Hand Lay-up Research Articles

Experimental investigation of mechanical and erosion properties of twill E-glass/sisal fiber reinforced hybrid polymer composite

Natural fiber-reinforced hybrids are a new topic of study in supramolecular chemistry. Such natural fabrics are low-cost fibers exhibiting good specific characteristics and low density. The tribological and mechanical properties of handwoven sisal/twill glass fabric reinforced polymer blends were scientifically investigated. Hand lay-up lamination specimens were created in a mould and dried under mild pressure at atmospheric conditions for 24 h. Each of the hybrid composites had four layers, with the quantity and location of glass layers varying to provide five distinct layering patterns. A group of any and all sisal lamination, on the other hand, had been created. ASTM standards were followed for sample preparation and evaluation. The results revealed that incorporating twill E-glass fiber with polymer composites may considerably improve the characteristics of the sisal combination. S5 hybrid composites reached maximum tensile and bending strengths of 74.26 MPa and 161.25 MPa, respectively. The wear of the S3 series laminated hybrid is lower (0.84 × 10–4) than that of the other hybrid compound and plain polymer material. The layering arrangement has a stronger impact on hybrid composites in terms of both mechanical and tribological characteristics. The results show how layering affects the mechanical and tribological properties of these new natural fiber-reinforced combinations. This presents exciting new opportunities for many material research and engineering applications, such as making strong, portable car parts.

Improving the quality of the ultrasonic welded thermoset-based composites using laser surface treatment

In this article, ultrasonic welding of glass fiber-reinforced thermosetting polymers which were surface-treated by laser engraving, is investigated. Composite samples were prepared by hand lay-up method. In the next step, surface treatment of the composite samples was performed by means of a high-power laser confirming two grooved and circular patterns. Polymethylmethacrylate and polypropylene as the amorphous and semicrystalline thermoplastic intermediate layers were incorporated to create a joining between the two thermoset parts. Besides, the welding time was considered in the three different levels. In order to investigate the microstructure of the welding zone, scanning electron microscopy analysis were accomplished. Besides, lap-shear tests were performed so as to evaluate the mechanical performances of the welded parts. Morphological studies indicated that in the surface-treated samples, the penetration of the intermediate material into the welded parts is much higher than neat samples and this leads to the superior interaction between the coupling layer and the surface-treated parts. Confirming the morphological outcomes, the results of the lap-shear tests specified that the application of surface treatment using laser engraving has increased the laps-shear strength almost 5.5 times compared to the samples without preparation.

Analysis and prediction of erosion behavior of epoxy composites using statistical and machine learning techniques

This work reports on the application of different machine learning (ML) techniques and statistical methods to analyze and predict the erosion wear performance of ramie fiber-reinforced epoxy composites. These composites, fabricated by conventional hand layup technique, are subjected to high-temperature erosion wear following a test schedule based on the design-of-experiments. The experimental database is used to determine the relative significance and contribution of individual parameter on the erosion wear rate using the analysis of variance. It suggests the impact velocity as the most significant factor contributing 81.2%, followed by impingement angle (13.56%), erodent temperature (0.06%) and stand-off distance (0.05%) to the wear rate. The data generated from experimentation are further processed to predict the erosion performance of the composites with a ML approach following four different algorithms such as support vector machine, decision tree, random forest and gradient boosting machine (GBM). The feature scores for different parameters in the above models are also evaluated to ascertain the contribution of each parameter, which consequently revealed that impact velocity and impingement angle with respective mean feature scores of 0.7538 and 0.1824 have maximum influence on the erosion rate. The performances of four different ML models are compared on the basis of their coefficient of determination (R2 value). It is found that the GBM outperforms other models with a R2 value as high as 0.9543 and has thus emerged as the best-performing prediction model. The possible mechanisms causing the wear loss are identified using electron microscopy.

