Potential Aerospace Applications Research Articles

Multiscale optimal design and fabrication of laminated composites

We present a general framework that digitally integrates the workflow for optimal design and fabrication of novel multiscale laminated fiber-based composites with spatially varying microstructure in each lamina of a flat or curved laminate. Given a design problem, our framework consists of three key components: 1) Design automation, 2) Material compilation, and 3) Digital fabrication. Design automation involves efficient simultaneous synthesis of optimal macroscale topology and spatially varying fibrous microstructure in a laminated composite, whereas digital fabrication comprises manufacture of the optimal structure. Material compilation is an intermediate process that translates the multiscale results of the design automation step to a digitally manufacturable arrangement of matrix and fibers within each layer of a laminate. These components constitute a digital thread and can be initialized by any method or process of choice. In this paper, we develop a multiscale topology optimization approach for design automation, new computational geometry algorithms for material compilation, and voxel-based material jetting for digital fabrication. We demonstrate and experimentally validate the extensive capabilities of our framework with various plate and shell structures that have potential applications in architecture, aerospace and soft robotics.

High-efficiency dual-responsive shape memory assisted self-healing of carbon nanotubes enhanced polycaprolactone/thermoplastic polyurethane composites

Shape memory assisted self-healing polymeric networks have been numerously explored due to their multi-functionality and sustainability. In this study, we prepare a kind of electrical and thermal dual-responsive shape memory assisted self-healing polymeric composites fabricated with polycaprolactone/thermoplastic polyurethane (PCL/TPU) and carbon nanotubes (CNTs) via a facile method. The CNTs/PCL/TPU composites use PCL/TPU blend as shape memory polymer matrix, PCL as healing agent and CNTs as reinforcement networks. CNTs greatly enhance mechanical strength of the composites with good electrical and thermal conductivity. Interestingly, the CNTs/PCL/TPU composites can be healed via electricity and heating respectively in tens of seconds with corresponding optimal healing efficiencies about 96% and 94%. Meanwhile, the composites can exhibit remarkable electro-active shape recovery property that assist to diminish the crack openings and then the healing agent would be molten to fill in the crack. Therefore, the proposed materials can offer great potential applications in biomedical, aerospace and microelectronics.

3D printed fiber reinforced polymer composites - Structural analysis

In this research, mechanical and structural properties of Continuous Fiber Reinforced Additively Manufactured (CFRAM) components are studied. Structural analysis is performed to understand the failure behavior of CFRAM components. Based on the SEM analysis of the tested parts, correlations between results of the mechanical test and microstructure of the parts have been investigated. CFRAM components are lightweight yet strong materials with a wide range of potential applications in auto industry, aerospace, sport goods, and medical tools. CFRAM components benefit from both cutting-edge 3D printing technology and fiber reinforcement to improve mechanical properties. Produced parts have lightweight compared with metals, strong mechanical properties, and short manufacturing time. In addition, thermoplastic polymer used for CFRAM components makes product recyclable. In this study, samples were printed using Markforged Mark Two printer and the effect of the fiber type, fiber orientations, infill density, and temperatures on tensile, fatigue, and creep properties were investigated. Carbon fiber (CF), fiberglass (FG), and Kevlar were used as reinforcing agents, and nylon as the base material. Microstructural analysis was conducted to investigate the fracture mechanism, morphology, and printing quality of the specimens. It was observed that the main failing mechanisms for CFRAM components are fiber pull-out, fiber breakage, and delamination. Further, it was understood that there is a correlation between the fiber stacking density and mechanical properties. Overall, the information provided in this study reports a unique knowledge base about the mechanical and structural behaviours of the components built with the CFRAM technology.

