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1
Spawanie elementów stalowych pod obciążeniem
Szewczyk Piotr
Inżynieria i Budownictwo
|
2021
|
R. 77, nr 5-6
235--238
PL
Przedstawiono próbę doświadczalnego oraz numerycznego oszacowania wpływu naprężeń początkowych podczas spawania na wartość odkształceń spawalniczych w momencie maksymalnego nagrzania elementu, jak również po jego całkowitym wystygnięciu.
EN
In the paper the influence of initial stress during welding on welding distortions in the maximum heating state and cooling state was presented. The problem was examined in empirical and numerical ways.
2
Content available Propagation of the torsional wave in an irregular self-reinforced composite material bounded between two half-spaces
Gupta Shishir, Das Sandip Kumar
Journal of Theoretical and Applied Mechanics
|
2020
|
Vol. 58 nr 4
971--982
EN
This research article is concerned with the analytical assessment and mathematical modelling to unveil the characteristic of a torsional wave in the irregular Earth’s crustal stratum. This investigation has been performed to clarify of possible occurrence of the torsional wave in an irregular self-reinforced composite layer bonded between dry sandy media and an isotropic elastic half-space. Rectangular and parabolic irregularities have been assumed at the interface of the intermediate layer and the lower half-space. In order to acquire the required dispersion equation, the appropriate boundary conditions with the assistance of displacement and stress components have been well satisfied. The effects of different affecting parameters such as reinforcement, sandiness, initial stress and irregularity parameters have been explored and explained by suitable graphs. Moreover, a comparative study has also been accomplished graphically for rectangular, parabolic, and no irregularities.
3
Content available Properties of alloys in the crystallization interval
Ružbarský Juraj
Multidisciplinary Aspects of Production Engineering
|
2019
|
Vol. 2, Iss. 1
375--381
EN
In the contribution the high growth of viscosity and initial stress of alloys in the crystallization interval with undercooling against of the liquidus follows from theoretical analysis. At these alloys used in pressure die casting the permissible undercooling that does not endanger pressure die casting operation. The application of the device for die temperature regulation ensures the safe operation.
4
Content available remote Rotation, initial stress, gravity and electromagnetic field effect on P wave reflection from stress-free surface elastic half-space with voids under three thermoelastic models
Abo-Dahab S. M., Rida S. Z., Mohamed R. A., Kilany A. A.
Mechanics and Mechanical Engineering
|
2018
|
Vol. 22, nr 1
313--328
EN
The present paper is devoted to investigate the influence of the rotation, thermal field, initial stress, gravity field, electromagnetic and voids on the reflection of P wave under three models of generalized thermoelasticity: Classical and Dynamical coupled model (CD), Lord-Shulman model (LS), Green-Lindsay model (GL), The boundary conditions at stress-free thermally insulated surface are satisfied to obtain Algebraic system of four equations in the reflection coefficients of various reflected waves. It is shown that there exist four plane waves; P1, P2, P3 and P4. In addition, the reflection coefficients from insulated and isothermal stress-free surface for the incident P wave are obtained. Finally, numerical values of the complex modulus of the reflection coefficients are visualized graphically to display the effects of the rotation, initial stress, gravity field magnetic field, thermal relaxation times and voids parameters.
5
Content available remote Impact of pre-stress, inhomogeneity and porosity on the propagation of Love wave
Gupta S., Pramanik A., Ahmed M.
Acta Geophysica
|
2018
|
Vol. 66, no. 5
855--866
EN
This work presents a mathematical modelling of Love wave transference through a pre-stress influenced anisotropic medium with heterogeneity between a sandy medium and an initially stressed anisotropic porous medium. Variable separation method has been induced in order to derive the frequency relation. Using appropriate boundary conditions at two interfaces, the dispersion equation has been obtained in its closed form. Possible particular cases are considered, and the corresponding results are consonant with the classical cases. Numerical computations have been employed to demonstrate the role of inhomogeneity factors, initial stresses and porosity, and are depicted by means of graphs which substantiates that those parameters immensely affect the Love wave velocity. In mineral prospecting and exploring technique in earth, the method and the results of this problem may be applicable.
