Evaluation of the Effect of the Difference between the Real Attachment Unit and the Sealing in the Study of the Stress-Strain State of the Solar Panel of a Small Spacecraft as a Result of a Temperature Shock

2022 ◽  
Vol 904 ◽  
pp. 27-33
Author(s):  
A.V. Sedelnikov ◽  
V.V. Serdakova

The author of this scientific paper studies the stress-strain state of the solar panel of a small spacecraft after a temperature shock. The temperature shock is caused by the entry or exit of a small spacecraft into or out the Earth's shadow. In this work is considered a one-dimensional model of thermal conductivity. It is assumed that the solar radiation flux falls properly on the solar panel. Violation of normality due to deformations is neglected. A special feature of this work is to take into account the actual fixing of the solar panel. The boundary conditions in the form of a seal are preserved. However, the mobility of the smallest spacecraft is taken into account as a result of the occurrence of a longitudinal force in the solar panel during a temperature shock. The results are compared with the simulation data without taking into account the mobility of the small spacecraft. The results of this work can be used in the design of small spacecraft for technological purposes to meet the requirements for microaccelerations.

Author(s):  
S. M. Akhmetov ◽  
◽  
M. T. Userbayev ◽  
Zh. U. Iklasova ◽  
A. B. Bolatova ◽  
...  

The stress-strain state (SSS) of a rod with an inhomogeneous layered structure is considered. On the basis of a brief review and analysis of the current state of research of rod systems, the relevance of the study of the SSS of layered-heterogeneous wooden structures is substantiated, taking into account the presence of different resistance of layers to tension and compression. On this basis, the authors solve the problem of determining the SSS of layered-heterogeneous wooden rods in creep conditions, where factors such as humidity and temperature, as well as the difference in the resistance of wood layers to stretching and compression are taken into account. When solving the problem, the mechanical-sorption creep of wood is also taken into account.


2021 ◽  
Vol 274 ◽  
pp. 02009
Author(s):  
Denis Nikolenko ◽  
Maxim Nikolenko ◽  
Anastasiya Filippova

The article focuses on the importance of the strength and durability of highways due to the projected increase in freight traffic. It also describes the consequences of uneven distribution of loads in traffic lanes, depending on the prevailing traffic in each lane. The studies, that were carried out earlier by various scientists, were taken into account, thankfully to which results were obtained on the composition of the traffic flow, the difference in the loading of road pavements, as well as the stress-strain state of road structures. As a result, a model that reflects the dependence of the influence of the speed of movement of vehicles on the dynamic deformation of structures, was developed. Consequently, a number of design solutions were established to ensure the required strength of all structures.


2020 ◽  
pp. 48-57
Author(s):  
Viktor Nosenko ◽  
Oleg Krivenko

At present, the tendency to build multi-storey residential buildings has become widespread in Ukraine. This is due to a number of reasons: significant increase in land prices in cities, dense urban development and the availability of appropriate equipment for the construction of such structures. One of the most common materials for multi-storey buildings is monolithic reinforced concrete. The main advantage of monolithic structures is the possibility of free spatial planning and the possibility of uniform redistribution of forces in the elements of the frame - the house works as one rigid entire structure. On the other hand, such structures require a long construction time and appropriate highly qualified control of monolithic works. Therefore, as an alternative, prefabricated reinforced concrete structures are used to accelerate the pace of construction. In this work, the influence of the rigidity of a precast reinforced concrete house on the stress-strain state of CFA piles foundation is investigated. The stress-strain state of a precast reinforced concrete building with two basement options is analyzed: precast and monolithic.                                                 The numerical modeling of the interaction of the system elements is used as a research method: soil base - foundation - aboveground structure. It was found that the replacement in a prefabricated house only one basement floor of precast concrete on a monolithic one affects the redistribution of forces, so the self-supporting wall is loaded 2.6 times, and the busiest wall, which rests on both sides of the floor slab, is unloaded to 2.1 times.  It was found that in the case of a basement made of precast reinforced concrete with a precast basement the difference efforts in pile heads (under the load-bearing walls) can differ 1.98 times, and in the case of a monolithic one 1.17 times. So it is mean, the monolithic foundation redistributed of efforts between the piles is more uniform. It is established that the monolithic reinforced concrete basement, in comparison with the prefabricated one, reduces the uneven settlement of the foundation by 2.4 times. When designing large-panel houses, it is advisable to provide a basement floor monolithic - this will allow to load the fundamental constructions more evenly, which in its reduction reduces the relative deformation of buildings and reduces their cost.


