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The prosthetic socket base material must have exhibited good mechanical properties. An experimental investigation about the behavior of different fibers reinforced laminated composite materials were done. This work has been done on seven laminated composites which were prepared by the Vacuum bagging technique from Polyester resin as a bonding matrix and reinforced with (Jute, Glass, Carbon, Perlon) fibers. Laminated specimens were characterized by mechanical tensile tests such as (Tensile Strength, Young’s Modulus, Elongation Percentage) and physical test (density) to measure specific strength and specific modulus. SEM test also had been studied for different laminated composite. The results of experimental work showed that the mechanical properties were changed with the type and number of reinforcing layers. So, the results showed that the best laminated composite specimens have three layers of Jute with four layers of Carbon fiber. Where tensile strength and modulus of elasticity reach (162 MPa. and 3.60 GPa.) respectively. And specific strength and specific modulus reach to (134 MPa.cm3/gm–2.544 GPa.cm3/gm). The smoothness of the fractured surface will increase, indicating a brittle to semi-ductile transformation, according to SEM results.

High-performance ballistic fibers, such as aramid fiber and ultra-high-molecular-weight polyethylene (UHMWPE), are commonly used in anti-ballistic structures due to their low density, high tensile strength and high specific modulus. However, their low modulus in the thickness direction and insufficient shear strength limits their application in certain ballistic structure. In contrast, carbon fiber reinforced epoxy resin matrix composites (CFRP) have the characteristics of high modulus in the thickness direction and high shear resistance. However, carbon fibers are rarely used and applied for protection purposes. A hybridization with aramid fiber reinforced epoxy resin matrix composites (AFRP) and CFRP has the potential to improve the stiffness and the ballistic property of the typical ballistic fiber composites. The hybrid effects on the flexural property and ballistic performance of the hybrid CFRP/AFRP laminates were investigated. Through conducting mechanical property tests and ballistic tests, two sets of reliable simulation parameters for AFRP and CFRP were established using LS-DYNA software, respectively. The experimental results suggested that by increasing the content of CFRP that the flexural properties of hybrid CFRP/AFRP laminates were enhanced. The ballistic tests’ results and the simulation illustrated that the specific energy absorption by the perforation method of CFRP achieved 77.7% of AFRP. When CFRP was on the striking face, the shear resistance of the laminates and the resistance force to the projectiles was promoted at the initial penetration stage. The proportion of fiber tensile failures in the AFRP layers was also enhanced with the addition of CFRP during the penetration process. These improvements resulted in the ballistic performance of hybrid CFRP/AFRP laminates was better than AFRP when the CFRP content was 20 wt% and 30 wt%.

Aircraft wings are designed with very low factor of safety to keep the aircraft weight minimum. Thus, for safe design of wings, stress analysis should be carried out under accurately estimated aerodynamic loads and this can be achieved only through coupled fluid-structure analysis. Moreover, modern aircraft wings are made of laminated composite structures and thus the purpose of this study is to employ ANSYS coupled fluid-structure analysis to find the best layup of composite wing of an aircraft that results in higher specific strength and specific stiffness. Firstly, Computational Fluid Dynamics (CFD) analysis has been carried out to find the actual aerodynamic load which is the pressure distribution around a three-dimensional wing. Then, this pressure distribution from CFD was used as a load input for detailed static structural analysis of the wing. Initially, strength and stiffness of an isotropic wing is evaluated and then the material of the wing was changed to composite laminates to achieve better structural performance with higher strength and stiffness to weight ratio. Stress analysis was carried out for different layups to predict the optimum layup that results in high strength and stiffness coupled with the least weight and it was found that the wing made of symmetric cross-ply laminate performs the best.

Negative Poisson’s ratio structures have attracted great interest due to its many excellent mechanical properties. In recent years, to improve the specific stiffness of the structure, the negative ...

Temperature is a paramount factor for shape memory polymer composites (SMPCs) to implement their shape recovery functions and present their high specific stiffness when applied in aerospace deployable structures. However, many existing studies focused on the thermo-mechanics and shape memory behaviors of SMPC were established based on uniform temperature distribution. This work explores the specific characteristics of thermal conduction behaviors of single-ply carbon fiber broken twill weave reinforced thermally induced resin-based SMPCs by multi-scale analysis method. The thermal conductivities are measured by the laser flash analysis (LFA) method, and the results are modified by the specific heat testing results from differential scanning calorimeter (DSC). The periodical dividing areas and multi-scale representative volume elements (RVEs) are developed to elaborate the thermal conduction behavior and uneven temperature distribution of 3–1 twill weave reinforced SMPCs. Through the finite element analysis (FEA) and comparisons, the particularity of twill breaking woven materials compared with other woven materials is shown. By comparing the experimental and numerical results of thermal conductivities, the multi-scale models and analysis of thermal conduction behavior are validated to be effective.

