Stress-strain state of a half-space in the neighborhood of a stiff sphere subjected to a normal load

1988 ◽  
Vol 24 (4) ◽  
pp. 331-336
Author(s):  
I. K. Senchenkov ◽  
V. I. Kozlov ◽  
I. G. Rubtsova ◽  
A. B. Oleinikov
Keyword(s):  
Half Space ◽  
Strain State ◽  
Normal Load ◽  
Stress Strain ◽  
Stress Strain State

NUMERICAL INVESTIGATION OF THERMOMECHANICAL PROCESSES UNDER SHORT-PULSED LASER IRRADIATION OF A HALF-SPACE

2021 ◽  
Vol 6 ◽  
pp. 55-65
Author(s):  
Kamila Storchak ◽  
◽  
Nina Yakovenko ◽  
Olga Polonevych ◽  
Irina Sribna ◽  
...  
Keyword(s):  
Residual Stress ◽  
Laser Irradiation ◽  
Half Space ◽  
Strain State ◽  
Thermal Stresses ◽  
Equations Of Motion ◽  
Thermomechanical Loading ◽  
Stress Strain ◽  
Stress Strain State ◽  
Residual Strains

The laser irradiation of metallic surfaces by intense heat sources is used for the generation of short probing pulses, which propagate into thin specimens and enable one to estimate their structure and mechanical properties within the framework of the classical acoustic approach. High thermal stresses and residual strains occur during the short-term irradiation of the surface of a construction by an energy source of high density. In the present work, we solve the axially symmetric problem of a half-space under thermomechanical loading. We take into account the influence of volume and inelastic characteristics of separate phases on the residual stress-strain state of the half-space. The statement of the problem includes: Cauchy relations, equations of motion, heat conduction equation, initial conditions, thermal and mechanical boundary conditions. The thermomechanical behavior of an isotropic material is described by the Bodner-Partom unified model of flow. The problem is solved with using the finite element technique. The numerical realization of our problem is performed with the help of step-by-step time integration. The equations of motion are integrated by the Newmark method. The residual stress-strain state is described using the method of numerical solution of the axisymmetric dynamic problem for a half-space under thermomechanical loading and the flow model. We established that microstructural transformations, which are taken into account due to the thermophase volume strain and dependence of inelastic characteristics of the material on the phase composition, significantly reduce residual inelastic strain and promote the appearance of compressive stresses. The three-zone region of residual stresses field formation is obtained.

Indentation of the cylindrical shell in the elastoplastic half-space

2018 ◽  
Vol 13 (3) ◽  
pp. 47-51
Author(s):  
A.A. Filippov
Keyword(s):  
Cylindrical Shell ◽  
Stress State ◽  
Half Space ◽  
Safety Factor ◽  
Strain State ◽  
Fracture Criterion ◽  
Steel Shell ◽  
Stress Strain ◽  
Stress Strain State ◽  
Steel Cylindrical Shell

The article deals with the problem of pressing the steel cylindrical shell into the elastoplastic half-space having a cylindrical concavity. The calculation and analysis of the stress-strain state of the steel shell and elastoplastic half-space. Given the dependence of the shear half-space, the safety factor and stress state in steel shell from the force pushing the shell in the half-space. The calculations were carried out for three radii of concavities and two types of half-space materials. It was assumed that the elastoplastic half-space obeys the Mohr-Coulomb fracture criterion.

