Aeronautical Materials Research Articles

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the author felt the need of thinking back to the past on what materials used to be prevalent and what materials have superseded them.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.

Review Regarding the Influence of Cryogenic Milling on Materials Used in the Aerospace Industry

In the aerospace industry, an important number of machined parts are submitted for high-performance requirements regarding surface integrity. Key components are made of materials selected for their unique properties and they are obtained by milling processes. In most situations, the milling process uses cooling methods because, in their absence, the material surface could be affected by the generated heat (temperatures could reach up to 850 °C), the residual stress, the cutting forces, and other factors that can lead to bad integrity. Cryogenic cooling has emerged as a pivotal technology in the manufacturing of aeronautical materials, offering enhanced properties and efficiency in the production process. By utilizing extremely low temperatures, typically involving liquid nitrogen or carbon dioxide, cryogenic cooling can significantly enhance the material’s properties and machining processes. Cryogenic gases are tasteless, odorless, colorless, and nontoxic, and they evaporate without affecting the workers’ health or producing residues. Thus, cryogenic cooling is also considered an environmentally friendly method. This paper presents the advantages of cryogenic cooling compared with the classic cooling systems used industrially. Improvements in terms of surface finishing, tool life, and cutting force are highlighted.

The Fabrication and Testing of Unmanned Aerial Vehicle (UAV) Wing Structure Using 3D Printing and Carbon Fibre Skinning Method

This study examines the efficacy of integrating 3D printing with carbon fibre skinning to construct wing structures for Unmanned Aerial Vehicles (UAVs). The primary objective is to enhance the structural integrity and material characteristics. The study performs static load tests, which demonstrate that wings reinforced with carbon fibre lamination can endure a substantially greater maximum stress of 29.43 N, in contrast to 14.391 N for wings produced only by 3D printing. The carbon fibre laminated wings have a greater load-bearing capability, as evidenced by the safety factor study. This analysis reveals that the permitted loads for carbon fibre laminated wings (19.61 N) are higher compared to 3D printed wings (9.594 N). The tensile testing of the specimens reveals that carbon fibre laminated wings demonstrate enhanced ductility, stiffness, and yield strength. Additionally, they withstand greater levels of maximum stress and strain, except for a slightly higher stiffness seen in 3D printed wings. This research highlights that carbon fibre laminated wings are typically more durable and versatile for many uses, although 3D printed wings may be favoured in situations when greater rigidity is necessary. In conclusion, the study effectively showcases the advantages of combining 3D printing with carbon fibre skinning in the construction of UAV wings. This research significantly contributes to the progress of UAV design and provides fresh insights in the fields of aeronautical engineering and materials science. It is particularly valuable for applications that require UAVs with exceptional performance, durability, and reliability.

Microstructure and mechanical properties of a first-generation single crystal superalloy CMSX-6

CMSX-6 alloy is a first generation of single crystal high temperature alloy and has been widely applied for the aeroengine and gas turbine blades. In the present study, the microstructure, tensile properties, stress rupture properties and fracture properties of the as-cast and heat-treated CMSX-6 alloy were investigated. The experimental results show that under the heat-treated condition the γ′ phase was about 0.5 μm, the volume fraction was about 66%, and the residual eutectic phase volume was 2%~5%. The tensile and stress rupture properties was similar that of the first generation of single crystal alloys, DD3 and DD407 developed by Beijing Institute of Aeronautical Materials and General Institute of Iron and Steel Research, China. And the results also indicate that CMSX-6 alloy has good fracture properties, oxidation resistance properties and corrosion resistance properties, and therefore CMSX-6 alloy has very good application prospect for the aeroengine and gas turbine blades materials.

Publisher Correction: Hygrothermal Effects in Aeronautical Composite Materials Subjected to Freeze–Thaw Cycling

Publisher Correction: Hygrothermal Effects in Aeronautical Composite Materials Subjected to Freeze–Thaw Cycling

Hygrothermal Effects in Aeronautical Composite Materials Subjected to Freeze–Thaw Cycling

Hygrothermal Effects in Aeronautical Composite Materials Subjected to Freeze–Thaw Cycling

Comparative study on the water droplet erosion behavior between stretched and casted aeronautical PMMA