Aluminum-based hybrid composites with new combinations of both hard ceramic particulates (5-10 wt.% SiC and 5-10 wt.% TiC) and ductile metallic (27 wt.% Cu) reinforcements are successfully synthesized via spark plasma sintering route to achieve significantly high specific hardness and specific modulus. The synthesized hybrid composites exhibit an adequate consolidation with marginal porosity and a clean particle–matrix interface, ensuring better particle–matrix bonding. Detailed microstructural characterization by electron microscopy and X-ray diffraction analysis further reveals that metallic copper particles could be successfully incorporated with marginal intermetallic formation by the interfacial reaction. Mechanical properties have been evaluated by macro-hardness and depth-sensing nano-indentation measurements. Among the fabricated ones, the Al-27wt.% Cup-5wt.%SiCp-5wt.% TiCp hybrid composite exhibits impressively high specific hardness (35 VHN/gcm−3), specific Young's modulus (33.9 GPa/gcm−3), and very high bulk modulus (28.2 GPa/gcm−3) when compared with the Al-based composites reported in the literature. This is attributed to the evolution of a novel microstructure consisting of SiC, TiC, and Cu particulates in a highly sub-structured aluminum-based matrix with a significant amount of dislocation density (6.6×1014 m−2). The elasto-plastic characteristics of the matrix are further explored through the depth-sensing nano-indentation technique.

Closed-cell porous aluminum is expected to be a prominent material in near future because of its light weight, high specific modulus of elasticity, high energy absorption efficiency and high sound-insulating capacity in the automotive and aerospace industries. Recently, a new method of foaming has been developed in which a precursor is formed using friction stir processing. In the friction stir processing route, a precursor is fabricated by embedding a mixture of blowing agent powder and stabilization agent powder into aluminum alloy plates by the significant stirring action of friction stir processing. By applying the friction stir processing route precursor method, the cost-effective Al-foam formation along with high productivity can be accomplished. In this study, titanium hydride powder has been used as the blowing agent as it is reported to be most compatible with aluminum matrix. The effect of percentage of stabilization agent, i.e. alumina powder on porosity of aluminum foams formed using friction stir processing route is analyzed. The porous aluminum formed with three different percentages of alumina is observed and their porosity is calculated. Also, the compressive performance of the obtained samples is observed in order to examine the alumina powder addition on mechanical properties of the obtained metal foam. This study aims at analyzing the significance of addition of the alumina into the blowing agent while developing the metal foam through friction stir processing route.

A method was developed and proposed to fabricate graphene-enhanced hollow microlattice materials, which include the three-dimensional (3D) printing, nanocomposite electroless plating, and polymer etching technologies. The surface morphology and uniformity of as-deposited coatings were systematically characterized and analyzed. Moreover, the mechanical properties of the microlattices were investigated through quasi-static compression tests. The results demonstrated that a uniform Nickel-phossphorous-graphene (Ni-P-G) coating was obtained successfully, and the specific modulus and strength were increased by adding graphene into the microlattice materials. The optimal mass concentration of graphene nanoplatelets was obtained after comparing the specific modulus and strength of the materials with different densities of graphene, and the strength mechanism was discussed.

Carbon fiber is a highly desired material for structural applications requiring high strength and stiffness and low weight but has seen only incremental improvements in properties over the last few decades. Further increases in carbon fiber specific properties, including specific strength and specific modulus, would further propel its unique capabilities. One method to produce high specific property carbon fibers for structural applications is the development of hollow carbon fibers. In this work, we report on the early development of polyacrylonitrile-derived structural hollow carbon fibers. Here, multifilament, continuous tow, polyacrylonitrile-based precursor hollow fibers were successfully produced utilizing a segmented arc spinneret approach. When batch oxidized, the hollow precursor fibers demonstrated evidence of oxidation proceeding from both the interior and exterior of the filament. Further results suggested that reducing the precursor hollow fiber wall thickness would allow for complete, homogeneous oxidation, thereby avoiding the skin-core structure often observed in commercial carbon fiber. Hollow carbon fibers were as small as 35 μm outer diameter, 22 μm inner diameter (6.5 μm wall thickness). At these diameters, the hollow carbon effective fiber specific strength was 0.54 N/tex and the effective specific modulus was 120 N/tex, approaching the effective specific modulus of T700S at 136 N/tex.