Silicon carbide whiskers enhance mechanical and anti-wear properties of PA6 towards potential applications in aerospace and automobile fields

The friction and thermal conductivity are two vital factors affecting braking components in manned aircraft. It is imperative to find a rational design basis for high-performance lightweight polymeric materials with excellent toughness, coefficient of friction, and thermal conductivity. In light of the outstanding mechanical strength, stiffness, and good dimensional stability of polyamide 6 (PA6), herein, we have demonstrated the fabrication of high-performance PA6 composites by adding one-dimensional SiC whiskers (SCWS) as both a reinforcement agent and anti-abrasion agent. The results show that addition of 2 wt% SiC whiskers (SCWS) increases the tensile strength of PA6 by 37.6% (reaching 58.2 MPa). Meanwhile, the elongation at break is over five times (around 280%) of that of the PA6 matrix, which means that the fracture toughness is increased around seven-fold. Moreover, the addition of 30 wt% SCWS reduces the coefficient of friction from 0.31 for the PA6 to 0.15, indicating improved anti-abrasion performance. Such significant improvements in both mechanical and anti-wear properties are primarily due to the high stiffness of SCWS and the strong interfacial interactions with the PA6 matrix. This work provides a facile approach to the design of mechanically robust, wear-resistant polymer composites which hold significant promise for producing advanced gears and bearing parts in aerospace and automobile applications.

Computational characterization of the structural and mechanical properties of AlxCoCrFeNiTi1−x high entropy alloys

AlCoCrFeNiTi is one kind of high entropy alloys with potential applications in aerospace, electronics and machinery manufacturing, etc. Its microstructure, thermodynamic and mechanical properties vary with Al and Ti contents. The disordered structures of AlxCoCrFeNiTi1−x (x = 0–1.0) alloys were generated and screened with the special quasi-random method. First-principles calculations with the Perdew–Burke–Ernzerhof functional and projector-augmented wave potential were carried out to further identify the structures and assess their thermodynamic and mechanical properties. The measured lattice constants and observed phase transition from bcc to fcc with Ti addition and Al reduction were reproduced in the calculations. The predicted transition point is at the Al content of about 8 at%. The heat capacity of the bcc and fcc structures exhibit similar temperature dependence, matching well with the empirical Dulong-Petit Model and the quantum Debye Model. The elastic constants and elastic moduli vary with the phase structures and compositions. The studied AlxCoCrFeNiTi1−x alloys are predicted to possess good comprehensive mechanical performances, especially for x = 0.8 and 0.6 for the bcc structures and x = 0.5 for the fcc structures. The addition/reduction of Al atoms from the systems alters the electron localization/delocalization that has considerable influence on the interatomic interaction strength in the alloy systems.

Microstructure and mechanical properties of as-built and heat-treated Ti-6Al-4V alloy prepared by cold metal transfer additive manufacturing

Ti-6Al-4V titanium alloy components fabricated by cold metal transfer additive manufacturing (CMTAM) have increasingly shown great potential in aerospace applications in recent years. In this work, the microstructure and mechanical properties of the as-built and heat-treated Ti-6Al-4V wall have been investigated, respectively. The results show that the as-built Ti-6Al-4V wall has the microstructure consisting of acicular α’ martensite with minority lamellar α+β and it results in a reasonable hardness and tensile strength. All α’ martensites could transform to α+β phase after 900 °C-4 h-furnace cooling and 1200 °C-2 h-furnace cooling heat treatment. By using the former or the latter heat treatments, a higher hardness or better ductility can be obtained for the CMTAM-fabricated wall, respectively. While, the tensile strength of the heat-treated sample is considerably lower than that of the as-built sample.

On the heterogeneous nature of deformation in a strain-transformable beta metastable Ti-V-Cr-Al alloy

Ti-10V-4Cr-1Al wt% (TVCA) is a new grade of titanium alloy, developed to combine twinning induced plasticity (TWIP) and transformation induced plasticity (TRIP) effects. The TVCA alloy exhibits a very high strain-hardening rate and an excellent balance between strength and ductility for great potential in aerospace applications. Deformation mechanisms are investigated using in-situ techniques as synchrotron X-ray diffraction (SXRD) and in-situ electron backscatter diffraction (EBSD) analysis during tensile strain, as well as transmission electron microscopy (TEM). The results reveal that permanent {332}<113> mechanical twinning and an unstable orthorhombic α” martensite are the major deformation products. This study aims at unveiling the interaction and co-deformation of the various deformation features, that lead to the outstanding mechanical properties of the alloy. The very high strain hardening rate could be explained by the simultaneous activation of two different deformation modes, the primary TRIP mode on one side, and the hybrid TWIP and secondary TRIP mode on the other one, in different grains, resulting in in-grain dynamic hardening (Hall-Petch)/softening (α” martensite) effects and meso-scale dynamic mechanical contrast. Selection of the deformation mechanism – TRIP or TWIP –, which seems to be inhomogeneous, at both the inter- and the intra-granular level, is investigated.

