Experimental Mechanics

, Volume 17, Issue 9, pp 339–346 | Cite as

Ten-deg off-axis test for shear properties in fiber composites

It is demonstrated that the 10-deg off-axis tensile test is an accurate and convenient test method for the intralaminar-shear characterization of unidirectional fiber composites
  • C. C. Chamis
  • J. H. Sinclair
Article
Received:
Revised:

Abstract

A combined theoretical and experimental investigation was conducted to assess the suitability of the 10-deg off-axis tensile-test specimen for the intralaminar-shear characterization of unidirectional composites. Composite mechanics, a combined-stress failure criterion and a finiteelement analysis were used to determine theoretically the stress-strain variation across the specimen width and the relative stress and strain magnitudes at the 10-deg plane. Strain gages were used to measure the strain variation across the specimen width at specimen midlength and near the end tabs. Specimens from Mod-I/epoxy. T-300/epoxy, and S-glass/epoxy were used in the experimental program. It was found that the 10-deg off-axis tensile-test specimen is suitable for intralaminar-shear characterization and it, is recommended that it should be considered as a possible standard test specimen for such a characterization.

Keywords

Epoxy Fluid Dynamics Test Specimen Strain Gage Failure Criterion 
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

E

normal modulus; subscripts define direction

F

combined-stress failure-criterion function

G

shear modulus—intralaminar

K

coupling coefficient in combined-stress failure-criterion function

S

uniaxial fracture stress; subscripts define direction

x, y, z

structural-axes orthogonal coordinate system withx taken along load direction

1, 2, 3

material-axes orthogonal coordinate system with 1 taken along fiber direction

ε

strain; subscripts define type, plane and direction

θ

orientation angle between structural and material axes measured positive counterclockwise

θg

orientation angle locating strain gage from load direction

σ

stress; subscripts define type, plane and direction

Subscripts

C

compression

c

structural-axes property

g

strain-gage reading

ℓ

ply (unidirectional composite) property

S

shear, symmetric

T

tension

x, y, z

structural-axes directions

1, 2, 3

material-axes directions

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References

  1. 1.
    Bert, C.W., “Experimental Characterization of Composites,”Comp. Mats.,8 Part 2,Chamis,C. C.,ed.,Academic Press,New York,73–133 (1975).Google Scholar
  2. 2.
    Daniel, I.M. and Liber, T., “Lamination Residual Stresses in Fiber Composites,” ITT Res. Inst. Rep. IITRI-D6073-1 (1975); also NASA CR-134826.Google Scholar
  3. 3.
    Chamis, C.C., “Failure Criteria for Filamentary Composites,” NASA TN D-5367 (1969).Google Scholar
  4. 4.
    Chami, C.C., “Failure Criteria for Filamentary Composites”STP 460. Composite Materials: Testing and Design, ASTM, New Orleans, 336–351 (1972).Google Scholar
  5. 5.
    “Transverse Sensitivity Errors,” Micro-Measurements, Tech. Note 137.Google Scholar
  6. 6.
    Chamis, C.C., Kring, J.F. and Sullivan, T.L., “Automated Testing Data Reduction Computer Program,” NASA TM X-68050 (1972).Google Scholar
  7. 7.
    Chamis, C.C. and Sullivan, T.L., “Combined-Load Stress-Strain Relationships of Fiber Composite Laminates,” NASA TM X-71825 (1976).Google Scholar
  8. 8.
    Daniel, I.M. and Liber, T., “Strain Rate Effects on Mechanical Properties of Fiber Composites,” IIT Res. Inst. Rep. IITRI-D6073-IV (1976); also NASA CR-135087.Google Scholar

Copyright information

© Society for Experimental Mechanics, Inc. 1977

Authors and Affiliations

  • C. C. Chamis
    • 1
  • J. H. Sinclair
    • 1
  1. 1.NASA Lewis Research CenterCleveland

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