Aircraft Materials Research Articles

The Corrosion Fatigue Behavior and Mechanism of AerMet 100 Steel in 3.5% NaCl at Room Temperature.

AerMet 100 steel is a new type of double-hardened high-strength steel, which is often used as landing gear material in amphibious aircraft. In the present paper, the corrosion fatigue behavior and mechanism of AerMet 100 high-strength steel in a 3.5% NaCl solution was studied by stress-controlled fatigue tests and a series of subsequent characterizations of the fracture surface, microstructure, and cracks. The results indicated that the fatigue life of AerMet 100 high-strength steel decreased with a decrease in the stress level in a 3.5% NaCl solution, satisfying the relationship lgN = -2.69 × 10-3 σ + 6.49. The corrosion fatigue crack usually initiated from the corrosion pit and propagated across the martensitic flat noodles. Meanwhile, the corrosion fatigue crack tip was filled with Cr2O3, Fe2O3, and amorphous material; it propagated in the transgranular mode by a slip dissolution mechanism. This study provides some engineering significant for the fatigue performance of AerMet 100 steel in a 3.5% NaCl solution.

Evolving trends and advanced applications of engineering materials in contemporary aircraft: a review

This review article discusses the engineering materials used in aircraft, with a focus on aluminum alloys, titanium alloys and composite materials, including where and why they are most used in aircraft. There are many research papers that deal in detail with materials such as aluminum alloys, titanium alloys and composites used in an aircraft, including theoretical and experimental results. However, the author felt that a review of aircraft materials was necessary, both for himself and to help others interested in similar topics. In addition, the author felt the need of thinking back to the past on what materials used to be prevalent and what materials have superseded them. One such example written in this study is the case of Aluminum that used to be the predominant material in aircraft structural components, has been increasingly supplanted by polymer composites in recent years due to their advantageous properties. It is hoped that from this review article the reader will be able to understand the general trend of recent developments in aeronautical engineering materials and be able to choose which path to follow and which area to focus on in their future research.

Drawing on bionics, a flexible silica fiber paper is designed with high temperature resistance and hydrophobic properties

In this paper, a flexible silica fiber paper (SFP) made of silica ceramic with excellent high-temperature resistance was prepared. After modification with fluorosilane, the contact angle of the modified fiber paper with water was 153°. At the same time, the modified fiber paper maintains the superhydrophobic properties even after high-temperature heat treatment (150 ± 1° after treatment at 400 °C) and shows excellent hydrophobic performance at high temperatures. The produced ceramic inorganic fiber paper has good comprehensive properties and is a promising skin material for aircraft.

Non-Contact Eddy Current Conductivity Measurements as an Effective Tool for Evaluating Aluminum Alloys in Aircraft

ABSTRACT Aluminum alloys (AAs) are pivotal materials in modern aircraft due to their superior mechanical properties and low weight. The structural integrity of these alloys, crucial for aircraft safety, heavily depends on heat treatment processes that alter their mechanical characteristics. Nondestructive evaluation (NDE) techniques, such as eddy current (EC) conductivity measurements, play a vital role in assessing these alloys throughout their lifecycle. EC methods enable the measurement of electrical conductivity, a structure-sensitive parameter that correlates with mechanical properties affected by heat treatments and operational stresses. This paper reviews the application of EC conductivity measurements in the aerospace industry, focusing on their role in assessing AA structural integrity. It discusses how EC methods can penetrate non-conductive coatings, crucial for in-service measurements without surface removal. Recent developments include a novel small-size EC probe and signal processing algorithms aimed at enhancing sensitivity to conductivity changes through dielectric coatings, up to 0.5 mm thick, commonly found in aircraft structures. Key findings include analyses of specific electrical conductivity (SEC) changes in AAs due to heat treatment deviations and long-term operational stresses, crucial for predicting residual life and maintaining safety standards. Case studies on aircraft wing skins and helicopter rotor blades demonstrate the practical application of EC conductivity meters in identifying critical damage zones. The methodology proves effective in evaluating localized degradation based on SEC distributions, thereby enhancing maintenance efficiency and aircraft safety. Overall, this research underscores the significance of EC conductivity measurements in advancing NDE practices for AAs in aircraft applications. The methodologies and findings presented aim to improve safety, durability assessment, and maintenance efficiency in the aerospace industry.