6
Content available remote Impact of Inhomogeneity on SH-type Wave Propagation in an Initially Stressed Composite Structure
Saha S., Chattopadhyay A., Singh A. K.
Acta Geophysica
|
2018
|
Vol. 66, no. 1
1--19
EN
The present analysis has been made on the influence of distinct form of inhomogeneity in a composite structure comprised of double superficial layers lying over a half-space, on the phase velocity of SH-type wave propagating through it. Propagation of SH-type wave in the said structure has been examined in four distinct cases of inhomogeneity viz. when inhomogeneity in double superficial layer is due to exponential variation in density only (Case I); when inhomogeneity in double superficial layers is due to exponential variation in rigidity only (Case II); when inhomogeneity in double superficial layer is due to exponential variation in rigidity, density and initial stress (Case III) and when inhomogeneity in double superficial layer is due to linear variation in rigidity, density and initial stress (Case IV). Closed-form expression of dispersion relation has been accomplished for all four aforementioned cases through extensive application of Debye asymptotic analysis. Deduced dispersion relations for all the cases are found in well-agreement to the classical Love-wave equation. Numerical computation has been carried out to graphically demonstrate the effect of inhomogeneity parameters, initial stress parameters as well as width ratio associated with double superficial layers in the composite structure for each of the four aforesaid cases on dispersion curve. Meticulous examination of distinct cases of inhomogeneity and initial stress in context of considered problem has been carried out with detailed analysis in a comparative approach.
7
Content available remote The effect of initial stress on generalized thermoviscoelastic medium with voids and temperature-dependent properties under Green-Neghdi theory
Othman M. I. A., Fekry M.
Mechanics and Mechanical Engineering
|
2017
|
Vol. 21, nr 2
291--308
EN
The present paper aims to study the effect of initial stress on the 2-D problem of a homogeneous, isotropic, generalized thermo-viscoelastic material with voids in the context of Green-Naghdi theory. The modulus of elasticity is taken as a linear function of reference temperature. The analytical expressions for the physical quantities are obtained in the physical domain by using the normal mode analysis. These expressions are calculated numerically for a specific material and explained graphically. Comparisons are made with the results predicted by (G-N II) and (G-N III) theory in the presence and absence of the initial stress and temperature-dependent properties.
8
Content available remote Reaction of plane waves from a rotating magneto-thermoelastic medium with two-temperature and initial stress under three theories
Othman M. I. A., Abo-Dahab S. M., Alsebaey O. N. S.
Mechanics and Mechanical Engineering
|
2017
|
Vol. 21, nr 2
217--232
EN
The model of the equations of generalized magneto-thermoelasticity in an isotropic elastic medium with two-temperature under the effect initial stress is established. The entire elastic medium is rotated with a uniform angular velocity. The formulation is applied under three theories of generalized thermoelasticity: Lord-Shulman, Green-Lindsay, as well as the coupled theory. The Harmonic function is used to obtain the exact expressions for the considered variables. Some particular cases are also discussed in the context of the problem. We introduce the equations of the velocity of p-wave, T-wave and SV-wave. The boundary conditions for mechanical and Maxwell’s stresses and thermal insulated or isothermal are applied to determine the reflection coefficients for p-wave, T-wave and SV-wave. Some new aspects are obtained of the reflection coefficients and displayed graphically and the new conclusions are presented. Comparisons are also made with the results predicted by different theories (CT, L-S, G-L) in the presence of rotation, initial stress, magnetic field, as well as, the two-temperature parameter on the reflection of generalized thermos-elastic waves.
9
Content available remote On generalized magneto-thermoelastic P-, T- and SV-waves propagation at the interface between two magnetized solid-liquid media with initial stress
Abo-Dahab S. M.
Mechanics and Mechanical Engineering
|
2017
|
Vol. 21, nr 4
897--917
EN
In this paper, we study the effects of magnetic field and initial stress on plane waves propagation. We have investigated the problem of reflection and refraction of thermoelastic waves at a magnetized solid-liquid interface in the presence of initial stress, in the context of CT (Classical theory) of thermoelasticity, the problem has been solved. The boundary conditions applied at the interface are: (i) continuity of the displacement, (ii) vanishing of the tangential displacement, (iii) continuity of normal force per unit initial area, (iv) vanishing of the tangential stress and (v) continuity of temperature. The amplitudes ratios for the incident P-, T-, and SV- waves have been obtained. The reflection and transmission coefficients for the incident waves are computed numerically, considering the initial stress and magnetic field effects and the results are represented graphically.