Flexural and impact performance of Kevlar/basalt fabric interlayer hybrid curved composites

FRP composite has become one of the most preferred materials in lightweight applications. Design freedom is a key benefit which is reflected in the choice of fibres, stacking sequence and others. Hybridisation of hard inorganic fibre and organic ductile fibres can lead to synergetic effects. In this paper, an interlayer hybrid curved laminated composite reinforced with woven Kevlar and basalt fabrics and manufactured by a hand lay-up process with epoxy resin was prepared. Experimental investigation on the flexural and impact properties of composite laminates has been performed. The results of the investigation showed that the placement of Kevlar fibres on the impact side can increase the impact and flexural strengths, sample H3 (K3B2K3B2) has the highest impact strength and absorbed energy among seven hybrid laminates, valued at 92.89 KJ/m2 and 2.48 KJ. Compared with H5(B4K6) improved 41.6% and 40.9%, respectively. However, H5 has the highest flexural strength, reaching 231.7 MPa. In addition, the use of basalt fabric on the impact reverse side or multi-layer hybrid structuring further improves the impact properties of the materials. A sandwich-structure composite with basalt layers in the middle and Kevlar layers on both sides shows further improvement in the flexural properties.

Vibration analysis of bio-inspired sandwich composite beam under rotating environment based on the Internet of Things technology

Sandwich composite materials with corrugated cores are mostly used in industries like aircraft, marine construction, automobiles, and construction. Sandwich composite constructions are made for their lightweight, high strength, and high stiffness, and also the sandwich core composite structures are useful for dynamic studies. A novel design inspired by a woodpecker beak microstructure creates fillet edge and champer edge designs. This novel design motivates us to achieve the energy absorbing results starting with free vibration studies followed by rotating environment vibration studies. ASTM E1876 standards, a non-destructive approach, are used to determine the material properties of carbon fiber-polylactic acid (CF-PLA) and glass fiber reinforced polymer (GFRP), along with alternative dynamic method (ADM) for core property evaluation. The hand lay-up technique is used for fabrication and evaluated for free vibration testing with appropriate boundary conditions. Internet of Things technology has been used for analyzing vibrations of sandwich structures in rotating environment setup with 250, 500, 750, and 1000 rpm. It was observed that the fillet edge pattern has a more efficient natural frequency than the champer edge pattern. Furthermore, the parametric evaluations were performed in various ply configurations in numerical simulations for free vibration and the rotating Environment. Also, the effective results are seen in fillet core bioinspired sandwich structure that achieves efficient stiffness in both free vibration and rotational environments, despite various boundary conditions and parametric circumstances. Therefore, the fillet edge 3D printed core design with particular GFRP factsheet orientation brings out the novelty of this research.

The Effect of Fiber Layer Orientation on the Properties of Hybrid Kenaf/Fiberglass Polyester Matrix Composite

A hybrid composite is a combination of two or more reinforced in a matrix. Hybrid composite will give better properties as compared to individual fiber-reinforced polymer composites. This research aims to study the effect of different fiber layer orientations on the properties of hybrid kenaf/fiberglass polyester matrix composite. Two types of the composite were produced which are Sample 1, the fiber layer orientation is fiberglass, kenaf fiber, kenaf fiber and fiberglass (FG-K-K-FG), and Sample 2, the fiber layer orientation is fiberglass, kenaf fiber, fiberglass, and kenaf fiber (FG-K-FG-K). The composite is manufactured using the hand lay-up technique and hot pressed. 50 g of unsaturated polyester resin and 12 g of hardener, Methyl Ethyl Ketone Peroxide (MEKP) were mixed and applied on top of every layer of fiber before being compressed at 100°C for 10 minutes. The properties of the hybrid composite were determined by completing five types of tests which are tensile test, impact test, water absorption test, thermogravimetric analysis (TGA), and scanning electron microscope (SEM). The results showed that Sample 2 (FG-K-FG-K) has higher tensile strength compared to Sample 1 (FG-K-K-FG) with the value of 30.97 MPa and 0.23 MPa respectively. For the water absorption test, Sample 1 (FG-K-K-FG) with a value of 239.21% has the highest water absorption properties compared to Sample 2 (FG-K-FG-K) with a value of 180.22%. Samples 1 and 2 have no obvious differences in terms of their thermal stability characteristics for the TGA test. For SEM, it is observed that both samples showed an attachment of adhesive between fiber layers and matrix. The overall conclusion is Sample 2 (FG-K-FG-K) has high mechanical properties but needs improvement for low water absorption.

