The integration of graphene oxide (GO) and natural silk into epoxy matrices offers a promising approach to developing high-performance composites for structural applications. This study examines the fabrication processes, focusing on sample preparation and testing of GO and natural silk-reinforced epoxy composites. A comprehensive literature review spanning 1990 to 2024 provides insights into the necessity of Vacuum-Assisted Resin Transfer Molding (VARTM) at 30 PSI, the role of ultrasonication in achieving homogeneous GO dispersion, strategies to prevent agglomeration, optimal reinforcement proportions, and challenges encountered during hybridization. Key findings, including the impact of high silk volume fractions (60–70%) on mechanical properties, are incorporated, offering a comprehensive guide for composite fabrication. The findings underscore the critical parameters for successful composite fabrication and performance enhancement. Key Words: Graphene Oxide, Natural Silk, Epoxy Composites, VARTM, Ultrasonication, Hybrid Reinforcements, Structural Applications

The integration of graphene oxide (GO) and woven natural silk as hybrid reinforcements in epoxy composites offers a novel approach to high-performance, sustainable materials for structural applications. Combining GO (0.3–1.5 wt.%) and natural silk (40–60% by volume) is hypothesized to significantly enhance tensile strength, flexural modulus, and impact resistance. Fabrication using Vacuum-Assisted Resin Transfer Molding (VARTM) and optimized GO dispersion through ultrasonication addresses challenges like GO agglomeration and fiber-matrix adhesion. Although experimental validation is pending, Theoretical predictions supported by finite element modelling (FEM) suggest significant improvements in tensile strength, flexural modulus, and impact resistance compared to neat epoxy. These composites hold promises for structural applications in aerospace, renewable energy, and automotive industries, meeting the demand for lightweight and sustainable engineering solutions.

Soft robotics has attained significant attention in recent years due to their infinite degree of freedom, adaptability, and safer interaction with humans and objects in various applications, such as robotics, biomedical devices, search and rescue operations, and wearable technology. However, the soft pneumatic actuator (SPA) is one of the most commonly and frequently utilized actuators in soft robotics due to its higher output at lower energy consumption. Further, an important development was the embedding/integration of soft and flexible sensors within the SPAs. This review article provides a comprehensive review of the frequently utilized SPA designs (McKibben, Pneu-Nets, and material jamming-based actuators), soft sensors (strain, pressure, temperature, tactile, flex, optical, and magnetic sensors), and SPAs with integrated or embedded soft sensors. Further, various emerging trends and breakthroughs in the SPA-sensors integration along with the limitations and challenges are discussed. Finally, it is found that there is an enormous amount of potential for revolutionizing the robotic and associated industries through the integration or embedding of soft sensors into SPAs. Even though there has been a lot of progress, there are still various challenges that need to be resolved and are provided in the future work section.

Lignocellulose or natural fiber-reinforced polymer composite development and research have found new applications in different fields in the last few decades. The present study explores the influence of fly ash and benzoylated Himalayan Agave fibers on the physical (density, void fraction, water absorption), mechanical (tensile strength, flexural strength, impact strength, wear resistance, hardness), and thermal properties of polyester composites. The content of fly ash (3–9 wt

Aluminium-lithium (Al-Li) alloy is the most prominent alloy used in the aerospace industry's internal structure and wings due to its improved physical and mechanical properties. The present study introduces a novel investigation into the joining of Al-Li alloy 2050-T84 using friction stir welding (FSW) at different tool velocity ratios (TVR) of 0.6, 0.8, and 1, respectively (i.e., the amalgamation of various process parameters like tool rotational speed (TRS of 600, 1000, and 1400 rpm and traverse speed of 60, 120, and 240 mm min-1) and constant tool tilt angle (1.5 degrees). A threaded taper tool was used for joining the Al-Li alloy 2050-T84. This work aims to ascertain the effects of varying tool velocity ratios (TVR; rotational speed/traverse speed) on macrostructure, grain size distribution in the nugget zone, and mechanical strength of the welded specimens. The experimental results reveal that increasing the tool velocity ratio increases the grain size and decreases the welded specimen's ultimate strength and hardness values. Higher tensile strength (403.2 MPa), micro-hardness values (122.15 HV0.1), and joint efficiency (75.49) of welded specimens are achieved at low TVR (0.6), and ductile failure is observed in all welded samples. Additionally, it is noticed that the stirred zone size increased with increasing the velocity ratio.

