scholarly journals Metal structure prediction in cross-wedge rolling processes

Author(s):  
G. V. Kozhevnikova ◽  
A. A. Abramov ◽  
K. A. Klimov

A method of computer prediction of the size of metal grains, their disorientation, grain boundaries and dislocation density, depending on the modes of cross-wedge rolling, is considered. The regularities of the formation of the parameters of the metal structure depending on the stress state are revealed by methods of computer simulation. The stress state is described by two parameters: the average stress and the parameter of the third invariant of the stress deviator. The effect of the stress state in the deformation zone on the metal structure parameters was determined for the first time. The new method allows improvement of the quality of products by computer optimization of rolling modes. The results of determining the metal structure and parameters of the stress-strain state in the deformation zone during hot rolling of the water pump shaft of steel 45 are presented. The verification and analysis of the data of virtual experiments on the formation of the structure of structural steels in the processes of cross-wedge rolling are carried out. To analyze the output data of the simulation, the parameters for predicting the calculation of grain boundaries and grain size were used. The created computer model for predicting the characteristics of metal structures, depending on the modes of plastic deformation, provides, at minimal cost and without carrying out field experiments, finding the optimal thermodynamic and stress-strain modes of plastic flow of metal, which guarantee the highest operational properties of the products obtained.

Author(s):  
G. V. Kozhevnikova

The peculiarity of cross-wedge rolling with one tool is the workpiece deformation with one tool and the fact that the workpiece is not supported with the tool from the opposite side. On both sides of the tool outside the contact with the workpiece, the workpiece is fixed with pairs of upper and lower tools, by means of which the axis of the workpiece is held in a constant position. Such conditions of rolling qualitatively change the deformation zone and, as a result, the stress-strain state.The change in the stress-strain state was qualitatively estimated by comparing the fields of slip lines in the traditional two-tools cross rolling and one-tool cross rolling. One-tool cross rolling increases the normal and average stress at the contact by 7.8–14.5 %, changes the average stress of the specimen from tensile to compressive one in the axial region. This circumstance significantly increases the resource of plasticity and allows rolling metals with limited plasticity without opening the axial cavity. Comparative studies of the stress-strain state from the traditional two-tools cross-wedge rolling and one-tool cross-wedge rolling in the axial region of the workpiece have been carried out by computer simulation.


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):  
P.I. Shalupina ◽  
◽  
Yu.V. Ragulina ◽  

The article deals with the issues of modeling the stress-strain state of a traction device designed for towing a heavy semi-trailer, on which the equipment of the base station of a mobile transport and reloading rope complex is placed. The main design loads are defined. Geometric and computational finite element models are constructed, taking into account the features of the metal structure. The method of gluing elements of the grid model is applied. On the basis of the performed calculations, conclusions are drawn about the compliance of the developed structure with the requirements of strength.


2020 ◽  
Vol 29 (6) ◽  
pp. 3906-3912
Author(s):  
Zhiquan Huang ◽  
Chuanlu Qi ◽  
Guowei Yang ◽  
Hongyu Lai ◽  
Yanchun Zhu ◽  
...  

2018 ◽  
Vol 284 ◽  
pp. 1332-1336
Author(s):  
N.L. Zaytsev

At the present time the assessment of stress-strain state of steel structures uses the results of coercive measurements. However, the methods presented in various works are contradictory and not deprived of errors of a methodological nature, which may lead to erroneous conclusions. This article reveals the analysis of disadvantages of the known methods and proposes possible ways to eliminate these shortcomings.


Author(s):  
Yury Melnik ◽  
Semen Zaides ◽  
Nikolaj Bobrovskij ◽  
Ngo Cao Cuong ◽  
Olesja Levitskih ◽  
...  

2017 ◽  
Vol 746 ◽  
pp. 3-9
Author(s):  
Vladimir G. Kolobov ◽  
Evgenii V. Aryshenskii ◽  
Yaroslav A. Erisov ◽  
Alexander Nam ◽  
Maksim S. Tepterev

The present study investigates the process of beverage can end forming from 5182 aluminum alloy. Stress-strain state during forming is analyzed using finite element method in PAM-Stamp 2G, and fracturing probability is evaluated based on V.L. Kolmogorov’s fracture criterion. It is established, that stress state does not provide the sufficient plasticity margin during ends forming. Blank material plasticity resource is depleted during preliminary and reverse drawing stages, defects accumulation during countersink forming is negligible. Minimum relative elongation value, responsible for fracture-free end forming, is 6% in the rolling direction.


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