APPROXIMATE DETERMINATION OF GEOMETRIC PARAMETERS OF THE SAG FOLLOWING THE EMBEDDING OF A PARABOLOID INDENTER INTO A HALF-SPACE

2021 ◽  
pp. 39-47
Author(s):  
Ali Yu. Albagachiev ◽  
◽  
A.M. Moiseenko ◽  
E.V. Zernov ◽  
A.V. Lut’yanov ◽  
...  
Keyword(s):  
Surface Layer ◽  
Analytical Solution ◽  
Half Space ◽  
Strain State ◽  
Geometric Parameters ◽  
Approximate Determination ◽  
Depth Of Penetration ◽  
Stress Strain ◽  
Stress Strain State

The problem of the indenter embedding into a half-space is formulated and solved. A concept of the elastic contact is used, which implies the uniformity of the stress-strain state in a surface layer. The process of the surface layer formation after mechanical treatment is studied. Based on the general theory of indenter penetration into a half-space, numerical and analytical solutions, determining the length and depth of penetration of a paraboloid into elastoplastic space, are obtained. According to the theory of indentation, the problem is reduced to the use of the method of approximate determination of geometric parameters of a bead, when a paraboloid is being embedded into elastoplastic space. An exact solution to the formulated problem allows one to obtain analytical dependences for calculating the velocities and to study the stress-strain state of the material in the half-space surface layer during the processing. The reliability of the obtained analytical solution is confirmed by numerical calculations without introducing additional hypotheses. Based on the analytical solution, the geometric parameters of the influx from the penetration depth are determined. Calculations can be performed at any embedding depth. Sag formation during the indenter embedding by 18 mm into plasticine specimens is considered as an example. It is shown that the rigid zone is insignificant or absent.

Microgeometrical characteristics of electrospark coatings in the initial state

2020 ◽  
Vol 98 (4) ◽  
pp. 33-39
Author(s):  
V. Tokaruk ◽  
◽  
O. Mikosianchyk ◽  
R. Mnatsakanov ◽  
N. Rohozhyna ◽  
...  
Keyword(s):  
Strain State ◽  
Normal Load ◽  
Base Material ◽  
Arithmetic Mean ◽  
Surface Plastic ◽  
Initial State ◽  
Stress Strain ◽  
Element Analysis ◽  
Electrospark Coating ◽  
Stress Strain State

Microgeometric parameters of the effect of discrete electrospark coatings on their stress-strain state have been evaluated for the case of using a combined technology of modification of duralumin D16, which includes the technique of electrospark alloying with subsequent surface plastic deformation of coatings formed. According to the profilograms of discrete electrical coatings, the curves of the bearing surface (Abbott curves) were constructed and the parameters that drastically affect tribological characteristics of the coatings were determined. It was shown that modification of duralumin D16 with a combined electrospark coating VK-8 + Cu reduces the arithmetic mean height of peaks in the top portion of the profile by 4.4 and 3.2 times, doubles the arithmetic mean depth of the profile core irregularities, increases the arithmetic mean depth of profile valleys by 1.8 and 1.1 times, in comparison with electrospark coatings from hard alloy VK-8 and copper, respectively. These parameters help to reduce the period of running-in of the contact surfaces strengthened by the combined electrospark coating VK-8 + Cu, increase their bearing capacity, contact durability and specific oil consumption. On the basis of the finite element analysis method of the Nastran software complex, a model of the stress-strain state of a discrete coating/base was designed and distribution of the main normal stresses was determined for a coating compactness of 60% under a normal load of 600 N. The performed modeling revealed advantages of a combined technology for formation of wear-resistant electrospark coatings, which consists in turning residual tensile stresses into compressive ones. When modifying the duralumin D16 with a VK-8 + Cu coating, on the coating surface and in the base material, compressive stresses (-93 MPa and -20 MPa, respectively) are formed, which provides a decrease in wear of the modified surface by two times compared to unmodified duralumin D16.

Stress-strain state of a half-space with shear displacement and rotation of a rigid sphere partly embedded in it

1991 ◽  
Vol 27 (1) ◽  
pp. 21-27
Author(s):  
I. K. Senchenkov ◽  
V. G. Savchenko ◽  
O. P. Chervinko ◽  
V. I. Bobyr'
Keyword(s):  
Half Space ◽  
Strain State ◽  
Shear Displacement ◽  
Rigid Sphere ◽  
Stress Strain ◽  
Stress Strain State
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