10
Wzmocnienie mostu stalowego wstępnie naprężonymi taśmami kompozytowymi CFRP
Siwowska P., Siwowski T.
Inżynieria i Budownictwo
|
2017
|
R. 73, nr 11
588--592
PL
Przedstawiono sposób wzmocnienia mostu stalowego za pomocą wstępnie naprężonych taśm CFRP. W ramach projektu badawczego R&D wykonano próbne obciążenie mostu przed wzmocnieniem i po wzmocnieniu. W wyniku wzmocnienia uzyskano redukcję ugięć dźwigarów wynoszącą 10÷20%, redukcję odkształceń stali 5÷10% przy prawie 60-procentowym wykorzystaniu nośności kompozytu. Opisano także technologię wzmocnienia.
EN
The strengthening of a steel bridge with pre-tensioned CFRP strips has been presented in the paper. In the scope of the R&D project the proof-tests before and after strengthening have been carried out. As a result of strengthening the following effects has been gained: 10-20% reduction of girder’s deflection, 5–10% steel strain reduction while near 60% utilization of CFRP composites. The strengthening technology has also been described in the paper.
11
Content available Effect of initial stress on the dynamic response of a multi-layered plate-strip subjected to an arbitrary inclined time-harmonic force
Dasdemir A.
International Journal of Applied Mechanics and Engineering
|
2017
|
Vol. 22, no. 3
521–537
EN
The forced vibration of a multi-layered plate-strip with initial stress under the action of an arbitrary inclined time-harmonic force resting on a rigid foundation is considered. Within the framework of the piecewise homogeneous body model with the use of the three-dimensional linearized theory of elastic waves in initially stressed bodies (TLTEWISB), a mathematical modelling is presented in plane strain state. It is assumed that there exists the complete contact interaction at the interface between the layers and the materials of the layer are linearly elastic, homogeneous and isotropic. The governing system of the partial differential equations of motion for the considered problem is solved approximately by employing the Finite Element Method (FEM). Further, the influence of the initial stress parameter on the dynamic response of the plate-strip is presented.
12
Content available remote Magnetoelastic shear wave propagation in pre-stressed anisotropic media under gravity
Kumari N., Chattopadhyay A., Singh A. K., Sahu S. A.
Acta Geophysica
|
2017
|
Vol. 65, no. 1
189--205
EN
The present study investigates the propagation of shear wave (horizontally polarized) in two initially stressed heterogeneous anisotropic (magnetoelastic transversely isotropic) layers in the crust overlying a transversely isotropic gravitating semi-infinite medium. Heterogeneities in both the anisotropic layers are caused due to exponential variation (case-I) and linear variation (case-II) in the elastic constants with respect to the space variable pointing positively downwards. The dispersion relations have been established in closed form using Whittaker’s asymptotic expansion and were found to be in the well-agreement to the classical Love wave equations. The substantial effects of magnetoelastic coupling parameters, heterogeneity parameters, horizontal compressive initial stresses, Biot’s gravity parameter, and wave number on the phase velocity of shear waves have been computed and depicted by means of a graph. As a special case, dispersion equations have been deduced when the two layers and half-space are isotropic and homogeneous. The comparative study for both cases of heterogeneity of the layers has been performed and also depicted by means of graphical illustrations.
13
Content available Wpływ naprężeń pierwotnych w górotworze na wielkość i rozkład stref zniszczeń wokół wyrobiska korytarzowego
Wesołowski M.
