scholarly journals МЕТОД ВИЗНАЧЕННЯ ХАРАКТЕРИСТИК ЗАГАЛЬНОГО НАПРУЖЕНО-ДЕФОРМОВАНОГО СТАНУ В СИЛОВИХ ЕЛЕМЕНТАХ КОНСОЛІ КРИЛА ВІД НАВАНТАЖЕННЯ ФУНКЦІОНУВАННЯ

2021 ◽  
pp. 26-40
Author(s):  
А. Г. Гребеников ◽  
Д. Ю. Жиряков
Keyword(s):  
Fatigue Life ◽  
Strain State ◽  
Center Of Pressure ◽  
Internal Force ◽  
Optimal Size ◽  
Stress Strain ◽  
High Lift ◽  
Stress Strain State ◽  
Ansys Cfx ◽  
Wing Box

When the high - lift system are released, the aerodynamic flow around the wing changes significantly, which in turn leads to a change in the stress-strain state of the wing. This is due not only to an increase in lift due to a change in the curvature of the wing and an increase in the wing area, but also a change in the position of the center of pressure relative to the wing chord. A significant increase in torque leads to a change in the stress-strain state of the wing mean joints. An aerodynamic calculation was performed using ANSYS CFX to obtain the position of the point of action of the lift force in each elements of the wing (slat, wing box and flap). Were obtained the relative positions of the points of action of the lift of individual parts of the wing: the slat, the wing box and the flap. These values were used to apply the forces acting from the high - lift system. The distributed air load was proportionally distributed across the slat, wing box and flap in accordance with the obtained aerodynamic calculations using ANSYS CFX. Plots of internal force factors were plotted, such as a diagram of shear force, bending and torque for wing configurations without extended high - lift system, as well as with takeoff and landing positions of high - lift system. Obtaining the value of the internal force factors, were used to create calculation models. The structural elements of the wing, in particular the attachment points of the high - lift system, operate in a complexly stressed state. This complicates the process of predicting the fatigue life of these elements. To obtain a competitive aircraft, it is necessary to develop new methods of wing design with widespread use of integrated systems. The study of the change in the stress-strain state of the wing with the extended position of the high - lift system makes it possible to predict the fatigue life with high accuracy. The process of creating and preparing a wing model for calculation, setting boundary conditions and choosing the optimal size of a mesh element is described. Obtaining aerodynamic characteristics using a CAE system to create a design model.

scholarly journals АНАЛІЗ СИЛ ФУНКЦІОНУВАННЯ ВІД’ЄМНОЇ ЧАСТИНИ КРИЛА ЛІТАКА ТРАНСПОРТНОЇ КАТЕГОРІЇ

2021 ◽  
pp. 4-20
Author(s):  
А. Г. Гребеников ◽  
Д. Ю. Жиряков
Keyword(s):  
Fatigue Life ◽  
Strain State ◽  
Integrated Design ◽  
Complex Stressed State ◽  
Design Element ◽  
Structural Elements ◽  
Wing Design ◽  
Stress Strain ◽  
High Lift ◽  
Stress Strain State

Each experimental design department has experience in determining design and operational loads for a given type of aircraft. The reliability of the data on the loading of a particular structural element determines the success of the aircraft being created. This is often confidential information. Much work has been investigated to improve the fatigue life of wing structural elements. With the development of integrated design methods, aircraft structure design can be performed in the shortest time, and with high technical excellence. In most cases, the fatigue life of wing elements is determined from the nominal stresses in the element. For a longitudinal structure set, it is customary to perform fatigue calculations directly using normal stresses in the element. For a more detailed specification of the fatigue life, it is necessary to have a general and local stress-strain state of a given structure. A feature of the work is to analyze the spectrum of loads acting on the wing console during a typical flight. The influence of high-lift devises (slats, flaps) on the shear forces and torque moment of the wing was analyzed. It has been shown that with the extensions high-lift devices, there is a significant increase in torque. These articles will make it possible to obtain the stress distribution of the detachable part of the wing under all operating modes. This, in turn, leads to a more thorough prediction of fatigue life. Since some operating loads can significantly change the distribution of the stress-strain state in the design element, and in turn change the fatigue life. The structural elements of the wing, in particular the attachment points for the high-lift devices, operate in a complex-stressed state. This complicates the process of predicting the fatigue life of these elements. To obtain a competitive aircraft, it is necessary to develop new methods of wing design with widespread use of integrated systems. This will contribute to obtaining a more optimal and perfect wing design

