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Experimental Mechanics

, Volume 4, Issue 11, pp 335–344 | Cite as

Plastic strains and energy density in cracked plates

Part I-experimental technique and results To facilitate presentation of data and comparison to available theory, this paper is divided into two parts: the first is primarily concerned with experimental procedure and results; and the second is concerned with correlation of data to elastic theory and a discussion of ductile fracture in light of experimental evidence
  • William W. Gerberich
Article

Abstract

A technique is presented which allows separation of the principal plastic strains within an enclave at a crack tip in relatively thin plates. For plates with a number of crack lengths, several degrees of tensile loading are applied to five ductile materials with widely varying mechanical properties. Principal plastic strain distributions, plastic distortional strain energy density and total plastic energy are determined within the resulting plastic encalves. It is shown that the degree of loading and strain hardening greatly affect the principal plastic strain and energy density distributions and that this is reflected in the amount of strain energy that can be plastically absorbed at a crack tip.

Keywords

Energy Density Fluid Dynamics Plastic Strain Density Distribution Crack Length 
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.

Nomenclature

a

half crack length

ΔA

incremental area within enclave

ɛ123

principal plastic strains

δ

relative retardation of 2.27×10−5 in. corresponding to first fringe order

E

tensile modulus of elasticity

F

loading factor defined in eq (7)

γoct

octahedral shear strain

k

strain optical coefficient

n

strain-hardening exponent

r, θ

polar coordinates

rmax

distance from crack tip along maximum extension of enclave

rp

arbitrary value to define elastic-plastic boundary

rp(θ)

shape of enclave

rp′

maximum extension of enclave measured at ɛ1=2000 μin./in

rθ=0o

distance from crack tip along line of crack extension

σ0

applied stress, gross section

σys

uniaxial yield stress

t

plate thickness

tc

thickness of photoelastic coating

τoct

octahedral shear stress

Up

plastic strain energy in one enclave

ω

plate width

Wd

plastic distortional strain energy density

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References

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Copyright information

© Society for Experimental Mechanics, Inc. 1964

Authors and Affiliations

  • William W. Gerberich
    • 1
  1. 1.Philco Research LaboratoryFord Motor Co.Newport Beach

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