scholarly journals Application of Numerical Methods for Research of Construction Design of Fastener Fractures

2021 ◽  
Vol 15 (2) ◽  
pp. 178-183
Author(s):  
Leonid V. Kolomiets ◽  
Aleksej Aniskin ◽  
Viktor F. Orobey ◽  
Alexander Daschenko ◽  
Aleksandr M. Lymarenko ◽  
...  
Keyword(s):  
Numerical Methods ◽  
Analytical Method ◽  
Strain State ◽  
General System ◽  
Boundary Elements ◽  
Cauchy Problems ◽  
Deformable Solid ◽  
Stress Strain ◽  
Stress Strain State ◽  
Method Of Boundary Elements

The work uses modern numerical methods of mechanics of a deformable solid to analyze the stress-strain state of orthopedic structures in order to improve them and improve the quality of treatment of patients. Among the many numerical methods, the attention of the authors was drawn to the finite element method and to the numerical and analytical method of boundary elements in the author's edition. Settlement models of both metal apparatuses and parts of a person’s arm with a fracture are constructed. The stress – strain state in various zones of the biomechanical system was calculated. It is shown that the numerical-analytical method of boundary elements allows obtaining more accurate results with fewer equations in the resolution system. It is noted that in the case of the considered biomechanical systems, its elements undergo tension – compression, shear, torsion, and bending. To consider them, solutions are presented for Cauchy problems, which are included in the general system of resolving equations of the MGE. It is shown that, unlike the FEM, the MGE simplifies the algorithm for calculating biomechanical systems. Comparison with the FEM results shows their good agreement, which proves the reliability of the calculation results of both methods.

ANALYSIS OF THE KINETICS AND DIRECTIONALITY OF ELASTOPLASTIC DEFORMATION AND FRACTURE

2019 ◽  
Vol 85 (6) ◽  
pp. 47-52
Author(s):  
N. A. Makhutov ◽  
I. V. Makarenko ◽  
L. V. Makarenko
Keyword(s):  
Numerical Methods ◽  
Fracture Mechanics ◽  
Fracture Surface ◽  
Elastoplastic Deformation ◽  
Strain State ◽  
Stress Strain ◽  
Nonlinear Fracture Mechanics ◽  
Stress Strain State ◽  
Nonlinear Fracture ◽  
Cycle Loading

Safety, survivability, and serviceability of the equipment are governed by the strength characteristics of the separate units and elements which can contain initial or operational defects such as superficial differently oriented semi-elliptical cracks. Numerical methods of calculation provide a large bulk of information about the stress-strain state (SSS) of those elements proceeding from the given algorithms for calculating the corresponding fracture models. Change in the type of the SSS near the crack contour when going from the bulk to the surface depends on the constraint of deformations along their front, i.e., on the 3D character of the SSS. Diagnostics of the form change of the defects (surface differently oriented semi-elliptic low-cycle cracks) is carried out on the basis of experimental results and numerical solutions. The data of the finite element modeling are implemented on the basis of macros of the ANSYS program complex. The regularity of the directionality of developing the elastoplastic fracture under low-cycle loading is studied. The proposed methodology is proved by the parametric equations of the kinetics of forming changes of the cracks under study in the fractographic analysis of the surfaces of their development. The results of testing samples with semi-elliptic cracks under low-cycle loading are used in analysis of the parameters of the morphology of the surfaces of the developed defects. The results of measuring fields of elastoplastic deformation intensity in the crack tip and geometrical characteristics of the fracture surface development are presented. Analysis of the dynamics of the local stress-strain state near the contour of multi-oriented defects in parts and structural units of the equipment showed a good agreement between the experimental parameters of the geometry of developing cracks and characteristics obtained by numerical methods. The presented parametric equations specify the characteristics of nonlinear fracture mechanics thus providing reliable estimation and forecasting of survivability, and safety of serviceability of the critical equipment. The deformation criteria of nonlinear fracture mechanics are used to demonstrate the dependence of fracture development on the 3D character of the stress-strain state indicating to the directionality of the geometric development of the fracture surface form.

scholarly journals Pore pressure when compacting two-phase soil

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Elefhan Agakhanov ◽  
Murad Agakhanov
Keyword(s):  
Pore Pressure ◽  
Strain State ◽  
Solid Mechanics ◽  
Water Pressure ◽  
Deformable Solid ◽  
Stress Strain ◽  
Two Phase ◽  
Tangential Stresses ◽  
Stress Strain State ◽  
Special Cases

In modern conditions, in relation to the total amount of accumulated professional knowledge, the volume of active information resources increases, and construction practice is constantly enriched with new experimentally-theoretically based accurate knowledge. Therefore, various programs are widely used when solving problems in ground bases. Despite the fact that modern numerical methods allow solving problems of any complexity, it should be noted that experimental and analytical methods are still relevant, and it is an effective combination of methods that leads to the development of mechanics, an organic combination of experimental research methods with the enormous computational capabilities of modern supercomputers. Methods for modeling the action of bulk forces are widely used in problems of deformable solid mechanics. Many known solutions have limitations and are given for special cases. The authors present the theoretical foundations of the elastic analogy method for modeling the effect of pore pressure on the soil. When posing the question, the following assumption is made that the liquid filling the pores of the soil does not perceive shear deformation. Tangential stresses that occur in the ground are only perceived by the ground skeleton. The water that fills the pores does not resist tangential stresses. In this case, the deformation of the soil skeleton from the action of hydrostatic water pressure, respectively, is a volumetric deformation. In this case, the components of the ball stress tensor are equal to the pore pressure. The article considers the use of the theory of volume forces in modeling the effect of pore pressure in the process of compaction of two-phase soil. In this case, we consider a one-dimensional problem for the case of deformation (compaction) of a two-phase soil layer thickness under the action of a distributed load of constant intensity. We believe that the consolidated layer lies on a rocky undeformable base. The authors consider various drainage conditions for the surfaces of the consolidated layer. Expressions are given for determining stresses and precipitation with creep, for the instantaneous stress-strain state and the final stress-strain state.

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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