2021 ◽  
Vol 74 (9) ◽  
pp. 2112-2117
Author(s):  
Natalia N. Brailko ◽  
Iryna M. Tkachenko ◽  
Victor V. Kovalenko ◽  
Anna V. Lemeshko ◽  
Alexey G. Fenko ◽  
...  

The aim of this research is to study the influence of size and location of wedge-shaped defects of teeth on stress and strain state of restorative material on the basis of biomechanical analysis. Materials and methods: Biomechanical analysis of the stress-strain state was performed on a jaw bone fragment with canine and premolar inclusion. Results: Tangential stress increase both in the adhesive layer and in restorative material with depth and width (medial-distal size) of restored wedge-shaped defects of teeth,. The most unfavorable loading on a tooth is a joint action of vertical and horizontal loading in lingual- vestibular or vestibular-lingual direction, depending on localization of the restored wedge-shaped defects of teeth. The formation of retention grooves in wedge-shaped defects of teeth reduces the value of the maximum tangential stress in the adhesive layer of restorative material to 25% and extends the longevity of restorations. Conclusions: The difference in maximal values of tangential stress increases in adhesive layer of restorative material with or without retention grooves with increasing depth of defect. Thus, it is advisable to form retention grooves in cases of wedge-shaped teeth defects that exceed 1.5 mm. In case of restoration of subgingival wedge-shaped defects of teeth of small height it is recommended to create one retention groove on the gingival or incisal planes of a carious cavity due to significant inconveniences, and sometimes impossibility of formation of traditionally located retention grooves.


Author(s):  
Mikhail Sainov ◽  
Igor Egorov ◽  
Konstantin Pak

Introduction. One of the main principles in designing modern ultra-high rockfill dams with reinforced concrete face is the principle of zoning rockfill of various quality in the dam body. It envisages that rockfill in the shell upper part should be compacted very carefully in order to minimize to the maximum the deflections of the reinforced concrete face. In the shell lower part it is allowed placing heterogeneous rockfill with less degree of compaction. Analysis of the results of field observations over settlements of the already constructed dams shows that this pattern of zoning may lead to considerable irregularity in distribution of rockfill deformation moduli between the upstream and the downstream parts of the dam. Numerical modeling of the existing Aguamilpa dam carried out by use arlier showed that this effect may be caused by unfavorable stress-strain state of the reinforced concrete face threatening with crack formation. Were come ended using dams of homogenous structure. However, this conclusion caused doubts of some experts. More detailed studies who see results are described in this article were conducted in order to confirm or disprove this conclusion. Materials and methods. The studies were conducted by finite element method on the example of 100 m high rockfill dam. Different alternatives of rockfill deformation properties in the shell upstream and downstream parts were considered. Results. Analysis of the results of studies confirmed the conclusions made earlier about the features of the rockfill dam reinforced concrete face stress-strain state. It was revealed that increase of rockfill deformation in the dam shell downstream part leads to appearance of additional tensile longitudinal force in the face. It increases the risk of appearance of through transversal cracks in the face. However, the heterogeneous structure of the dam shell may not have a decisive impact on stress values because the value of bending moment plays a great role. Conclusions. The results of the fulfilled study as well as modern dam construction practice show the necessity of modifying the traditional pattern of rockfill zoning in the dam body. It is necessary to provide decrease of differences in rockfill deformation of the upstream and downstream parts of the dam.


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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