthotropic plates with elliptical holes

2017 ◽  
Vol 52 (3) ◽  
pp. 152-161 ◽  
Author(s):  
Nando Troyani ◽  
Milagros Sánchez
Keyword(s):  
Stress Concentration ◽  
Master Curve ◽  
Orthotropic Materials ◽  
Finite Width ◽  
Rectangular Plates ◽  
Analysis And Design ◽  
Circular Holes ◽  
Elliptical Holes ◽  
Concentration Factors ◽  
Stress Concentration Factors

The importance of the role played by the so-called stress concentration factors (or symbolically referred to as Kts) in analysis and design in both mechanical and structural engineering is a well-established fact, and accuracy and ease in their estimation result in significant aspects related to engineering costs, and additionally on both the reliability in the design of parts and/or in the analysis of failed members. In this work, rectangular finite width plates of both isotropic and orthotropic materials with circular and elliptical holes are considered. Based on two key observations reported herein, it is shown in a partially heuristic engineering sense, that Howland’s solution curve for the stress concentration factors for finite width plates with circular holes subjected to tension can be viewed as a master curve; accordingly, it can be used as a basis to rather accurately estimate stress concentration factors for isotropic finite width tension rectangular plates with centered elliptical holes and also rather accurately used to estimate stress concentration factors for orthotropic finite width rectangular plates under tension with centered elliptical holes. Two novel concepts are defined and presented to this effect: geometric scaling and material scaling. In all the examined and reported cases, the specific numerical results can be obtained accurately using a hand-held calculator making virtually unnecessary the need to program and/or use other complex programs based on the finite element method, just as an example. The maximum recorded average error for all the considered cases being 2.62% as shown herein.

Strengthening of Circular Holes in Plates Under Edge Loads

1944 ◽  
Vol 11 (3) ◽  
pp. A140-A148
Author(s):  
Leon Beskin
Keyword(s):  
Stress Concentration ◽  
Critical Stress ◽  
Hydrostatic Stress ◽  
Axial Stress ◽  
Theory Of Elasticity ◽  
Stress Distributions ◽  
Common Basis ◽  
Circular Holes ◽  
Concentration Factors ◽  
Stress Concentration Factors

Abstract In this paper, stress distributions are determined around strengthened circular holes in plates submitted to edge loads at infinity. Various proportions of circular strengthenings are considered, and three conditions of applied edge loads are investigated; uniform hydrostatic stress, uniform shearing stress, uniform axial stress. Stress distributions are found by methods of theory of elasticity, and the results are given in the form of stress-concentration factors. In order to reduce the results to a common basis, the stress-concentration factors have been defined by the ratio of the critical stress, computed by the distortion-energy theory, to the critical stress at infinity, which is the critical stress in the plate without hole.

Stress Concentration Effects in Short Cylindrical Vessels With Holes Subjected to Tension: A Complete Account

2005 ◽  
Vol 127 (2) ◽  
pp. 184-189 ◽  
Author(s):  
Nando Troyani ◽  
Nelson Jaimes ◽  
Gaetano Sterlacci ◽  
Carlos J. Gomes
Keyword(s):  
Stress Concentration ◽  
Elastic Shell ◽  
Critical Factor ◽  
Circular Cylinders ◽  
Stress Concentrations ◽  
Concentration Effects ◽  
Analysis And Design ◽  
Circular Holes ◽  
Concentration Factors ◽  
Stress Concentration Factors

Whenever regular geometric discontinuities are present the so called stress concentration factors concept is widely used in both analysis and design of loaded components especially when subjected to fatigue, frequently the working condition of vessels. However, recent observations suggest that the influence of member length on the magnitude of the stated factors was not considered in previous analyses. In this work, this observation was studied in the context of cylindrical vessels and it was found that in this case, as well, length could be a critical factor when computing stresses developed as a result of externally applied loads. Accordingly, the values of the finite element calculated theoretical stress concentration factors are computed, for the case of short circular cylinders with circular holes subjected to axial tension, in the context of elastic shell theory, and are presented in a fashion similar to existing published results. It is shown that significantly larger stress concentrations appear for shorter members. The transition length concept defining the threshold between long cylinders and short cylinders is discussed in the context of this study and reported as well.

Theoretical Stress Concentration Factors for Short Rectangular Plates With Centered Circular Holes

1999 ◽  
Vol 124 (1) ◽  
pp. 126-128 ◽  
Author(s):  
N. Troyani ◽  
C. Gomes ◽  
G. Sterlacci
Keyword(s):  
Stress Concentration ◽  
Rectangular Plates ◽  
The Finite Element Method ◽  
New Concepts ◽  
Circular Holes ◽  
Transition Length ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Theoretical Stress ◽  
Theoretical Stress Concentration Factor

This work shows that the theoretical stress concentration factor depends on the length of the member in addition to the established other standard geometric parameters. In particular, the in-plane theoretical stress concentration factors for short rectangular plates with centered circular holes subjected to uniform tension are determined using the finite element method. It is shown that these factors can reach significantly larger values than the corresponding existing ones for long plates. The value of the transition length between long and short plates is computed and reported as well. Two new concepts are defined, short members and transition length.

Effect of Length on Stress Concentration for Short Cylindrical Members With Holes

2004 ◽  
Author(s):  
Nando Troyani ◽  
Gaetano Sterlacci ◽  
Nelson Jaimes ◽  
Carlos J. Gomes
Keyword(s):  
Stress Concentration ◽  
Critical Factor ◽  
Circular Cylinders ◽  
Stress Concentrations ◽  
Analysis And Design ◽  
Axial Tension ◽  
Circular Holes ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Novel Concept

As is well known stress concentration will appear in any application where some form of geometric discontinuity is present. To deal with such situations the so called Stress Concentration Factors (SCF) concept was developed and is widely used in both analysis and design of loaded components especially when subjected to fatigue, usually the working condition of vessels. However, recent observations suggest that the influence of member length on the magnitude of the stated SCF’s was not considered. In this work, this observation was studied in the context of cylindrical vessels and it was found that in this case, as well, length could be a critical factor when computing stresses developed as a result of externally applied loads. The values of the Finite Element (FE) calculated Theoretical Stress Concentration Factors (TSCF’s) are computed, for the case of short circular cylinders with circular holes subjected to axial tension, and presented in a fashion similar to existing published results. It is shown that significantly larger stress concentrations appear for short members. The novel concept of transition length, that defines the threshold between long plates and short plates, is discussed in the context of this study and reported as well.

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