Vol 47, No 6 (2018)

The spatial vibrations of a pipeline and the fluid inside it are considered with respect to the horizontal axis passing through supports under the action of internal shock pressure. The coupling between the internal pressure, curvature variation, and deformation of the pipeline circumference is taken into account. The bending and torsional deformations of the pipeline are divided into two sequential stages: inertial and inertial-elastic. The first support is rigid and fixed, and the second support may translate frictionlessly in the horizontal direction. Numerical modeling is performed. The analysis of the calculation results is given for special parameter values. The approximated analytical solutions are also presented.

In this paper, we developed and tested new protective devices, such as resonant stabilizers of wave processes, which allow completely neutralizing the negative impact of vibrations and hydraulic shocks in pipelines. The resonant stabilizer has significantly smaller (by 5–10 times) dimensions, material consumption, and competitive cost and does not require the use of additional pumping equipment, automation systems, and tanks, which, along with the simplification of operations, significantly increases the efficiency and reliability of the pipeline systems.

The basic concepts of an applied technique of finite-element inelastic analysis are presented for the connections of intersecting shells. The determination of the limit load as a parameter that assigns the bearing capacity to a structure is also presented. The results of computations with the developed program SAIS are compared to the experimental results obtained by testing a cylindrical vessel model with a nonradial branch pipe. The dependencies for the nonradial connections are provided, which show a significant decrease in the limit load when the branch pipe is inclined from the radial position. The results of the parametric analysis are given, which demonstrate the effect of the inclination angle of the branch pipe and the diameter ratio of the branch pipe and vessel on the value of the limit load.

The problem of reduction of the mass of parts due to an increase in the strength characteristics of the material of these parts by forming an ultrafine grain structure using the method of combined severe deformation including multiaxial forging with further upsetting with torsion is solved. The results of mechanical tensile tests and metallographic tests of titanium are presented, as are the thermal processing modes increasing the plasticity while keeping sufficiently high strength characteristics, which allow selecting the thermomechanical processing parameters required for a certain article.

This paper presents research results concerning the influence of ultrasonic burnishing on the structure and mechanical properties of ultra-fine grain titanium alloys: commercial pure titanium BT1-0 and an over stoichiometric alloy with the shape memory Ti_49.3Ni_50.7. It was shown by the methods of optical microscopy and transmission electronic microscopy that in the surface layer of 20 μm thickness, the ultrasonic burnishing in coarse-grained titanium forms a nanostructure with a grain size of 100 nm, and it additionally decreases the size of crystals from 100 to 30 nm in the nanostructural titanium nickelide. The ultrasonic treatment of alloys greatly increases the strength and micro- and nanohardness of the surface layer, decreases the roughness, forms the gradient nanostructure, improves the lifetime, and expands the functionalities of the items.

The paper presents the results of metallographic studies of the geometric parameters of hardened zones depending on the laser processing mode. Based on the results of regression analysis, plots were constructed for surfaces showing the effect of the power, velocity, and transverse oscillations of the beam on the width and depth of hardened zones. High-frequency beam scanning increases the performance of laser hardening by 1.6–2.5 times.