Prediction of contact-fatigue damage to rails using computational-experimental methods

2020 ◽  
Vol 86 (4) ◽  
pp. 46-55
Author(s):  
N. A. Makhutov ◽  
V. S. Kossov ◽  
E. S. Oganyan ◽  
G. M. Volokhov ◽  
M. N. Ovechnikov ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Service Life ◽  
Software Package ◽  
Strain State ◽  
Contact Fatigue ◽  
Cumulative Distribution ◽  
Stress Strain ◽  
Stress Strain State ◽  
Contact Fatigue Life ◽  
The Impact

Analysis of the operational data related to rails failure showed that contact-fatigue defects consistently hold a prominent place. The goal of the study is to show the possibilities of using modern numerical methods in calculation assessment of the service life of rails before the onset of contact fatigue crack formation on a running surface depending on the values of axial load. To calculate a stress-strain state in the area of contact interaction between the wheel and rail a detailed finite-element model implemented in the MSC. Marc software package is used. The analysis revealed complex multiaxial and non-proportional nature of the stress-strain state. The Brown – Miller multiaxial fatigue model implemented in the MSC. Fatigue software package was taken to determine accumulation of the contact fatigue damages on a rail running surface. The model is based on the assumption that maximum fatigue damages in the metal occur in the area with the maximum shear stress. The impact of normal stresses in this area is also taken into account. The results of a comparative computational analysis of the rail life time confirm that the service life decreases with increasing axial loads, all other conditions being the same. With a share of 20% of freight trains with axle loads of 25 tonf in a daily pattern one should expect a decrease in the contact fatigue life of rails by 3 – 4 %. It is possible to improve the method for prediction of the contact fatigue life of rails in terms of experimental definition of the fatigue and strength characteristics of the rail steel depending on the degree of hardening of the running surface, their probabilistic properties and the use of a cumulative distribution of vertical forces taking into account the structure of the freight traffic passing through the section.

scholarly journals The investigation of the stress-strain state of beam crossings with a truss-form supporting element of the operating pipeline

2020 ◽  
pp. 71-84
Author(s):  
Т. Yu. Pyrih ◽  
Ya. V. Doroshenko ◽  
Ya. І. Matviichuk
Keyword(s):  
Strain State ◽  
Bending Moment ◽  
Isosceles Triangle ◽  
Internal Force ◽  
Gas Pipeline ◽  
Stress Strain ◽  
Scientific Publications ◽  
Stress Strain State ◽  
Supporting Element ◽  
Longitudinal Strains

The areas of application and advantages of the over-ground piping or pipe section layout are given. The classification according to the design features of the most common systems of overhead pipeline crossings on the basis of generalization of scientific publications and experience of pipeline construction are considered. The authors indicate the ranges of the effective spans for rectilinear single-span and multi-span crossings without compensators of longitudinal strains (with the fixed ends) and also in multi-span systems with compensators depending on the diameter of pipes, nominal pipe wall thickness and brand of pipe steel for gas, oil and oil-products pipelines respectively. The description of the design of beam systems of overhead pipeline crossings with a truss-form supporting element of the operating pipeline is given and the procedure for estimating their stress-strain state is suggested. According to the constructed cargo and unit calculation schemes of the truss with a cross-section in the form of an isosceles triangle (height – 3 m, width – 2.02 m) the stiffness coefficients of elastic-malleable supports is determined. The selection of cross-sections of truss members is carried out, the required deflections of the pipeline and the emerging internal force factors (bending moments and reactions of elastic-malleable supports) at the points where the pipeline rests on the truss are found. The strength of the pipeline to the action of the maximum bending moment is checked and the possibility of the cross-water layout of the beam crossing of the gas pipeline is shown. This is the  gas pipeline with the length of . It has compensators with a truss-form supporting element which eliminates the use of intermediate supports. Thus, it was shown that the truss makes it possible to double or triple the length of the span using no intermediate supports and preserving sufficient horizontal rigidity.

scholarly journals METHODS DEVELOPMENT OF STRENGTH AND RELIABILITY ANALYSIS OF ROLLING-STOCK BEARING STRUCTURE USING MATHEMATICAL MODELING METHODS

2020 ◽  
Vol 2020 (3) ◽  
pp. 29-37
Author(s):  
Vladimir Kobishchanov ◽  
Dmitriy Antipin ◽  
Dmitriy Rasin ◽  
Marina Manueva
Keyword(s):  
Mathematical Modeling ◽  
Finite Element ◽  
Fatigue Life ◽  
Strain State ◽  
Rolling Stock ◽  
Finite Element Models ◽  
Stress Strain ◽  
Stress Strain State ◽  
Bearing Structure ◽  
Pivot Joint