Przegląd Górniczy
|
2016
|
T. 72, nr 6
98--105
PL
W artykule przedstawiono wyniki modelowania numerycznego wpływu naprężeń pierwotnych na zachowania się skał w rejonie wyrobiska korytarzowego. Ocenę zmian zachodzących w rejonie wyrobiska wykonano przy wykorzystaniu dwóch modeli numerycznych: sprężysto-plastycznego izotropowego oraz anizotropowego ubiquitous joint. Jak wykazały przeprowadzone symulacje komputerowe wzrost udziału poziomych naprężeń pierwotnych częściowo redukuje zniszczenia górotworu wokół wyrobiska, wynikające z działania naprężeń ścinających. Jednocześnie wzrost naprężeń poziomych zwiększa deformacje wyrobiska. Jest to szczególnie widoczne w przypadku modelu ubiquitous joint.
EN
This paper presents numerical modeling results of the initial stress size influence on rocks behaviour in the dog heading area. The changes taking place in the heading area have been evaluated with the use of two numerical models: the isotropic elasto-plastic model and the anisotropic ubiquitous joint model. Computer simulations show that the increase of horizontal initial stresses participation partly reduces damages of rock mass around the heading, caused by shearing stresses. At the same time the increase of horizontal stress enlarges deformations of the heading. This is particularly visible in the ubiquitous joint model.
14
Content available Modelling of SH-waves in a fiber-reinforced anisotropic layer over a pre-stressed heterogeneous half-space
Kakar R., Kakar S.
Journal of Theoretical and Applied Mechanics
|
2016
|
Vol. 54 nr 2
463--475
EN
Modelling of SH-waves in an anisotropic fiber-reinforced layer provides a great deal of support in the understanding of seismic wave propagation. This paper deals with the propagation of SH-waves in a fiber-reinforced anisotropic layer over a pre-stressed heterogeneous half-space. The heterogeneity of the elastic half-space is caused by linear variations of density and rigidity. As a special case when both media are homogeneous and stress free, the derived equation is in agreement with the general equation of the Love wave. Numerically, it is observed that the velocity of SH-waves decreases with an increase in heterogeneity-reinforced parameters and decrease in initial stress.
15
Content available Effect of initial stress and gravity field on micropolar thermoelastic solid with microtemperatures
Othman M. I. A., Tantawi R. S., Hilal M. I. M.
Journal of Theoretical and Applied Mechanics
|
2016
|
Vol. 54 nr 3
847--857
EN
The purpose of the present article is the study of the effect of the gravity field on an initially stressed micropolar thermoelastic medium with microtemperatures. The analytical method used to obtain the formula of the physical quantities is the normal mode analysis. The comparisons are established graphically in the presence and the absence of gravity, initial stress and micropolar thermoelasticity. The main conclusions state that the gravity, initial stress and the micropolar thermoelasticity are effective physical operators on the variation of the physical quantities. The microtemperatures are very useful theory in the field of geophysics and earthquake engineering.
16
Content available remote Effect of Corrugation and Reinforcement on the Dispersion of SH-wave Propagation in Corrugated Poroelastic Layer Lying over a Fibre-reinforced Half-space
Singh A. K., Das A., Lakshman A., Chattopadhyay A.
Acta Geophysica
|
2016
|
Vol. 64, no. 5
1340--1369
EN
The presence of porosity and reinforcement in a medium is an important factor affecting seismic wave propagation and plays vital role in many geophysical prospects. Also, the presence of salt and ore deposits, mountains, basins, mountain roots, etc. is responsible for the existence of corrugated boundary surfaces of constituent layers. Such facts brought motivation for the present paper which deals with the propagation of SHwave in a heterogeneous fluid-saturated poroelastic layer with corrugated boundaries lying over an initially stressed fibre-reinforced elastic halfspace. Closed form of dispersion relation has been obtained and is found in well agreement to classical Love wave equation for isotropic case. The effect of corrugation, wave number, undulation, position parameter, horizontal compressive/tensile initial stress and heterogeneity on phase velocity has been analysed through numerical computation and graphical illustration. Moreover, comparative study exploring the effect of presence and absence of reinforcement in half-space on dispersion curve is the major highlight of the current study.
17
Content available Analysis Of Factors Affecting Gravity-Induced Deflection For Large And Thin Wafers In Flatness Measurement Using Three-Point-Support Method
Liu H., Dong Z., Kang R., Zhou P., Gao S.
