Failure Predictions for Carbon/Epoxy Tape Laminates with Wavy Plies

Abstract

Accurate matrix-dominated constitutive properties can be a key to accurate failure models for polymermatrix composites. This work shows the effect of nonlinear interlaminar shear stressstrain relations on delamination failure predictions for thick IM7/8552 carbon/epoxy tape laminates with wavy plies. Nonlinear finite element model (FEM) predictions and subsequent test correlations are presented. The interlaminar shear stressstrain relations are generated using short-beam shear tests and a digital image correlation full-field strain measurement technique. Test data for the wavy-ply coupons show that nonlinear shear stressstrain response is required for accurate failure prediction.

Tensile failure of laminates containing an embedded wrinkle; numerical and experimental study

“…The linear-elastic material properties are given in Table 1. The data points for the non-linear shear for IM7/8552 were obtained from [7] with an exponential curve of the following form to fit the data:…”

“…In this work, A and B were found to be 145 and 38 by fitting to the data given in [7]. These two parameters were supplied to the VUMAT subroutine as user inputs.…”

“…Tensile failure of composite laminates containing wrinkle has been previously studied by El-Hajjar and Petersen, Bloom et al and Makeev et al [5][6][7]. Steel rods of different diameter were used by El-Hajjar and Petersen [5] to artificially induce waviness in unidirectional and multidirectional carbon-epoxy tests.…”

“…They concluded that a detailed 3D finite element analysis might be necessary for this problem due to the complex failure mechanisms and their interaction. Makeev et al [7] tested thick-section carbon-epoxy multidirectional tape laminates with different grades of wrinkle severity. DIC was used to measure strain in components during loading until complete failure.…”

Control of Compressive Fatigue Delamination Propagation of Impact Damaged Composites Using Discrete Thermoplastic Interleaves

“…Makeev et al [17] demonstrated that increased shear stress concentration at the ply waviness location around the Z-pin is what determines the effect on the mechanical properties of a composite. This is one reason why Z-pinning inherently reduces the pristine strength of a composite.…”