scholarly journals Grapho-analytical studies of deformation in deformed thin-walled contours

2020 ◽  
Vol 23 (9) ◽  
pp. 7-11
Author(s):  
Bogdan Sheludchenko ◽  
Yaroslav Yarosh ◽  
Andrii Zabrodskyi ◽  
Andriy Kondratiuk ◽  
Victor Biletskiy ◽  
...  
Keyword(s):  
Elastic Shell ◽  
Operational Reliability ◽  
Analytical Models ◽  
Geometrical Parameters ◽  
Initial Shape ◽  
Operational Feature ◽  
Elastic Shells ◽  
Power Load ◽  
Thin Walled ◽  
The Given

Increasing the levels of operational reliability of technical means of modern production involves, in particular, the optimization of the deformation parameters of individual components of these tools. The main deformation-operational feature of such structures as elastic shells of the pneumatic periphery of mobile vehicles, and individual links of long-link cargo chains is a stochastic change of their shape in contact with the deformed environment. The basis for the optimization of the operational reliability of deformed thin-walled circuits of such structures under power load is to determine the ratios of their geometric parameters, in which the process of deformation under load does not transform their initial shape from “folded” (out-of-bounds) state to “foldless” state toroidal surfaces, which should be described using the Cassini family of ovals. Based on the established regularities of changing the configuration of the meridian of soft elastic shell and flat closed structures, which are deformed by external loads, three main conditions of using model typical contours of Cassini ovals as graph-analytical models of elastic shells of pneumatic mobile periphery chains. These conditions of graph-analytical modelling include: closedness and continuity of the curvature of the toroidal surface; generalization of the initial shape of the surfaces of toroidal contours; reduction of variable geometric shapes of contours to a single generalized equation. The results of the given grapho-analytical researches allow to define design structural and geometrical parameters of tires of engines of mobile means and separate links of cargo chains with the increased operational indicators of reliability of their work.

scholarly journals Mathematical model of nonlinear deformation of three-layer shells

2020 ◽  
Vol 17 (3) ◽  
pp. 94-100
Author(s):  
V. V. Karpov ◽  
◽  
E. A. Kobelev ◽  
Keyword(s):  
Mathematical Model ◽  
Modulus Of Elasticity ◽  
Nonlinear Deformation ◽  
Single Layer ◽  
Geometrically Nonlinear ◽  
Elastic Shells ◽  
Arbitrary Type ◽  
Study Results ◽  
Thin Walled ◽  
The Given

The article presents the study results of geometrically nonlinear deformation of elastic shells of arbitrary type with consideration of transverse shifts. There is constructed a new mathematical model of nonlinear deformation of thin-walled elastic isotropic three-layer shells. Each layer of the shell is made of different materials, but with similar shear modules. The thickness of the layers can be different. Averaging of all three layers becomes possible, and deformation of a three-layer shell as a single-layer shell with the given characteristics of the modulus of elasticity and the Poisson's ratio can be considered.

scholarly journals INFLUENCE OF CREEP CONCRETE ON SPACE STABILITY THIN-WALLED DOME COVERINGS

2021 ◽  
Vol 1 (24) ◽  
Author(s):  
Ekaterina Prokshits ◽  
Sergey Gridnev ◽  
Olga Sotnikova ◽  
Iana Zolotukhina
Keyword(s):  
Theory Of Elasticity ◽  
Deformation Condition ◽  
Software Systems ◽  
Geometrical Parameters ◽  
Loss Of Stability ◽  
Construction Mechanics ◽  
Body Construction ◽  
Calculation Results ◽  
Load Action ◽  
Thin Walled