Considering the double requirements of performance and cost, the metal-carbon fiber reinforced polymer (CFRP) tubes, which combine the benefits of the high specific stiffness of the CFRP and the stable deformation of the metal, is becoming an important form of energy absorption structure. This paper investigated the effects of interfacial connection condition on the damage behavior and energy absorption characteristics of an Al/CFRP hybrid tube under three point bending loading by simulation and experiment. Four different interfacial connection conditions, which were caused by surface treatment of Al tube and changing the connection mode between Al tube and CFRP tube, were studied. Based on the experimental results, the SEA value of hybrid tube under surface treatment is 3 % higher than that of hybrid tube without surface treatment, and the SEA value of the secondary bonding hybrid tube is increased by 10.5 %, compared with that of the sleeve connected hybrid tube. Three-point bending simulation model based on Hashin’s damage initiation criterion and energy based damage evolution scheme is carried out. The interfacial connection conditions are simulated by setting different contact settings. The results of simulation and experiment are consistent on the force displacement curve and the strain nephogram, which proves the validity of the finite element model. Through the analysis of the stress nephogram of the Al layer and the CFRP layer which are closest to the interface layer, the influence of the interface connection conditions on the energy absorption of the hybrid tube is further analyzed. The results showed that the energy absorption of the hybrid tube is affected by the interaction between heterogeneous materials and increases with the increase of the interfacial adhesion strength. The present contribution improves the energy absorption of the hybrid tube, which is applied to the energy absorption device of the automobile, and provides a method to improve the bonding strength between heterogeneous materials.

In this study, the Rayleigh wave velocity, which is an important parameter in ground vibration analysis, is determined directly in an unbounded soil medium using numerical modelling with ABAQUS. The Rayleigh wave (R-wave) velocity is determined from the displacement time response of the finite element model at a single station for far-field condition. Using the results, a linear prediction equation is proposed to determine the R-wave velocity of the soil. For this a 2D finite element model coupled with infinite elements in the boundary is developed which is subjected to dynamic loading. After establishment of the presence of R wave in the soil medium using particle movement and validation of displacement time response with analytical models, the R wave velocity is determined using positive peak particle vertical displacement. The effect of material properties of soil medium, such as modulus of elasticity, density and Poisson ratio, on Rayleigh wave velocity are investigated using differential sensitivity analysis. The analysis shows that the modulus of elasticity has positive correlation with highest sensitivity coefficient whereas density and Poisson ratio have negative correlations with R wave velocity. A prediction equation is developed for R wave velocity for the input variables, the square root of specific modulus and Poisson ratio, using multiple linear regression in MATLAB. The accuracy and usefulness of the predictive equation is validated by comparing the predicted values of R wave velocity with values obtained from analytical model and field/lab measurements. Applying the predictive equation for the range of soil properties available in the literature, the R wave velocity of different soil types and conditions are evaluated, which can be used for the analysis and mitigation of ground vibration problems.

Textile composites are applied to aerospace and automotive industries because they have good fatigue characteristics, and higher specific stiffness and strength compared to metallic materials. In addition, textile composites have better out-of-plane performances such as the resistance of impact and inter-laminar delamination, in addition to greater structural flexibility than the traditional unidirectional composite materials. In this paper, we studied a stiffness prediction method for the effective stiffness of triaxial braided composites accounting for manufacturing parameters such as fiber volume fraction, number of filaments in a yarn, braiding angle, and gap between fiber yarns. The repeating unit cell (RUC) of the triaxial braided composites and the geometric model of yarn architecture were defined in consideration of the gap between adjacent yarns. The gap size between yarns was measured from the photographic image of the cross-section of the triaxial braided composite specimens. The fiber yarn discretization method and the stress averaging method were applied to predict the effective mechanical properties of triaxial braided composites. The predicted properties by the proposed model have good agreement with experimental results.

Aluminum alloys reinforced composite materials have been widely used in automobile, aeronautical and other commercial applications. Aluminum composites are light weight material with high specific strength, specific modulus, stiffness, heat resistant,eco-friendly and have extreme properties so used in large volumes. Due to these circumstances;we have to reduce the price and weight of the composites, improve and increase physical and mechanical properties. One of the ways to reduce the cost of composites is reducing the cost of reinforcement by using cheap, weightless, and easily available materials like fly ash and improving the properties by adding sic. These properties are achieved through the properties intrinsic in them and the size, shape, orientation, weight and distribution. Several casting methods are used by the industries to manufacture the composite products, and each casting method has its own pros and cons. In traditional process, defects of pore formation due to gas, shrinkage porosities are regular and these defects decrease the mechanical properties and integrity of the end product. To overcome such defects,comparatively better squeeze casting method can be implemented.