Impact Resistance Enhancement of GLARE Composite Laminates Reinforced with Shape Memory Alloy Wires

This study investigates the impact resistance of Glass Laminate Aluminum Reinforced Epoxy (GLARE) composite laminates by incorporating shape memory alloy (SMA) wires. The influence of varying percentages of pre-strain (0%, 1%, 3%, and 5%) on the SMA wires embedded in the GLARE composites was examined. Laminate composites were made by hand lay-up method using 1100 series aluminum, glass laminate, epoxy resin, and nitinol wire. Impact testing was carried out using the Charpy (un-notched) method. The results demonstrate that the presence of SMA wires significantly enhances the impact resistance of the laminates. The energy absorption capacity of the laminates was found to increase with increasing pre-strain percentage. The highest impact resistance was observed in the specimens with 3% pre-strain, which exhibited a 35.2% increase in energy absorption compared to the specimens without SMA wires. However, a further increase in pre-strain to 5% resulted in a 21.5% decrease in energy absorption due to the higher fraction of stress-induced martensite, limiting the shape memory effect. Additionally, the damage analysis revealed that the absence of SMA wires led to severe debonding and delamination in the GLARE laminates. Conversely, specimens with 3% pre-strain exhibited the least damage, with limited debonding observed only in the front interface of the aluminum and epoxy-laminated fiberglass layers. The higher damage resistance of these specimens is attributed to their optimal energy absorption capability. Based on the findings, it is recommended to further investigate alternative shape memory alloy materials to determine their impact resistance enhancement potential compared to the current SMA wires. Additionally, conducting experiments with pre-strain percentages in the range of 3-5% would provide a better understanding of the maximum achievable performance. Furthermore, microscale observations should be conducted to gain more detailed insights into the damage mechanisms of the tested specimens.

A relationship of tightening torque and initial load of dental implant of nano bio-silica and bamboo fiber-reinforced bio-composite material

Due to entry of body fluid like saliva, blood, etc. in the dental implant assembly lowers the preload value, thus dental implant abutment tightening torque loses. In this article a novel chitosan-reinforced bamboo and nano bio-silica-reinforced five composite materials (CP, CF, C1, C2, and C3) are fabricated using the hand layup method, and their mechanical, biocompatible, and moisture absorption properties are observed and discussed. The present study examines the impact of friction and Young’s modulus on the correlation between torque and starting load in dental implant abutment screws, utilizing the attributes of a bio-composite material. C2 bio-composite composite material exhibits the highest tensile strength (139.442 MPa), flexural strength (183.571 MPa), compressive strength (62.78 MPa), and a minimum value of 1.35% absorption of water. C3 is tested with no cytotoxicity, while C3 and CF exhibit weak biofilm resistance against S. aureus gram-positive bacteria. The C2 bio-composite material demonstrated a maximum initial load of 20 N with a tightening torque of 20 N-cm, under both 0.12 and 0.16 coefficients of friction. The simulated results were compared with several theoretical relations of torque and initial load and found that the Motos equation holds the nearest result to the obtained preload value from finite element analysis. Overall, the experimental findings suggest that the C2 bio-composite material holds significant potential as a prominent material for dental implants or fixtures.