Rain droplet erosion is a potential threat in aviation, especially for forward-facing components such as windshields of aircraft. To comprehend and mitigate such hazards, a comparative study was conducted on two kinds of commonly used aeronautical PMMA materials: casted and biaxially stretched. The study aimed to investigate the water droplet erosion (WDE) behavior and the underlying damage mechanism. A modified pulsed water jet erosion facility was constructed to mimic the impact of successive water droplets. The influence of impact velocity on the WDE behavior was explored and quantitative evaluations of volume loss, surface entrance area, and erosion depth were conducted. Results revealed that the increase in impact velocity leads to faster damage initiation and a larger erosion rate. Compared with the stretched sample, the casted sample exhibits higher erosion resistance. The stretched sample exhibits a funnel-shaped cavity with a flat bottom, while the casted sample shows a tapered crater with shallow depth. The cavity shape can influence the subsequent flow fields and stress distribution, thereby affecting the development of erosion entrance and depth. Microscopic analysis of the erosion cavities revealed different damage mechanisms at each stage of erosion. The stretched sample exhibited exfoliation of fine flakes and denudation of large pieces due to stress waves and lateral jet-induced shear, whereas hydraulic penetration had a more pronounced effect on the casted sample. The cushioning effect of the water film was also studied, noting a gradual reduction in its effectiveness with increasing impact velocity.

Using corpus linguistics to create tasks for teaching and assessing Aeronautical English

This article presents the theoretical basis for corpus linguistics applied to Aeronautical English teaching and assessment followed by practical examples on how to use corpora to develop tasks for both purposes. It originates from the design of two webinars held remotely at the end of 2020, and promoted by the International Civil Aviation English Association. The webinars were targeted at Aeronautical English teachers, material designers, and test developers with little or no previous knowledge of corpus linguistics with the aim of guiding the audience in preparing step–by–step tasks using corpora. We share the work involved in the task design suggested, bridging the gap between research and practice. We conclude by outlining limitations, and suggesting prospects for future research.

Neuron-like thermal silica bridge between boron nitride nanosheets with hard-soft composite structure to enhance thermal conductivity and anti-icing properties on CFRP

Carbon fiber reinforced polymer (CFRP) composites are popular as novel aeronautical material for its high strength and low density. However, CFRP is unfit for aircraft electric deicing system due to its low thermal conductivity and hydrophilicity, which leads to more serious icing phenomenon and inhibition of de-icing effect. Inspired by neuron structure, the thermal silica bridge in BNNS@SiO2 composite coatings were designed to improve the in-plane thermal conductive from 1.647 to 6.702 W/mK by sol–gel method and spraying technology. Hard SiO2 particles and soft boron nitride nanosheets (BNNS) constitute hard-soft composite structure with hydrophobicity, anti-icing properties (4.09 times icing delay time) and abrasion resistance (kept 98.7% after 180 abrasion cycles). Under the combined action of thermal conductivity and hydrophobicity, the 53.8% energy saving of de-icing system was realized under the heating power of 3 W. Meanwhile, the thermal conductive/hydrophobic composite coating both possessed insulation and flame retardant.

Molecular dynamic simulations of Ti-6Al and Fe-12Cr alloys for their heat transfer and oxygen transport behaviors

The heat transfer and oxygen transport behaviors of Ti-6Al and Fe-12Cr alloys directly affect their aeronautical material application. In order to investigate the flame retardant mechanism in atomic scale, molecular dynamic (MD) simulations were performed to study the heat transfer and oxygen transport performances of Ti-6Al and Fe-12Cr alloys in the linear and uniform heating treatment. Next, the ignition performances of Ti-6Al and Fe-12Cr alloys were further verified by the frictional ignition tests. Therefore, this is a multi-scale research with a novel combination of MD simulations and ignition tests. Those obtained results show that the heat is more concentrated at the heating edge of Ti-6Al alloy while at the same heating rate. This leads to the intensification of atomic motion at the heating edge, and reduces the structural thermal stability of Ti-6Al alloy’s heating edge. Therefore, the heat transfer performance of Fe-12Cr alloy at the same state is better than that of Ti-6Al alloy. When there is an oxide layer on the surface of these two alloys, Fe-12Cr alloy can inhibit the oxygen transfer more effectively than Ti-6Al alloy, and further improve its flame retardant property. In addition, the frictional ignition tests with Ti alloy rotor under the same airflow environment show that the critical airflow velocity of the Fe-12Cr alloy stator is about 114[Formula: see text]m/s higher than that of Ti-6Al-4V alloy stator at 384∘. Generally, according to MD simulations and frictional ignition tests, it could be concluded that the flame retardancy of Fe-12Cr alloy is higher than Ti-6Al alloy.

Study on the Thermal Distribution Characteristics of a Molten Quartz Ceramic Surface under Quartz Lamp Radiation.

