The paper reports on a study of the deformation and failure of uniaxially loaded graphite/epoxy plates with holes and to determine the influence of hole size on failure. Two laminates with holes of various diameters were used. They were instrumented with strain gages and photoelastic coatings. Strains on the hole boundary become nonlinear at strain levels between 0. 006 and 0. 0065 corresponding to applied stresses of 110 MPa and 172 MPa for the two laminates, respectively. On one, the maximum strain on the hole boundary reaches values up to twice the ultimate strain of the unnotched laminate. In the other, the compressive stress on the hole boundary around the loading axis produces local delamination causing stress and strain redistribution. The effect of hole diameter on strength reduction was satisfactorily described by using the average stress criterion with characteristic lengths of 3. 8 mm and 5 mm. There is a critical hole diameter below which the laminates become insensitive to it. In the case of the quasi-isotropic laminate, strength reduction was found to be independent of notch geometry.
|Original language||English (US)|
|Number of pages||16|
|Journal||[No source information available]|
|State||Published - Dec 1 1978|
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