Metrology and Measurement Systems
|
2015
|
Vol. 22, nr 4
531--546
EN
Accurate flatness measurement of silicon wafers is affected greatly by the gravity-induced deflection (GID) of the wafers, especially for large and thin wafers. The three-point-support method is a preferred method for the measurement, in which the GID uniquely determined by the positions of the supports could be calculated and subtracted. The accurate calculation of GID is affected by the initial stress of the wafer and the positioning errors of the supports. In this paper, a finite element model (FEM) including the effect of initial stress was developed to calculate GID. The influence of the initial stress of the wafer on GID calculation was investigated and verified by experiment. A systematic study of the effects of positioning errors of the support ball and the wafer on GID calculation was conducted. The results showed that the effect of the initial stress could not be neglected for ground wafers. The wafer positioning error and the circumferential error of the support were the most influential factors while the effect of the vertical positioning error was negligible in GID calculation.
18
Content available remote Mechanical Behavior and Modeling of Initially Stressed Membranes
Maj C., Zając P., Szermer M., Lobur M
Machine Dynamics Research
|
2013
|
Vol. 37, No. 2
65-70
EN
Modeling of microstructures is one of the most important step in the project. In its early stage the analytical modeling is usually used. The need of use of as fast as possible method is a primary source of errors for each designer. The simple analytical model is commonly used in order to obtain basic performance of the device. However, it is the source of error due to some simplifications. In this paper, the comparison between the analytical model and FEM simulation is presented taking into consideration maximal membrane deflection, membrane form and stress distribution. The initial stress of the membrane has been taken into account as a primary source of mismatch. Finally, the error depending of initial stress has been estimated. All simulations has been performed for small deflection of the membrane.
19
Content available remote Effects of initial stresses on guided waves in unidirectional plates
Zhang X. M., Yu J. G.
Archives of Mechanics
|
2013
|
Vol. 65, nr 1
3-26
EN
The guided wave propagation in unidirectional plates under gravity, homogeneous initial stress in the thickness direction and inhomogeneous initial stress in the wave propagating direction is investigated in this paper based on the theory of mechanics of incremental deformations. The Legendre orthogonal polynomial series expansion method is used to solve the coupled wave equation. Two different wave propagating directions, the fiber orientation and the vertical fiber orientation, are discussed respectively. The effects of the initial stresses on the Lamb-like wave and shear-horizontal (SH) wave are respectively investigated. The effects of the initial stresses on the dispersion curves and on the displacement and stress distributions are discussed.
20
Content available remote Nieliniowość geometryczna oraz odkształcalność postaciowa w analizie układów prętowych
Obara P., Szczecina M.
Zeszyty Naukowe Politechniki Rzeszowskiej. Budownictwo i Inżynieria Środowiska
|
2012
|
z. 59, nr 3/II
405-412
PL
W pracy przeprowadzona została nieliniowa analiza uwzględniająca duże gradienty przemieszczeń, ale małe gradienty odkształceń, przy założeniu liniowych związków konstytutywnych dla materiału jednorodnego i izotropowego. Wyprowadzone zostało nieliniowe, ścisłe w ramach przyjętych założeń, wyrażenie na odkształcenie podłużne włókna położonego w dowolnej odległości od osi pręta. W rozważaniach uwzględniono wpływ odkształcalności postaciowej, czyli bazowano na klasycznej teorii Timoshenki [1]. Podano wzory na macierze: sztywności liniowej, naprężeń wstępnych oraz początkowych odkształceń elementu prętowego. Przeprowadzono również ścisłą i przybliżoną analizę stateczności początkowej mającą na celu określenie wpływu smukłości prętów na nośności krytyczne.
EN
The nonlinear analysis, which takes into account large gradients of displacements but small gradients of deformation, assuming linear constitutive relations for homogeneous and isotropic material, was carried out. The nonlinear, exact in its assumptions formula for deformation of the longitudinal fibre, located at any distance from the axis of the rod was derived. The discussion includes the influence of non-dilatational strain, based on the classical theory of Timoshenko [1]. The matrices of linear stiffness, initial stress and initial deformation of a rod element were given. Exact and approximate analyses of initial stability were performed to determine the influence of rod slenderness on the value of critical load.
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