Narrow Results

This work reports the preparation of SiO₂ and TiO₂/poly (vinyl butyral) nanocomposites with enhanced dynamic mechanical properties. Silica and titania nanoparticles were introduced in the matrix as the neat powder and as colloidal sol using the melt mixing process. Composites reinforced with colloidal sol silica and titania showed higher mechanical properties than the ones reinforced with as-received particles. When sol TiO₂ particles are used, the highest increase of storage modulus of about 54% is obtained for 5 wt% loading, while for sol SiO₂, the storage modulus increases with the addition of nanosilica with the largest increase of about 99% for 7 wt% loading. In addition, nanocomposites were introduced within Kevlar/PVB composites. The addition of 5 wt% silica and titania colloidal sol lead to the remarkable increase of the storage modulus for about 98 and 65%, respectively. Largest contribution of nanoreinforcements in lowering the glass transition temperature is observed for 7 wt% loading of TiO₂ and SiO₂ colloidal sol.

This study aims to investigate a finite element analysis on Al/CFRP Hybrid composites with a flaw in-between bonding surfaces. 2D model was considered to simplify the 4-layered structures with a circular flaw. The determination of debonding condition on multi-layered hybrid composites is subtle because the crack paths are unpredictable. In this model, the crack profiles depend on the applied stress, materials, bonding strengths and initial shapes of the flaw. The main idea is to find the key reason of failure on this material by means of fracture mechanics approach. The crack opening profiles are interesting to determine what kinds of factors are more influential for the structure. Williams expansion was used to analyze the profiles by the simulation results. We finally take into account the results to discuss the main fracture mechanism with the influential factors.

In this study, the effect of powder particle contents on the mechanical properties of aluminum-based hybrid composites produced by warm accumulative roll bonding (WARB) process was investigated. Three hybrid composite groups with fully annealed AA1060 strips, 1wt.% of MnO₂ and 0, 7.5 and 15wt.% of TiO₂ were first roll-bonded and then the ARB process continued up to eight rolling cycles. In the WARB process, the samples were preheated at 300^∘C for 5min before each rolling cycle. It was realized that increasing the number of ARB cycles with 0 and 7.5wt.% of TiO₂ particles improved the uniformity of TiO₂ particles distribution in the aluminum matrix. Also, in samples with high contents of TiO₂ particles (15%), TiO₂ clusters converted into small clusters with a better distribution through the aluminum matrix. Also, by increasing the number of cycles and TiO₂ wt.% up to 15%, the tensile strength, elongation, tensile toughness and average Vickers microhardness of hybrid composites were increased first and decreased then. Moreover, the effects of ARB cycles and TiO₂wt.% on the fracture surface of hybrid composites have been studied by scanning electron microscopy (SEM). It was found that all the samples fabricated with one and two ARB cycles exhibited a typical ductile fracture containing deep dimples, whereas by increasing the TiO₂wt.% and ARB cycles, a combination of ductile and shear ductile fracture have been detected in the fracture behavior.

Composite materials are combinations of distinct materials, engineered to create new materials with specific properties. Stir-casting method is used to prepare composites, it involves heating Aluminium Alloy (Al 8011) reinforced with B₄C (Boron Carbide) and fly ash at 5, 10, and 15vol.%. The molten material is poured into a die to prepare the samples for testing. The composite’s density is measured by the principle of Archimedes, which decreases as the reinforcing particles increase, and then density and porosity are compared. The wear test specimen was prepared as per standard. The design model is generated by applying the RSM (Response Surface Methodology) equation with various parameters like load, sliding velocity of the pin, and track distance with values of 1–2kg, 1.5–2.5m/s, and 1000–3000m, respectively. The developed ANOVA (Analysis of Variance) result suggests that the created model is significant. The validation test was run and the results showed mean value of 0.0021356 and this value is in the 95% prediction range. The SEM (Scanning Electron Microscope) images of wear-tested composite show the delamination layers and deep groves. EDS (Energy Dispersive Spectroscopy) is used with electron microscopes to determine the chemical composition of wear out specimens. By the end of this study, it is discovered that the wear rate lowers with increasing reinforcement percentage while increasing with load and sliding velocity.

This paper highlights the reinforcement of two different fibers in the manufacturing of hybrid laminate composites. The feasibility of glass and carbon fiber-based hybrid composites is proposed for various high performances due to their versatile mechanical properties. However, anisotropic and non-homogeneity nature creates several machining challenges for manufacturers. It can be regulated through the selection of proper cutting conditions during the machining test. The effect of process constraints like spindle speed (rpm), feed rate (mm/min), and stacking sequences ($C)$ was evaluated for the optimum value of thrust force and Torque during the drilling test. The cost-effective method of hand layup has been used to fabricate the composites. Four different hybrid composites were developed using different layers of carbon fiber and glass fiber layers. The outcomes of variables on machining performances were analyzed by variation of feed rate and speed to acquire the precise holes in the different configurations. The application potential of the proposed composites is evaluated through the machining (drilling) efficiency. The optimal condition for the drilling procedure was investigated using the multiobjective optimization-Grey relation analysis (MOO-GRA) approach. The findings of the confirmatory test show the feasibility of the MOO-GRA module in a machining environment for online and offline quality control.