Mechanical characterization & regression analysis of Calamus rotang based hybrid natural fibre composite with findings reported on retrieval bending strength

Research on Bio-based natural fiber material promoted the development of reinforcement and expand their possible structural applications. In this study, fibers are extracted from the stem of Calamus rotang (common rattan-Indian Species). Further, the fiber is processed to get novel hybrid combinations with glass fibers by manual hand lay-up technique. Three sets of samples were prepared for the different volume fractions of 60:40, 30:30:30, and 60:32:8 of glass fiber/epoxy as neat composite sample (NCS), a hybrid combination of C. rotang /glass fiber with epoxy as modified reinforced composite sample (MRCS) and glass fiber/epoxy with calamus stem powder as modified matrix composite sample (MMCS) respectively. Mechanical tests including tensile, flexural, impact, and ILSS tests are conducted as per ASTM Standards. Comparative studies have been done to evaluate the effect of novel species of C. rotang on mechanical properties with neat GFRP composites. Addition to this regression analysis has been carried out to achieve the experimental correlation for tensile and bending tests. Microstructural analysis for all the tested samples has been done to assess the fracture mode. Novel findings on retrieval bending strength for MMCS has been reported for the first time for composite materials. Study proves that novel species have a significant impact on the basic properties of materials.

Interleaving Carbon-Glass Veil in Glass Epoxy Composite for Improved Mode-I Fracture Toughness – A Hybrid Approach

The present study investigates the influence of hybrid interleaving technique using Glass and Carbon veils to improve the mode-I fracture toughness in Glass epoxy laminates. Commercially available non-woven Carbon and Glass veils with different areal densities were used to develop hybrid interleaved composites. Two approaches of interleaving, namely inter-ply and inter-weaved veils, were followed to manufacture the interleaved composite laminates using the hand layup technique. Double Cantilever Beam (DCB) samples were tested to estimate the interlaminar fracture toughness (IFT). Test results indicate that the inter-ply interleaved composite (I-C30G30) exhibited an improved initial and propagation fracture toughness of about 16.98% and 3.08%, respectively. A decreased IFT during initiation and propagation was observed for I-C15G30 and I-C20G30 when compared to plain samples. In case of inter-weaved veil interleaving approach, an improved fracture toughness (GIC and GIP) of about 7.96% and 12.94%, respectively, was observed for W-C15G30 sample, nevertheless W-C20G30 and W-C30G30 showed a drop in fracture toughness (GIC) of an about 12.15% and 9.22%, respectively, and an improvement in fracture toughness (GIP) of about 12.37% and 13.82%, respectively, when compared to plain sample. Scanning electron photo images (SEPI) of cracked laminates witnessed the fracture mechanisms involved in hybrid ply interleaved and non-interleaved composite laminates.

Impact and Compression Behavior of Habesha Moringa/Bamboo Fiber Reinforced Epoxy Composites

ABSTRACT Nowadays, synthetic fiber composites are in decline because of their high initial cost and detrimental impact on the environment. The main aim of this work is to develop natural fiber composite materials that are made from moringa and bamboo fibers by using the hand lay-up method by maintaining a constant 40 vol.% of epoxy content. Both the natural composites were treated with NaOH and also compared with their hybrid composite. The mechanical properties, such as compression, hardness, impact, tensile, flexural properties were investigated. Additionally, thermo gravimetric analysis of composites was also carried out. The biggest boost in compressive strength was seen in bamboo with 60% volume, with improvements ranging from a pure resin value of 13.06 to 68.43% compared to moringa 60% and 30–30% moringa-bamboo. The maximum rise in impact strength was recorded by BM-30/30 at 21J. In addition to this, the highest hardness value was observed by moringa-reinforced composites (MM-60) and noted to be around 40.83 HV. Tensile and flexural properties of all the composites reveal improvement as compared with neat epoxy composites. Bamboo exhibits a considerable improvement in thermal stability as compared with other compositions. Scanning electron micrographs were used to analyze the structure-property correlations.