The task was set, due to the capabilities of modern software systems, to assess the effect of the increase in inelastic deformations under prolonged load action on the loss of stability of thin-walled dome coverings. The study of the dependences of the forms of the loss of stability of dome covering from creep concrete that will help further with optimization calculations when determining of the most influencing parameters of designs. Calculation results of thin-walled concrete dome roof of circular outline under the influence of operational loadings with use of two modern program complexes are given in article. It is investigated intense and deformation condition of dome coverings as a part of construction from position of forecasting of possible forms of loss of stability, with use of opportunities of the final and element «MidasCivil» computer system. In work provisions of the theory of elasticity, mechanics of deformation of solid body, construction mechanics and also methods of mathematical modeling based on application of finite element method are used. The received results give the chance to rationally select geometrical parameters and material of design and also to set structural strength safety factors at the solution of problems of stability of different covers taking into account possible creep of material.

scholarly journals MULTIPARAMETRIC OPTIMIZATION OF THE SHAPE AND THICKNESS OF INSULATED ENERGY EFFICIENT CONSTRUCTED BUILDING WITH A SPECIFIC NUMBER OF FACES

2021 ◽  
pp. 196-204
Author(s):  
Viacheslav Martynov
Keyword(s):  
Energy Efficiency ◽  
Energy Efficient ◽  
Heat Losses ◽  
Geometrical Parameters ◽  
Energy Efficient Buildings ◽  
Multiparametric Optimization ◽  
Heat Influx ◽  
Number Of Faces ◽  
The Given ◽  
First Time

To calculate the optimal parameters of outbuildings, a mathematical model and method for optimizing the shape and resistance of heat transfer for opaque and transparent structures with a certain constant number of faces, building volume and amount of insulation to minimize the thermal balance of enclosing structures with the environment during the heating period In the course of calculations the geometrical parameters of translucent, opaque structures in the heat-insulating shell of buildings are determined taking into account heat losses, heat influx from solar radiation by the criterion of ensuring minimum heat losses through enclosing structures, rational parameters (buildings) The given technique and mathematical models should be used in the future in the design of energy efficient buildings in the reconstruction and thermal modernization of buildings. This will increase their energy efficiency and, accordingly, the energy efficiency class of buildings. For the research faceted attached building in the form of a triangular pyramid, the reduction in heat loss was 14.82 percent only due to the optimization of the shape and redistribution of the insulation. Similar results were obtained for other initial forms. For the first time, a computerized method was proposed, an algorithm and application package Optimparam for multiparameter shape optimization and insulation of translucent and opaque structures for outbuildings with a given number of arbitrarily arranged faces were developed.

Early Developments for a Semi-Analytical Model of Weld Induced Residual Stress

2007 ◽  
Author(s):  
Jess M. Bromley ◽  
Hassan Alizadeh ◽  
David J. Smith ◽  
Christopher E. Truman
Keyword(s):  
Residual Stress ◽  
Analytical Model ◽  
Thermal Processing ◽  
Complete Solution ◽  
Analytical Models ◽  
Thermal Processes ◽  
Rapid Testing ◽  
Plastic Slip ◽  
Computationally Expensive ◽  
The Given

The generation of plastic slip and residual stress by thermal processes is particularly difficult to understand and simulate. Modelling such problems is computationally expensive when approached numerically and extremely complex to approach analytically. ‘Semi-analytical’ models, in which analytical thermoelastic solutions are combined with approximate models of plasticity, offer a way to bridge this gap and have the potential to allow the rapid testing of parameter sensitivities before one launches a time-consuming full numerical model. However the construction of such models within such a thermal framework poses its own problems. An initial requirement for any such semi-analytical model is a complete solution to the elastic only response of the material to the given loading process. In this paper we focus on the formulation of such a solution for the simplest case relevant to welding or similar thermal processing. We verify the solution developed against finite element predictions and then further investigate it. In doing so we explain how the nature of this solution, especially its predicted yielding behaviour, has ramifications for the successful creation of a full semi-analytical solution.

scholarly journals Optimal Design of Piezoelectric Cantilevered Actuators for Charge-Based Self-Sensing Applications

