The development and research activity is connected to the production of newer and more functional products. Innovative processes are being developed and applied; services and projects are delivered. Products are work items that should be initially designed, then manufactured and finally sold and utilized. Examples of products may be airplanes, ships, cars, machine tools, gears, crankshafts, drive shaft, tubes as well as gasoline, electricity and gas, etc. The product has to meet the expectations of the future use. It is characterized by a set of functional features. In the case of machines and their capabilities and performance, for example, durability, reliability, resulting from the characteristics represented by the structural units forming the structure. The formation of the desired features of the surface layer in the technological process is an important problem due to the ability of the elements of kinematic pairs to fulfil the function as long as possible foreseen for them. The article presents results of experimental studies of turning cast steel grade GX2CrNiMoCuN25-6-3-3. The aim of the research was to determine the geometry of the cutting edge and the technological parameters of cutting that are conducive to obtaining the roughness in the field of very accurate machining. It can achieve the appropriate technological quality of the workpiece surface. After these experimental studies was determined that there is a reduction roughness using suitable inserts. Turning was made for the duplex cast steel. The technological parameters of machining process were used: feed rate f = 0.1-0.2 mm/rev, depth of cut ap = 0.5 mm, cutting speed vc = 50-100 m/min. Turning was made using universal lathe CDS 500x1000 equipped with CCMT carbide tipped inserts.
The aerodynamic research into models of an aircraft aims at creating the main characteristics of aerodynamic forces and moments and the aerodynamic characteristics of coefficients of aerodynamic forces and moments, based on real dimensions. The method of 3D printing was used to create a model of an aircraft. The model with the previously set printing parameters and commands for a 3D printer, in the right order, was imported into MakerBot Print. The final stage was printing the model. The printed components of the model of an aircraft were imperfect due to the incorrectly set printing parameters. The model with the previously set printing parameters and commands for a 3D printer, in the right order, was imported into MakerBot Print. The final stage was printing the model. The printed components of the model of an aircraft were imperfect due to the incorrectly set printing parameters. The printing parameters were corrected in the next printing sessions so the surfaces of the components were good enough and grinding was unnecessary. Some excess material was removed in each of the printed components, and the slots were cleaned. Then, the individual models were put together.
The article describes the technique of creating a model of an aircraft to map its exact geometry for experimental wind tunnel research. 3D printing enables us to experimentally investigate a created geometry, in particular to investigate further prior to releasing an aircraft to service. The 3D model employs the model created in line with the previous CFD analysis.
Małgorzata Wojtas, Agnieszka Sobieszek and Tomasz Szczepanik
The paper presents test bench method for verifying the fatigue life of the rotor blades, working in operating conditions in a position steady flight (autorotation), on the aviation construction called the gyroplane. One of the critical elements of this design is the main rotor, which in its modern versions takes the form of advanced composite structures subjected to loads in flight complex variable, the nature of which differs from the well-known operating conditions of helicopter rotors. The article includes a description of the test object, which are composite rotor blades designed specifically to work in autorotation, the specificity of loads of autorotation rotor, and method of implementation of the gyroplane rotor work cycles in the test bench. The main aim of this research is to evaluate the sustainability of the composite blades under the gyroplane operating loads with the goal to allow the rotor to operate in the air. The tests were carried out for 100 hours of gyroplane flight at loads do not exceed the maximum operating loads, and for several hours under a load higher than operating. During test for the evaluation of composite structure, the infrared camera with dedicated software IRNDT was used. The reached showed structural integrity in critical mounting section of the blade.
Flow control inside the aviation landing gear shock absorbers is nowadays performed by fixed orifices or by the half-active spring based valves located inside of the device. All of the mentioned solutions are optimized on limited, mostly to one, landing scenarios due to their non-adjustable nature (even spring based valves are treated as passive due to their lack of actual real-time controllability). The easiest way of full hydraulic fluid flow control is to mount in its way a valve, which is able to seamlessly open and close causing the flow to change in wide range. Unfortunately, most of the used solutions are too large or not fast enough to fit the shock absorber requirements. The most promising way is to design tailor-made valve based on a piezo crystal actuator, which is most suitable due to its size and speed. Such a design has been made and tested by the engineers of the Institute of Aviation in Warsaw in Landing Gear Laboratory. In this article, the author describes test campaign of the hydraulic piezo-valve. Several tests have been made in order to assess the design correctness and to determine the basic parameters of the valve. Achieved results, presented in this article, show the full functionality of the solution in laboratory tests according to the design assumptions .
The aeroelastic phenomena analysis methods used in the Institute of Aviation for aircraft, excluding helicopters, are presented in the article. In industrial practice, a typical approach to those analyses is a linear approach and flutter computation in the frequency domain based on normal modes, including rigid body modes and control system modes. They are determined by means of the finite element method (FEM) model of structure or a result of ground vibration test (GVT). In the GVT case, relatively great vibration amplitudes are applied for a good examination of a not truly linear structure. Instead or apart from the measure of generalized masses, a very theoretical model is used for mode shapes cross orthogonality inspection and improvement. The computed or measured normal mode sets are the basis for flutter analysis by means of several tools and methods, like MSC.Nastran and ZONA commercial software as well as our own low-cost software named JG2 for the flutter analysis of low speed aeroplanes and for a preliminary analyses of other aircraft. The differences between the methods lie in determining normal mode set, unsteady aerodynamic model, flutter equation formulation, time of analysis, costs, etc. Examples with results comparison obtained by means of distinguished methods are presented. Some works in the field of aeroelastic analysis with nonlinear unsteady aerodynamic in the time domain using Tau-code and ANSYS Fluent software were also performed. Aeroelastic properties of deformed structures, like a sailplane with deflected wings, can be also analysed. The simplest way of this analysis is the semi-linear approach in which the deflections modify the aircraft geometry for normal modes determination.
