Numerical and experimental investigation of out-of-plane fiber waviness on the mechanical properties of composite materials

Abstract

The limited capability to predict material failure in composite materials and specifically in wavy composite layers has led to high margins of safety for the design of composite structures. Thus, the full lightweight potential of this class of materials is left unused. To understand the complex failure behavior of composite materials containing out-of-plane fiber waviness under compressive and tensile loading, a non-linear 2D material model was implemented in ABAQUS and validated with extensive experimental test data from compression and tensile tests. Each test was recorded by a stereo camera system for digital image correlation to resolve damage initiation and propagation in detail. This study has shown excellent agreement of numerical simulations with experimental data. In a virtual testing approach various parameters, i.e. amplitude, wavelength and laminate thickness, have been studied. It was found that the failure mode changed from delamination to kink shear band formation with increasing laminate thickness. The wavelength has shown minor influences compared to amplitude and laminate thickness.

Mechanisms of Origin and Classification of Out-of-Plane Fiber Waviness in Composite Materials—A Review

“…While amplitude A and wavelength L are most commonly used to describe the wave (Figure 2), the maximum deviation θmax is considered to have the greatest impact on the mechanical properties. Important influencing parameters such as maximum deviation of the fiber orientation from the original orientation, as well as the laminate thickness [12], have received little attention in previous investigations. The wave pattern is typically represented mathematically as sinusoidal waves [13,14].…”

“…The influence of wavy layers strongly depends on the affected thickness of the laminate ( Figure 36). Especially in thin-walled laminates with a correspondingly large degree of waviness (t << A), in addition to the influences on the material properties, structural influences [12] become apparent. In such cases, a complex mix of both material and structural type behavior leads to strongly nonlinear geometric constraints, requiring the calculation of stresses resulting from the bending of the wave.…”

Application of Microwave Polarimetry to the Characterization of Fiber Misalignment in Composites

“…Manufacturing of these composite structures often involves the placement of carbon or glass fibers into uniform sheets where all the fibers are placed with a specifically-chosen orientation. Any deviation from the desired orientation can result in a drastic degradation in mechanical performance of the resulting manufactured composite [2]- [4]. This requirement has led to an increased usage of automated manufacturing methods, such as Automated Fiber Placement (AFP) and Automated Tape Laying (ATL) [5].…”

The Impact of Draping Effects on the Stiffness and Failure Behavior of Unidirectional Non-Crimp Fabric Fiber Reinforced Composites

“…Such deformation modes significantly decrease the stiffness in fiber direction [ 9 , 10 ]. While the material properties of composites with imposed waviness have been widely evaluated [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ], the impact of the FVC change has not been evaluated yet. In addition, the resulting strength in waviness direction was in most cases analyzed by compressive loads only.…”

“…Especially, a systematical analysis of the resulting strength for tensile and compressive loads in conjunction with analytical predictions is not yet available. Furthermore, most studies deal with out-of plane waviness [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ], while a focus on in-plane waviness [ 16 , 17 ] is also rare.…”