Effect of hybrid filler loading (Polyalthia longifolia seed and graphite) on the mechanical and thermal properties of vinyl ester composites

AbstractThis research paper focuses on the use of solid biomass waste, specifically a combination of Polyalthia longifolia seed (PLSF) and graphite (GH) powder, as reinforcements in vinyl ester (VE) composites. The composites were produced via the hand layup method, with the filler concentration varying from 0 to 15 wt% of PLSF and 0–9 wt% of graphite. The objective was to examine the influence of the hybrid filler on the mechanical characteristics of the composites. The mechanical properties of composites prepared from P. longifolia seeds and graphite powder were experimentally characterized. These properties included tensile strength, flexural strength, impact resistance, and hardness. The hybrid composite had a maximum tensile strength of 48.4 MPa, and its tensile modulus was 1.66 GPa. The hybrid filler at 15% wt% of PLSF and 6% of graphite has the highest flexural strength, which is around 148 MPa. The ultimate impact strength and hardness were measured to be 41.3 kJ/m2 and 44.5, respectively, after the addition of 15 and 6 wt% of hybrid filler. In comparison to neat vinyl ester resin, the PLSF/GH‐VE composites exhibited an increase in tensile, flexural, impact, and hardness of 2.69, 1.82, 3.03, and 1.59 times, respectively. Hybrid composite surfaces were analyzed using scanning electron microscopes to determine surface characteristics and fractured surfaces. In addition, the PLSF/GH‐VE composites have been utilized in the production of components for four‐wheelers.Highlights Investigated the impact of hybrid filler‐reinforced vinyl ester composites. Mechanical and thermal properties were experimentally characterized. Surface characteristics and fractured surfaces were examined. PLSF/GH‐VE composites are used in producing components for four‐wheelers.

Epoxy-based CFRP composites with induced single and multiple delaminations: flexural performance under four-point loading using digital image correlation

ABSTRACT The present work explores the effect of induced single and multiple circular delamination(s) on both the strength and stiffness of carbon/epoxy composite laminate subjected to pure bending. The laminates consisted of stacking sequence [0/0/45/-45/90/45/-45/90]S. They were manufactured using the hand layup method and vacuum bagging technique. The composites contained delamination(s) at the centre. The multiple delaminations have different sizes. They were inserted in a triangular pattern. Flexural tests were conducted in displacement control mode. The intact composite failed without delamination. The existence of multiple delaminations highly deteriorated the structural integrity and as a result the flexural properties decreased as compared to composites containing single delamination. Plies of the delaminated composite beams buckled locally on the compression side. Hence, the local out-of-plane displacement at the centre of the defect was measured using 3D DIC. The local out-of-plane displacement was higher in composites of induced multiple delaminations. Additionally, surface displacements and strains were measured at the region of interest. The causes of degradation in flexural performance and damages are also explained in detail.

Improving the mechanical properties of Glass Reinforced Plastics by slight mechanical compression

Glass reinforced plastics (GRPs) are composite materials that have been used widely in engineering. Mechanical properties of fabricated GRP products depend on the type and arrangement of reinforcement, the type of the plastic as well as the reinforcement to plastic ratio. Some of these factors are interdepended in determining the quality of the final product. In the present study, the influence of applying mechanically a slight pressure during fabrication on the properties of GRP specimens, was investigated. Specimens were fabricated using the hand lay-up method and were further processed either by a vacuum bag compression or a mechanically applied pressure. The properties of the produced composite specimens were then determined experimentally. The application of mechanical compression was found to improve their properties. The effect of the mechanically applied compression or vacuum was evident as a reduction of the specimens’ internal void volume compared to the non-compressed ones, resulting in an increase in the density by 9–12% and a reduction in the thickness of the specimens by 15–20%. Additionally, the tensile and flexural strength of the specimens were increased by more than 15% and 5% respectively when pressure was applied mechanically, reflecting an improvement in GRPs’ mechanical properties.

