Aircraft Construction Research Articles

Analysis of impact events at arbitrary locations for isotropic plates and their main driving variables

Plates are widely used for lightweight structures in various disciplines, e.g. aircraft construction. However, these plates are susceptible to lateral forces due to impacts from falling tools, bird strikes, collisions with objects, etc. These impacts can occur anywhere on the plate. Here we report the dependence of the impact location on the impact itself. We use a semi-analytical approach that is verified in a code-to-code analysis using a commercial FE solver. Based on this code, a strong dependence of the impact location as well as the mass ratio of impactor and plate is found for the plate deflection and contact force. In addition, a general explanation for impact events is developed, leading to the distinction between small and large mass impacts. This work supports previous findings on the influence of mass ratio and completes the understanding of impact events at arbitrary locations.

НАБЛИЖЕНИЙ МЕТОД ЕКСПЕРТНИХ ОЦІНОК ЕФЕКТИВНОСТІ ЗАСТОСУВАННЯ ПОЛІМЕРНИХ КОМПОЗИЦІЙНИХ МАТЕРІАЛІВ У КОНСТРУКЦІЯХ ЦИВІЛЬНИХ ЛІТАКІВ НА ОСНОВНИХ ЕТАПАХ ЖИТТЄВОГО ЦИКЛУ

In connection with the growing use of polymer composite materials all over the world and in domestic aircraft construction in civil aircraft of the transport category, the analysis of forecasting methods of their application at the main stages of the life cycle of this class of structures becomes an urgent problem.Efficiency, as the ratio between the achieved result and the resources spent on its achievement, can be interpreted as the ratio between the total quality indicators of the created object and the total costs.However, quality indicators are such metrological characteristics, the quantitative measurement of which in most cases is difficult or almost impossible. In this regard, the qualimetric quality indicators acquire the qualimetric form of qualitative characteristics. Qualimetric characteristics make it possible to operate during their analysis by a productive method of expert assessments of criteria for the implementation of any object, including composite structures of aircraft aggregates. As a criterion for predicting the effective volume of use of composite structures, an analogue of D.L. quality at the stages of their life cycle. The numerical values of each level of the stages of the life cycle are assessed by an expert according to the proposed five-level general identification tables with the subsequent summation of the criterion indicators by stages of the life cycle, making it possible to determine both the efficiency of using composites at individual stages and its integral value for all main stages. The relative value of the efficiency criterion can be represented in monetary terms by multiplying it by an equivalent established on the basis of metrological (qualimetric) methods and means of assessing the results of a particular production.

Application and evaluation of the technical condition of composite materials in aircraft and unmanned aerial vehicles by acoustic emission method of nondestructive testing

Introduction. The paper analyzes the application of composite materials as the main determining method of reducing the mass of the airframe and an unmanned aerial vehicle. Advanced nondestructive testing methods provide assessing the technical condition of these materials, as well as determining stress concentrators on the airframe and an unmanned aerial vehicle with high accuracy in order to make a decision on the further operation of this object under control. The objective of the work was to increase the accuracy and efficiency of the assessment of crack resistance of composite materials through the acoustic emission control.Materials and Methods. This paper presents the nomenclature of composite materials used in the construction of various aircraft, including unmanned aerial vehicles. The most possible probable defects of these materials due to the influence of operational factors are presented. The applied methods of nondestructive testing of composite material and selection of the most suitable one according to specific advantages were compared. An experiment was carried out to determine the strength limits of carbon fiber using a hardware and software complex by acoustic emission method. The research results are presented in the form of drawings projected by the hardware and software complex.Results. The application of the acoustic-emission method of composite material control is described.Discussion and Conclusions. The results obtained experimentally can be used in the process of determining the strength limits of various composite materials by the acoustic emission method of nondestructive testing to assess the technical condition in mechanical engineering, shipbuilding, and aircraft construction. The paper is recommended to researchers involved in the design of aircraft and unmanned aerial vehicles.