Piotr Rybak, Zdzisław Hryciów, Bogusław Michałowski, Andrzej Wiśniewski and Michał Wojciechowski
The extortions that result in the vibrations of a hull of the combat vehicle have an impact on the tracked combat vehicle during the off-road driving. They may have a negative impact on the crew, internal equipment, shooting accuracy. A level of the hull loads depends on quality of the suspension system, which main responsibility consists in minimising an amplitude of the vibrations. Therefore, it is necessary both to improve a structure of the suspension system, and its components, as well as their optimisation.
The tests of the driving smoothness of the vehicle and quality of the suspension elements can be realised both within a frame of the model tests and while driving in the real conditions. The assessment criteria of the driving smoothness are directly related to the negative influence of the vibrations to the human body. The suspension quality should be assumed both upon an execution of the vehicle prototype, and during the design or modernisation phase. It results both in reducing the time, and minimisation of the costs and risk related to the structure development. The model tests enable to evaluate the driving smoothness and comfort prior to an execution of the prototype. The tests on the test tracks in the final phase of the development are carried out in order to evaluate the driving smoothness.
The article presents a mathematical model of a permanent magnet motor, powered by a three-phase source of sinusoidal voltage, and a control method. Cooperation between numerical integration algorithms in the differential equation system of the motor and an inverter has been verified. The results of numerical simulations are presented in a graphic form. This article is an extension of the publication , in which a model of a drive system was proposed, consisting of: a battery, a supercapacitor and a method of controlling these energy sources during a driving cycle of a vehicle. For vector control, the mathematical model of a synchronous machine in the dq coordinate system is the most common one. The most important feature of this control method is the fact that the iq component of the rotor current vector determines the value of motor torque, and the component id – the value of magnetic flux. In the article, the emphasis is put on how inverters work. Their basic task is to generate such currents iabc or voltages uabc to obtain torque without ripples. It leads to development of different control concepts for achieving this goal, which are related to the modelling of magnetic fluxes in a stator and in an inverter.
Sławomir Michalak, Andrzej Żyluk, Andrzej Szelmanowski and Jerzy Borowski
The article presents the selected methods of identifying static and dynamic properties of the measuring paths to the extent necessary for the proper integration of on-board systems with the helmet-mounted flight parameter display system. It presents the methods of identifying static and dynamic properties of the WR-10MK on board variometer as one of more difficult identification elements. Its identification was carried out on the basis of the basic dependencies of the International Standard Atmosphere and the instruments construction’s parameters. It built a mathematical model describing the physical phenomena associated with vertical speed measurement. This model differs from the models found in the literature in terms of detail and description accuracy. On this basis, in the Simulink environment, it built a simulation model corresponding to its mathematical model. The non-linear model was the starting point for the construction of the linearized model based on the operator transmittance. The developed models were evaluated for errors of vertical speed’s dynamic indications. This allowed assessing the usefulness of the individual models for further works on ensuring the correlation of indications of the on-board variometer and the SWPL-1 helmet-mounted flight parameter display system. The presented simulation models include design details, as well as the characteristics of technological errors and disturbances of a stochastic nature. Another approach to the issue of identification is to use the characteristics provided by the manufacturer in the form of approximate characteristics of a module.
Riveted joints are a common location of fatigue cracks in aircraft metal structures. Fatigue life of such joints as well as a place of cracks nucleation is strongly influence by a stress distribution in sheets, which is a result of residual stresses (mainly after riveting) and stresses induced by external loads. Stress distribution in two-row lap joint was investigated with the use of Finite Element Method. The joint consist of two 1.5 mm sheets and two protruding rivets with diameter equal to 4 mm, made of 2024 T3 (sheets) and 2117 T4 (rivets) aluminium alloys. The simulations covered a riveting process and tensile stages. The 3D models of joint with the universal rivets and with the brazier, rivets with a compensator were prepared. Elastoplastic material properties as well as geometric nonlinearity and contact phenomena were included. The results of simulations show that the residual stress distribution after release of tensile loading varies significantly from the distribution after riveting only. This fact should therefore be taken into account in a fatigue life estimation of such joints performed based on a FE calculation. The paper presents also the influence of the analysed rivet geometry on the stress distribution at the sheets faying surfaces.
The article presents the modelling of the combustion process of liquid fuels using professional ANSYS FLUENT software. This program allows modelling the dynamics of compressible and incompressible, laminar and turbulent flows as well as heat exchange phenomena with occurrence and without chemical reactions. The model presented in the article takes into account the influence of the gas phase on the liquid phase during the fuel combustion process. The influence of velocity and pressure of the flowing gas and the type of flow has a significant impact on the combustion of liquid fuels. The developed model is fully reliable and the presented results are consistent with experimental research. The occurrence of a laminar sublayer in a turbulent flow was confirmed, and the thickness of this layer and the turbulent layer significantly influences the course of the combustion process. The use of the flat flow model reflects the basic phenomena occurring during the combustion of liquid fuels under turbulent conditions. The use of the program for flows with different flow velocity profiles is justified. It gives important information about the processes taking place during the combustion of liquid fuels. The results of numerical tests are presented graphically. The article presents graphs of velocity field, absolute pressure, power lines, temperature and density.