Sensors ◽  
2019 ◽  
Vol 19 (11) ◽  
pp. 2582 ◽  
Author(s):  
Joël Bafumba Liseli ◽  
Joël Agnus ◽  
Philippe Lutz ◽  
Micky Rakotondrabe
Keyword(s):  
Objective Function ◽  
Geometrical Parameters ◽  
Optimization Approach ◽  
Element Analysis ◽  
Modeling And Analysis ◽  
Multi Objective ◽  
Sensing Applications ◽  
Piezoelectric Cantilever ◽  
Space Saving ◽  
The Given

Charge-based Self-Sensing Actuation (SSA) is a cost and space-saving method for accurate piezoelectric based-actuator positioning. However, the performance of its implementation resides in the choice of its geometry and the properties of the constituent materials. This paper intends to analyze the charge-based SSA’s performances dependence on the aforementioned parameters and properties for a piezoelectric cantilever. A model is established for this type of Piezoelectric Actuator (PEA), and a multi-objective function is defined. The multi-objective function consists of the weighted actuator and sensor objective functions of the PEA. The analytical optimization approach introduced herein aims to assess the evolution of the defined multi-objective function across a defined set of geometrical parameters and material properties and highlights the existence of a subset of solutions for an optimal charge-based SSA’s implementation. The commercially-available finite element analysis software, COMSOL Multiphysics, is used on the parametric model of the given structure to validate the analytical model. Then, experiments are conducted to corroborate the numerical and analytical modeling and analysis.

scholarly journals Modelling performance an air transport network operated by subsonic and supersonic aircraft

2020 ◽  
Vol 124 (1281) ◽  
pp. 1702-1739
Author(s):  
M. Janić
Keyword(s):  
Social Performance ◽  
Economic Feasibility ◽  
Transport Network ◽  
Air Transport ◽  
Analytical Models ◽  
Commercial Aircraft ◽  
Supersonic Aircraft ◽  
Route Network ◽  
Fuel Consumption And Emissions ◽  
The Given

ABSTRACTThis paper deals with modelling the performance of an air transport network operated by existing subsonic and the prospective supersonic commercial aircraft. Analytical models of indicators of the infrastructural, technical/technological, operational, economic, environmental, and social performance of the network relevant for the main actors/stakeholders involved are developed. The models are applied to the given long-haul air route network exclusively operated by subsonic and supersonic aircraft according to the specified “what-if” scenarios.The results from application of the models indicate that supersonic flights powered by LH2 (Liquid Hydrogen) could be more feasible than their subsonic counterparts powered by Jet A fuel, in terms of about three times higher technical productivity, 46% smaller size of the required fleet given the frequency of a single flight per day, 20% lower sum of the aircraft/airline operational, air passenger time, and considered external costs, up to two times higher overall social-economic feasibility, and 94% greater savings in contribution to global warming and climate change. These flights could be less feasible in terms of about 70-85% higher aircraft/airline operational costs, 70% and 19% higher fuel consumption and emissions of Green House Gases, respectively, and 6-13% higher noise compared to the specified acceptable levels.

scholarly journals Characterization of Impacts of Elastic-plastic Spheres

2020 ◽  
Vol 64 (2) ◽  
pp. 165-171
Author(s):  
Bence Szabó ◽  
Attila Kossa
Keyword(s):  
Plastic Material ◽  
Analytical Models ◽  
Material Models ◽  
Elastic Plastic ◽  
Analytical Functions ◽  
Elastic Plastic Material ◽  
Explicit Dynamic ◽  
The Impact ◽  
The Given

This work presents explicit dynamic finite element simulations of various impacts of elastic-plastic solid spheres with flat walls. Different  analytical models describing the mechanics of the impact phenomenon are also presented. Elastic and elastic-plastic material models for the sphere and the wall are considered during the analyses. The applicability of these different models is demonstrated and their accuracies are investigated. Closed-form analytical functions are proposed to describe the relationship between the initial velocity of the sphere and the investigated contact characteristics for the given material models. Analysis is carried out to study the effect of the friction coefficient as well as the angle of impact for various cases.