Synthesis, characterization and structural thermally rearrangement of ortho-amide functional benzoxazine containing acetylene group

A novel ortho-amide functional benzoxazine monomer containing acetylene group has been synthesized in this study. The chemical structures of synthesized monomer are confirmed by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. The polymerization behaviors including both ring-opening polymerization of oxazine ring and polymerization of acetylene functionality are investigated by in situ FTIR and differential scanning calorimetry (DSC). The activation energy of polymerization has also been studied, and the activation energy of the polymerization is determined to be 104.4 kJ/mol and 103.1 kJ/mol, respectively, according to Kissinger and Straink methods. In addition, the benzoxazole formation during the thermal treatments is analyzed by solid state 13C NMR. The resulting thermoset derived from benzoxazine monomer exhibits excellent thermal stability and low dielectric constant, indicating its potential applications in aerospace, electronics industries and other composite areas requiring high performance polymeric matrix.

Discoloration mechanism, structures and recent applications of thermochromic materials via different methods: A review

Thermochromic material is a kind of smart material whose color will vary as the result of the phase transition caused by the temperature change. The characteristics of thermochromic materials are the memory functions to the temperature, having great potential applications in aerospace, military, anti-counterfeiting technology, construction and other fields. In recent years, many kinds of thermochromic materials have been prepared by different methods and their discoloration mechanisms are various according to published literatures. In this paper, the classification, discoloration mechanism, preparation methods, application fields and development trend of thermochromic materials are reviewed.

Aluminum metal matrix composites a review of reinforcement; mechanical and tribological behavior

This review aims to explore the fundamental mechanical and tribological behavior Aluminum matrix composites (AMCs) reinforced with different reinforcements. Aluminum matrix composites are considered to be the new emerging class of materials which are having the tailored properties for specific applications. AMCs are the advanced engineering materials having superior properties as comparison to other conventional aluminum alloys. AMCs exhibits attractive properties such as high hardness, better yield strength, strength to weight ratio, high thermal conductivity, low coefficient of thermal expansion, superior wear and corrosion resistance. In recent times, because of these properties they have repealed keen interest for various potential applications in aerospace, automotive and various other structural applications.. Extensive research and development has been made in the Al-based MMCs with every possible alloy and different reinforcements so as to get the material of desired properties. By suitable use of different reinforcements in the Al metal matrix a wide range of properties combination can be obtained. The fundamental mechanical and tribological behavior of different reinforcements under dry and wet lubricated sliding conditions is recently being studied. It is reported that various reinforcement were successfully employed to decrease friction and wear in various applications. A comprehensive review is provided with the aim to analyze such properties of different reinforcements.

See-Through Solutions

X-ray computed tomography is increasing the size and sophistication of the parts it can investigate, expanding its potential aerospace applications

Tailoring the properties of a polymer nanocomposite with a magnetic field

The properties of nanocomposites can be tailored by organizing nanoparticles within the polymer matrix, that is, for potential aerospace, automobile, and infrastructure applications. Multiwalled carbon nanotubes are coated with nickel to produce hybrid Ni‐MWNT nanoparticles. These magnetized nanoparticles are introduced into an epoxy matrix at a relatively low 0.25%–1% volume fraction and oriented along particular directions with an external magnetic field . Changing this alignment makes it possible to tailor the properties of the resulting composite material, that is, its tensile strength, microscopic elastic modulus, and electrical resistivity. The alignment imparts anisotropic properties to the bulk material, but when the nanoparticles are aligned in perpendicular directions in two sequential layers, this coupled orientation produces an overall isotropic composite material. The tensile strength of a nanocomposite containing 0.25 vol% of aligned Ni‐MWNT nanoparticles is ∼9% higher than of pure epoxy. Its AC electrical resistivity along the alignment direction is reduced by ∼20% in comparison with an epoxy composite containing a similar volume fraction of randomly dispersed nanoparticles. These outcomes reveal that, even at a relatively low nanoparticle volume fraction, the alignment of Ni‐MWNTs in epoxy with an external magnetic field induces property anisotropy, which can be tuned through multidirectional alignment. POLYM. COMPOS., 40:779–788, 2019. © 2018 Society of Plastics Engineers

