Experimental Mechanics

, Volume 7, Issue 6, pp 279–280 | Cite as

On the definitions of strain and their use in large-strain analysis

In this technical note, authors point out that experimentally obtained strain, using the standard engineering definition, in one coordinate system may be transformed to another coordinate system regardless of the magnitude of the strain
  • V. J. Parks
  • A. J. Durelli


It is pointed out that when strains are computed from a displacement field, the engineering definition of strain(l f l i )/l i has advantages in respect to other definitions used in finite-strain theory. Tensorial transformations can still be used easily by means of Mohr's circle. Illustrations for the case of Eulerian and Lagrangian strains are shown. The comments may be of particular interest to experimental analysts.


Mechanical Engineer Fluid Dynamics Displacement Field Lagrangian Strain Tensorial Transformation 
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  1. 1.
    Parks, V.J., andDurelli, A. J., “Various Forms of Strain-Displacement Relations Applied to Experimental Strain Analysis,”Experimental Mechanics,4, (2)37–47 (Feb. 1964).Google Scholar
  2. 2.
    Sokolnikoff, I. S., “Mathematical Theory of Elasticity,” 2nd Ed., McGraw-Hill (1951).Google Scholar
  3. 3.
    Eringen, A. C., “Nonlinear Theory of Continuous Media,” McGraw-Hill (1962).Google Scholar

Copyright information

© Society for Experimental Mechanics, Inc. 1967

Authors and Affiliations

  • V. J. Parks
    • 1
  • A. J. Durelli
    • 1
  1. 1.Mechanics DivisionThe Catholic University of AmericaWashington, D. C.

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