Finding the Dynamic Range of Recorders During Impact Tests

In aircraft construction, when creating samples of new equipment, impact tests are often performed, both of individual components and of the entire product. It requires to introduce non-destructive testing devices into production, it is one of the most important factors in accelerating scientific and technological progress, raising the quality and competitiveness of manufactured products. Applying modern means of non-destructive testing, there is the problem of their protection from external vibrations, which affect the sensitivity, accuracy and reliability of high-precision measurements. In such cases the conversion of measuring information during powerful vibration and impact tests, as a rule, is carried out by piezoelectric acceleration sensors. Although to provide impact testing, there is a need to develop and use stand-alone recorders. The main requirements for these recorders are to ensure the autonomy and operability of the recorder on board the test product and to ensure the synchronization of the registration of the impact load.

Economic and Environmental Aspects of Aircraft Recycling

Aircraft recycling can be considered as an important step on the path to sustainable aviation, as valuable resources used in aircraft construction can be returned for use in a circular economy by these activities. Our results have shown that the market for aircraft recycling is emerging with great future relevance due to the increasing number of aircraft retirements expected in the future. The costs of recycling per aircraft vary by aircraft class and number of engines. The costs range from USD 109,000 for a twin-engine regional jet to USD 268,000 for a four-engine widebody jet. The costs for a twin-engine narrowbody jet lie in between at USD 138,000. In this paper, we investigated the economic efficiency of aircraft recycling expressed as the ratio of average dismantling and recycling costs per aircraft and engine in USD compared with the achieved environmental benefit in average tons recycled material or re-used parts. This ratio revealed that aircraft recycling leads to notable environmental benefits as a large share (60%) of the total structural weight is being re-used at given costs. The average economic efficiency is estimated at 1,666 USD/ton for a widebody aircraft, 3,531 USD/ton for a narrowbody jet and 6,693 USD per ton for a regional jet. In future, aircraft recycling will be facing a number of major challenges as the number of retired aircraft will increase and the share of composite material to be recycled will rise significantly in the medium and long term - for which material no satisfying technological recycling solution exists today. In addition, the environmental pressure from politics and society is expected to be increasing in future. Against this background, we recommend to effectively enforce ambitious recycling standards for retired aircraft on a global level. Furthermore, as recycling technologies for aircraft composite materials are not mature currently, significant R&D investments are needed for these technologies.

Review on -hybrid composite materials for structures

The review article of this paper represents the reduced availability of natural resources, the increasing costs of production, and the apparent limit to our ability to fabricate high strength-to-weight metallic components necessitated the development of new materials to meet the demands of aerospace technology. These materials are called advanced composite materials and will be used to replace some of the metals currently used in aircraft construction. Advanced composites are materials consisting of a combination of high-strength stiff fibers embedded in a common matrix (binder) material, generally laminated with plies arranged in various directions to give the structure strength and stiffness. The much stiffer fibers of boron, graphite, and Kevlar have given composite materials structural properties superior in strength to the metal alloys that they have replaced

Some Aerospace Applications of 7075 (B95) Aluminium Alloy

Nowadays, aluminium alloys are of growing interest to scientists and are widely used in aerospace and allied industries due to their inherent lightness, high strength to weight ratio, excellent thermal and electrical conductance, good reflectivity and low working cost. Among the conventional structural materials used in aerospace applications aluminium alloys are frontrunners. This is due to the ability of modern aluminium alloys to achieve unique combination of properties, through alloying and heat treatment, tailored to particular applications. Aluminum alloy 7075 (B95) is a high-strength alloy that works in extreme conditions and is used in modern construction of aircraft, spacecraft and satellites. In this mini-review, we will briefly focus on some of the existing and growing applications of some 7xxx aluminum alloys, in particular 7075 (B95), in the aerospace industry. Possible options for continuing work in this area are considered, and some Bulgarian developments are presented.