Role of Reinforcements on the Mechanical and Tribological Behavior of Aluminum Metal Matrix Composites – A Review

The target of this review is to explore the fundamental mechanical and tribological behaviour of different reinforcements on Aluminium matrix composites (AMCs). Aluminium matrix composites are the new emerging materials of this generation which can be tailored and engineered to obtain specific required properties for special applications. AMCs are recognizably different category of advanced engineering materials having superior properties over other conventional aluminium alloys. AMCs exhibits attractive properties of high hardness, better yield strength, strength to weight ratio, high thermal conductivity, low coefficient of thermal expansion, superior wear and corrosion resistance. Due to this they have repealed keen interest in recent times for various potential applications in aerospace, automotive and various other structural applications. Use of AMCs is constantly growing over the years, because of its better physical, mechanical and tribological properties as compared to other metal matrix composites. Extensive research and development has been made in the Al-based MMCs with every possible alloy and different reinforcements so as to get the material of desired properties. By suitable use of metal matrix and the reinforcement a wide range of properties combination can be obtained. The fundamental mechanical and tribological behavior of different reinforcements under dry and lubricated sliding conditions is recently being studied. It is shown that various reinforcement were used in metal matrix can be successfully employed to decrease friction and wear in tribological applications. A comprehensive review is provided with the aim to analyze such properties of different reinforcements. Moreover, the application of different reinforcements in the field of tribology for reducing friction and wear for better lubrication will be explored.

Modeling and analysis of functionally graded cylindrical shell

Functionally gradient materials (FGM) are special composites which are having potential applications in aerospace, automotive, marine, electronic, and medical etc. In FGMs, properties changes in direction by gradually varying composition of various elements for a specific requirement. Hence FGMs are used in most of the applications to improve the efficiency and performance. Applications of FGMs are widely explored in many applications however there are few fields yet to be explored. FGM made cylindrical shells are being used in structural applications. The stress distribution of FGM made cylindrical shell for given load conditions have to be analyzed. Hence in this work, modeling and structural analysis have been carried out on a graded cylindrical shell with varying elemental composition from inner surface to the outer surface. Distribution of volume fraction of the elements is calculated using power law for cylindrical shell modeling. Static structural analysis of cylindrical shell which is exposed to internal pressure performed and results are verified with analytical solutions.

Micro Stress Evaluation and Analysis in FRP Composites for Rocket Motor Casing

The current research is carried out to compare the structural behaviour of a rocket motor casing which is made of fiber reinforced polymer matrix composite materials. The analysis is carried out on FRP Composites made of different fiber materials such as S-Glass and Graphite individually combined with low and high modulus phenolic resin as coating and the matrix materials respectively. An analytical model has been developed based on cylindrical composite assemblage consists of fiber, coating, matrix and composite are the constituent phases of the composite and the analysis is carried out using Mathematica software. The above mentioned fibers with phenolic resin are considered for the analysis as they provide high specific strength and specific stiffness. The results of this analysis are compared with allowable strengths of corresponding constituent phases. These materials have potential applications in aerospace and pressure vessels industry. The micro stress distribution pattern is studied at different temperature and moisture conditions and compared between these materials.

Role of Fabrication Route on the Mechanical and Tribological Behavior of Aluminum Metal Matrix Composites – A Review

Aluminum matrix composites (AMCs) are the new emerging materials of this generation which can be tailored and engineered to obtain specific required properties for special applications. AMCs are recognizably different category of advanced engineering materials having superior properties over other conventional aluminum alloys. AMCs exhibits attractive properties of high hardness, better yield strength, strength to weight ratio, high thermal conductivity, low coefficient of thermal expansion, superior wear and corrosion resistance. Due to this they have repealing keen interest in recent times for various potential applications in aerospace, automotive and various other structural applications. Use of AMCs is constantly growing over the years, because of its better physical, mechanical and tribological properties as compared to other metal matrix composites. Extensive research and development has been made in the Al-based MMCs with every possible alloy and different reinforcements by using different synthesis techniques so as to get the material of desired properties. By suitable use of metal matrix and the reinforcement a wide range of properties combination can be obtained. This paper attempts to review the role of different types of fabrication routes in the AMCs. In this paper we also briefly discuss the major fabrication-synthesis techniques, properties characterization, applications and the future scope of AMCs.