Summary Two-dimensional (2D) covalent organic frameworks (COFs) are promising polymeric crystalline nanomaterials with broad applications. However, the understanding of their mechanical properties and fracture mechanisms remains elusive. Here, we report a quantitative in situ tensile study of ultrathin COFTAPB-DHTA films. The fracture strength was measured to be 0.75 ± 0.34 GPa, and the tensile modulus was measured to be 10.38 ± 3.42 GPa, with a nominal density of 0.393 g/cc, thus having specific strength equivalent to Kevlar (2 GPa·cc/g), and specific modulus comparable with titanium alloys (23 GPa·cc/g). In addition, the fracture toughness was measured to be 0.55 ± 0.09 MPa√m, and it was found that the crack propagation could be insensitive to the pre-crack when the size of pre-crack is below a critical value, leading to intriguing flaw insensitivity in such ultrathin nanomaterials. This work provides in-depth insights into the fracture properties of 2D COF films and lays a foundation for their future applications.

Carbon nanotubes (CNTs) are regarded as the next generation of one-dimensional super-strong nanomaterials due to their extraordinary mechanical properties. Recently, much attention has been dedicated into super-strong CNT-based fibers resulting from twisting operation. However, the roles of a promising compression operation on the mechanical enhancement mechanisms of CNT fibers (CNFs) are not clear. Especially, the combined twisting-compression effect has not been known. In this work, with using coarse-grained molecular dynamic simulation method, the tensile mechanical properties and mechanical enhancements of randomly-distributed CNT fibers (RDCNFs) were studied. It was found that the mechanical performances of such RDCNFs could be significantly improved by increasing CNT length or decreasing initial bending degree of CNTs. Furthermore, both specific strength and specific modulus can be effectively tuned by twisting and compressing operations, where self-locking and unhitching mechanisms of CNT knots play critical roles. On the other hand, following theoretical guidance, a super-strong CNF with the maximum specific strength up to 296 mN/tex (∼6.8 GPa) was designed and fabricated. This work provides a theoretically and experimentally support to design super-strong CNT-based fibers and lays a foundation for their future applications.

Effects of incising parameters were studied relative to the drying performance and properties of super–fast dried oil palm wood. Different incising depths (1/3, 1/2, 2/3, and 100% of the total thickness) and distance (38 mm and 50 mm) were made on the oil palm wood boards prior to the super-fast drying procedure. All the boards achieved the desired moisture content after drying. Drying defects were minimal, as only two boards indicated end checks and surface checks defects. The board density ranged from 0.44 g/m3 to 0.60 g/m3, and the thickness swelling and water absorption of the boards ranged from 8.3% to 12.5% and 45% to 67%, respectively. The specific modulus of rupture and elasticty ranged from 0.35 N m3/kg mm2 to 0.77 N m3/kg mm2 and from 77.64 N m3/kg mm2 to 118.40 N m3/kg mm2, respectively. It can be concluded that the hole distances did not exert significant effect on the properties, with exception of specific modulus of elasticity. A hole depth of 1/3 mm was preferable, since the surface looked like no incision had been made and the sample had good physical and flexural properties.

Due to their high specific strength, specific stiffness, and toughness, aramid fabrics have been used in various applications, especially those involving bulletproofing. The bulletproof capability and mechanical properties of aramid fabrics can be enhanced at the mesoscale with shear thickening fluid (STF) coatings; however, little is known about the microscale characteristics of STF-coated aramid fabrics. This study aimed to investigate the microscale rate-dependent behavior of STF-coated single aramid fibers inside aramid yarns using a newly proposed testing method, in which a high shear rate is applied to STF-coated yarns and fibers in a single-fiber pull-out test.