Buckling of Fibre-Reinforced Plastic-Steel Torispherical Shells Under External Pressure

1988 ◽  
Vol 202 (6) ◽  
pp. 409-420 ◽  
Author(s):  
G D Galletly ◽  
A Muc
Keyword(s):  
External Pressure ◽  
Experimental Results ◽  
Steel Shell ◽  
Elastic Buckling ◽  
Geometrical Parameters ◽  
Initial Shape ◽  
Buckling Modes ◽  
Reinforced Plastic ◽  
Composite Layers ◽  
Spherical Caps

The paper deals with the buckling of torispherical shells consisting of a steel external layer plus different numbers of composite layers. It is assumed that the total thickness of the fibre-reinforced plastic (FRP)-steel shell is constant but that the thickness of the steel and of the composite may be varied. In the paper it is shown (a) how the orientation of the fibres and the composite lamina thicknesses affect the elastic buckling modes and (b) how substantial increases in elastic buckling pressures may be achieved by reinforcing the steel torispheres with layers of composite. The analysis is carried out for various values of the geometrical parameters describing torispheres, including spherical caps. The influence of the yielding of the steel layer on the buckling pressures of FRP-steel torispheres is also discussed. As might be expected, it is necessary to take plasticity into account when predicting the buckling pressures of these shells. Some experimental results are given which confirm this expectation. The effect of initial shape imperfections in the shells is also considered briefly. However, the dearth of experimental results on FRP-steel shells prevents a proper evaluation of the way in which imperfections decrease their buckling strength.

A Nonlinear Design Theory of Supercavitating Cascades

1975 ◽  
Vol 97 (4) ◽  
pp. 430-437 ◽  
Author(s):  
B. Yim ◽  
L. Higgins
Keyword(s):  
Design Theory ◽  
Leading Edge ◽  
Geometrical Parameters ◽  
Nonlinear Method ◽  
Vortex Model ◽  
Spiral Vortex ◽  
Nonlinear Design ◽  
Double Spiral ◽  
The Given ◽  
Blunt Leading Edge

A nonlinear method of finding two-dimensional supercavitating sections in a cascade is developed. The load distribution is taken from linear theory for low drag super-cavitating foils in a cascade. The double spiral vortex model is used for the cavity termination. Linear and nonlinear theories are compared with special emphasis put on analyzing the blunt leading edge. The foil-cavity shape, the cavity drag and the cavitation number can be obtained by a computer program from the given cavity length and geometrical parameters of the cascade.

scholarly journals Regimes of wrinkling in pressurized elastic shells

2017 ◽  
Vol 375 (2093) ◽  
pp. 20160330 ◽  
Author(s):  
Matteo Taffetani ◽  
Dominic Vella
Keyword(s):  
Finite Element ◽  
Stability Analysis ◽  
Detailed Analysis ◽  
Indentation Depth ◽  
Elastic Shell ◽  
Analytical Techniques ◽  
Finite Element Simulations ◽  
Media Theory ◽  
Threshold Analysis ◽  
Elastic Shells

We consider the point indentation of a pressurized elastic shell. It has previously been shown that such a shell is subject to a wrinkling instability as the indentation depth is quasi-statically increased. Here we present detailed analysis of this wrinkling instability using a combination of analytical techniques and finite-element simulations. In particular, we study how the number of wrinkles observed at the onset of instability grows with increasing pressurization. We also study how, for fixed pressurization, the number of wrinkles changes both spatially and with increasing indentation depth beyond onset. This ‘Far from threshold’ analysis exploits the largeness of the wrinkle wavenumber that is observed at high pressurization and leads to quantitative differences with the standard ‘Near threshold’ stability analysis. This article is part of the themed issue ‘Patterning through instabilities in complex media: theory and applications.’

Sign in / Sign up

Export Citation Format

Share Document