In-situ formation of surface “self-protective” graphitic layer on phenolic resin-based thermal protection composites

Phenolic resin (PR) composites are widely utilized as thermal protection materials for high-speed aircraft, where their protection mechanisms have been investigated in earlier studies. However, it remained indistinct about the evolution behavior of the outermost surface and its subsequent effects on the ablation performance. Herein, this work re-investigated the morphological transformation and chemical conversion on the outermost surface of a silica fiber-reinforced PR board after ablation by means of combined experimental characterizations at micro- and nanoscale (SEM, TEM, Raman spectroscopy, XRD, XPS) and computational study (ReaxFF-based molecular dynamic simulation). For the first time, our study revealed that its outermost ablated surface demonstrated a distinct evolution behavior in terms of both the in-situ formation of “self-protective” graphitic layer and the radial redistribution of surface carbonaceous substances with different degrees of graphitization, leading to varied ablation resistance along the radial direction of the PR board. In addition, the computational study investigates the ablation-induced graphitization and its influence on the ablative resistance of PR surface. It indicated that, at equivalent energy flux density, PR with graphitized structures exhibited improved thermal protection performance, which can be attributed to decreased thermal conductivity and increased density, leading to a reduced ablation recession rate. Such revelation provides an alternative route in the design of PR-based ablative materials with enhanced ablation resistance.

Recent approaches of interface strengthening in fibre metal laminates: Processes, measurements, properties and numerical analysis

Recently, there is a pressing need for high-performance and lightweight structural materials in aircraft and automobile industry; fibre metal laminates (FMLs) are suggested ideal candidates for aviation industry. FMLs are hybrid composite material comprised of thin-metal sheets and fibre-reinforced polymers (FRPs). By combining the features of both components, FMLs possess high tolerance to fatigue damage, exceptional impact resistance and an outstanding weight-to-strength ratio. However, maintaining high structure integrity of FML layers – without debonding – remains the primary challenge in FMLs-based structures. The present review explores the recent developments in manufacturing techniques and surface treatments aimed at enhancing the interfacial strength between FML layers. Recently, adding nanofillers into FRPs and FMLs is gaining attention. These nanofillers can enhance mechanical performance of FRPs/FMLs, strengthen the interface in FMLs; and add functionalities such as gas and water impermeability. The article discusses the recent studies on employing nanofillers in FMLs and adhesively bonded structures; and their (nanofillers) role in enhancing the crack resistance of FMLs. It also explores failure mechanisms in FMLs through experimental methods and advanced numerical simulations. A comprehensive review of the existing studies assists in understanding the complex failure mechanisms, aiming to find optimal input conditions that yield desired mechanical performance. Furthermore, the article introduces machine learning techniques in adhesively bonded structures and potential application in FMLs-related research. The article concludes with perspectives on the limitations, current challenges, and future prospects for FMLs and nanofiller-reinforced FMLs.

Non-destructive testing methods commonly used in aviation

Non-Destructive Testing (NDT) methods play a pivotal role in ensuring the safety and reliability of aircraft in the aviation industry. This article provides a comprehensive overview of the NDT techniques commonly employed in aviation to assess the structural integrity and performance of aircraft components and materials without causing any damage. The article discusses the significance of NDT in aviation, highlighting the importance of early defect detection, maintenance cost reduction, and enhanced operational safety. It delves into various NDT methods, such as ultrasonic testing, eddy current testing, radiographic inspection, magnetic particle testing, and dye penetrant testing, explaining their principles and applications. In addition, in this article, the advantages and disadvantages of NDT methods and which methods are used in which part of the aircraft are mentioned. Understanding these NDT methods is crucial for aviation professionals, as they contribute to the continued airworthiness of aircraft, ensuring that passengers and crew can travel safely and confidently.