Searching for lightweight, economic, bio-degradable, recyclable and eco-friendly material with high specific strength and high specific modulus to reinforce polymer composites finds a viable and potential solution in natural fiber. In the present work, zero cost plentifully accessible Coccinia grandis stem fiber (CGSF) with high cellulose content, specific mechanical properties and salient surface features to ensure good bonding with the polymer matrix is comprehensively characterized for its physical, chemical, thermal, mechanical, surface roughness and microstructural properties. Initially, CGSF is qualified and used as a reinforcement in the fabrication of composite with polyester resin (CGSFC). The critical length of fiber and the best percentage addition of fiber reinforcement were determined based on mechanical testing, which were found to be 40 mm and 40% (wt), respectively. Mechanical properties increased with amount of fiber up to 40% (wt), where fiber pullout, debonding and matrix failure occurred systematically to provide maximum load transfer capability to the composite. Thermal analysis of the fiber confirmed its thermal stability till 250 °C, which is sufficient for any polymeric material. Tensile strength of about 50 MPa, better flexural strength, sufficient energy absorption capacity and hardness affirm the CGSF composite as an alternative structural material for various engineering applications.

Structural lightweighting is a key initiative in the automotive sector due to regulatory, customer, and powertrain demands. This research focuses on reinforcing aluminum sheet metal in strategic locations using ultrasonic additive manufacturing (UAM), as guided through an iterative optimization and simulation process. Among the three models used, the most successful is the multi-step model (MSM) which simulates the forming of tailored blanks and the unloading processes to accurately map the hardening and the residual stress in hat and reinforcement sections. The MSM shows that approximately 65% of the mass can be saved by replacing a large gauged sheet metal hat section with a discretely reinforced hat section. Further increases in specific energy absorption (SEA) and additional mass savings can be expected when utilizing higher specific strength and specific stiffness materials for reinforcement such as titanium alloys, composites, or ceramic materials, all of which have been demonstrated with UAM.

Materials for different structural and machine elements have gained importance from last two decades. With the hi-tech age, scientists are interested in specialised materials with specific properties. So, in last two decades utilization of composite materials has been rapidly increasing in order to fulfil the requirements of Aeronautical, space and nuclear sectors. Fibre reinforced polymer matrix composites gained significance role by replacing the conventional metallic materials in many aspects though they are having high performance characteristics, high specific stiffness and strength, weight saving ability, tailored into any critical structural shape, resistance to fracture and fatigue, damage tolerance and greater resistance to oxidation. Present study provides a brief review on various composites used in aeronautical engineering with focus on specific characteristics and features of composites required for aerospace structural members and their benefits.

This study presents the tensile properties and cost-property efficiency analyses of a novel composite material type composed of expanded polystyrene as filler, chopped glass fibers as reinforcement agent and epoxy resin as matrix material. Composite specimens were fabricated via expanded polystyrene beads with two different densities, two different length of chopped glass fibers and three levels of fiber/filler weight ratios. Specimens were subjected to tensile tests and cost property analyses were carried out. Experimental studies revealed that novel composite specimens had significantly low density and high specific modulus. Cost-property efficiency analyses revealed that the novel composite is relatively highly efficient material and could be utilized instead of its more expensive counterparts such as conventional plastics or laminated composites especially for non-load bearing applications.

Some important properties of the metal foams that make them attractive materials for various purposes are their excellent stiffness to weight ratio (light-weight structure), ability to take up strain by crushing at controlled pressure (energy and impact absorption), order of magnitude higher damping capacity as compared to the solids (mechanical damping), higher natural flexural vibration frequencies (vibration control), reasonable sound absorbing capacity accompanied by durability and fire resistance (acoustic absorption), and, high area of contact accompanied by high thermal conductivity (heat exchanger). Often foam is joined or connected to cover sheets of the same metal and the whole part together is called a foam sandwich. Among all the metal foams aluminium metal foam has found the widest and diverse application. This article covers important recent literature on laser processing viz. laser forming, laser welding, laser cutting and laser additive manufacturing of metal foams. Prior to this, a link is established between foam/foam sandwich and laser processing techniques stating the limitations of other relatively more conventional processing techniques. Future research direction regarding different laser processing techniques using metal foams has also been outlined.

Polymer matrix composites are being widely used in various applications area like as aerospace, construction, shipbuilding, automobile industry etc, due to excellent Mechanical properties and rich hydroxyl group used in surface modification the application area of nanocellulose is increasing day by day. Nanocellulose can be extracted from agricultural waste such as sugarcane bagasse, cotton linter, rice husks, and can be used as a reinforcing material for composites which gives very high Specific stiffness and strength, Elastic modulus of nanocellulose is predicted more than the Kevlar fiber and specific strength is approximately 7–8 times higher than stainless steel as reported in several literature. In this paper extraction technique of nanocellulose and fabrication of polymer matrix composites has been explained, Elastic modulus of composites can be obtained and verified by rule of mixture. Due to its low toxicity, renewable nature, nanoscale dimension and good biocompatibility the future scope of nanocellulose is very wide. Nanocellulose have rich hydroxyl groups which is used for surface treatment of materials, mechanical properties of nanocellulose such as high stiffness and strength are attractive to use it as a filler for composites which gives better mechanical and thermal properties. Nanocellullose composites are used in various application such as in biomedical for tissue repair, drug delivery and implants of some body parts, in paper and packaging industry, in electronic industry such as time- temperature integrator, gas and leak detector etc.