Silicone copolymers bearing reactive vinyl and hydride functionalities: Synthesis, characterisation and particulate composite thereof for specialty applications

High molecular weight vinyl terminated poly (dimethyl-co-diphenyl)siloxane polymer (V-PDMPS) was synthesised by a multistage process including hydrolysis of precursor chlorosilanes and their anionic polymerization followed by chain termination. The low molecular weight hydride functional crosslinker for V-PDMPS, trimethylsilyl terminated poly (dimethyl-co-methylhydrogen-co-diphenyl)siloxane, (TMS-PDMHS) was synthesised by ring opening polymerisation of cyclic siloxanes. These two novel addition curable polymers were characterized by FTIR, NMR and chromatographic methods. Further, the role of catalyst and moderator in determining the rheological characteristics of the system was studied in detail. V-PDMPS was compounded with both pristine quartz and surface functionalised quartz (TMCS- quartz) in different compositions and the effect of these fillers in determining the adhesive, mechanical and rheological properties of the elastomer was investigated. The addition curable silicone polymer based formulations with low outgassing characteristics and having adequate mechanical and rheological properties developed in this study can find potential applications in aerospace, especially as adhesive.

Future cryogenic switchgear technologies for superconducting power systems

This paper introduces cryogenic switchgear that is needed for protection and control purposes in future multi-terminal superconducting power systems. Implementation of cryogenic switchgear is expected to improve system reliability and minimize overall volume and weight, but such switchgear is not available yet. Design of cryogenic switchgear begins by referring to conventional circuit breakers, a brief review of state-of-the-art switchgear technologies is presented. Then, promising cryogenic interruption media are identified and analysed with respect to physical and dielectric properties. Finally, we propose several cryogenic circuit breaker designs for potential aerospace, marine and terrestrial applications. Actuation mechanism for cryogenic switchgear is also investigated.

Parameter Characterization in Processing of Silver – Aluminum Based Electrical Contact Materials

AbstractAn electrical contractor is one which plays significant role in day todays life in industries as well as in home appliances. In current scenario the materials for conducting purpose has an overwhelming research capability. Now a day the silver based electrical contact composite material have provided the potential applications in aerospace and automobile industries. Among silver based contact material the silver cadmium oxide and silver tin oxide plays a vital role in fabrication of electrical contactors. In this research an attempt has been made to study the influence of adding Aluminum with silver based electrical contact composite materials by two different processing routes namely stir-casting and powder metallurgy. Silver and aluminum matrix plays a virtual role in composite world owing to their highest conductivity. Optimum parameters were identified for attaining the maximum properties such as conductivity, hardness, density, and porosity of composition. By this better conducting property and mechanical property of the electrical contact can be improved by this system. Thus a screening test has be conducted with addition of Al with silver tin oxide compositions hence this paper aims to process the aluminum - silver based electrical contact materials by stir casting processing and powder metallurgy route and compare the results obtained.

Mechanical and tribological behaviour of tungsten carbide reinforced aluminum LM4 matrix composites

ABSTRACTAluminum-based metal matrix composites (AMCs) play a vital role for potential applications in aerospace and automotive industries. This paper explores the experimental analysis of a composite with aluminum LM4 alloy as the matrix and tungsten carbide (WC) as the reinforcement material. The composite specimens were fabricated by the stir casting process. The reinforced ratios of 5, 10 and 15 wt.% of WC particulates were stirred in molten aluminum LM4 alloy (AALM4). Once the composite is solidified, the specimens are prepared to the required ASTM dimensions and tested for various mechanical properties such as tensile strength, impact strength and hardness. Moreover, the tribological behavior of the composite was studied using the pin-on-disc wear test apparatus. X-ray diffraction (XRD) analysis was conducted to analyze the various elements present in the composites. Finally, the scanning electron microscope (SEM) analysis reveals the uniform distribution of WC particles in Aluminum LM4 alloy matrix. The improvement in mechanical properties – hardness, impact strength and tensile strength – was achieved for the increase in the addition of wt.% of WC particles in the LM4 matrix. The decrease in mass loss was observed for the composite containing 15 wt.% of WC during the wear test among the various composites tested.