scholarly journals Choice of parameters of oscillatory actions in the molding of reinforced concrete products

2018 ◽  
Vol 251 ◽  
pp. 03006
Author(s):  
Vitaly Vasiliev
Keyword(s):  
Shock Wave ◽  
Wave Propagation ◽  
Reinforced Concrete ◽  
Wave Packet ◽  
Experimental Studies ◽  
Concrete Mixture ◽  
Practical Recommendations

The process of propagation of a wave packet in the concrete mixture during the formation of reinforced concrete products by harmonic and shock-vibrational actions was considered. It was shown that the displacement of the layers of the concrete mixture during the propagation of the shock wave is directed against the direction of wave propagation, providing a sealing effect. On the basis of experimental studies, practical recommendations are given for determining the rational thickness of the compacted concrete mixture, depending on the frequency of oscillations.

Experimental studies on shock wave propagation in laser produced plasmas using double wavelength holography

1989 ◽  
Vol 71 (1-2) ◽  
pp. 76-80 ◽  
Author(s):  
M.A. Harith ◽  
V. Palleschi ◽  
A. Salvetti ◽  
D.P. Singh ◽  
G. Tropiano ◽  
...  
Keyword(s):  
Shock Wave ◽  
Wave Propagation ◽  
Experimental Studies ◽  
Shock Wave Propagation

Improvement Of Curvilinear Diagrams Of Concrete Deformation

2019 ◽  
pp. 99-104
Keyword(s):  
Reinforced Concrete ◽  
Peak Load ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Deformation Model ◽  
Reinforced Concrete Structures ◽  
Significant Difference ◽  
Deformation Diagrams

Problems when calculating reinforced concrete structures based on the concrete deformation under compression diagram, which is presented both in Russian and foreign regulatory documents on the design of concrete and reinforced concrete structures are considered. The correctness of their compliance for all classes of concrete remains very approximate, especially a significant difference occurs when using Euronorm due to the different shape and sizes of the samples. At present, there are no methodical recommendations for determining the ultimate relative deformations of concrete under axial compression and the construction of curvilinear deformation diagrams, which leads to limited experimental data and, as a result, does not make it possible to enter more detailed ultimate strain values into domestic standards. The results of experimental studies to determine the ultimate relative deformations of concrete under compression for different classes of concrete, which allowed to make analytical dependences for the evaluation of the ultimate relative deformations and description of curvilinear deformation diagrams, are presented. The article discusses various options for using the deformation model to assess the stress-strain state of the structure, it is concluded that it is necessary to use not only the finite values of the ultimate deformations, but also their intermediate values. This requires reliable diagrams "s–e” for all classes of concrete. The difficulties of measuring deformations in concrete subjected to peak load, corresponding to the prismatic strength, as well as main cracks that appeared under conditions of long-term step loading are highlighted. Variants of more accurate measurements are proposed. Development and implementation of the new standard GOST "Concretes. Methods for determination of complete diagrams" on the basis of the developed method for obtaining complete diagrams of concrete deformation under compression for the evaluation of ultimate deformability of concrete under compression are necessary.

Phenomenological analysis of shock-wave propagation in weakly ionized plasmas

AIAA Journal ◽  
1998 ◽  
Vol 36 ◽  
pp. 816-822
Author(s):  
Igor V. Adamovich ◽  
Vish V. Subramaniam ◽  
J. W. Rich ◽  
Sergey O. Macheret
Keyword(s):  
Shock Wave ◽  
Wave Propagation ◽  
Phenomenological Analysis ◽  
Shock Wave Propagation ◽  
Ionized Plasmas ◽  
Weakly Ionized

Methodology of studying the mechanical properties of composite materials (reinforced concrete)

2018 ◽  
Vol 84 (12) ◽  
pp. 61-67
Author(s):  
V. A. Eryshev
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Experimental Studies ◽  
Analytical Relationship ◽  
Hardened Concrete ◽  
Deformation Model ◽  
Joint Work ◽  
Concrete Shrinkage ◽  
Axial Tension ◽  
Tension And Compression

