PSI - Issue 13

Ahmed Sohail et al. / Procedia Structural Integrity 13 (2018) 450–455 Author name / StructuralIntegrity Procedia 00 (2018) 000 – 000

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properties. Higher stiffness and strength of 3D orthogonal woven composites in all three direction makes them competitive against laminated composites and other 3D textile architectures, Gu and Zhili (2002), Tan et al. (2000). 3D woven architectures can be tailored in accordance with their application in the structure to get more optimized properties in addition to the better delamination resistance and damage tolerance, Quinn et al. (2003), particularly in the through-thickness direction, Mouritz et al. (1999). By adding or replacing the fiber tows with those of different materials, the enhanced material properties can be achieved for 3D woven composites. Hybridization for the carbon-fiber 3D woven composite has shown improved notch sensitivity, better impact resistance and improvement in fracture toughness Munoz et al. (2014). However, some problems associate with these kinds of 3D architectures like during the manufacturing process of liquid resin molding pockets with rich resin and voids are likely to occur. Due to the crimping of fiber tows during weaving process it is more likely that mechanical properties of the overall material can be degraded, and most importantly complex architecture makes it difficult for the designers to predict the mechanical properties and behavior under impact loadings for such kind of materials. In order to mechanically characterize the 3D woven composites, one way is to simplify the complex structure without compromising on the overall structure characteristics, some examples are binary model, unit-cell, and mosaic model, developed in the past. Both low and high velocity impact behavior of 3D woven composites have been studied in the past. Baucom et al (2005) compared the low velocity impact behavior of 3D orthogonal woven composites and 2D plain-weave laminate. It was concluded that the 3D composites absorbed more energy by breaking binder fibers and could take more strikes before complete penetration. Chen and Hodgkinson (2009) carried out both low and high velocity impact tests on 3D orthogonal composites and non-crimp fabrics. The results showed that the 3D composites exhibited superior impact resistance and higher Compression After Impact (CAI) strength than NCF in both low and high velocity tests, and also showed no delamination. Lv and Gu (2008) compared high velocity impact properties with quasi static indentation properties of 3D orthogonal woven composites. The behavior under impact process of 3d woven composites have also been determined through numerical techniques considering the expensive nature of experimental analysis of the same. Various researchers have developed different Finite element models and techniques to analyze the behavior of 3D woven composites under impact loading. Ji et al. (2007) developed an FE model which was built by using solid elements to determine the failure behavior of 3D woven composite under quasi-static and dynamic loadings. Lv and Gu (2008) and Hao et al. (2008) characterize the damage behavior of 3d woven composites under high velocity impact by developing the FE model which was built in ABAQUS and using brick elements. Sun et al. (2009) introduces a unit cell approach to develop a numerical model to characterize the damage behavior under high velocity impact of 3D woven orthogonal composites. Munoz et al. (2015) performed experimental and numerical study on the impact behavior of hybrid 3D orthogonal woven composites. The FE model was based on the embedded element method to depict the through the thickness z-yarns. It can be concluded that while discussing the numerical modeling of impact behavior of 3D woven composites, most of the researchers have adopted the solid meshing techniques and to depict the material constitutive and damage behavior user-subroutine was deployed. Despite the potential of continuum shell elements, very few researchers adopted the technique to develop the numerical model for the impact behavior of composites. Current study targets to provide the reliable simulation technique for the impact behavior of 3D woven composites and the accurate prediction of the impact damage behavior under high velocity impact. To predict the constitutive and damage behavior of composites during the high velocity impact process, a combination of cohesive contact and continuum shell elements is proposed in finite element model. Delamination behavior is characterized by introducing the cohesive contact between the two adjacent laminas using the traction separation law, while damage, induced during the impact process in the single layer of composite laminate, is depicted by continuum shell elements with Hashin failure criterion. Connector elements containing the failure behavior are introduced into the model to represent the z-yarns of the 3D woven composite. The proposed FE model presented good agreement with experimental results to capture the damage phenomenon during the impact process.