Abstract
The paper describes the use of the embedded-strain-gage technique for the measurement of the strain distribution below a circular surface of contact supporting normal and tangential forces while the bodies in contact are rolling together.
A brief description is given of the method used for embedding strain gages at very small depths below the surface of a model sphere of epoxy resin. The rig used for pressing the model against another sphere of the same material, driving one of them and restraining the other, is also described together with the instrumentation.
A preliminary series of static tests shows that the measured subsurface strains are in good agreement with Hertz's theory of contact. For tests under rolling conditions, the recorded results of a strain gage under different load levels are easily converted to a common nondimensional scale by photographic enlargement or reduction of the original recorded trace. A special Wheatstone-bridge configuration also permits the direct measurement of orthogonal shear strains by combining the output of the gages of embedded rectangular rosettes. Some typical results are given.
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Abbreviations
- a :
-
radius of the circular surface of contact, in
- E :
-
Young's modulus, psi
- P :
-
normal (i.e., radial) load acting on the bodies in contact, lb
- p o :
-
maximum pressure at the center of the surface of contact, psi
- T :
-
total tangential force on the surface of contact acting in theX-direction, lb
- μ:
-
coefficient of sliding friction
- T/μP :
-
ratio of applied tangential force to limiting tangential force
- x,y,z :
-
rectangular coordinate system having its origin at the center of the surface of contact (see Fig. 1)
- ∈ x , ∈ y , ∈ z , γ xz :
-
normal and shear strain components
- ν:
-
Poisson's ratio
References
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The contents of this paper are part of a PhD thesis submitted by the first author to the University of Sheffield, England.
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Bazergui, A., Meyer, M.L. Embedded strain gages for the measurement of strains in rolling contact. Experimental Mechanics 8, 433–441 (1968). https://doi.org/10.1007/BF02327407
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DOI: https://doi.org/10.1007/BF02327407