Aluminium based metal matrix composites have been widely used in various applications such as automotive, defense, marine, electronics and automobile sectors because of its excellent strength to weight ratio, excellent stiffness to weight ratio with better resistance to wear and corrosion. The mechanical properties of matrix are strengthened by reinforcing particles, fibers and whiskers. These reinforcements act as load bearing elements which resists cracks during its applications. Wear is one of the predominant factors and wear resistance can be improved by increasing the hardness of material. These composites can be made by various manufacturing process such as solid state process and liquid metallurgy route. The review of mechanical properties and wear resistance of aluminium matrix composites by various manufacturing processes have been discussed.

Recent atomic manipulation by an AFM tip created the first sp-hybridized carbon material – cyclo[18]carbon. Herein, we revealed the unique mechanical properties of cyclo[18]carbon by the first principle calculations. Under uniaxial tension, cyclo[18]carbon is ultra-elastic as demonstrated by a small Young’s modulus of 0.11 TPa and a tiny specific tensile stiffness of 7.0 × 106 N·m/kg, which are one and two orders of magnitude smaller than those of other carbon materials, respectively. The expansion and contraction of cyclo[18]carbon exhibit a relatively high specific stiffness of 9.95 × 108 N·m/kg, and it would be broken with an energy requirement of 34.14 eV. While uniaxial tension enables the insulator-semiconductor transition of cyclo[18]carbon, expansion enlarges its energy gap. Furthermore, the strain energy was proposed as a function of bond angle and bond length for uniaxially-stretched and expanded/contracted cyclo[18]carbon respectively, which sheds light on predicting the mechanical properties of certain materials. The unique properties of cyclo[18]carbon are of great interest for its potential use as an ultra-elastic molecular O-ring in nanomechanical system and molecular electronics and devices.

Fiber-reinforced polymer matrix composites have high specific stiffness and high strength to weight ratio draw the attention of researchers to enhance the properties of the composite with a reduced cost. The performance of the composites is being affected by fiber volume fraction and microparticulate reinforcement. Fiber volume fraction can be controlled with vacuum pressure. A medium calcined alumina micro particulates (Al2O3) was considered as a 3% weight percentage of the matrix at random. The particles were distributed using mechanical stirrer and spraying machines. The parametric effect was studied using tensile test data and erosion wear test data. From the results, it was observed that the particulate addition may increase the erosion resistance of the composite.

Dielectric materials demonstrating ultralow permittivity, excellent mechanical property and durability under humid environment are highly demanded for the rapid development of 5G communication systems. Herein, a series of porous fluorinated polyarylene ether nitrile (FPEN) films having ultralow permittivity and excellent mechanical property that can be used under moisture environment are prepared by a delayed phase inversion approach. Due to the introduction of low molar polarity fluorinated substituents and porous structures, the porous FPEN films show ultralow dielectric constant of lower than 1.40 at 1 kHz and hydrophobic surface with the water contact angle higher than 90°. In addition, the porous FPEN films also exhibit an ultralow dielectric constant (

The application of high temperature materials is the key to technological advancement in engineering, particularly in the aerospace and automotive industries, where materials are expected to satisfy stringent operating requirements. New heat-resistant, light-weight materials, such as intermetallic gamma titanium aluminides (γ-TiAl) based alloys are attracting attention, and showing a great potential to meet severe operational demands due to their superior properties such as low density, high melting temperature, high specific yield strength, high specific stiffness, and excellent creep resistance. Consequently, γ-TiAl alloys have a great potential for high temperature applications in the aerospace and automotive industries. On the other hand, they are also well known as hard-to-machine materials due to poor ductility at low to intermediate temperatures that result in low fracture toughness and a fast fatigue-crack growth rate. In addition, there is no evidence in the open literature of these materials being subjected to production machining. These disadvantages have hindered their widespread application in industry. In this work, a rhombic turning tool is investigated to explore the machinability of γ-TiAl and to develop a cost-effective environmentally benign machining process. A set of central composite design (CCD) experiments are carried out for optimization of the machining process. The cutting parameters varied are cutting speed, feed rate, and depth of cut. Responses measured included thrust force, feed force, cutting force, specific cutting energy, surface roughness, chip morphology, and surface integrity. From the analysis of experimental data, quadratic models are developed, and 2-D contour and 3-D surface plots are drawn. Results obtained are of significant importance in terms of machinability of γ-TiAl and its application in the manufacturing of diesel engine valves and other tribological engine components subjected to operating temperatures range of 400 oC to 800 oC.

