Off-Axis Test of a Composite

More on the Influence of End Constraints on Off-Axis Tensile Tests

“…Here again, the correctness of this model in simulating a corresponding physical test, such as that reported in [2], is unclear, since the degree of distortion at the grip ends is uncertain. Therefore, the remarks made above for Case 1 are also pertinent here.…”

“…Also presented for comparison is the relation developed by Pagano [2] are also presented for comparison. From Table 1, it is seen that the degree of error associated with E ~ and G' as calculated from expression (6) for nonrotating grips can be quite high.…”

“…In the actual test there is the added possibility of nonequilibrated moments propagating out from under the grips. However, in the spirit of the accuracy of the experimental results reported in [2], it would appear that for a rotating fixture, the shear stress effects, which are necessary to deform the specimen consistent with the grips, must be rather thoroughly dissipated into the grips themselves. Therefore, the major portion of any inaccuracy associated with this test is probably due to the prevention of Poisson type contraction.…”

“…Results from [2] are reproduced in Figure 15. Corresponding data for rotating grips from the present effort are listed in Table 2.…”

“…For short specimens, however, nonrotating grips should be avoided unless accurate strain gage measurements can be made. A rotating grip fixture similar to that in [2] would appear to offer promise for accurately testing short specimens; i.e., llw < 4. Perhaps extensometers may be employed in this latter case to record eo = 4~,/.~ instead of expensive strain gages.…”