Investigating the impact of TiO2 filler on abrasive wear characteristics of bamboo fiber-reinforced epoxy composites using the Taguchi method

Purpose The purpose of this study is to investigate the impact of titanium oxide (TiO2) filler on the abrasive wear properties of bamboo fiber reinforced epoxy composites (BFRCs) using a Taguchi approach. The study aims to enhance the abrasive wear resistance of these composites by introducing TiO2 filler as a potential reinforcement, thus contributing to the development of sustainable and environmentally friendly materials. Design/methodology/approach This study focuses on the fabrication of epoxy/bamboo composites infused with TiO2 particles within the Wt.% range of 0–8 Wt.% using hand layup techniques. The resulting composites were subjected to wear testing according to ASTM G99-05 standards. Statistical analysis of the wear results was carried out using the Taguchi design of experiments (DOE). Additionally, an analysis of variance (ANOVA) was used to determine the influential control factors impacting the specific wear rate (SWR) and coefficient of friction (COF). Findings The study illuminates how integrating TiO2 filler enhances abrasive wear in epoxy/bamboo composites. Statistical analysis of SWR highlights abrasive grit size (grit) as the most influential factor, followed by normal load, Wt.% of TiO2 and sliding distance. Analysis of the COF identifies normal load as the primary influential factor, followed by grit, Wt.% of TiO2 and sliding distance. The Taguchi predictive model closely aligns with experimental results, validating its reliability. The morphological study revealed significant differences between the unfilled and TiO2-filled composites. The inclusion of TiO2 improved wear resistance, as evidenced by reduced surface damage and wear debris. Originality/value This research paper aims to integrate TiO2 filler and bamboo fibers to create an innovative hybrid composite material. TiO2 micro and nanoparticles show promise as filler materials, contributing to improved tribological properties of epoxy composites. The utilization of Taguchi’s DOE and ANOVA for statistical analysis provides valuable guidance for academic researchers and practitioners in optimizing control variables, especially in the context of natural fiber reinforced composites.

Experimental investigation on the mechanical and wear behavior of epoxy/Indian almond/peepal hybrid composites

Abstract Natural fiber-based hybrid composites are gaining more attention in industrial usage due to their low cost, environmental friendliness, and simplicity of processing. In this research, an effort was made to create hybrid natural composites using Indian almond and peepal fibers for applications in the automotive industry. Composites were prepared with different volume fractions of Indian almond and peepal fibers using the hand layup process. The mechanical and tribological properties of the composites were tested. The epoxy/40 wt% peepal composite showed superior performance compared to all other composites due to the better strength of peepal fiber. Moreover, the same composite displayed the least wear loss and coefficient of friction (COF). The present study confirms that peepal fiber composites match the strength properties of existing industrial composite materials, and that they may be some of the alternative composites for automotive applications.

Characterization of Water Absorption, Thickness Swelling and Diffusion Coefficient of Natural Fiber/Epoxy Bio-Composites for Applications in Aquatic Environment

The aim of this work was to study the suitability of wood flour, fluted pumpkin stem and rice husk flour/epoxy bio-composites for application in aquatic environment. The water absorption, thickness swelling and diffusion coefficient of wood flour, fluted pumpkin stem flour, rice husk flour/epoxy bio-composites were investigated. Composites were prepared by the hand layup method at varying weight percentages of filler reinforcement (10, 20 & 30%). The increase in the addition of the fillers enhanced the water absorption, thickness swelling and diffusion coefficient of the composites. However, after 14 days of immersion, all the composites attained an equilibrium state. It was observed that with 30wt% filler loading, the fluted pumpkin stem flour epoxy composites showed the highest water absorption of 40.5%, diffusion coefficient of 10.80x10-8m2/s, followed by the wood flour epoxy composite with water absorption of 35.3%, diffusion coefficient of 8.17x10-8m2/s, while rice husk flour epoxy composites had the lowest water absorption of 16.5%, diffusion coefficient of 6.12x10-8m2/s. The same trend was observed for the composites with 20 and 10 wt% filler loading. In terms of thickness swelling, the wood flour composite showed 1.62%, followed by fluted pumpkin stem flour composite 1.40% and rice husk flour composite 0.35% with 30wt% filler loading. A similar trend was observed for the composites with 20 and 10wt% filler loading. This study can be useful to comprehend the effect of water absorption on the performance of natural fiber composites and help in creating designer compositions for use in building, construction and automotive.