The strut bar is one of the most crucial mechanical parts used in the moving parts of automobiles where high hardness is required. In this work, the numerical and experimental analyses of a strut bar which is made of a Glass Fiber Reinforced Polymer (GFRP) composite are performed. The GFRP composite strut bar is fabricated and the experimental results are taken by performing various tests such as tensile, compression, and impact, flexural according to ASTM standards. Then, the numerical analysis is also carried out for the conventional and the fabricated struts using the finite element analysis software. The GFRP composite strut model shows improvement in specific strength and specific modulus.

The work presented in this paper is motivated by the fact that use of natural fiber materials for structural and non-structural applications have increased within the last two decades. In addition to the known benefits of composite materials as structural elements such as high specific modulus, high specific strength and low thermal conductivity, composites of natural fibers are eco-friendly materials and have minimum effect on environment and human health. However, the mechanical and structural performance of diverse natural fiber composites still need closer scrutiny. The objective of this study is to characterize the mechanical properties of a novel Acacia tortilis fiber reinforced polyester composite using experimental methods. In particular, the study focuses on determining the tensile and flexural properties of the composite at different fiber volume ratio, which was fabricated by hand lay-up methods. The results show that Acacia tortilis fiber reinforced polyester composites have generally competitive strength and Young’s modulus compared with common natural fiber reinforced composites such as sisal, kenaf, coir natural fiber reinforced composite materials. In addition, NaOH treated samples exhibited higher strength and Young’s modulus compared with their untreated counterparts, with few exceptions.

In recent years, applications of chopped carbon fibre polymer composites have been rapidly increasing and the majority of the components made from these materials are subjected to cyclic loading. It is used for the structural parts of automobiles and aircraft due to their high mechanical properties such as light weight, high specific tensile strength, high modulus, and high specific stiffness, outstanding wear resistance, short moulding times and high recyclability. Among all composites manufacturing methods, injection moulding processes can properly control the process and ability of different volume fraction by weight percentage of chopped carbon fibre and nylon 66. It was observed from manufacturing methods that improved processability, high time efficiency, good compatibility and interface of the composite materials. Strength is calculated by rule of mixture method for chopped carbon fibre reinforced nylon 66 composites compared to carbon steel. For 30% chopped carbon fibre reinforced nylon 66 composites optimum tensile and flexural strength are observed. Similarly, for 60% chopped carbon fibre reinforced nylon 66 composites optimum compression strength are observed. The weight of composites was found to be 5.54 times lighter than carbon steel. Further, FESEM results show that for plain specimens has no surface damage. During the tensile test, most of the fibres were pulled out and some of them break out due to fracture. During the flexural test, more severe damage to fragmented carbon fibres, crushed, delaminating between carbon fibres and matrix was observed. Similarly, during compression test, strong adhesion of bonding between the chopped carbon fibres and matrix occurs, due to higher compression force, resulting in no much damage but only small groves and voids.

A hybrid composite consists of two or more types of reinforcements to make a composite depending on the application. Due to their high specific stiffness and strength, fibre-reinforced polymeric composites are widely applied in diverse applications. The beauty of this combination (fiber–matrix system) is that it provides high fracture toughness at high strength levels, a property impossible to obtain with a single material. In this paper, the processing of polystyrene-based matrix composite (roofing tiles) is presented. Tensile testing of the specimen is performed on an Instron Testing Machine. The fabricated composites having a microcellular structure were used for making roofing tiles and building structures. The prepared samples were checked for hardness. These cellular composites are characterized by average cell diameter and cell density. The Microcell Distribution Index (MDI) has been proposed for the characterization of cell morphology. Microcellular injection moulded specimens for roofing tiles were analyzed for the effects of moulding parameters over microcell distribution. Various injection moulding parameters were analyzed for their effect over cell morphology characterized by cell size, cell density and distribution pattern. Effects of injection rate, back pressure, melt temperature and barrel residence time are being studied in the present work.

