scholarly journals Research of the Stress-Strain State of Glued Wooden Structures After Prolonged use in Various Extreme Conditions

2018 ◽  
Vol 463 ◽  
pp. 042028
Author(s):  
A.V. Karelsky ◽  
S.I. Roshina ◽  
I.N. Bardin
Keyword(s):  
Strain State ◽  
Extreme Conditions ◽  
Stress Strain ◽  
Stress Strain State ◽  
Wooden Structures

scholarly journals Mathematical model of the stress-strain state of a rod with an inhomogeneous layered structure

2021 ◽  
Vol 82 (4) ◽  
pp. 14-22
Author(s):  
S. M. Akhmetov ◽  
◽  
M. T. Userbayev ◽  
Zh. U. Iklasova ◽  
A. B. Bolatova ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Layered Structure ◽  
Strain State ◽  
Stress Strain ◽  
Stress Strain State ◽  
Current State ◽  
Tension And Compression ◽  
The Difference ◽  
State Of Research ◽  
Wooden Structures

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.

scholarly journals Mathematical modeling of stress-strain state of elements of joints of wooden structures on glued fiberglass washers

2021 ◽  
Vol 2131 (3) ◽  
pp. 032095
Author(s):  
M V Ariskin ◽  
D O Martyshkin ◽  
I V Vanin
Keyword(s):  
Mathematical Modeling ◽  
Bearing Capacity ◽  
Strain State ◽  
Single Component ◽  
Stress Strain ◽  
Design Models ◽  
Stress Strain State ◽  
Deformed State ◽  
Wooden Structures

Abstract Design models of single-component and three-component samples were developed on glued fiberglass washers in order to investigate the stress-strain state (SF) of the elements of joints of wooden structures. The picture and the nature of the actual stressed-deformed state of the wooden element with glued washers are obtained. Quite high bearing capacity of wooden structures connection is shown.

scholarly journals The phenomenon for the wood creep in the reinforced glued wooden structures

2018 ◽  
Vol 245 ◽  
pp. 03020 ◽  
Author(s):  
Svetlana Roshchina ◽  
Mikhail Lukin ◽  
Mikhail Lisyatnikov ◽  
Artem Koscheev
Keyword(s):  
Cross Sections ◽  
Composite Structures ◽  
Strain State ◽  
Basic Material ◽  
Design Standards ◽  
Stress Strain ◽  
Stress Strain State ◽  
Glue Joint ◽  
Long Acting ◽  
Wooden Structures

For the composite structures based on wood, that include reinforced wooden structures, allowance for the influence of wood specific features as a building material allows us to evaluate its structural design as accurately as possible and ensure the required reliability and durability. Creep that causes wood deformations evolving in time can be referred to the specific properties of wood to a greater extent affecting the operation of the reinforced wooden structures. Taking into account the state of the issue to determine the effect of the long-acting loads on the stress-strain state of the reinforced glued wooden structures, the article considers the application of the theory of elastic heredity as the most applicable to assess the deformability of wooden structures in time. The conducted experimental and theoretical investigations and the reinforced glued wooden structures observations during the operational process have shown that their stress-strain state changes significantly under the load over time. Glue compositions used to connect reinforcement with wood ensure their reliable joint operation, however, as the result of the wood creep where wood is the basic material, the redistribution of forces between the reinforcement and wood occurs there on and off. At the same time normal stresses in the reinforcement and the glue joint “reinforcement - wood” increase in the calculated cross sections while they decrease in the wood, which is caused by a change (decrease) in the wood elastic modulus. Allowance for the wood creep in the design of the reinforced wooden structures will allow to determine the stress - strain state of the structure in the design more precisely. Therefore, when developing the reinforced wooden structures design standards, this factor must be taken into account.

scholarly journals Stress-strain state of sandwiched coating and its node connections under static load

2021 ◽  
Vol 23 (3) ◽  
pp. 118-128
Author(s):  
S. V. Deordiev ◽  
M. Y. Belichenko ◽  
M. A. Krasiev ◽  
M. V. Butenko
Keyword(s):  
Strain State ◽  
Static Load ◽  
Experimental Studies ◽  
Environmentally Friendly ◽  
Structural Elements ◽  
Stress Strain ◽  
Stress Strain State ◽  
Frame Work ◽  
Wooden Structures

Today, the interest in wooden structures is being increased mainly because wood is an environmentally friendly material. In this regard, quite new wooden materials are developed between the 20th and 21st centuries. Improved are the methods for joining wooden elements and joints of structures. The paper presents the experimental studies of the sandwiched coating consisting of two frame work blocks, and nodal connections under the static load. It is shown that the stress distributes in the coating and on the surface of the nodal connections. The stresstrain curves are suggested for the nodal connections and structural elements of the coating.