Date-Palm-Based Sustainable Hybrid Composite with Cotton and Kevlar Fibre Participation

This research aims to evaluate the physical and mechanical performance of three types of hybrid composites made of date palm (Phoenix dactylifera L.) (DP), additional layers of cotton (DP/C) and Kevlar fibres (DP/K). The fibres were formed into flat sheets and employed as reinforcement layers embedded in a polyester matrix. Three-layer and five-layer hybrid composites were created using the hand layup method. The layers have alternative longitudinal–transversal orientation. The composites were investigated for density, thickness swelling (TS), water absorption (WA), flexural strength and modulus of elasticity (MOE) properties. Moreover, the composites were subjected to cycles of water immersion, freezing and drying, and the changes in mass and mechanical performance were analysed before and after the cyclic testing. The hybrid composite with Kevlar as the inner layers displayed better physical and mechanical properties when compared to the other two hybrid composites. A stereo-microscopic investigation revealed that poor adhesion between the layers of composites contributed to a reduction in the mechanical properties of DP/C and DP hybrid composites. The DP/C composite had the highest thickness swelling and water absorption, with the water uptake more pronounced than in the cases of the other composites. The hybridisation of date palms with Kevlar fibres improved the properties of the hybrid composites.

An experimental investigation of the effect of carbon nanotubes addition and shot peening process on the ballistic limit of fiber-metal laminates

The present research has experimentally investigated the effect of adding multi-walled carbon nanotubes (MWCNTs) and shot peening operations on the ballistic behavior of fiber-metal laminates (FMLs). The unreinforced and reinforced FMLs with 0.2 wt.%, 0.4 wt.%, and 0.6 wt.%. of MWCNTs were manufactured by hand lay-up method and subjected to shot peening operations. Finally, the specimens were exposed to the ballistic impact test using a cylindrical projectile with a conical head. The best result was obtained for 0.4 wt.% of MWCNTs, in which the ballistic limit and absorbed energy increased by 6.80% and 13.75% for non-shotted and by 8.50% and 17.45% for shotted samples, respectively. This demonstrates the positive effect of shot peening in increasing the ballistic limit through a combination of work hardening and compressive residual stresses in the aluminum layers. However, mechanical performance decreased in samples containing 0.6 wt.% of MWCNTs due to nanoparticle agglomeration. The fracture surfaces of the samples were also analyzed by scanning electron microscopy, and the results indicated an improvement in the adhesion properties at the interface between the fibers and matrix in the reinforced samples, achieved through mechanisms such as crack bridging and MWCNTs pull-out.

Investigating silicon nanoparticles modified sandwich polymer composites for enhanced mechanical performance

ABSTRACT This study investigates the morphology and mechanical behaviour of a bidirectional interply hybrid sandwich polymer composite panel with the addition of silica nanoparticles (SiNPs). The investigation assesses the enhanced performance of sandwich polymer composite panels, focusing on their ability to withstand compression, Euler’s buckling axial load-bearing capacity, and surface roughness when subjected to low-velocity impact events that are barely perceptible for aircraft, automobile, and wind turbines. The composite panel was constructed using interply bidirectional Kevlar, carbon, and glass fibers, an epoxy matrix, and polyurethane (PUR) foam, with the incorporation of four different weight percentages of silica nanoparticles (0%, 2%, and 4% of SiNPs). The sandwich composite panel was fabricated using the hand lay-up technique, following a novel quasi-static stacking sequence method (01 K/01 C/01 G/PUR/01 G/01 C/01 K). Among these composite panels, the addition of 4 wt.% silicon nanoparticles exhibited the highest strength and axial load-carrying capacity compared to the other sandwich composite panels (0 wt.% and 2 wt.%). The mechanical characterisation results showed maximum compressive strengths of ca. 3 MPa, ca. 5 MPa, ca. 10 MPa, and ca. 8 MPa for the 0 wt.%, 2 wt.%, 4 wt.% and 6 wt.% of silica nanoparticles-added composite panels, respectively.