This paper presents the experimental study of fiber type, fabric structure, orientation of fabric plies and thickness on the ballistic impact behavior of aramid and ultra-high molecular weight polyethylene (UHMWPE) composite laminates. Aramid composite laminates are reinforced by three kinds of fabric structures and UHMWPE composite laminates are reinforced by two kinds of fabric structures. The laminates are fabricated via autoclave curing process. The ballistic behavior of composite laminates is evaluated by ballistic limit velocity, and energy absorbed at ballistic limit. Through a series of ballistic tests, it is demonstrated that unidirectional composite laminates exhibit higher ballistic limit velocity and energy absorption on unit weight basis compared to other laminates. Interesting results are shown by UD-UHMWPE-H62® and UD-UHMWPE-Endumax® fabric-reinforced laminates. Orientation of fabric plies is found to have insignificant effect on ballistic behavior irrespective of material type. A bi-linear relationship is found between the ballistic limit velocity, energy absorption and specimen thickness.

The development of polymer composites containing natural fibers as a sustainable alternative material for certain engineering applications, particularly aerospace and automotive applications, is a popular area of research. In this study, the mechanical properties of flax, jute and jute/carbon woven fabric composites were investigated and compared with those of 3 K carbon woven fabric composites. The results of this study demonstrate the utility of natural fibers in composite applications. Furthermore, it is observed that the mechanical properties of natural fibres are significantly affected by changes in temperature. Experimental results prove that the mechanical properties of natural fiber composites are significantly lower than those of carbon fiber composites, but the hybridization of carbon and jute fibers can result in a composite material with enhanced mechanical properties.

The focus of this paper is to evaluate the mechanical and dynamic mechanical properties of woven jute fabric-reinforced green epoxy composites as a function of modification of jute fibers by enzyme, CO₂ pulsed infrared laser and ozone treatments. The treated jute fibers were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. Composites were prepared by the hand layup method and compression molding technique and the resin curing process was optimized with the help of differential scanning calorimetry. The treatments resulted in the enhancement of flexural and impact properties. Statistical analysis of mechanical properties of composites, done by one-way analysis of variance, showed significant differences between the results obtained. Dynamic mechanical analysis (DMA) results revealed that treated composites have a higher storage modulus over the range of temperature. A positive shift of loss modulus and tangent delta peaks of treated composites to higher temperature was observed. The reduction in the tangent delta peak height of treated composites was also observed due to improvement in fiber/matrix interfacial adhesion. The degree of interfacial adhesion between the jute fiber and green epoxy was anticipated using the adhesion factor obtained through DMA data. Complex modulus variations and phase behavior of composites was studied by Cole–Cole analysis.

In this study, the mechanical properties of composite materials obtained from carbon and carbon-aramid hybrid woven fabrics produced in different constructions with the same yarn and under the same production conditions were determined, and the effects of weaving structure and hybridization on the mechanical properties were investigated. For this purpose, the geometric properties of carbon fabrics made from 12 K carbon yarn with four different weaving structures and two carbon-aramid hybrid fabrics made of 12 K carbon yarn and aramid yarn with two different structures were defined, and the mechanical properties of the composite materials were investigated under uniaxial tensile loading. The mechanical properties of the composite materials produced from the carbon and carbon-aramid hybrid fabrics were compared. The effects of weaving structure and hybridization on the mechanical properties were determined. Based on the weaving construction, Young’s modulus and the tensile strength declined approximately 34–39% and 24–27%, respectively. However, Young’s modulus was 16–63% higher than the expected value for the hybrid composites.

In the current study, the effect of the thickness and the foam density in three-dimensional integrated woven sandwich composites on quasi-static mechanical properties under three-point bending was investigated. Bending modulus and core shear modulus were determined by subjecting the samples, which were cut with varying span lengths according to their core thicknesses, to three-point bending test. Obtained results were optimized by taking core thickness, foam density and panel weights into consideration. Damages that occurred on the tested samples were reported. When compared to conventional foam core sandwich composites, it was found that three-dimensional integrated sandwich composites have superior mechanical properties and due to the fact that the pile yarns in the core and the foam support each other, contrary to conventional sandwich composites no catastrophic core breakage occurs under load, thus the load bearing capacity of the structure is sustained.

Registration of acoustic emission (AE) events during tensile loading of fiber-reinforced composites allows the damage caused by these events to be defined and monitored, including damage initiation and progression thresholds. It also provides frequency-based recognition of different types of damage and comparison of its intensity in materials with different reinforcement architectures. The paper reports results of AE registration for 3D non-crimp orthogonal woven (3DNCOW) carbon/epoxy composites. The observed repeatability and spatial distribution of AE events confirm that damage initiation and development are uniform over the tensile sample. The damage characterization by AE is compared with the morphology of damage observed on the specimen cross-sections at characteristic stages of the damage development. The main parameter distinguishing damage mode obtained from the AE registration is the AE energy. It has however been found that the peak frequency of the AE events does not correlate directly with the sequence of the observed damage modes. AE events of high peak frequency, assumed to be related to fiber fracture, suggest that it starts at a later stage than predicted by the Weibull statistics of fiber strength.