Structure and mechanical properties of a refractory Al7.5(NbTiZr)92.5 medium-entropy alloy subjected to long-term annealing and oxidation

Recently, Al-containing refractory high/medium-entropy alloys (RH/MEAs) have attracted special attention from materials scientists worldwide. Some of these alloys demonstrated an excellent combination of high-temperature strength and room-temperature tensile ductility provided by the formation of a structure consisting of body-centred cubic (bcc) matrix and B2 nanodomains/particles. However, oxidation resistance and phase stability, and, more importantly, the resulting mechanical properties of the Al-containing RH/MEAs, which are critical characteristics for high-temperature structural materials, remain unexplored. Herein, these aspects were extensively investigated for the Al7.5(NbTiZr)92.5 (in at%) alloy having an initial bcc + B2 structure. The alloy was subjected to long-term (500 h) annealing or oxidation tests at 600, 700, and 800 °C followed by the evaluation of mechanical properties during uniaxial tension at 22 and 600 °C. Microstructural studies of the specimens exposed to long-term annealing showed the formation of Zr5Al3 particles that precipitated along the grain boundaries and within grain interiors. The volume fraction of these particles was the highest (∼16 %) after annealing at 600 °C and the lowest (∼0.5 %) after annealing at 800 °C. Oxidation tests revealed that the alloy was prone to pesting phenomena, which intensified with the temperature. The alloy could sustain pesting only up to 10 h at 600 °C, while it experienced a complete disintegration into powder after 5 h at 800 °C. The poor oxidation resistance originated from the formation of volumetric, non-protective (Al,Nb,Ti,Zr)O4 oxide. While insignificantly affecting the strength, long-term annealing or oxidation deteriorated the ductility of the Al7.5(NbTiZr)92.5 alloy both at 22 and 600 °C. The Zr5Al3 phase embrittled the alloy after long-term annealing at 600 or 700 °C, but marginally reduced the ductility in the 800°C-annealed specimens due to the low volume fraction and relatively homogeneous distribution of this phase. The oxidation for 1 h decreased the room-temperature ductility owing to the premature macroscopic localisation of plastic deformation induced by synergistic effects from the volumetric (Al,Nb,Ti,Zr)O4 oxide. This study highlights the necessity for the examination of a set of properties of promising RH/MEAs to critically assess perspectives of these alloys to find applications as new high-temperature materials in aircraft and aerospace sectors.

Ultralow shrinkage polyimide hybrid aerogel composite enhanced with organic fibers for thermal protection

AbstractPolyimide (PI) aerogels possess a rather potential in thermal protection material for aircraft, owing to their low thermal conductivity, high thermal stability, and low bulk density. However, the large shrinkage of pure PI aerogels is still a challenge in the complete preparation process. Herein, a kind of PI hybrid aerogel composite was prepared successfully by introducing polyurethane fiber as the reinforcing agent. The aerogel composite could realize the enhancement for the pure PI aerogels from a micro/macroscopic perspective, ultimately ensuring the ultralow shrinkage rate of 3.52%. Due to the inhibition of the shrinkage characteristic, the aerogel composite obtained achieved excellent thermal insulation, especially retaining a low temperature of 40.7°C despite the hot surface temperature reached up to 150°C. Besides, the lightweight low‐density, exceptional flame resistance, and self‐extinguishing properties were reflected from PI hybrid aerogel composite constructed, including the outstanding hydrophobic feature (water contact angle of 120°). The PI hybrid aerogel composite as prepared may be used for the thermal management of aircraft in a great measure, illustrating the feasible strategy of fabricating PI‐based aerogel composites.

Preparation of a Gradient Anti-Oxidation Coating for Aircraft C/C Composite Brake Disc and Its High-Temperature In Situ Self-Healing Performance.