scholarly journals STRESS-STRAIN STATE OF CURVED LAMINATED WOODEN ELEMENTS DURING PRODUCTION

2020 ◽  
Vol 5 (4) ◽  
pp. 51-59
Author(s):  
Alexander Schmidt ◽  
Keyword(s):  
Strain State ◽  
Initial Stresses ◽  
Internal Stresses ◽  
Shear Stresses ◽  
Stress Strain ◽  
Stress Strain State ◽  
Operational Load ◽  
Study Results ◽  
The Impact ◽  
Wooden Structures

Introduction: The stress-strain state (SSS) of curved laminated wooden elements may differ significantly from the SSS of straight laminated wooden elements, not only in terms of the curvature but also in terms of production specifics and operational load. A curved element is produced by bending wooden planks (lamellae) and gluing them together. In the process, the structure is subjected to initial internal stresses, as the lamellae tend to straighten out again. After production is complete, the element experiences unequal initial internal stresses, which alters its strength properties in different directions in relation to the timber fibers. At a later point, this is going to contribute to the stresses that the structure experiences under external pressure. The Russian and foreign regulations (SP, EuroCode 5, DIN) do not pay sufficient attention to this fact, which has merited this study. Methods: For the aforementioned purpose, we review a mathematical model of the SSS emergence in curved laminated wooden elements. We roughly divide the process into two stages: stage 1 involves bending separate lamellae, gluing them together, and pressing them down; stage 2 involves pressing out the laminated package. This results in prestress, which is a combination of tangential, radial, and shear stresses. Results: Our study results in a visual representation of the total prestress during stages 1 and 2. Such a representation allows for predicting stresses in curved laminated wooden structures under alternating operational loads. Discussion: We highlight the impact of the relaxation of initial stresses, which requires further study. Depending on the direction and amount of operational load, the curved laminated section of a structure may “attempt” to straighten out (i.e. with a decrease in curvature), or may curve even further. This is not properly reflected in the guidelines for wooden structures’ design and needs to be examined further.

scholarly journals The effect of shear deformations on the stressed state of the wooden elements of the composite section on inclined metal rods

2019 ◽  
Vol 97 ◽  
pp. 04028
Author(s):  
Vladimir Linkov
Keyword(s):  
Cross Section ◽  
Strain State ◽  
Normal Stresses ◽  
Shear Deformations ◽  
Stress Strain ◽  
Flexible Links ◽  
Stress Strain State ◽  
Transverse Bending ◽  
Composite Section ◽  
Wooden Structures

Wooden structures of composite cross-section can be made on flexible links in the form of inclined metal rods (NMS) without the use of glue. The compliance of joints is manifested in the shear deformations of the elements to be joined and reduces the carrying capacity of the composite wooden structures. The article discusses the effect of compliance of NMS-compounds in the form of inclined screwed rods on the stress-strain state of the wooden structures of the composite section. The results of tests for transverse bending of composite wooden elements of natural dimensions are presented. The effect of deformations of mutual shear of joints on deflections on normal stresses in the middle of the span of structures and stresses in inclined screwed rods is considered. It was established experimentally that a linear dependence of the form is observed between shear deformations and other parameters of the stress-strain state of structures Y = a*X + b, increase in shear deformation of NMS-compound on screwed rods on 1 mm leads to an increase in deflections, stresses in the construction of a composite section and in inclined rods on 8,39 mm, 0,24 MPa и на 20,8 MPa respectively.

КОНСТРУКТИВНО-ТЕХНОЛОГІЧНІ ОСОБЛИВОСТІ ХВОСТО-ВИХ БАЛОК СІТЧАСТОГО ТИПУ З ПОЛІМЕРНИХ КОМПО-ЗИЦІЙНИХ МАТЕРІАЛІВ ВЕРТОЛЬОТІВ ТРАНСПОРТНОЇ КАТЕГОРІЇ

2020 ◽  
pp. 15-30
Author(s):  
А. Г. Гребеников ◽  
И. В. Малков ◽  
В. А. Урбанович ◽  
Н. И. Москаленко ◽  
Д. С. Колодийчик
Keyword(s):  
Finite Element ◽  
Strain State ◽  
Layer Structure ◽  
Metal Structure ◽  
Element Model ◽  
Stress Strain ◽  
Element Analysis ◽  
Mesh Structure ◽  
Stress Strain State ◽  
Mesh Structures

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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