A refined method for calculating three-layer structures (TLS) in the zones of edge effects is considered, taking into account the influence of the approach of load-bearing layers on the stress-strain state (SSS) of the TLS. To determine the SSS of TLS, approximating strain distribution functions in the filler are used, which should correspond to the actual work of three-dimensional structures. Keywords: three-layer structure, load-bearing layer, approach of layers, approximating function, filler. hairulla213@mail.ru

Objectives This article discusses the evaluation of the effectiveness of three-layer pipes of a symmetric and asymmetric structure. For this, the stress-strain state of three-layer pipes of different materials under the influence of internal pressure is investigated. Pipeline structures today occupy important positions in the infrastructures of many countries. Trunk structures affect the economy, industry. Every year, new safety requirements are added to the reliability indicators of these structures.Method The calculation is carried out by numerical methods, namely using the finite element method (FEM), implemented in the LIRA PC.Result The calculation of the pipes is performed, on the load from the transported medium, applied to the inner contour of the pipe. Moreover, for three-layer pipes of all variants, Nx tensile stresses along the generatrix, Ny ring tensile stresses and Txy shear stresses in the xy plane were determined. Isopoles of tensile and shear stresses are given.Conclusion The numerical results showed that the use of less deforming material as a material for the manufacture of asymmetric bearing layers leads to a redistribution of stresses in the bearing layers and aggregate, and this must be taken into account when designing three-layer pipes.

Objectives. In this research, we set out to explore the possibility of increasing the resistance of three-layered panels with a pyramid filler filled with fibrous material to dynamic loads. Although issues associated with dynamic impact, penetration of solid bodies and breaking of solid barriers have always been of interest, particularly in military affairs, they are increasingly attracting the attention of researchers investigating various industrial problems.Method. A calculation was performed using the finite element method (FEM), which is widely used in various areas including construction. The possibility of calculating the movement of a solid body in fibrous material using the FEM, namely using the LIRA-SAPR software, was considered.Results. From the constructed models, it can be seen how the striker moves inside the fibrous material. Therefore, using the SC LIRA-SAPR allows the work of the filler to be assessed while a solid body moves inside it. The results of the calculation of striker movement in fibrous material depending on the speed of the body (striker) and the density of the filler (fibre) are shown in figures.Conclusion. The conducted numerical studies showed that a discrepancy between the calculation results for a three-layered structure under dynamic loads using the FEM and analytical dependencies was about 10%.

ObjectivesThis article discusses the evaluation of the possibility of application of three-layer pipelines. For this purpose, the stress-strain state of three-layer pipes under the action of internal pressure is investigated. The largest in the modern world are considered to be the main pipewater. They are mainly used to transport oil and gas from production sites to processing plants. Pipelines are intended for movement of liquid, gases and other environments and first of all it is water pipelines. As you know, main and technological pipelines are IP-elite club that cares only metal buildings, the construction of which consume Xia millions of tons of steel. On the other hand, one of the main indicators of efficiency of trunk pipelines is their material consumption. As a rule, trunk pipelines have a long length, and therefore an unreasonable increase in the even thickness of the pipe walls by at least 1 mm leads to an overspending of steel by de-siyatki and even hundreds of thousands of tons. In this regard, to the calculations of the main pipe wires for strength should be given the most serious attention.MethodsThe calculation is carried out by numerical methods, namely with the help of finite element meto-da (FEM), implemented in the PC "LIRA".ResultsThe calculation of the pipes is performed on the load from the transported medium applied to the inner contour of the pipe. In this case, for the three-layer pipe (the first option) and for the pipes of the second and third options, the ring tensile stresses and strains were determined. The isofields of tensile and shear stresses are given, the comparative graphical dependence of ring tensile stresses is constructed.Conclusion.The obtained numerical results showed that the selected calculation scheme (var.1), that is, the representation of the continuous section of the pipe in the form of a three-layer, is correct. The discrepancies between the data obtained are related to the rotation of the section along the radius of the pipe. In General, the results of calculations showed the possibility of using a three-layer pipe wall for transportation of various media.Acknowledgment.This work was supported by a grant from the President of the Russian Federation (MK-6112.2018.8)

Objective. The development of structures and calculation of metal-wood crane beams are associated with specific difficulties. The article discusses the methods of calculation and design of metal-wood crane beams. In this case, an algorithm is described that allows designing systems that are rational in terms of material consumption. Methods. As an example, a metal-wood beam with a span of 12 m is used, which is supported by overhead cranes with a load capacity of 30 tf. The operation of a metal-wood crane beam was compared with a glue laminate crane beam without reinforcement. The reinforcement elements are "discarded" and replaced with elasto-yielding supports to calculate a glue laminate beam reinforced with metal elements (or a metal-wood beam). The flexibility of these supports is taken into account using the elastic support ratio r, which is determined depending on the stiffness of the supports, and the force in the metal elements is derived from the nodes balance. Result. In both variants of loading metal-wood crane beams, it was shown that the greatest bending moment occurred when the bridge wheel was located above the elastic support. Conclusion. It is rational to use a metal-wood crane beam when operating bridge cranes with a lifting capacity of up to 30 tf; metal-wood crane beams are recommended to be designed with spans up to 12 m; the comparison of glue laminate crane beams with metal-wood beams showed that metal-wood beams were 40-55% more efficient.