Nonlinear numerical analysis of the V-notched rail shear test specimen

V-Notched rail (VNR) shear test is a fairly recent shear test method and has been standardized as ASTM D7078. In the present research, shear properties of glass/epoxy specimens were evaluated by the VNR test method and compared with the three-rail shear test results. Shear modulus obtained by the two test methods are almost the same, however, VNR gives the shear strength around 36% greater than the three-rail test. Considering the observed nonlinearity in the experimental shear stress-strain diagram, nonlinear finite element analysis of the VNR specimen was performed by developing UMAT subroutine. Numerical analysis showed such non-uniformity in the shear stress and shear strain distribution between the notches. To take into account the non-uniformity, a correction factor for shear modulus and shear strength are introduced to correct about 8% and 4% error in the shear strength and shear modulus, respectively. The effect of some errors which are likely to occur during the test, was also studied. Finally, uncertainty analysis was employed to evaluate the quality of measurement. Uncertainty values are determined as 3.6% of the shear strength and 1.7% of the shear modulus measured value.