The purpose of the present paper is to study the effect of hybridation, stacking sequences and fiber orientation on the damping properties of unidirectional carbon/flax fiber reinforced epoxy composites. Non-hybrid and hybrid laminates with different stacking sequences were produced by molding vacuum process. Free vibration tests with an impulse technique were performed on test specimens to investigate the dynamic behavior. Finite element analysis was used to model damping to evaluate the different energies dissipated in the material layer directions of the carbon/flax composites. Close agreement was found between the experimentally measured values and those derived from the numerical simulation for the damping coefficients. The results obtained show that flax layers had a significant effect on damping properties.

Hybrid graphene oxide (GO) with metal ions have become very promising for many applications including catalyst, thermal conductive paper, magnetic devices, energy storage and electronics. In this paper, GO was mixed with trivalent rare earth ions, LaCl₃ to prepare GO/LaCl₃ hybrid composites. The GO/LaCl₃ hybrid composites were tunable by controlling the ratio of LaCl₃ to GO. The interaction between GO and LaCl₃ includes the coordination of La³⁺ with carboxyl groups at the edges of GO, the coordination of La³⁺ with epoxides and hydroxyls, and the electrostatic force between La³⁺ and aromatic bonds of GO. The La³⁺ preferred the coordination with the oxygen-containing groups of GO sheets first. However, the electrostatic absorption of La³⁺ was the main factor that controls the deposit of GO/LaCl₃ composites. The GO/LaCl₃ hybrid structures were also investigated.

Modern aerostructures are predominantly of curved construction characterized by a skin and stiffeners. The latest generation of large passenger aircraft also mostly uses composite materials in their primary structure and there is trend toward the utilization of bonding of subcomponents. A stiffener is a simple beam attached to the skin to support the applied load. The stiffeners are provided to improve the bending stiffness of the panel which then improves the structural efficiency. Metals, unlike composites, offer plasticity effects to evade high stress concentrations during postbuckling. Under compressive load, composite structures show a wide range of damage mechanisms. A pre-damaged configuration is loaded to study the effect of delamination location and mode for delamination initiation and propagation. A parametric study is conducted to investigate the effect of the location of the delamination propagation when delamination is embedded inbetween plies of the stiffener, with the cases (i) delamination embedded at front and inbetween plies of the stiffener, (ii) delamination embedded at middle and inbetween plies of the stiffener, (iii) delamination embedded at the end and inbetween plies of the stiffener. Further, the influence of the location of the delamination in between plies of stiffener on load carrying capacity of the panel is investigated. The effect of delamination location on crack growth and collapse behavior is analyzed using analysis tool. The effect of delamination location on crack growth and collapse behavior is analyzed with numerical method of Virtual Crack Closure Technique.

There is increasing demand for Carbon Fiber Reinforced Polymers (CFRP) especially in aerospace engineering. Due to their high specific strength-to-weight ratio, these composites offer more characteristics and considerable advantages when compared to metals. Metals, unlike composites, offer plasticity effects to evade high stress concentrations during post-buckling. Under compressive load, composite structures show a wide range of damage mechanisms where a set of damage modes combined together may lead to the structural collapse. The numerical analysis is conducted to investigate the effect of the dual cracks growth for the cracks embedded between plies of the skin and between plies of the stiffener hat. The dual fractured configuration is loaded to study the impact of dual cracks on load carrying capacity of the skin–stiffener joint and mode of fracture initiation and growth. Numerical method of Virtual Crack Close Technique is applied for predicting interlaminar crack initiation and interlaminar crack growth as well as in-plane crack mechanisms to predict the design of crack free joint.

This article focuses on investigating the dynamic behavior of hybrid composites involving natural fibers. The objective of this study is to examine and evaluate the effectiveness of recently used hybrid composite materials. The primary materials utilized are glass fiber-reinforced plastic. Plastic is applied to the surface of fiber-reinforced epoxy composites. Natural fibers are also used in other materials, polyester-based hybrid composites. The breakage pressure of the double shear test in the first composition has been improved from 1.10 to 1.38kN. The hardness rating was enhanced from 76.15 to 87.99. The interlamination experimental findings improved from 7.96 to 8.52kN. The results showed that a hybrid with a 50:50 comparable strand ratio of glass and sisal outscored a hybrid with a small fraction of sisal fiber. The second composite describes the effects of natural filler loading at 5%, 10%, and 15% on the mechanical behavior of a polyester-based hybrid. Materials created in a reputable environment for automotive and marine applications. Both hybrid nanocomposite preparation methods are tested, and the findings are validated. The electrical and mechanical characteristics of the materials are also validated and demonstrated to be superior to other current composites. This study highlights composite materials and technological advances and discusses natural fibers’ rich history and promise in many applications.