More and more researchers are studying the heat transfer performance of aeronautical materials at high temperatures. In this paper, we use a quartz lamp to irradiate fused quartz ceramic materials, and the sample surface temperature and heat flux distribution were obtained at a heating power of 45~150 kW. Furthermore, the heat transfer properties of the material were analyzed using a finite element method and the effect of surface heat flow on the internal temperature field was investigated. The results show that the fiber skeleton structure has a significant effect on the thermal insulation performance of fiber-reinforced fused quartz ceramics and the longitudinal heat transfer along the rod fiber skeleton is slower. As time passes, the surface temperature distribution tends to stability and reaches an equilibrium state. The surface temperature of fused quartz ceramic increases with the increase in the radiant heat flux of the quartz lamp array. When the input power is 5 kW, the maximum surface temperature of the sample can reach 1153 °C. However, the non-uniformity of the sample surface temperature also increases, reaching a maximum uncertainty of 12.28%. The research in this paper provides important theoretical guidance for the heat insulation design of ultra-high acoustic velocity aircraft.

Improving the Wear and Corrosion Resistance of Aeronautical Component Material by Laser Shock Processing: A Review.

Since the extreme service conditions, the serious failure problems caused by wear and corrosion are often encountered in the service process for aeronautical components. Laser shock processing (LSP) is a novel surface-strengthening technology to modify microstructures and induce beneficial compressive residual stress on the near-surface layer of metallic materials, thereby enhancing mechanical performances. In this work, the fundamental mechanism of LSP was summarized in detail. Several typical cases of applying LSP treatment to improve aeronautical components' wear and corrosion resistance were introduced. Since the stress effect generated by laser-induced plasma shock waves will lead to the gradient distribution of compressive residual stress, microhardness, and microstruture evolution. Due to the enhancement of microhardness and the introduction of beneficial compressive residual stress by LSP treatment, the wear resistance of aeronautical component materials is evidently improved. In addition, LSP can lead to grain refinement and crystal defect formation, which can increase the hot corrosion resistance of aeronautical component materials. This work will provide significant reference value and guiding significance for researchers to further explore the fundamental mechanism of LSP and the aspects of the aeronautical components' wear and corrosion resistance extension.

Review on Anti-Fatigue Performance of Gradient Microstructures in Metallic Components by Laser Shock Peening

Laser-shock-peening technology is an international research hotspot in the surface-strengthening field, which utilizes the mechanical effects of laser-induced plasma shock waves to effectively improve the fatigue performance of metallic components by introducing the gradient microstructures and compressive residual stress into the surface layer of processed materials. The fatigue failure caused by high-frequency vibrations in aeroengines during service is the most important threat to flight safety, and this case is more prominent for military aeroengines because their service situation is harsher. The present paper focuses on components such as high-temperature components, fan/compressor blade, and thin-walled weldments, and it systematically introduces the researching findings about surface nanocrystallization and compressive residual stress formation mechanism in typical aeronautical metallic materials treated by laser shock peening. The contents mainly involve the characteristics, formation process, fatigue resistance mechanism, thermal stability of residual compressive stress, and nanocrystallization generated by laser shock peening.

Fatigue Crack Growth Behavior and Failure Mechanism of Nickel-Based Alloy GH4169 under Biaxial Load Based on Fatigue Test of Cruciform Specimen

Due to the complex geometry and various cyclic loads, aeroengine components are often in a multiaxial complex stress state during service. Multiaxial fatigue is a major cause of many air accidents. It is of great significance to study the fatigue failure mechanism of aeronautical materials. This paper carries out biaxial fatigue tests on cruciform specimens and uses the surface replication method to record the initiation and propagation process of crack. Based on these fatigue tests, this paper studies the multiaxial fatigue characteristics of nickel-based alloy GH4169 for aeroengines and analyzes the fatigue crack growth behavior and failure mechanism of nickel-based alloys under a complex multiaxial stress state.

Retired Aircraft Recovery: Based on Stackelberg Game Method from the Perspective of Closed-Loop Supply Chain

At present, the recovery and disposal of decommissioned aircraft have not yet formed a complete system in China. In this paper, a two-channel closed-loop supply chain model composed of an aeronautical materials manufacturer, an aircraft manufacturer, and a third-party recycler is established theoretically. The situation of supply chain recycling under the leadership of the Aeronautical Materials manufacturer, aircraft manufacturer, and third-party recycler is studied. In addition, the third-party recycler and centralized decision making are analyzed through game theory. The results show that the overall revenue of the supply chain is optimal under centralized decision making, but not Pareto optimal under decentralized decision making. Therefore, a revenue-sharing contract is used to coordinate and optimize the supply chain. Finally, the influence of different power structures and model parameters on the two-channel closed-loop supply chain model and the effect of contract coordination are discussed by numerical analysis.