The mechanical properties of a complex composite material formed by steel and hardened concrete, are studied. A technique of operative quality control of new credible concrete and reinforcement, both in laboratory and field conditions is developed for determination of the strength and strain characteristics of materials, as well as cohesion forces determining their joint operation under load. The design of the mobile unit is presented. The unit provides a possibility of changing the direction of loading and testing the reinforced element of the given shape both for tension and compression. Moreover, the nomenclature of testing equipment and the number of molds for manufacturing concrete samples substantially decrease. Using the values of forcing resulting in concrete cracking when the joint work of concrete and reinforcement is disrupted the values of the inherent stresses and strains attributed to the concrete shrinkage are determined. An analytical relationship between the forces and deformations of the reinforced concrete sample with central reinforcement is derived for axial tension and compression, with allowance for strains and stresses in the reinforcement and concrete resulted from concrete shrinkage. The results of experimental studies are presented, including tension diagrams and diagrams of developing axial deformations with an increase in the load under the central loading of the reinforced elements. A methodology of accounting for stresses and deformations resulted from concrete shrinkage is developed. The applicability of the derived analytical relationships between stresses and deformations on the material diagrams to calculations of the reinforced concrete structures in the framework of the deformation model is estimated.

EXPERIMENTAL STUDIES OF REINFORCED CONCRETE STRUCTURES WITH CROSS-SHAPED SPATIAL CRACK UNDER TORSION WITH BENDING

2020 ◽  
Vol 92 (6) ◽  
pp. 13-25
Author(s):  
Vl.I. KOLCHUNOV ◽  
◽  
A.I. DEMYANOV ◽  
M.M. MIHAILOV ◽  
◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Experimental Determination ◽  
Calculation Method ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Design Parameters ◽  
Reinforced Concrete Structures ◽  
Experimental Scheme

The article offers a method and program for experimental studies of reinforced concrete structures with cross-shaped spatial crack under torsion with bending, the main purpose of which is to check the design assumptions and experimental determination of the design parameters of the proposed calculation method. The conducted experimental studies provide an opportunity to test the proposed calculation apparatus and clarify the regularities for determining deflections, angles of rotation of extreme sections, and stresses in the compressed zone of concrete. For analysis, the article presents a typical experimental scheme for the formation and development of cracks in the form of a sweep, as well as characteristic graphs of the dependence of the angles of rotation of end sections.

scholarly journals Observation of the shock wave propagation induced by a high-power laser irradiation into an epoxy material

2013 ◽  
Vol 46 (23) ◽  
pp. 235501 ◽  
Author(s):  
Romain Ecault ◽  
Laurent Berthe ◽  
Michel Boustie ◽  
Fabienne Touchard ◽  
Emilien Lescoute ◽  
...  
Keyword(s):  
Shock Wave ◽  
Wave Propagation ◽  
Laser Irradiation ◽  
High Power ◽  
Shock Wave Propagation ◽  
High Power Laser ◽  
Power Laser ◽  
Epoxy Material

scholarly journals Study on X-ray Induced Two-Dimensional Thermal Shock Waves in Carbon/Phenolic

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3553
Author(s):  
Dengwang Wang ◽  
Yong Gao ◽  
Sheng Wang ◽  
Jie Wang ◽  
Haipeng Li
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Wave Propagation ◽  
Thermal Shock ◽  
Anisotropic Material ◽  
Energy Deposition ◽  
X Rays ◽  
Two Dimensional ◽  
X Ray ◽  
Deposition Depth

Carbon/Phenolic (C/P), a typical anisotropic material, is an important component of aerospace and often used to protect the thermodynamic effects of strong X-ray radiation. In this paper, we establish the anisotropic elastic-plastic constitutive model, which is embedded in the in-house code “RAMA” to simulate a two-dimensional thermal shock wave induced by X-ray. Then, we compare the numerical simulation results with the thermal shock wave stress generated by the same strong current electron beam via experiment to verify the correctness of the numerical simulation. Subsequently, we discuss and analyze the rules of thermal shock wave propagation in C/P material by further numerical simulation. The results reveal that the thermal shock wave represents different shapes and mechanisms by the radiation of 1 keV and 3 keV X-rays. The vaporization recoil phenomenon appears as a compression wave under 1 keV X-ray irradiation, and X-ray penetration is caused by thermal deformation under 3 keV X-ray irradiation. The thermal shock wave propagation exhibits two-dimensional characteristics, the energy deposition of 1 keV and 3 keV both decays exponentially, the energy deposition of 1 keV-peak soft X-ray is high, and the deposition depth is shallow, while the energy deposition of 3 keV-peak hard X-ray is low, and the deposition depth is deep. RAMA can successfully realize two-dimensional orthotropic elastoplastic constitutive relation, the corresponding program was designed and checked, and the calculation results for inspection are consistent with the theory. This study has great significance in the evaluation of anisotropic material protection under the radiation of intense X-rays.

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