We studied a gradient anti-oxidation coating of C/C composite materials for aircraft brake discs with a simple process and low costs. The gradient coating consists of two layers, of which the inner layer is prepared with tetraethyl orthosilicate (Si (OC2H5)4), C2H5OH, H3PO4 and B4C, and the outer layer is prepared with Na2B4O7.10H2O, B2O3, and SiO2 powder. The experimental results show that after being oxidized at 700 °C for 15 h, the oxidation weight loss of the sample with the coating was only -0.17%. At the same time, after 50 thermal cycles in air at 900 °C, the sample's oxidation weight loss was only -0.06%. We conducted the 1:1 dynamic simulation test for aircraft brake discs, and the brake disc did not oxidize, thus meeting the requirements for aircraft use. In addition, the anti-oxidation mechanism of the coating was analyzed via scanning electron microscopy (SEM), X-ray diffraction (XRD), differential thermal analysis (DSC-TGA), and high-temperature in situ SEM.

Thermal modal analysis of hypersonic composite wing on transient aerodynamic heating

Considering the influence of thermal stress and material property variations, this study employs the Navier–Stokes equations and Fourier heat conduction law to establish a semi-implicit time-domain numerical analysis method for hypersonic aerothermal-structural coupling. Study the temporal variation pattern of different regions of the composite material wing under aerodynamic heating. Using the obtained transient temperature field of the wing, the thermal modal of the wing at different time points is calculated using the finite element method. Additionally, it conducts an analysis and discussion on the factors influencing the thermal modal. Composites can be effectively utilized as thermal protection materials for aircraft. During the aerodynamic heating process, the leading edge temperature reaches thermal equilibrium first, followed by the trailing edge, and the belly plate experiences a slower thermal response. Temperature rise significantly affects higher-order modes, with the change in material properties during the early stages of heating being the dominant factor. This leads to a faster decrease in natural frequency. As heat conduction progresses, the influencing factors of thermal stresses gradually increase, and the natural frequency decreases slowly or even rises.

Application of carbon fiber composite materials in aircraft

Carbon fiber composite is a material with excellent mechanical properties. Compared with other high-performance fiber materials, carbon fiber composites have the advantages of high strength and high modulus even at ultra-high temperatures. In addition, the carbon fiber composite material also has excellent electrical and thermal conductivity and electromagnetic shielding performance. Carbon fiber composites are widely used in the aircraft manufacturing industry due to their incomparable performance with other composite materials. In recent years, the amount of carbon fiber composite materials in newly developed aircraft products has reached more than 50%. This paper aims to explore the application of carbon fiber in aircraft, and to reflect the importance of carbon fiber composite materials by comparing models that use composite materials and models that do not use composite materials. The study explores the application of carbon fiber composite materials in aircraft through a comprehensive literature analysis and review. Key findings indicate significant advantages of these materials in enhancing aircraft performance, including reduced weight and increased strength. The paper also discusses the challenges in manufacturing and environmental impacts, offering insights into future research directions for sustainable aviation technologies.

Influence of axial pressure on the Payne effect of natural rubber vulcanizates

Rubber nanocomposites are key materials for aircraft or automobile tires, which are often subjected to the combined effect of pressure and shear during service. However, the effect of pressure on their strain softening under large amplitude oscillatory shear is not yet clarified. Herein a strain-controlled rotational rheometer is used to investigate the influence of axial pressure on the Payne effect of vulcanized natural rubber composites. Under high axial pressure, the Payne effect of rubber vulcanizates is remarkably suppressed, mainly attributed to the increasing intermolecular local friction hindering wall slip and nonlinear stretching of the rubber network. Furthermore, low temperature, high frequency and high filler fraction may weaken the suppression behavior. The investigation may reveal the role of axial pressure in the strain softening of vulcanized rubber.

Effect of Hyperthermal Hybrid Gas Composition on the Interfacial Oxidation and Nitridation Mechanisms of Graphene Sheet.

Graphene is one of the most promising thermal protection materials for high-speed aircraft due to its lightweight and excellent thermophysical properties. At high Mach numbers, the extremely high postshock temperature would dissociate the surrounding air into a mixture of atomic and molecular components in a highly thermochemical nonequilibrium state, which greatly affects the subsequent thermal chemical reactions of the graphene interface. Through establishing a reactive gas-solid interface model, the reactive molecular dynamics method is employed in this study to reveal the influences of the thermochemical nonequilibrium gas mixture on the thermal oxidation and nitridation mechanisms of graphene sheet. The results show that three distinctive stages can be recognized during bombardment of various nonequilibrium gas components toward the graphene sheet: (i) collision and surface adsorption stage, (ii) gas-solid heterogeneous reaction stage, and (iii) gas phase homogeneous reaction stage. The surface catalysis effect is found to be dominant during the first two stages, which can influence the following ablation behavior of graphene significantly at high-temperature conditions. Moreover, surface catalysis, oxidation, nitridation, and ablation mechanisms between nonequilibrium gas and graphene interface are revealed, which is of high relevance for future interfacial design and application of graphene as a thermal protection material.

