MECHANICAL CHARACTERISTICS OF REINFORCED AND THREE-LAYER SHELLS BASED ON METAMATERIALS, TAKING INTO ACCOUNT OPERATIONAL DAMAGE

Abstract— The conventional design in aeronautical engineering is reinforced shell, which for most structures is a thin shell with a stringer set. This article compares the behavior of a conventional reinforced shell and a spaced shell metamaterial structure with a reinforced set using the example of a main airplane pressure bulkhead. The evaluation criterion is to ensure the required level of residual strength when the limiting state is reached.

Download Full-text

Experimental study of the overconsolidation and saturation effects on the mechanical characteristics and residual strength of Chlef river sandy soil

Periodica Polytechnica Civil Engineering ◽

10.3311/pp.ci.2010-2.06 ◽

2010 ◽

Vol 54 (2) ◽

pp. 107 ◽

Cited By ~ 4

Author(s):

Noureddine Della ◽

Hanifi Missoum ◽

Ahmed Arab ◽

Mostefa Belkhatir

Keyword(s):

Experimental Study ◽

Sandy Soil ◽

Residual Strength ◽

Mechanical Characteristics ◽

Saturation Effects

Download Full-text

Bionic approach to design of bridge structures. Part 2: Finite-element modeling of an arch pedestrian bridge designed using the bionic approach

Russian journal of transport engineering ◽

10.15862/34sats319 ◽

2019 ◽

Vol 6 (3) ◽

Author(s):

Artur Karahanyan ◽

Ilya Ovchinnikov ◽

Igor Ovchinnikov

Keyword(s):

Finite Element ◽

Finite Element Modeling ◽

Software Package ◽

Mechanical Characteristics ◽

Bionic Design ◽

Limiting State ◽

Pedestrian Bridge ◽

Element Modeling ◽

Pedestrian Bridges ◽

Bridge Structures

It is noted that today in Russia the problem of applying the bionic approach in the design of bridges, despite the appearance of a number of works, is little studied and needs to be further developed. Briefly discusses the main loads on bridge structures and features of the calculation of bridges. It is indicated that practically no attention is paid to the problem of correctly determining loads and impacts. The features of the calculation method for limiting states are discussed and attention is paid to the fact that the method does not take into account that structures in most cases reach the limiting state not because of an increase in load, but because of improperly designed section sizes, due to changes in the mechanical characteristics of materials under the influence of the environment, due to the appearance and development of defects and damage, both distributed and local in nature. It is also indicated that in the method the deformation calculation is practically separated from the strength calculation and there is a discrepancy in the hypotheses used in this case. The rest of the article gives examples of applying the bionic approach to the design of arch pedestrian bridges and discusses the idea of sustainable design. In the final part, we consider the problem of finite element modeling of a pedestrian arch bridge with inclined arches (butterfly bridge), designed using the bionic approach. For the calculation, the Midas Civil software package was used. Plots of stresses, displacements from various combinations of loads are given. It is indicated that the use of the bionic approach in the design of bridge structures has great potential in terms of creating interesting inventions, especially since this branch of engineering design is a very little studied, innovative area of scientific interest for a large number of engineers, researchers, scientists today. Bionic design is an effective tool for finding new solutions for bridge structures.

Download Full-text

The method for determining the parameters of the diagrams of a truncated-wedge destruction of cylindrical samples of rocks

Naukovyi Visnyk Natsionalnoho Hirnychoho Universytetu ◽

10.33271/nvngu/2021-1/047 ◽

2021 ◽

pp. 47-52

Author(s):

L. M. Vasyliev ◽

D. L. Vasyliev ◽

O. Ye. Nazarov ◽

M. G. Malich ◽

V. O. Katan

Keyword(s):

Mathematical Modeling ◽

Rock Mass ◽

Residual Strength ◽

Strength Criterion ◽

Contact Friction ◽

Calculation Algorithm ◽

Limiting State ◽

Rock Samples ◽

Calculation Results ◽

Experimental Values

Purpose. Development of an analytical method for calculating the parameters of complete diagrams longitudinal tension deformation for the truncated-wedge shape of destruction of cylindrical rock samples to control the stress-strain state of the rock mass and effective destruction of these materials during disintegration. Methodology. Analytically, by developing a mathematical model of the fracture process of cylindrical rock samples with their truncated-wedge form of crack development, an algorithm is created for calculating the full deformation diagram from the acting tension using the experimental values of four indicators of material properties the shear resistance limit, internal and external friction coefficients and elastic modulus. The method is based on the improved Coulomb strength criterion, supplemented by the parameters of contact friction and allowing one, using the theory of slip lines, to calculate the limiting state of the material at the tip of cracks developing from the edges of the sample of the correct geometry, taking into account the release of part of the material from the load and compliance with Hookes law deformation of the sample bearing area and the specific force on it. Findings. The method of mathematical modeling makes it possible to determine the ultimate strength and residual strength of cylindrical rock samples using four property indicators that can be experimentally established by simple methods. Originality. For the first time, analytical modeling of the process of destruction of cylindrical rock samples with their truncated-wedge form of destruction was carried out, taking into account the internal contact friction depending on the properties of the rock material and external contact friction. Practical value. The proposed method of mathematical modeling and the calculation algorithm make it possible to determine the limit and residual strength of rock samples using four property indicators, which can be established experimentally by simple methods under laboratory conditions of enterprises of the mining and metallurgical complex. The calculation results can be quickly used to control the state of the rock mass and effective destruction upon disintegration.

Download Full-text

An Energy Analyser for Contrast Enhancement in STEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100052183 ◽

1974 ◽

Vol 32 ◽

pp. 434-435

Author(s):

H.T. Pearce-Percy

Keyword(s):

Contrast Enhancement ◽

Bending Angle ◽

Magnetic Sector ◽

Conventional Design ◽

Bending Radius ◽

Sector Type

Recently an energy analyser of the uniform magnetic sector type has been installd in a 100KV microscope. This microscope can be used in the STEM mode. The sector is of conventional design (Fig. 1). The bending angle was chosen to be 90° for ease of construction. The bending radius (ρ) is 20 cm. and the object and image distances are 42.5 cm. and 30.0 cm. respectively.

Download Full-text