The tribological behaviour of High Velocity Oxygen Fuel (HVOF) thermal spray deposited coatings, namely Ni-Al-Ag-MoS2 (NAMB0), Ni-Al-Ag-MoS2-5 wt. % h-BN (NAMB5), Ni-Al-Ag-MoS2-7.5 wt% h-BN (NAMB7.5) and Ni-Al-Ag-MoS2-10 wt% h-BN (NAMB10), onInconel 718 as substrate material were assessed against an alumina ball as a counterface. The tests were performed using a rotary tribometer under "ball on disc configuration" at various testing loads of 5, 10, 15, 20 N and a fixed sliding speed of 0.5 m/s at room temperature (RT) of 25 C-?. The weight percent of MoS2 and Ag as a solid lubricant were kept constant whereas h-BN wt% was varied in the coated samples i.e. 0, 5, 7.5 and 10 wt. According to test results, as the load increases from 5 to 15 N, both coefficient of friction (COF) and wear rate exhibit a decreasing trend in nature, thereafter, by increasing the load up to 20 N, the reverse action is evident. However, the coating having 7.5 wt% h-BN along with MoS2 and Ag has revealed the best tribological behaviour under the investigational parameters. The observed behaviour has been attributed to the synergistic effect of Ag, MoS2 and h-BN and optimum content of h-BN in NAMB7.5 coatings enhances the tribological performance to its apex.

This research paper investigated the hardness and tribological performance of novel Grewia optiva/Basalt fiber reinforced hybrid polymer composites. Two different configuration of hybrid composite that is, woven and chopped fiber reinforced composite are considered for the study. The chopped fiber configuration of the composite is further divided into two types based on fiber length and wt%. The fiber lengths studied are 6 and 12 mm while the wt% studied are 0, 6, and 12 wt%. Woven fiber reinforced composite is divided into five configurations based on wt% of G. optiva fiber with 0, 3, 6, 9, and 12 wt%. In all configurations, maximum fiber content of 12 wt% is maintained. B6/GO6 composite exhibits minimum specific wear rate and maximum hardness among all the compositions. Wear experimental results are analyzed by Taguchi optimization technique and based on the five levels and four control factors (sliding velocity, fiber loading, sliding distance, and normal load) L-25 partial orthogonal array was suggested for the woven fiber reinforced composites. Fiber content is the main control parameter for hardness testing and L-9 orthogonal array was suggested according to four control factors and three levels.

In many industrial applications, the thermal performance of natural fiber-reinforced polymer composites attracts much technical and scientific attention. Compared to produced natural fiber polymer composites (NFPCs), the thermal behavior of natural fiber composites is often the most researched subject. Thermal properties may be important in instances involving temperatures exceeding the thermal conductivity, thermal stability, curing, and processes used in heating procedures. Several studies have determined their unique thermal properties, notably thermogravimetric analysis (TGA) of natural fiber-reinforced polymer composites. This review examines the effect of temperature on mass loss in natural leaf fibers collected from a variety of plants. Furthermore, natural fiber-reinforced polymer composites are used in a wide range of technological applications, but their diversity is limited due to temperature changes during cooling or heating, necessitating a thermogravimetric analysis before usage in a specific application. TGA was a fundamental thermal analytical approach that was easy, ideal, stable, sensitive, and superb. The thermal analysis also provides important information on glass transition temperatures, thermal expansion, softening points, composition changes, and phase shifts on materials of varied shapes when exposed to a constant load as a function of temperature. This focuses on the fundamentals and experimental thermal analysis of natural leaf fiber–reinforced thermoset polymer composites with or without chemical treatment of fiber for both research and technical applications and their use in various engineering fields, from vehicle manufacturing to civil construction.