Development of a Cognitive Assessment Instrument for Simple Business, Energy and Aircraft Materials via Wordwall

Cognitive assessment of kids who still frequently use paper documents and certain school-provided software. The objective of this study is to develop a legitimate, dependable, efficient, and useful tool that may be used to teach static electricity concepts through wordwalls. This study use the ADDIE model in conjunction with the Research and Development technique. Purposive sampling is the sampling technique used, taking into account samples that have finished business, energy, and basic aviation material for science education. 52 individuals served as the samples. The study is being conducted at SMP 1 PGRI in Semarang City. Using SPSS software version 2019 and Ministep, the data analysis technique involves testing the validity, reliability, efficacy, and practicality of test instruments and questionnaires. The study's findings demonstrate that the creation of a wordwall-based cognitive instrument on static electricity learning outcomes is valid, dependable, and practically implemented, as evidenced by the instrument's 0.79 sufficient category score, 74.9 average score, and 61.40% production rate based on student responses. This means that future researchers can build on this tool to suit their needs and the reference tools that are used to assess learning.

Sustainable selection of microwave absorbing materials: A green evaluation under interval-valued intuitionistic fuzzy environment

Environmentally friendly technology is being used by industries all over the world, and engineers in the manufacturing and materials industry are embracing sustainable business models. In this paradigm, materials are processed using economically and environmentally sound methods. The use of microwave-absorbing materials (MAMs) in low-altitude observatory aircraft and the rise in electromagnetic pollution have brought them to light. The main aim of this study is to select an ideal MAM with excellent physical, electromagnetic, chemical, and thermal properties, which also fulfills sustainability aspects based on expert judgments. In this regard, we have proposed a new hybrid framework consisting of Modified Digital Logic (MDL), a subjective weighting method in combination with the measurement of alternatives and ranking according to compromise solution (MARCOS) under an interval-valued intuitionistic fuzzy (IVIF) environment to select an optimum MAM. Furthermore, this research work contributes to streamlining the selection process by consolidating the plethora of work available in the literature on the synthesis and characterization of MAMs. A database is created for 160 potential candidate materials in C, S, X, and Ku bands for carbon-based materials, including carbon nanotubes (CNT), graphene, reduced graphene oxide (rGO), carbon fibers, and biomass-derived materials. These materials are then passed through successive screening stages to shortlist 14 materials, which are ranked subsequently over a set of 15 crisp and ambiguous criteria. This comprehensive study simultaneously caters to quantitative and qualitative information extracted from experimental work, material resource packs, or expert evaluations. The findings highlight CNT/Fe (20 wt%, E) (Al1) as the most suitable candidate for MAM application with outstanding electromagnetic properties. Finally, the results are compared with extant approaches to check the reliability of the proposed framework. In addition, sensitivity analysis is carried out to establish the feasibility and robustness of the obtained results.

Structural design and material comparison for aircraft wing box beam panel

This paper aims to present a comprehensive investigation to obtain the structural calculations needed to design a rigid panel of aluminum alloy for the wing box beam of an ATR 72–500 aircraft. For this design process, several types of materials, including composites like CFRP, are considered so it is possible to compare the actual existing part made of aluminum to them, thus checking the advantages these new materials offer. The research presents an introduction to structural design and provides a study of the relevant literature. The aircraft's principal characteristics and performance abilities were collected so that structural loads can be computed. Research used several methods, a design using conventional methods, applying the theory of elasticity is performed using the Theory of Farrar, allowing us to obtain an analytical solution to the problem, followed by checking the obtained results using Ansys FEM software combined with the parts being designed with CATIA. Furthermore, this same panel is calculated using composite materials instead of conventional aluminum, allowing us to compare both solutions. This research shed light on the intricate process of aircraft structural design, materials selection, and calculation methodologies, highlighting the ongoing pursuit of new and advanced materials. This paper makes clear that using composite materials presents several advantages over traditional ones, allowing for lighter, safer, more fuel-efficient, and more sustainable aircraft. The use of composite materials in the construction of airplane structures is driven by many factors. The results show that the chosen composite materials reduce weight, are durable, have low maintenance requirements, reduce noise, enhance fuel economy, and are resistant to corrosion.