The purpose of the work is a procedure formation for the analysis of strength and reliability of rolling-stock bearing structure using methods of mathematical modeling. Its appraisal is shown by the example of improvements in a universal gondola car bearing structure. The procedure offered is formed by a mathematical modeling of bearing structure dynamic loading in the rolling-stock operation including shunting movement encounters. At the first stage of the procedure the dynamic computer simulations of a rail crew movement on way roughness are under development. As a result of modeling there are defined dynamic loads influencing a bearing structure in operation. The analysis of the stress-strain state of the bearing structure is carried out on the basis of detailed shell finite element models. The computation is carried out in a dynamic position through the method of the direct integration of nodal-relocation equations. The estimate of bearing structures fatigue life in a pivot area was carried out on the basis of the linear hypothesis of fatigue damages summation, the power approximation of a material fatigue curve and scheming dynamic stresses affecting the structure through the method of complete cycles. Within the limits of the procedure the history of loading was presented as a step function. On the basis of the results of a stress-strain state in the bearing structure of a gondola car body in a static and dynamic location there is carried out the analysis of fatigue life in a pivot area of the gondola car and the conclusions were drawn regarding crack-like defect occurrence in a center plate arrangement of a frame. There are offered three versions for updating the pivot joint of a gondola car with the purpose of its fatigue life increase. For each version of updating there are developed corresponding detailed finite element models of the pivot area and on their basis the analysis of strength and fatigue life is performed. On the basis of computation results and taking into account the manufacturability of center plate arrangement production an efficient version is recommended for updating a pivot joint of a gondola car. The pivot joint modernization according to the version offered allowed decreasing maximum acting stresses in the pivot joint by 27% and increasing service life of the welded joint elements up to 29 years.

КОНСТРУКТИВНО-ТЕХНОЛОГІЧНІ ОСОБЛИВОСТІ ХВОСТО-ВИХ БАЛОК СІТЧАСТОГО ТИПУ З ПОЛІМЕРНИХ КОМПО-ЗИЦІЙНИХ МАТЕРІАЛІВ ВЕРТОЛЬОТІВ ТРАНСПОРТНОЇ КАТЕГОРІЇ

2020 ◽  
pp. 15-30
Author(s):  
А. Г. Гребеников ◽  
И. В. Малков ◽  
В. А. Урбанович ◽  
Н. И. Москаленко ◽  
Д. С. Колодийчик
Keyword(s):  
Finite Element ◽  
Strain State ◽  
Layer Structure ◽  
Metal Structure ◽  
Element Model ◽  
Stress Strain ◽  
Element Analysis ◽  
Mesh Structure ◽  
Stress Strain State ◽  
Mesh Structures

The analysis of the design and technological features of the tail boom (ТB) of a helicopter made of polymer composite materials (PCM) is carried out.Three structural and technological concepts are distinguished - semi-monocoque (reinforced metal structure), monocoque (three-layer structure) and mesh-type structure. The high weight and economic efficiency of mesh structures is shown, which allows them to be used in aerospace engineering. The physicomechanical characteristics of the network structures are estimated and their uniqueness is shown. The use of mesh structures can reduce the weight of the product by a factor of two or more.The stress-strain state (SSS) of the proposed tail boom design is determined. The analysis of methods for calculating the characteristics of the total SSS of conical mesh shells is carried out. The design of the tail boom is presented, the design diagram of the tail boom of the transport category rotorcraft is developed. A finite element model was created using the Siemens NX 7.5 system. The calculation of the stress-strain state (SSS) of the HC of the helicopter was carried out on the basis of the developed structural scheme using the Advanced Simulation module of the Siemens NX 7.5 system. The main zones of probable fatigue failure of tail booms are determined. Finite Element Analysis (FEA) provides a theoretical basis for design decisions.Shown is the effect of the type of technological process selected for the production of the tail boom on the strength of the HB structure. The stability of the characteristics of the PCM tail boom largely depends on the extent to which its design is suitable for the use of mechanized and automated production processes.A method for the manufacture of a helicopter tail boom from PCM by the automated winding method is proposed. A variant of computer modeling of the tail boom of a mesh structure made of PCM is shown.The automated winding technology can be recommended for implementation in the design of the composite tail boom of the Mi-2 and Mi-8 helicopters.

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