ВІЙСЬКОВА ЕКОНОМІКА АВІАЦІЙНО-КОСМІЧНОГО КОМПЛЕКСУ УКРАЇНИ ЯК ОБ’ЄКТ ІНСТИТУЦІОНАЛЬНИХ ТРАНСФОРМАЦІЙ

The article defines the military economy from the standpoint of a broad approach as an institutional environment for the functioning of the national economy in martial law, as well as in the narrow sense as areas of specific economic relations that ensure national military security, organization and implementation of military construction, training of military and security structures. to the defense and armed defense of the state. It is shown that the military economy and the civilian economy are subsystems of the national economy, which intersect in terms of dual-use output. The aerospace complex is defined as a subsystem of the national economy and a common set of civil and military economies, which includes the air transport complex and the aerospace complex. The general and special effects of their activity, as well as the peculiarities of the products of the production segment of the aerospace complex are determined. The main directions of development of the industrial aerospace complex are substantiated. The significant strategic influence of aerospace technologies on the achievement of Ukraine's military security is shown. The state and prospects of the aerospace complex in the institutional transformation of the military economy are systematized. It is proved that the military sector of aircraft construction should become the driving force of development of the whole military-defense complex due to mass production of new generation equipment. Ways of system technological updating of military aviation and air defense for strengthening of Ukraine's defense capability are substantiated. The strengths and weaknesses of the domestic aerospace complex have been identified, as well as measures to strengthen its competitiveness have been proposed: strengthening cooperation with other countries in the field of defense industry; licensed production of weapons and military equipment; their purchase or leasing from foreign suppliers; technology transfer; public-private partnership mechanisms; growth of the share of private and foreign financial resources in the implementation of aerospace projects.

СВІТОВИЙ РИНОК ТЕХНОЛОГІЙ У СФЕРІ АВІАЦІЇ ЯК ФОРМА РЕАЛІЗАЦІЇ МІЖНАРОДНИХ НАУКОВО-ТЕХНОЛОГІЧНИХ ВІДНОСИН

International scientific and technological cooperation in the aviation sector plays a decisive role for the transfer, use and production of knowledge, contributes to the innovative development of aviation, in particular the emergence of new types of aircraft, new business models of international airlines, modernization of airport infrastructure, reduction of the impact of aviation on the environment and increase security. The main reasons for the rapid development of the world technology market in the field of aviation are the unevenness of the economic development of countries, the monopolization of aircraft construction by large companies that are able to finance the conduct of valuable research and design works, the strengthening of competition in the world market of air transport, etc. Within the scope of the scientific research, the key areas are singled out and the modern system of international scientific and technological cooperation in the aviation sphere is characterized. It has been established that today for Ukraine, international scientific and technological cooperation in aviation acquires extremely important features in the context of the revival of the economy in the war and post-war period. The methodological basis of the research is both general scientific and special methods of scientific knowledge: descriptive-analytical, analysis and synthesis, methods of quantitative and qualitative comparisons. The information base of the article is monographic studies and periodical scientific publications of Ukrainian and foreign economists, materials and analytical reports of international organizations, international consulting companies and analytical centers. Research results can be used for scientific substantiation and further creation of appropriate conditions for the development of international scientific and technological relations, in particular in the aerospace field, ensuring an appropriate system of financing innovations with the involvement of the public and private sectors, funds of international financial institutions, the development of private companies in aerospace industry, substantiation of the mechanisms of military and post-war restoration of the air transport system of Ukraine.

