Modeling of influence of planar defects on plasticity of powder materials by computational methods of micromechanics

2021 ◽  
Vol 2021 (3) ◽  
pp. 77-85
Author(s):  
A. Kuzmov ◽  
◽  
M. Shtern ◽  
P. Korobko ◽  
◽  
...  
Keyword(s):  
Yield Strength ◽  
Strain State ◽  
Internal State ◽  
Unit Cell ◽  
Powder Materials ◽  
Stress Strain ◽  
Damaged Material ◽  
Stress Strain State ◽  
Interparticle Contacts ◽  
Damaged Materials

Based on the energy concept of the critic stress state, a three-parameter model of plasticity of the Cam-Clay type was formulated. For this phenomenological model, the dependences of the determining parameters on the porosity and damage were found by the method of micromechanical averaging on the unit cell corresponding to the porous damaged material of powder origin. The plastic multi-responce (different yield strength in tension and compression) behavior of this material is found by micromechanical averaging on a unit cell. According to the mechanics of composites, the geometry of the cell represents the structure of a heterogeneous material and the boundary conditions on a unit cell make it possible to relate the stress-strain state at the macro- and meso-level. The averaging was carried out by computer simulation using the finite element method with an adaptive mesh, which was automatically condensed in places of a large gradient of the stress-strain state. The structure of the representative cell corresponds to a powder origin material with "imperfect", partially stratified, interparticle contacts. In the proposed model the rheological response of a porous damaged material is specified by three moduli, and the structure of such a material is described by two internal state parameters: porosity and the degree of delamination of interparticle contacts. That is, the rheological moduli are functions of porosity and damage. Accordingly, a number of values of each of the moduli were calculated for a certain discrete range of density and damage. The advantage of this approach is precisely in focusing on powder origin materials and not generally on any damaged materials, which makes it possible to take into account the real structure of the damaged material using the methods of mechanics of microheterogeneous materials. According to the simulation results, in particular, it was found that the yield strength for shear is significantly (30%) less sensitive to damage than the yield strength for uniaxial tension. Keywords: theory of plasticity, powder materials, micromechanics, damaged materials, 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.

Methods and Technologies of Parallel Computing for Mathematical Modeling of Stress-Strain State of Constructions Taking into Account Ductile Fracture

2014 ◽  
Vol 46 (11) ◽  
pp. 23-35 ◽  
Author(s):  
Elena A. Velikoivanenko ◽  
Alexey S. Milenin ◽  
Alexander V. Popov ◽  
Vladimir A. Sidoruk ◽  
Alexander N. Khimich
Keyword(s):  
Mathematical Modeling ◽  
Parallel Computing ◽  
Ductile Fracture ◽  
Strain State ◽  
Stress Strain ◽  
Stress Strain State

Use of Terrestrial Laser Scanning for Assessment of Tank Aluminum Roofs Stress-Strain State

2017 ◽  
pp. 11-17
Author(s):  
G.G. Vasilyev ◽  
◽  
I.A. Leonovich ◽  
A.P. Salnikov ◽  
◽  
...  
Keyword(s):  
Laser Scanning ◽  
Strain State ◽  
Terrestrial Laser Scanning ◽  
Stress Strain ◽  
Stress Strain State
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