Thermoelastic stress analysis measures temperature variations in loaded solids and relates these to associated stresses. For orthotropic materials, the measured signal is proportional to a linear combination of the normal stress changes in the directions of material symmetry, and K1 and K2 are thermo-mechanical coefficients. Quantitative thermoelastic stress analysis of orthotropic composites necessitates (i) determination of the above two thermo-mechanical coefficients (i.e. calibration), and (ii) separation of the stresses. Although calibration procedures can take different forms, K1 and K2 can be experimentally determined most reliably and easily from calibration specimens of the same material, paint coating, loading frequency and ambient conditions as the test structure. Such calibration specimens typically employ a geometry and loading for which the state of stress or strain is known theoretically, or independently determined. Loaded beams, a diametrically-compressed disk, or uniaxial tensile coupons have been used for isotropic materials. Orthotropic materials usually necessitate testing two calibration specimens, with their principal material directions interchanged respectively. The present paper demonstrates the ability to determine both K1 and K2 from a single diametrally-loaded orthotropic composite (graphite/epoxy) disk. To be able to determine both coefficients from a single calibration specimen is advantageous. Disks are also easy to machine and load, rendering them very convenient for calibration.

1.
Patterson, E. A., and Rowlands, R. E., 2006, Handbook on Experimental Mechanics, Springer, USA, Chap. 3.
2.
Feng
Z.
,
Zhang
D.
,
Rowlands
R. E.
, and
Sandor
B. I.
,
1992
, “
Thermoelastic determination of the individual stresses in loaded composites
”,
Experimental Mechanics
,
32
(
2)
, pp.
89
95
.
3.
Ju, S. H., and Rowlands, R. E., Submitted 2005, “Thermoelastic determination of crack-tip coordinates in composites”, International Journal of Solids and Structures.
4.
Stanley
P.
, and
Garroch
C.
,
1999
, “
A thermoelastic disc test for the mechanical characterisation of fibre-reinforced moulded composites: theory
”,
Composites Science and Technology
,
59
, pp.
371
378
.
5.
Garroch
C.
, and
Stanley
P.
,
1999
, “
A thermoelastic disc test for the mechanical characterisation of fibre-reinforced moulded composites: application
”,
Composites Science and Technology
,
59
, pp.
379
389
.
6.
Quinn
S.
, and
Dulieu-Barton
J . M.
,
2002
, “
Identification of the sources of non-adiabatic behaviour for practical thermoelastic stress analysis
”,
Journal of Strain Analysis
,
17
(
1)
, pp.
59
71
.
7.
Jones, R. M., 1999, Mechanics of Composite Materials, Taylor & Francis, Philadelphia, USA.
8.
Van Cauwelaert
F.
, and
Eckmann
B.
,
1994
, “
Indirect tensile test as applied to anisotropic materials
”,
Materials and Structures
,
27
, pp.
54
60
.
9.
Prabhakaran
R.
, and
Xu
H.
,
2001
, “
Determination of elastic constants of composites with a circular disk specimen
”,
Advanced Composite Letters
,
10
(
3)
, pp.
127
133
.
10.
Okubo
H.
,
1952
, “
The stress distribution in an aeolotropic circular disk compressed diametrically
”,
Journal of Mathematics and Physics
,
31
, pp.
75 to 83
75 to 83
.
This content is only available via PDF.
You do not currently have access to this content.