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Journal of Materials Science

, Volume 17, Issue 10, pp 2947–2954 | Cite as

A modified Weibull treatment for the analysis of strength-test data from non-identical brittle specimens

  • J. W. Kennerley
  • J. M. Newton
  • P. Stanley
Article

Abstract

Powder compacts (e.g., pharmaceutical tablets) manufactured on commerically available machines are not strictly identical but show inevitable variability in their weights, thicknesses and compaction pressures. Consequently, the variability in fracture-stress data obtained from such brittle specimens is greater than that due to the inherent strength variability of the material itself. A modified Weibull analysis has been developed so that a more accurate estimate of the inherent variability of the mechanical strength of the material can be derived from test data obtained from commercially produced compacts; its application is illustrated.

Keywords

Polymer Brittle Compaction Test Data Mechanical Strength 
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

D

diameter

f(ρυ)

relative frequency of occurrence of specimens with densityρ and volumeυ

F

minimization function

i

ascending rank number of a fracture stress

m

Weibull modulus

Ntot

number of specimens in a batch

N(ρυ)

number of specimens with densities in the rangeρ toρ + dρ and volumes in the rangeυ toυ + dυ

Pf

failure probability

pu

upper punch compaction pressure

t

thickness

υ

volume

w

weight

Wf

fracture load

ρ

density

σf

fracture stress

¯σf

mean fracture stress of a batch

¯σf(ρυ)

mean fracture stress of specimens with densityρ and volumeυ

σ0

scale parameter or normalizing factor

σu

location parameter or threshold stress

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References

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Copyright information

© Chapman and Hall Ltd. 1982

Authors and Affiliations

  • J. W. Kennerley
    • 1
  • J. M. Newton
    • 2
  • P. Stanley
    • 3
  1. 1.Department of PharmacyUniversity of NottinghamNottinghamUK
  2. 2.Department of PharmacyChelsea CollegeLondonUK
  3. 3.Simon Engineering LaboratoriesUniversity of ManchesterManchesterUK

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