Effect of process parameters of Plain Water Jet on the cleaning quality, surface and material integrity of Inconel 718 milled by Abrasive Water Jet

Abrasive Water Jet (AWJ) is considered as a promising milling method for difficult-to-machine aeronautical materials as Inconel alloy 718 (IN718). However, grit embedment during AWJ is known as a detrimental effect on certain applications as aircraft repair, where surface condition may play an important role on additive material technologies. To overcome this problem, Plain Water Jet (PWJ) has been used in the present study as cleaning process and demonstrated to be an effective method to remove grit particles from the surface with marginal alterations of surface state. In this paper, firstly the influence of AWJ process parameters on abrasive embedment and surface texture on IN718 specimens milled by AWJ were addressed. Then these surfaces were subjected to PWJ cleaning process and were extensively characterized in terms of grit embedment, surface texture and roughness, erosion depth, microhardness and residual stresses. Before cleaning, the milled surfaces presented a grit embedment level varying between 7 % and 14 %. One setting condition was selected for performing PWJ cleaning which reduced the grit level up to a quarter of the initial total surface area (less than 4 % in all cleaned surfaces) without relatively modifying neither the surface texture nor the erosion depth. Comparable microhardness gradients were observed before and after PWJ cleaning which corresponded to ∼ 30 % higher than the bulk values at surface and then decreased beneath the surface up to 200 µm before to reach bulk value (∼ 245 HV). Compressive residual stress state at surface initially induced by AWJ milling in some surfaces remained unchanged after PWJ process but in other ones was slightly relieved (∼ 50 MPa). Residual stresses after PWJ process resulted from − 630 MPa to – 315 MPa depending on the milling process parameters.

Research on the Construction of Aviation Materials Industry College under the Background of New Engineering

The construction of new engineering is the direction of my country engineering education reform based on the new requirements of my country's strategic development, the new situation of international competition and the new requirements of Lide Shuren. An important carrier of the docking industry chain, aviation materials are an indispensable part of the aviation industry. This paper takes the College of Aeronautical Materials Industry under the background of new engineering as the object, and takes the College of Materials Engineering of Xi'an Aeronautical University as an example to study its construction content such as talent training mode, in order to provide reference and reference for the school to carry out the construction of new engineering.

Towards Sustainable Composite Manufacturing with Recycled Carbon Fiber Reinforced Thermoplastic Composites.

Currently, the vast majority of composite waste is either landfilled or incinerated, causing a massive burden on the environment and resulting in the loss of potentially valuable raw material. Here, conventional pyrolysis and reactive pyrolysis were used to reclaim carbon fibers from aeronautical scrap material, and to evaluate the feasibility of using reclaimed carbon fibers in structural components for the automotive sector. The need for fiber sizing was investigated as well as the behavior of the fiber material in macroscopic impact testing. The fibers were characterized with the single fiber tensile test, scanning electron microscopy, and the microbond test. Critical fiber length was estimated in both polypropylene and polyamide matrices. Tensile strength of the fiber material was better preserved with the reactive pyrolysis compared to the conventional pyrolysis, but in both cases the interfacial shear strength was retained or even improved. The impact testing revealed that the components made of these fibers fulfilled all required deformation limits set for the components with virgin fibers. These results indicate that recycled carbon fibers can be a viable option even in structural components, resulting in lower production costs and greener composites.

Multiaxial fatigue behavior and life prediction of 2198-T8 Al-Li alloy notched tubular specimen based on DIC technique

2198-T8 aluminum-lithium alloy is an advanced aeronautical engineering material. The multiaxial fatigue tests of notched specimens are conducted with the variables of notch diameter, notch number, and equivalent stress amplitude, respectively. The strain field and fatigue life are characterized and calculated by digital image correlation (DIC) technique. The results show that: the fatigue life decreases with the increase of notch diameter, number of notches, and the equivalent stress amplitude. The strain curves calculated by VIC-3D are similar to those obtained by the testing. The normal and shear strain concentration becomes obvious at 80% to 90% fatigue life, and the surface cracks appear at 95% fatigue life, typical multiaxial fatigue morphologies including tire patterns and wear fatigue striations are observed on the fracture surface. The feasibility of the DIC technique to characterize multiaxial fatigue behavior is verified. The modified SWT model provides fine life prediction results with all predicted data within a factor of two.

A Polynomial Equation Model for Fatigue Crack Propagation in an Aeronautical Steel Material

The model widely used in the fatigue crack growth study in materials science and fracture mechanics is the Paris-Erdogan, which relates the stress intensity factor with the subcritical crack growth, under a fatigue regime. In this work, a seven degree polynomial is used as an alternative to model the crack propagation behavior and to be able to analyze the three regions charts of the cycles by load, in contrast to the common model that it performs at a slight approximation of the propagation phase of the trinca (region II). Finally, a comparison has been made between the proposed model and the secant method by the ASTM 647,2000 standard that adjusts the points obtained experimentally. This proposed equation is new as another alternative analytical model for which the adjustment parameter “R” are compared in relation to the classical approach in a aeronautical ABNT 4130 steel.