Організаційне забезпечення авіаційної діяльності

Abstract. The experience of successful aviation structures has shown that the effectiveness of their activities is largely determined by organizational support. There are four main approaches to the definition of "organizational support": structural, regulatory, process and system. It is proposed to define "organizational support" as a system of processes and procedures for sustainable operation of the enterprise in accordance with the developed strategy and objectives, which ensures orderliness of elements and relations by organizing the relationship between departments, providing them with necessary resources and establishing effective external communications. The following definition of organizational support of aviation activity is offered. establishing effective external communications. The definition contains elements of structural, regulatory, process and system approaches. Among the structural elements of "organizational support of aviation activities" are: organizational structure, which determines the composition and location of units of aviation entities, the internal order of elements and relations; creation of a rational production structure and organization of the main production processes, which are aimed at the implementation of the necessary production functions and performance of production tasks by the subjects of aviation activities and their units; resource support for the functioning of aviation entities - logistical, financial, personnel, information, methodological, etc .; organization of internal relations between the divisions of aviation entities and effective external communications. The aim of further research should be to study the specifics of organizational support of various aviation entities in the main production chain in the field of aviation and related support services, from basic and applied research in aircraft construction to the provision of aviation services. Key words: organizational support, aviation activity, aircraft, aviation, air traffic organization, air traffic service, use of airspace, use of aircraft, organizational structure, resource provision.

Model Identifying the Airfoilicing Process Beginning on the Basis of Aircraft Flight Parameters

Aircraft icing is the process of changing the state of concentration of water contained in the air in the form of steam into a solid form accumulating on the surface of aircraft construction elements during a flight or results from the direct accumulating of ice crystals on the aircraft surface. The process of aircraft icing is complex and depends on many variable factors related to atmospheric conditions and aircraft flight parameters. The goal of work is to develop a deterministic model for identifying the beginning of the icing process depending on the aircraft flight parameters on the basis of CFD simulations.

Investigation of the accuracy and convergence of the results of thin shells analysis using the PRINS program

The theoretical foundations of compatible finite elements construction for static and dynamic analysis of single-layer and multilayer shells are discussed. These finite elements are implemented in the PRINS computer program. The paper presents verification tests to investigate the accuracy and convergence of the results of calculating various shells using these finite elements. Shell structures are widely used in various fields of technology - construction, mechanical engineering, aircraft construction, shipbuilding, etc. Specialists on the design and calculation of such structures need a reliable and accessible tool for the practical problems solving. Computer program PRINS can be one of such tools. It can be effectively used by engineers of design and scientific organizations to solve a wide class of engineering problems related to the calculations of shell structures. The paper describes the finite elements of the shells, implemented in the PRINS program. The results of verification calculations are presented, which confirm the high accuracy of this program.

VIBRATION ANALYSIS OF SINGLE LAP JOINT OF COMPOSITE PLATES BASED ON VARIATIONS OF PLATE THICKNESS AND OVERLAP LENGTH

Adhesive bonding is widely used for joining metals or composites in marine, aircraft, automotive, railroad, and civil construction industries. Adhesive single lap joint offers many advantages in terms of time and cost savings, has good damping characteristics, and provides high joint strength compared to another conventional joint. In this study, an analysis of free vibration of composite single lap joint has been carried out using by modal analysis solver i.e. ANSYS. Optimization study is then carried out to obtain the optimal design for vibration resistance. The simulation results of the natural frequency for each variation of joint thickness and overlap length are obtained through this study. The results show that increasing thickness and overlap length will increase the value of natural frequency as well, thus giving better vibration resistance. It is found that the optimum thickness and overlap length are 2.54 mm and 70 mm, respectively. The results point out the importance of joint thickness and overlap length for the vibration resistance of single lap joint of composite plates.

Aerospace Industry and Aluminum Metal Matrix Composites

Researchers have turned to search for new materials that will meet all the aerospace industry requirements. When it is almost impossible to achieve this with a single material, composite materials have been studied, and there have been great developments in this field. Many elements are used in aircraft construction, but aluminum is the most preferred due to its low density, good castability, high strength, corrosion resistance, and good fatigue strength. However, its strength and stiffness limit its usability. To solve this problem, aluminum is combined with various elements. Aluminum metal matrix composites are an example of this. Aluminum metal matrix composites are preferred in aircraft applications due to their high specific modulus and good mechanical and thermal properties. This review provides information on the use of aluminum metal matrix composite materials in the aerospace industry.