Due to high specific modulus, the demand for lightweight structures made of sandwich panels is ever increasing in many Industrial sectors. Numerous research efforts have been taken by various researchers in this area in terms of weight and cost optimization. Sandwich panels consist typically of two thin face sheets and a lightweight thicker core and the core is joined with the face sheet by adhesive bonds. These panels find wide application in public transport industry, aeronautical sectors, tooling machines, serigraphy and building industries. The bond strength between face sheet and the core depends essentially on the method of manufacture and the geometrical characteristics of the core. Flat-wise tensile tests are recommended to evaluate the bond strength as well as maximum temperature to which the panels can be exposed during service. The results of tensile tests are used in selecting resin materials for engineering applications. Tensile properties frequently are included in material specifications to ensure quality. This paper discusses the experimental method for assessing the Flat-wise tensile tests and the results obtained for sandwich panels bonded with different resins.

Carbon fiber-reinforced composite materials are widely employed in aircraft structures due to their high specific strength and high specific modulus. However, the poor impact resistance of carbon fiber reinforced composites creates challenges for aircraft design and maintenance. The introduction of a layer of glass fibers in the hybrid composites can effectively improve the impact performance of the composite laminate. In this work, finite element models for low-velocity impact of carbon fiber laminate and glass fiber laminate are established and validated. A VUMAT subroutine in Abaqus is implemented to evaluate the progressive damage of the composite materials, and a cohesive-zone model is employed to simulate the interface failure behavior. The impact resistance of hybrid composite laminates is systematically studied based on the results of the finite element simulation. Ten different hybrid configurations are studied and compared with a composite laminate having a single type of fiber reinforcement. The numerical results for the global mechanical response, damage modes and characteristics are extracted and systematically discussed. The results suggest that laminates having carbon fiber layers on the top and bottom surfaces with glass fiber layers between them perform the best in terms of energy absorption. When the glass fiber layers are used for the top and bottom surfaces with carbon fiber layers as the core, the presence of a carbon fiber layer with a ±45 ° orientation can help to reduce the damage area.

Carbon fiber reinforced polymer (CFRP) composites have excellent mechanical properties, specifically, high specific stiffness and strength. However, most CFRP composites exhibit poor impact resistance. To overcome this limitation, this study presents a new plain-woven CFRP composite embedded with superelastic shape memory alloy (SMA) wires. Composite specimens are fabricated using the vacuum-assisted resin injection method. Drop-weight impact tests are conducted on composite specimens with and without SMA wires to evaluate the improvement of impact resistance. The material models of the CFRP composite and superelastic SMA wire are introduced and implemented into a finite element (FE) software by the explicit user-defined material subroutine. FE simulations of the drop-weight impact tests are performed to reveal the superelastic deformation and debonding failure of the SMA inserts. Improvement of the energy absorption capacity and toughness of the SMA-CFRP composite is confirmed by the comparison results.

The necessity for high performance and low-cost materials caused the researchers worldwide to switch the focus from monolithic to composite materials. In the recent pasts, a significant effort has been made in this direction to fabricate numerous combinations of metal matrix composites. Among the MMCs, aluminum-based composites are treated as the most promising structural materials due to their high corrosion, wear resistance, specific modulus, and weight for automobile and aerospace applications. Aluminum MMCs were produced by various fabrication process after considering different reinforcement particles, such as borides, carbides, oxides, nitrides, and their combinations. Aluminum MMCs revealed excellent mechanical and wear characteristics owing to the formation of stable reinforcement particles in the composites. In the present review article, recent advances in processing, microstructure, wear, and mechanical characterization of aluminum composites reinforced with different particles are addressed. The future scope of these composites is also briefly discussed at the end of the manuscript.

Carbon fiber reinforced plastic (CFRP) composites are extremely attractive in the manufacturing of structural and functional components in the aircraft manufacturing field due to their outstanding properties, such as good fatigue resistance, high specific stiffness/strength, and good shock absorption. However, because of their inherent anisotropy, low interlamination strength, and abrasive characteristics, CFRP composites are considered difficult-to-cut materials and are prone to generating serious hole defects, such as delamination, tearing, and burrs. The advanced longitudinal–torsional coupled ultrasonic vibration assisted drilling (LTC-UAD) method has a potential application for drilling CFRP composites. At present, LTC-UAD is mainly adopted for drilling metal materials and rarely for CFRP. Therefore, this study analyzes the kinematic characteristics and the influence of feed rate on the drilling performance of LTC-UAD. Experimental results indicate that LTC-UAD can reduce the thrust force by 39% compared to conventional drilling. Furthermore, LTC-UAD can decrease the delamination and burr factors and improve the surface quality of the hole wall. Thus, LTC-UAD is an applicable process method for drilling components made with CFRP composites.