Analysis of the stress-strain state in zones of concentration under repea static loading

1988 ◽  
Vol 20 (11) ◽  
pp. 1452-1455
Author(s):  
V. I. Dobrovol'skii
2018 ◽  
Vol 272 ◽  
pp. 244-249 ◽  
Author(s):  
Volha Semianiuk ◽  
Viktar V. Tur

Fiber reinforced polymer (FRP) bars are widely used in building structures, especially that are exposed to the aggressive environment influence and other special conditions. Nevertheless, due to the low FRP (e.g. glass, basalt, aramid fibers reinforced polymers) bars modulus of elasticity, exceeding crack opening width, as well as deflections can be observed. FRP bars pretensioning is considered as an effective method of its structural performance increasing. Physico-chemical method of the FRP bars pretensioning based on the self-stressing concrete utilizing is an alternative to the mechanical method and in its turn doesn’t need for special devices and anchorage systems as well as qualified personnel. Assessment of the initial stress-strain state obtained during self-stressing concrete expansion stage in the reinforced self-stressed members is presented. Diagram method of the self-stressing parameters verification based on the static loading tests results is presented. Comparison of the initial stress-strain state obtained during concrete expansion stage and predicted by the proposed model, as well as assessment of its influence on the behavior at the static loading stage in cases of the self-stressed reinforced with FRP bars members and traditionally reinforced with steel bars self-stressed members was performed.


2020 ◽  
pp. 28-36
Author(s):  
Volodymyr Sedin ◽  
Vladyslav Kovba ◽  
Yurii Volnianskyi ◽  
Kateryna Bikus

A full-scale experiment was conducted to study the operation of a multi-helix screw pile under static pressing and pulling load in dusty clay soil. Based on the full-scale test of a multi-helix screw pile under static loading in dusty clay soil, numerical modeling of the stress-strain state of the base of the multi-helix screw pile was performed. Multi-helix screw piles are actively used all over the world, and have also become widespread in Ukraine. Foundations made of multi-helix screw piles are often used for industrial construction as well as the foundations of low-rise buildings and structures. Despite the growing demand for the use of multi-helix screw piles in modern construction, there is no official document calculating the features of their design and bearing capacity of a multi-helix screw pile. This poses a number of new tasks for engineers and geotechnical: a) development of new modern calculation methods; b) development and use of modern normative documents and recommendations for the calculation of foundations from multi-helix screw piles in various soil conditions; с) use of computer-aided design systems for calculation of complex geotechnical tasks; d) development of calculation models that will take into account nonlinear models of deformation of materials and soil base. Foundations made of multi-helix screw piles are a promising direction in the field of foundation construction due to the reduction of the duration of the foundation and its economic. This requires the development of regulations with recommendations for the calculation and use of multi-helix screw piles in the field of foundation construction, development of modern calculation models for the calculation of bearing capacity and settling of multi-helix screw piles in different geological conditions. Based on the results of the field study of the work of multi-helix screw piles in clay soils, numerical modeling of the stress-strain state of the base of the multi-turn pile was performed, and their results were compared.


2020 ◽  
Vol 8 (5) ◽  
pp. 4619-4623

In the article on an example of the autotractor trailer, load-carrying capacity of 4 tons considers the technique for calculating the stress-strain state of the trailer frame. The comparative analysis of results of theoretical and experimental researches is given. It is established, that the deviations of the maximum values of stress at driving on road with tar coating of satisfactory quality is in limits of 4 %, on gravel roads with worn areas - 10 %, on the rotary strip with ridges in height of 8-12 cm and step of 90 cm - 11 %, on a deep ditch depth of 40-45 cm and width 100-150 cm - 9 %.


Author(s):  
А. Г. Гребеников ◽  
И. В. Малков ◽  
В. А. Урбанович ◽  
Н. И. Москаленко ◽  
Д. С. Колодийчик

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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