Civilians in demining territories in the West of the Russian Soviet Republic: legal regulation and administrative practices of regional authorities (1942–1946)

The article on the basis of archival sources, most of them introduced into scientific turnover for the first time, examines the legal regulation and realities of involvement of civilian population in demining of territories in the West of the Russian Soviet Republic in 1942–1946. Demining was the most important measure of the authorities, a condition for the establishment of peaceful life, the revival of the economy, the implementation of state plans. The scarcity of material and human resources available to the state led to the mobilisation of civilians for this task, especially – young people of pre-conscription age. Despite the voluntary participation in demining, regional and district authorities widely used their administrative resources both in the recruitment of demining teams through the Osoviakhim grassroots structures and military enlistment offices, and to facilitate their work. Faced with the inability of district teams of the Society for the Assistance of Defence, Aircraft and Chemical Construction (Osoaviakhim) to complete demining alone, the leadership of the western regions of the Russian Soviet Republic insisted that the most difficult areas be cleared by sapper units of the Red Army. By the end of 1946, the joint work of Osoaviakhim deminers and military sappers had completed the clearance of the territories of the West of the Russian Soviet Republic.

Studying phase formation of 12Х18Н10Т alloy and copper after friction welding

The technology of joining alloy 12X18H10T and copper has been studied. The use of friction welding is proposed. Modern development of technology requires the use of new technologies and materials. Despite the increase in the use of composite materials, and especially on the basis of the polymer matrix, metal alloys remain indispensable. Due to their physical and mechanical properties, metal-based alloys are used in rocket and space technology, mechanical engineering, and other industries. Goal. The aim of this work is the reason for the decrease in the mechanical properties of the connection 12Х18Н10Т – М1, which were obtained under suboptimal conditions. Friction welding was developed in early 1956 in the USSR. Since the 1960s, other countries have also begun to develop friction welding. This tool is a type of pressure welding, during which the metal is heated by friction of one of the parts of the product. At the end of the process, the final connection takes place. This type of welding is used in aircraft construction, rocketry, machine building, etc. In Ukraine, research in this direction is conducted at the Eugene Paton Institute of Electric Welding. The parameters of the friction welding technological process are considered. Results. The samples of welded joints 12Kh18N10T + M1 were studied. The following methods were used: mechanical tests; metallographic and electro-microscopic studies; hardness measurements; micro-X-ray spectral study. Originality. Welding joints with low strength were investigated; they were obtained for the following parameters: relative rotation speed 0.4 m/s, pressure during heating 80 MPa, pressure during forging 80 MPa, upset value 9 * 10-3 m samples with low strength varied in the deformed layer of steel from the joint surface to the base metal from 3240 MPa to 2450 MPa; in a deformed copper layer from 1020 MPa to 690 MPa. On samples that had high strength, the microhardness varied on the steel side from 2260 MPa in the contact surface to 2160 MPa, and in copper from 590 MPa to 460 MPa. Fig. 1 shows the microstructure of the deformed zones of the welded joint 12X18H10T, obtained according to the optimal parameters. Practical value. The reason for the decrease in the mechanical properties of the 12Х18Н10Т – М1 joint was established.