The present investigation addresses the influence of fly ash filler material on physico-mechanical properties (water absorption, tensile, flexural, impact, and hardness) and abrasive wear on alkali-treated (2% NaOH) chopped Himalayan agave fiber randomly oriented compound with polyester resin. The physico-mechanical properties such as void fraction, water resistance capability, tensile, flexural, impact, hardness, and dry abrasive wear characteristics of Himalayan agave fiber/polyester composites was determined. The maximum tensile strength (30.09 MPa), flexural strength (54.51 MPa), impact strength (30.24 J/m2), and hardness (42.5 HV) were observed at 15 wt.% of Himalayan agave fiber and fly ash. The abrasive specific wear rate of the composite was studied at four different factors, i.e., fiber loading (5–15 wt.%), normal load (10–30 N), fly-ash content (5–15 wt.%), and speed (50–150 rpm) using Taguchi’s method L9 orthogonal array. The study determined that the control parameters of fiber loading (15 wt.%), normal load (10 N), fly-ash content (15 wt.%), and speed (100 rpm) exhibited the least specific abrasive wear rate. The SEM analysis of worn abrasive surfaces revealed the micro-cuts, fiber breakage, micro-plowing, cracks, and wear debris as the dominant wear mechanism.

Penetration of composites in the wind and aerospace sector is very critical for sustainable business growth. The primary focus is toward a reduction in composite weight and thereby the cost of the material. Further, advancement in the improvement of the mechanical strength of the composites can lead to the development of lightweight high-performance composites which is imperative for these growing market sectors. This review focus on various ongoing researches on graphene and natural silk being used as nano reinforcement in the epoxy composites that have shown significant potential to enhance the mechanical properties and thereby result in reducing the weight of the structural members used in wind turbine and aircraft. Also, this review explores the novel concept of graphene and natural silk fiber being used as combined reinforcement materials for the development of high-performance epoxy composite materials.

In structural applications, Epoxy resin finds extensive application for its low cost, high strength to low weight ratio, higher amenability with superior dimensional stability in elevated temperatures, and chemical inertness. Furthermore, graphene has been extensively used as reinforcement materials to enhance strength and tensile/flexural stiffness. In contrast, natural silk within the other natural fibres showed higher impact strength and ductility, good biodegradability, and excellent biocompatibility for a reinforcement filler material. Several ongoing field research on graphene and natural silk as an individual reinforcement in the epoxy composites have shown significant positive results. This paper concentrates on the research gap of hybridization of graphene and natural silk fibres (SF) as a combined reinforcement material to develop lightweight and high-performance epoxy composite material for structural applications. This paper discusses the suitable material selection and fabrication process for hybrid GO/SF epoxy composite. Graphene Oxide (GO) choice for the reinforcement on epoxy resin by (0,0.5,1,1.5,2,3 and 5) % volume fractions via wet transfer ultrasonication process and plain-woven Bombyx mori silk for 60% SF reinforcement discussed in the paper. The optimum volume fraction of GO and SF promoting significant improvements of the epoxy resin composites’ mechanical properties needs further evaluation during material characterization.

In recent times, demand for light weight and high strength materials fabricated from natural fibres has increased tremendously. The use of natural fibres has rapidly increased due to their high availability, low density, and renewable capability over synthetic fibre. Natural leaf fibres are easy to extract from the plant (retting process is easy), which offers high stiffness, less energy consumption, less health risk, environment friendly, and better insulation property than the synthetic fibre-based composite. Natural leaf fibre composites have low machining wear with low cost and excellent performance in engineering applications, and hence established as superior reinforcing materials compared to other plant fibres. In this review, the physical and mechanical properties of different natural leaf fibre-based composites are addressed. The influences of fibre loading and fibre length on mechanical properties are discussed for different matrices-based composite materials. The surface modifications of natural fibre also play a crucial role in improving physical and mechanical properties regarding composite materials due to improved fibre/matrix adhesion. Additionally, the present review also deals with the effect of silane-treated leaf fibre-reinforced thermoset composite, which play an important role in enhancing the mechanical and physical properties of the composites.

