Experimental Mechanics

, Volume 13, Issue 12, pp 519–525 | Cite as

Alleviation of the stress concentration with analogue reinforcement

Stress concentration around a hole in a plate is reduced by placement of reinforcement following stress trajectories
  • R. A. Heller
  • T. Chiba
Article

Abstract

In order to reduce the stress concentration around a hole in a plate, new, “analogue” reinforcements instead of reinforcing rings were used in this investigation. In two of these specimens, reinforcements with different volume fractions were arranged to coincide with the stress trajectories for an infinite plate with a hole under uniaxial tension. Two other specimens containing straight rectangular-grid-type reinforcements were made by using a photofabrication method. Specimens were then prepared by sandwiching these reinforcements between two epoxy-resin plates. Plane specimens, i.e., without reinforcement, were also made of the same epoxy resin for comparison.

The stress concentrations at the edge of the hole under uniaxial tension were determined by photoelastic techniques. The measured stress-concentration factors were compared with well-known values for an infinite, isotropic, homogeneous plate containing a hole. Results were also compared with published data on [90/0/90/0]s 7-ply laminated composite plates, and on plates strengthened with reinforcing rings.

A definite reduction in stress concentration was observed on specimens containing analogue reinforcement.

Keywords

Epoxy Mechanical Engineer Fluid Dynamics Stress Concentration Uniaxial Tension 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

List of Symbols

a

radius of hole

b

half width of plate

f

material-fringe value

nmax,na

fringe order at edge of hole; at remote location

r

radial coordinate

vf, vm

volume fraction of reinforcement; of matrix

x,y

longitudinal and transverse coordinates

E, EL, ET, E45

moduli of elasticity: isotropic, longitudinal, transverse; at 45 deg

Ef, Em

moduli of elasticity for reinforcement; matrix

G, GLT

shear moduli: isotropic, orthotropic

Kti, Kz

stress-concentration factors: isotropic, orthotropic

α

angle formed by longitudinal axis and slope of stress trajectory

ννLT

Poisson's ratios: isotropic, orthotropic

ϕ

tangential coordinate

σ,σθτγθ

stress components in cylindrical coordinates

σx,σyτx,y

stress components in Cartesian coordinates

τmax,σa

maximum longitudinal stress; at remote location

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Copyright information

© Society for Experimental Mechanics, Inc. 1973

Authors and Affiliations

  • R. A. Heller
    • 1
  • T. Chiba
    • 2
  1. 1.Department of Engineering Science and MechanicsVirginia Polytechnic Institute and State UniversityBlacksburg
  2. 2.Musushi Institute of TechnologyTokyoJapan

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