Experimental study of basalt fiber/steel hybrid laminates under low-velocity impact

Due to their excellent impact resistance, fibre-metal laminates are widely utilised in modern engineering industries such as the construction of aircraft, vehicles and ships. In this study, the low-velocity impact characteristics of basalt fibre/steel hybrid laminates with different lay-up structures were studied with a drop hammer. This was done through a series of low-velocity impact experiments with different hammer head shapes and impact energies. It can be seen from the results that the impact behaviour of hybrid laminates largely depends on the shape of the hammer head, impact energy and lay-up structure. The sharper the hammer head, the smaller the peak impact load and the greater the displacement. When the hammer head penetrates the laminate, apparent shear failure occurs under the impact of the flat hammer head. Petal-like fractures caused by tensile tear failure occur under the impact of the hemispherical and conical hammer head. Low-energy impacts may result in large plastic deformation, delamination and debonding in the layers. High-energy impacts may also lead to fibre and metal fractures as well as perforation damage. Consequently, the laminate absorbs the energy from overall deformation under low-energy impact, but mainly absorbs the energy generated by various fibre and metal fractures under high-energy impact.

Measuring and Testing Composite Materials Used in Aircraft Construction

This paper is focused on the use of special composite materials for the construction of aircraft components. It focuses on measuring and testing the strength of reinforced composite materials used in damaged aircraft parts repairs. To determine the layer required to repair a part of the aircraft, it is necessary to know the strength limit of the material and its parts. The article describes experimental measurements of manufactured composite samples that have been subjected to tensile stress. Aim of the performed tensile tests was to determine the maximum tensile stress that the composite materials are able to transmit until they are damaged. Measurement determining the maximum stress level is important to ensure the required safety of the aircraft structure on which the composite structure was repaired.

Investigation of the Effect of Modifying the AlSi7Mg0.3 Alloy with a Fast-Cooled Master Alloy Using Heat Treatment

The development of modern high-tech industries of industrial production is impossible without the development of new methods for processing materials with high mechanical characteristics. There is a growing need for an increase in the proportion of parts made of aluminum alloys, a more complex configuration of cast parts, an increase in their reliability and durability in operation, etc. All this poses for metallurgists and foundry workers the task of creating new technologies for producing alloys, improving the technical and economic characteristics of structural materials, improving the quality and reducing the cost of castings.Hypoeutectic silumins have good casting properties, good weldability, machinability and corrosion resistance. However, they are prone to the formation of a coarse needle-like state, which reduces their useful characteristics. To eliminate this phenomenon, it is necessary to apply special technologies and the most common is their modification, which provides grain refinement. This makes it possible to use silumins for the manufacture of castings of complex shapes with increased density and low shrinkage porosity. Such parts can withstand average loads in critical units. Aluminum-silicon alloy AK7 or (ASi7Mg0.3) is a typical silumin, which is in demand in the automotive industry, construction, aircraft construction, machine, automobile and tractor production. It is appreciated for its good casting properties, weldability, machinability and corrosion resistance.

Influences of Elastic Foundations and Material Gradient on the Dynamic Response of Polymer Cylindrical Pipes Patterned by Carbon Nanotube Subjected to Moving Pressures.

Composite materials are frequently used in the construction of rail, tunnels, and pipelines as well as in the construction of aircraft, ships, and chemical pipelines. When such structural elements are formed from new-generation composites, such as CNT-reinforced composites, and their interaction with the ground, there is a need to renew the dynamic response calculations under moving pressures and to create new mathematical solution methods during their design. The aim of this study was to analyze the influences of elastic foundations (EFs) and material gradient on the dynamic response of infinitely long carbon nanotube (CNT)-based polymer pipes under combined static and moving pressures. The CNT-based polymer pipes resting on the EFs were exposed to the axial and moving pressures. The uniform and heterogeneous reinforcement distributions of CNTs, which varied linearly throughout the thickness of polymer pipes, were considered. After setting the problem, the fundamental equations derived to find new analytical expressions for dynamic coefficients and critical velocity, which are dynamic characteristics of cylindrical pipes reinforced by the uniform and linear distributions of CNTs, were solved in the framework of the vibration theory. Finally, numerical computations were performed to examine the effects of EFs on the critical parameters depending on the characteristics of the pipes, the speed of moving pressures, the shape of the distribution of CNTs, and the change in volume fractions.