The present research focuses on studying the physical, mechanical, and abrasive wear behavior of the hemp/nettle natural fiber woven mat reinforced with the polyester matrix. The hemp and nettle fibers woven mats were reinforced into the polyester matrix by simple hand-layup, and after that compression molding process was used to fabricate the composites. The water absorption, tensile, flexural, and impact properties were studied using a hemp/nettle hybrid composite. This study found that increasing the amount of hemp and nettle fiber in polyester from 3 to 9 wt% increased the mechanical properties of hybrid composites. The higher weight percentage (9 wt%) of hemp/nettle fiber in polyester hybrid composites exhibited the highest tensile (42.41 MPa), flexural (78.52 MPa), impact (22.72 kJ/m(2)) strength, and a higher hardness value of 46.7 HV. Finite element analysis simulation is conducted on mechanical properties (tensile, flexural, and impact strength). The minimum abrasive specific wear rate of hybrid composites is 0.00827 mm(3)/Nm found in the 9 wt% of hemp/nettle fiber composite at 10 N of normal load and 200 RPM, through Taguchi's approach (L-9 orthogonal array). The contribution of control factors in a hybrid composite is studied by analysis of variance. The surface morphological studies were performed to examine the abraded worn surface by abrasive wear to study the behavior of the wear mechanism using the scanning electron microscope.

Remarkable progress has been established in the field of nanoenergetic materials (mixture of nanoscale fuel and oxidizer) since the advent of nanotechnology. Combustion of nanoenergetic materials depends on many key factors like synthesis route, equivalence ratio, morphology of constituents, and arrangements and handling of materials. For tailoring and tuning of the combustion properties of nanoenergetics, sound knowledge of the reaction mechanism is needed; in this review article a schematic study on the reaction mechanism is presented. By employing various routes and strategies in synthesizing and nanoengineering of the fuel or/and oxidizer to realize a significant evolution from normal physical mixing of nanopowders to the formulation of core/shell nanostructures, the nanoenergetic materials achieved the best ever combustion properties in terms of combustion reactivity, ignition sensitivity, energy density, etc. Overall, in this article, a critical state-of-the-art review of the existing literatures has been conducted to feature the main developments in the molecular combustion modeling of melting, oxidation, and core-shell reaction/diffusion of nanoaluminum and the molecular modeling of combustion reactivity and ignition sensitivity of nanoenergetic materials.

This research paper addresses the experimental investigation on physico-mechanical and Taguchi-designed sliding wear properties of novel Himalayan agave fiber (fiber's sizes of 3mm, 5mm, 7mm and fiber's loading of 5wt.%, 7wt.% and 9wt.%) reinforced polyester composites. The tensile and impact strength were observed to increase with increase in fiber's size and loading delivering maximum tensile of 25.43MPa and impact strength of 45.55J/m2 at fiber's size and loading of 7mm and 9wt.% respectively. The maximum flexural strength (47.02MPa) and hardness (48.01Hv) were achieved with polyester composites having 7wt.% fiber loading at different fiber's size of 7mm and 5mm respectively. The sliding wear rate of composites was studied at different sliding velocity (1.5–4.5m/s), fiber's size (0–7mm), normal load (10–25N), and sliding distance (500–2000m) using Taguchi technique. The study demonstrated that the sliding velocity, fiber's size, sliding distance and normal load are the significant control parameters in descending order affecting the sliding wear rate.

This manuscript investigates the effect of various chemical treatments (potassium hydroxide, potassium permanganate and eco-friendly sodium bicarbonate) of Himalayan agave fibers (HAF) of size 7 mm on its physical, mechanical (tensile, flexural, impact, hardness and water absorption) and abrasive wear performance of HAF/polyester composites. The fibers were chemically treated at different concentration of 5, 10 and 15% of these chemicals for 24 h and reinforced at 10 wt% of fiber loading into polyester resin. Sodium bicarbonate fiber treated composite showed maximum tensile strength (145 MPa), flexural strength (214.5 MPa), impact strength (3.65 J cm−2), and hardness (30.33 Hv) with least water absorption as compared to other chemically treated HAF reinforced polyester composites. The optimum concentration of KOH and KMnO4 treatment were arrived at 10 and 15% concentration respectively with both exhibiting comparable results. The dry abrasive specific wear rate of composites was studied at three different factors i.e. chemical concentration (5–15 wt%), normal load (10–30 N), and speed (50–150 RPM) using Taguchi technique L9 orthogonal array. The sodium bicarbonate composite treated HAF based composites exhibited least specific abrasive wear rate. The scanning electron microscope (SEM) analysis of worn surfaces revealed the fiber breakage, debonding, debris, crack surface and micro-ploughing as the prominent wear mechanism.