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This paper presented an experimental and numerical investigation on the low velocity impact response of thermoplastic hybrid composites reinforced with Kevlar/basalt fabrics. Two hybrid and one Kevlar homogeneous composite laminates were manufactured with polypropylene as a resin. In the hybrid composites, one hybrid composite (H-1) was manufactured with alternate stacking of four layers of basalt and four layers of Kevlar and the second hybrid composite (H-2) was manufactured with four Kevlar layers on front face and four basalt layers on back face. Low velocity impact tests were performed using a drop-weight impact equipment at three different energies (25J, 50J and 75J). Among the two hybrid composites H-1 hybrid composite exhibited 15.58-20.79% and 13.47-20.47% improvement in the peak force and energy absorption, respectively, than the H-2 hybrid composite. The peak force and energy absorption of Kevlar homogeneous composite was also improved by 10.07-14.37% and 5.38-11.29%, respectively, due to hybridization. A three dimensional (3D) dynamic finite element software, Abaqus/Explicit, was implemented to simulate the experimental results of low velocity impact tests. A user-defined material subroutine (VUMAT) based on Chang-Chang linear-orthotropic damage model was implemented into the finite element code. The predictions from numerical simulation were found to be in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

Characterization of Kevlar-Polypropylene based composite material system under high strain rate loading has been investigated using Split Hopkinson Pressure Bar (SHPB) test for varying specimen aspect ratios. Flat laminates of 16, 24 and 30 layered Kevlar composite were compression molded and laser machining to get cylindrical specimensof desired aspect ratios. Based on SHPB experiments, stress-strain plots were obtained and analysed to reveal compressive material behaviour as function of growing strain rate. The peak stress, strain and toughness exhibited considerable increase with growing strain rate of loading. With increasing strain rates peak specimen stress increased by 90%, for lowest thickness composite. The aspect ratio studies suggests application of thin laminates for better performance of composite laminates. [ABSTRACT FROM AUTHOR]

In this study, the influence of hybridization on the compression response of thermoplastic matrix-based composites under high strain rate loading was investigated. The intra-ply and inter-ply hybrid composites were manufactured with Kevlar/Basalt yarns as the reinforcements with Polypropylene as a matrix. Cylindrical composite specimens were laser cut from the flat compression moulded laminates. The composite specimens were loaded under high strain rate using split-Hopkinson pressure bar setup at strain rates ranging from 2815/s to 5481/s. The study revealed differences in the rate-dependent growth of peak stress, peak strain and toughness with the strain rate. Intra-ply hybrid composites with alternate weaving of Kevlar and basalt yarns exhibited highest peak stress as compared to the Inter-ply hybrid composites (alternate layers of Kevlar and basalt fabrics) and another intra-ply composite containing Kevlar in the warp and basalt in the weft direction. Whereas in inter-ply hybrid composite, with Kevlar as the loading face attained higher stress, while composite with Basalt as the loading face attained higher strain. SEM micrographs revealed that Kevlar on the loading face can bear the impact with lesser delamination as compared to the Basalt on the loading face. Damage studies revealed that Kevlar fiber surface loading results in higher stress as compared to basalt (brittle) surface loading with lower overall damage. • The influence of hybization on the high strain rate resposne of thermoplastic composites. • Intra-ply hybridization excels over inter-ply hybridization. • Placement and direction of yarns is crucial in intra-ply hybridization. • Higher areal density fabrics are replacable with hybrid fabrics of lower areal density. [ABSTRACT FROM AUTHOR]

In the present work, dynamic compression response of polypropylene (PP) based composites reinforced with Kevlar/Basalt fabrics was investigated. Two homogeneous fabrics with Kevlar (K3D) and Basalt (B3D) yarns and one hybrid (H3D) fabric with a combination of Kevlar/Basalt yarns were produced. The architecture of the fabrics was three-dimensional angle-interlock (3D-A). Three different composite laminates were manufactured using vacuum-assisted compression molding technique. The high strain rate compression loading was applied using a Split-Hopkinson Pressure Bar (SHPB) set-up at a strain rate regime of 3633–5235/s. The results indicated that the dynamic compression properties of thermoplastic 3D-A composites are strain rate sensitive. In all the composites, the peak stress, toughness and modulus were increased with strain rate. However, the strain at peak stress of Basalt reinforced composites (B3D, H3D) decreased approximately by 25%, while for K3D specimens it increased approximately by 15%. The K3D composites had a higher strain rate as compared to the B3D and H3D composites. In the case of K3D composite, except strain at peak stress, remaining dynamic properties were lower than the B3D composite, however, hybridization increased these properties. The failure mechanisms of 3D-A composites were characterized through macroscopic and scanning electron microscopy (SEM). [ABSTRACT FROM AUTHOR]