Optimising Offset Defence Implementation as Fulfilment Efforts in Fighters Aircraft Materials and Technology

This research aims to investigate the implementation of defense offset as a strategy to address the gap in the supply of materials and technology for fighter aircraft among countries. In this context, the gap arises due to the complexity and high costs associated with fighter aircraft development. Many countries, particularly those with limited technological and manufacturing capabilities, face challenges in acquiring and developing advanced aircraft. This gap negatively impacts their defense capability enhancement efforts. Therefore, the concept of defense offset emerges as a potential solution. Defense offset is a strategy in which foreign aircraft manufacturers provide compensation in the form of technology transfer, investment in the local defense industry, or research and development collaboration to the purchasing country. Through steps such as identifying material and technological needs, planning clear offset agreements, transferring relevant technology, developing the local industry, supplying materials, research and development collaboration, as well as monitoring and evaluation, the implementation of defense offset can be optimized. This research employs a qualitative method with a descriptive approach, involving a literature study to gain in-depth information about defense offset implementation and its impact on the material and technology gap in fighter aircraft. The results include the identification of factors influencing the success of defense offset implementation, political, economic, and strategic implications, as well as the benefits obtained by purchasing countries. In conclusion, through the optimization of defense offset, purchasing countries can reduce the gap in materials and technology for fighter aircraft, enhance domestic defense industry, and strengthen national defense capabilities. With the right strategy, defense offset can be an effective tool in addressing the gap in fighter aircraft material and technology, thereby fortifying national defense.

Multi-Physics Digital Model of an Aluminum 2219 Liquid Hydrogen Aircraft Tank

Future liquid hydrogen-powered aircraft requires the design and optimization of a large number of systems and subsystems, with cryogenic tanks being one of the largest and most critical. Considering previous space applications, these tanks are usually stiffened by internal members such as stringers, frames, and stiffeners resulting in a complex geometry that leads to an eventual reduction in weight. Cryogenic tanks experience a variety of mechanical and thermal loading conditions and are usually constructed out of several different materials. The complexity of the geometry and the loads highlights the necessity for a computational tool in order to conduct analysis. In this direction, the present work describes the development of a multi-physics finite element digital simulation, conducting heat transfer and structural analysis in a fully parametric manner in order to be able to support the investigation of different design concepts, materials, geometries, etc. The capabilities of the developed model are demonstrated by the design process of an independent-type aluminum 2219 cryogenic tank for commuter aircraft applications. The designed tank indicates a potential maximum take-off weight reduction of about 8% for the commuter category and demonstrates that aluminum alloys are serious candidate materials for future aircraft.

Literatur Review: Analisis Pengembangan Media Pembelajaran dalam Mata Pelajaran IPA Materi Pesawat Sederhana pada Siswa Sekolah Dasar

One of the primary school subjects that is compulsory for students to study is Natural Sciences (IPA). In conducting the learning process a teacher needs to prepare models and methods as well as what media is chosen to help the teacher deliver the material. So that students can receive the material well and work the matter properly and improve the student's learning outcomes from before learning to after learning. This research is to find out what models and media can be applied in IPA learning on simple aircraft material. This article is written using the research method of a library review. This research includes the study of libraries to gather information and analyze literature. Of the eight articles scanned with one or two using similar learning models and other learning media showed positive results for students and teachers. Improved student learning about simple aircraft material became better. Some models and learning media on simple aircraft material are a reference to teachers in implementing the IPA learning process well and achieving the entire learning plan.