Mathematical Simulation of Cramped Bending of Sheet Parts Using Finite Element Analysis

2016 ◽  
Vol 685 ◽  
pp. 186-190 ◽  
Author(s):  
Е.V. Eskina ◽  
E.G. Gromova

The paper describes the method of manufacture of profiles in cramped bending conditions using polyurethaneThe scope of studies included stress-strain state of elastic die and parent sheet, as well as the influence of the basic process parameters on characteristics of the produced items using ANSYS software.

Author(s):  
Volodymyr Maliar

The main destructions of asphalt concrete pavement are rut, transverse cracking, fatigue failures, peeling, etc. When the pavement cools, lowtemperature damages can occur for various reasons. The sources of damages that cause such failures are not well studied, so this problem is relevant. Goal. The aim of this work was to determine the stress-strain state inside the volume of asphalt con-crete during cooling on the basis of a two composite three-dimensional model using the method of computer simulation in response to the changing structured bitumen properties. Methodology. The method of finite element analysis of the stress-strain state of the composite material was used. The material is represented by a three-dimensional (3D) model pro-posed by prof. B.S. Radovsky. Results. The finite element analysis method was used to calculate the average thermal stresses in asphalt concrete during cooling in accordance with increase of viscosity of bitumen section, which is located in asphalt concrete in a structured state. This consideration is realized on the basis of changes in a number of bitumen properties in the contact zone, in particular, the changes in the glass transition temperature. It is shown that the thermal stresses that occur during cooling by limiting the movement of asphalt concrete in the construction reach the strength values at negative temperatures, which can be used to estimate the temperature of crack formation in asphalt concrete under the condi-tion of its action in pavement (Tcr). The values of these stresses depend on the cooling rate, the bitumen content, its viscosity and structure. Originality. For the first time, it was found numerically that in the sample of asphalt concrete, which is free from restriction of movements, there are internal thermal stresses during cooling due to the difference of bitumen thermal expansion coefficients and stone materials. These stresses are up to 87 percent of the average thermal stresses that occur in the compressed sample. Practical value. The possibility of rapid estimation of thermal stresses with the possibility of predicting low-temperature cracks in asphalt concrete is shown.


Author(s):  
А. Г. Гребеников ◽  
И. В. Малков ◽  
В. А. Урбанович ◽  
Н. И. Москаленко ◽  
Д. С. Колодийчик

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.


Author(s):  
Serhii Nemchynov ◽  
Illya Nachovnyy ◽  
Alexander Khristenko ◽  
Vasyl Babenko

In the article the stress-strain state of the main cylinder of the hydraulic press for the manufacturing of large-sized plastic products has been investigated using software of finite-element analysis. It is established that the stress-strain state is characterized by a general and local uneven distribution of stresses and displacements. The nature of the distribution of stresses, deformations, displacements, safety factors along the length of the cylinder allowed conditionally divide the cylinder into three characteristic zones: flange zone, Lame zone, bottom zone. In each of the zones we found the areas in which the maximum stresses and strains are observed. It was found that the maximum equivalent stresses calculated according to the Huber-Mises energy theory of strength are observed on the inner surface of the cylinder, and in their fillets in the zones of the bottom and flange. A comparative analysis of the stresses and displacements determined by the Lame formulas and the finite element method showed that in the Lame zone their values do not change significantly. Studies on the influence of the radius, which varied over a wide range, and the fillet angle, made it possible to establish the region of maximum principal and equivalent stresses and reduce their magnitude. The calculations revealed the fillet region in which the axial tensile stresses act and determine the fillet angle at which the axial stresses are equal in magnitude and sign The study allowed to change the geometry of the cylinder, reduce the stress in the cylinder fillet and its weight. The results of the study can be applied to improve the existing and design of new hydraulic presses of the chemical industry, as well as the basis for further research.


Author(s):  
Рetro Reznik ◽  
Sergiy Grebenchuk ◽  
Roman Koreniev ◽  
Vitaliy Bondarenko

The article deals with coatings in the form of the specific steel shells. After a detailed analysis certain number of accidentsand collapses, these collapses can be classified as “progressive” collapse. The main purpose of the article is the developmentof design algorithms for evaluation of the stress-strain state and preventing the progressive collapse of the specific steelshells. The method of prevention progressive collapse has been developed in the form of a constructive modernization.The comparative finite-element analysis of the strained-strain state of the specific shells original models, models of discretecontinualribbed shells (with constructive upgrading) and models of solid ribbed shells has been carried out. From the analysisresults it can be concluded that the proposed modernization method can be considered as one of the possible options forpreventing progressive collapses and increasing the bearing capacity of specific steel shells.


Author(s):  
L.L. Myagkov ◽  
S.M. Sivachev

The failure of aluminum pistons of diesel engines is often associated with formation of cracks originating at the bowl rim. The appearance of cracks is a consequence of thermal fatigue of the material due to low-frequency cycles of heating and cooling of the piston during the engine start-up, operation at various speed and load conditions, and subsequent shutdown. To assess the lifetime of the bowl rim, it is necessary to simulate non-isothermal elastoplastic deformation of the alloy using material plasticity and creep models available in finite element analysis software (e.g. ANSYS). This paper presents the results of uniaxial tensile and creep tests of proportional specimens made from piston blanks of the V-type diesel engines YaMZ-658. The piston material is AlSi12CuNiMg silumin alloy. The article describes methods for determining constants in plasticity and creep models. The results of numerical simulation of the piston’s stress-strain state for the start — nominal power mode — stop cycle using the finite element method are presented. Conclusions about the presence of plastic and creep strains at the piston edge are drawn.


2019 ◽  
Vol 135 (5) ◽  
pp. 5-13
Author(s):  
Petr V. Burkov ◽  
◽  
Petr V. Burkov ◽  
Vladimir P. Burkov ◽  
Damir L. Vakhitov ◽  
...  

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