Construction of strength diagrams for a brittle body with defects of elliptical shape

1972 ◽  
Vol 5 (3) ◽  
pp. 270-272
Author(s):  
L. L. Libatskii
Keyword(s):  
Brittle Body ◽  
Elliptical Shape

scholarly journals Analysis on Heat Transmission and Fluid Flow Attributes in Solar Air Accumulator Passage with Diverse Faux Jaggedness Silhouettes on Absorber Panel

2019 ◽  
Vol 8 (5S3) ◽  
pp. 32-41 ◽  
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Optimum Shape ◽  
Solar Air Heater ◽  
Artificial Roughness ◽  
Heat Transmission ◽  
Number Range ◽  
Elliptical Shape ◽  
Shape Pattern

There is a necessity to investigate the heat transmission and fluid cascade peculiarities of solar air convectors using varying faux irregular surface and shapes on absorber sheet, so that the solar devices utilize maximum amount of available solar radiated heat energy during day time. These artificial roughness shapes are use for the enhancement of thermal performance. This need arises from the fact that the heat circulation and liquid cascade trait have been investigated by the previous investigators only for the cases that differ considerably from those relevant to solar air brazier having different screen matrix placed in the planes parallel to the flow direction and that the radiant energy being absorbed in depth. In our present research paper we investigating experimentally the behavior of artificial irregularities located over absorber platter of solar air heater vessel of varying shapes like trapezoidal, sin wave, rectangular, alternative elliptical shape pattern etc, with different Reynolds Number range 4000 to 24000, mass flow rate on Nusselt Number and Friction Factor and also find the suitable optimum shape for heat transmission enhancement. The results indicated the best heat transfer enhancement results for the alternative elliptical shape pattern among other artificial roughness with range of 0.0786kg/s – 0.475kg/s mass flow rate with thermal efficiency near about 78%.

scholarly journals ASSESSMENT OF THE STRENGTH OF A COMPOSITE PACKAGE WITH INTERNAL DEFECTS ACCORDING TO VARIOUS FAILURES CRITERIA UNDER THE INFLUENCE OF UNSTEADY LOAD

2020 ◽  
Vol 17 (35) ◽  
pp. 1218-1230
Author(s):  
Aleksandr L. MEDVEDSKIY ◽  
Mikhail I. MARTIROSOV ◽  
Anton V. KHOMCHENKO ◽  
Darina V. DEDOVA
Keyword(s):  
Polymer Composite ◽  
Longitudinal Direction ◽  
Polymer Composite Material ◽  
Aviation Industry ◽  
Structural Elements ◽  
The Finite Element Method ◽  
Fracture Criteria ◽  
Safety Factors ◽  
Elliptical Shape ◽  
And Behavior

One of the priority tasks of the modern aviation industry is to increase the economic efficiency of aircrafts. In the context of solving this problem, when creating new aircrafts, polymer composite materials (PCM) are increasingly used. Particular attention is paid to structural elements, damage to which can lead to a decrease in the strength of an airframe as a whole. Therefore, an essential task in the design, maintenance, and operation of the test is to study the effect of interlayer defects on the strength and behavior of PCM structures under the influence of unsteady loads. This work is devoted to a numerical analysis of the behavior of a plate made of a polymer composite material (PCM) under unsteady load considering interlayer defects of an elliptical shape, as well as an assessment of the strength of a composite package according to various fracture criteria. The problem is solved by the finite element method using the LS-DYNA software package. Then, using the method of mathematical modeling, the interlayer separation of an elliptical shape was analyzed, which allowed to evaluate the strength of the plate and fiber according to the criteria of Hashin, Puck, Chang-Chang, and LaRC03 and compare the results. It was found in the study, that the failure indices and safety factors, which were obtained using various criteria (Hashin and Chang-Chang), have the same distribution, since the dependence of the implemented fracture mode (fiber compression in the longitudinal direction) is identical. Analysis.

Synthesis and optoelectronics properties of diblock copolymer of P3HT containing thiol-side chains and its hybrid nanocomposite

RSC Advances ◽  
2016 ◽  
Vol 6 (112) ◽  
pp. 110686-110694 ◽  
Author(s):  
Yisha Qiao ◽  
Yixuan Du ◽  
Yinfeng Liu ◽  
Yunbo Li
Keyword(s):  
Absorption Spectra ◽  
Diblock Copolymer ◽  
Side Chains ◽  
Hybrid Nanocomposite ◽  
Broad Absorption ◽  
Elliptical Shape ◽  
Weight Content ◽  
Hybrid Nanoparticle ◽  
Nanoparticle Film

DP-P3HT-SH in global, leaf-like and elliptical shape states exhibiting broad absorption spectra between 300 nm and 650 nm, and the conductivity values of a DP-P3HT-S-AuNPs hybrid nanoparticle film as a function of the weight content of AuNPs.

A Design of Coverage Area for Textured Surface of Sliding Journal Bearing Based on Genetic Algorithm

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Hui Zhang ◽  
Mahshid Hafezi ◽  
Guangneng Dong ◽  
Yang Liu
Keyword(s):  
Genetic Algorithm ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Textured Surface ◽  
The Novel ◽  
Eccentricity Ratio ◽  
Coverage Area ◽  
Elliptical Shape ◽  
Bearing Load ◽  
Rectangular Grids

This paper aims to improve the tribological performance of journal bearings by optimizing the coverage area of circular microtextures in divergent region of the sleeve. A numerical model is proposed to calculate the friction coefficient and bearing load of textured journal bearings. The surface of the sleeve is divided into rectangular squares. Textures that located at the center of rectangular grids are assumed to be present or absent, marked as 1 and 0, respectively. Afterward, different texture coverage area arrangements are evolved and selected based on the genetic algorithm (GA). The area of semi-elliptical shape is obtained as the novel and preferable textured coverage area design for journal bearings. Influences of width and eccentricity ratio are discussed, which confirm the semimajor and semiminor axes of the semi-elliptical shape of texture coverage area equal to one-third of the circumferential length and half of the width of the journal bearing, respectively.

scholarly journals Optimization of Geometric Parameters of Thermal Insulation of Pre-Insulated Double Pipes

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 1012 ◽  
Author(s):  
Dorota Krawczyk ◽  
Tomasz Teleszewski
Keyword(s):  
Heat Flux ◽  
Heat Conduction ◽  
Cross Section ◽  
Thermal Insulation ◽  
Major Axis ◽  
Heat Losses ◽  
Sectional Area ◽  
Cross Sectional ◽  
Elliptical Shape ◽  
Half Axis

This paper presents the analysis of the heat conduction of pre-insulated double ducts and the optimization of the shape of thermal insulation by applying an elliptical shape. The shape of the cross-section of the thermal insulation is significantly affected by the thermal efficiency of double pre-insulated networks. The thickness of the insulation from the external side of the supply and return pipes affects the heat losses of the double pre-insulated pipes, while the distance between the supply and return pipes influences the heat flux exchanged between these ducts. An assumed elliptical shape with a ratio of the major axis to the minor half axis of an ellipse equaling 1.93 was compared to thermal circular insulation with the same cross-sectional area. All calculations were made using the boundary element method (BEM) using a proprietary computer program written in Fortran as part of the VIPSKILLS project.

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