This paper investigates the characterization of in-plane shear properties of thermoplastic composites reinforced with Kevlar/basalt fabrics. Different fabrics had architectures of two dimensional plain woven (2D-P) and three dimensional angle-interlock (3D-A). Intralayer hybridization was performed during the weaving of the fabrics with the combination of Kevlar and basalt yarns. Five 2D-P and three 3D-A composite laminates were manufactured with polypropylene (PP) as a matrix, using compression molding. Iosipescu shear tests were carried out to evaluate the in-plane shear properties. The experimental results revealed that the shear properties including shear modulus, shear strength and shear failure strain of homogeneous composites were improved by 6.5–14.9%, 4.3–19.7%, and 3.2–46.7%, respectively. Similarly, change in the fabric architecture from 2D-P to 3D-A also enhanced the shear strength and shear failure strain by 32.0–41.6% and 7.2–22.5%, respectively. Intralayer hybrid composites had better in-plane shear properties than the interlayer hybrid composites. The fracture morphologies of the specimens were examined by scanning electron microscopy (SEM). [ABSTRACT FROM AUTHOR]

The present work reported the mechanical characterization of novel polypropylene (PP) composites reinforced with three-dimensional angle-interlock (3D-A) Kevlar/basalt fabrics. Two homogeneous fabrics with Kevlar (K3D) and basalt yarns (B3D), and a hybrid fabric (H3D) with a combination of both Kevlar and basalt yarns were produced. Three types of two layer 3D-A composites were manufactured using vacuum-assisted compression molding method. Static tensile and in-plane compression tests were carried out on the manufactured composites. The mechanical behavior of the three 3D-A composites was compared in terms of stress-strain response, elastic modulus, strength and failure strain. Influence of hybridization on the mechanical behavior of the 3D-A composites was also studied. Significant improvement in the tensile behavior of 3D-A homogeneous composites was observed due to hybridization. Meanwhile, there was no considerable improvement in in-plane compression behavior. The damage patterns for in-plane compression loading were examined through scanning electron microscopy (SEM) to explore the possible damage patterns such as matrix cracking, fiber failure, delamination and deformation. Numerical simulations were carried out using ABAQUS/Standard, by implementing a user-defined material subroutine (VUMAT) based on the Chang-Chang linear orthotropic damage model. Good agreement between experimental and numerical simulations was achieved in terms of damage patterns. [ABSTRACT FROM AUTHOR]

Experimental and numerical investigations are carried out to determine the low velocity impact (LVI) response of three different polypropylene (PP) composites. Three dimensional (3D) angle-interlock fabrics with Kevlar, basalt and a hybrid combination of both are produced. 3D composites are manufactured with these three fabrics using vacuum-assisted compression molding process with PP resin. LVI tests are conducted using a drop-weight impact equipment at the energy level of 240 J. The LVI response of the three 3D-PP composites is compared in terms of peak force, energy absorption and damage modes. The experimental results indicate that the basalt 3D composites showed 6.62–13.73% higher peak force and H3D composites absorbed 7.67-48.49% more energy than the remaining composites. Results indicate that there is a considerable enhancement in the energy absorbing capability of hybrid composites as compared to Kevlar/PP and basalt/PP composites. Numerical simulations are carried out using the commercial finite element (FE) code ABAQUS/Explicit. A user-defined material subroutine (VUMAT) based on Chang-Chang linear orthotropic damage model, is implemented into the FE code. Good agreement between experimental and numerical simulations is achieved in terms of impact response characteristics. [ABSTRACT FROM AUTHOR]

The present study deals with the quasi-static and high strain rate characterization of Kevlar-129 based thermoplastic composites. Two different thermoplastic matrices, namely, Polypropylene (PP) and Polyetherimide (PEI) were used to manufacture composite laminates. Quasi-static compression tests were performed at strain rates of 0.041 s−1 and 0.045 s−1. High strain rate tests were performed using a split Hopkinson pressure bar apparatus within the strain rates ranging from 2548 s−1 to 4379 s−1. Stress-strain relations reveals the rate-sensitive behaviour of composites. Kevlar/PP (K-PP) showed higher peak stress under quasi-static loading as compared to the high strain rate test. Comparable peak stresses were revealed under quasi-static and high strain rate loading for Kevlar/PEI (K-PEI) composite. Also, high strain rate compression properties such as peak stress, peak strain and toughness of K-PP were 25%, 27% and 6% higher than that of the K-PEI composite. The failure mechanisms of both the composites were characterized through macroscopic and scanning electron microscopy. K-PP failed majorly due to matrix crush and fibre failure while K-PEI failed due to shear cracking. Damage study reveals that a single fibre based composite system can be tailored to act as an energy-absorbing or dissipating material system by varying the thermoplastic matrix materials. • Static and dynamic compressive properties of Kevlar reinforced high-performance polymers. • Kevlar/Polypropylene outperforms over Kevlar/Polyetherimide under both the quasi-static and high strain rate loads. • The quasi-static strength of Kevlar/Polypropylene is 25% higher than its high strain rate strength. • Polypropylene matrix results in ductile failure, while the Polyetherimide matrix results in brittle failure. [ABSTRACT FROM AUTHOR]