Wyniki wyszukiwania - BazTech

1

Monitorowanie tunelu i jego otoczenia z wykorzystaniem strunowej i światłowodowej techniki pomiarowej DFOS

Sieńko Rafał, Bednarski Łukasz, Howiacki Tomasz, Zuziak Katarzyna, Monsberger Christoph

Drogownictwo

|

2022

|

nr 7-8

248--260

PL

Infrastruktura tunelowa charakteryzuje się bardzo dużymi konsekwencjami potencjalnej awarii. Konieczne jest zatem właściwe kontrolowanie stanu jej deformacji poprzez pomiary wybranych wielkości fizycznych, np. odkształceń, temperatur i przemieszczeń, umożliwiających finalnie ocenę bezpieczeństwa budowy i eksploatacji danego tunelu. W artykule omówiono możliwości zastosowania punktowych pomiarów czujnikami strunowymi oraz geometrycznie ciągłych pomiarów światłowodowych DFOS. Współcześnie coraz częściej wykorzystuje się zalety obu tych technologii w celu stworzenia hybrydowych systemów monitorowania.

EN

Very high consequences of potential failure characterise tunnel infrastructure. Thus, it is necessary to properly control its deformation state by measuring selected physical quantities, e.g. strains and displacements, enabling the safety assessment of a given tunnel during its construction or operation. The paper discusses the possibilities of spot measurements by vibrating wire gauges and geometrically continuous measurements by distributed fibre optic sensors (DFOS). Today, the advantages of both technologies are increasingly being combined to create hybrid monitoring systems.

2

Assessment of the early-age strains and stresses in 2D restrained self-stressed members

Tur Viktar V., Sannikava Volha H.

Budownictwo i Architektura

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2020

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Vol. 19, no 4

85--94

EN

The paper presents the implementation of the modified strains development model (MSDM) for the two-way restrained self-stressed members such as expansive concrete-filled steel tubes and expansive concrete plane elements with arbitrary orthogonal reinforcement. The analytical approach allows defining the restrained strains and stresses in any 2D restraint conditions by following the iterative procedures and accounting for the elastic-plastic behaviour of expansive concrete at an early age. The consistency of the proposed method was confirmed by assessing the experimental results of the two series of the expansive concrete-filled steel tubes and three series of the expansive concrete plane members with mesh reinforcement in the centre of gravity.

3

Application of fiber optic FBG techniques in analysis of strain in engineering machines

Juraszek Janusz

New Trends in Production Engineering

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2019

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Vol. 2, Iss. 1

480--485

EN

The paper presents the use of fiber optic FBG strain sensors for analysis of deformations of machines and devices including those used in mining techniques. FBG strain sensors have many advantages over classic strain measurements using electro resistance strain gauges. They are characterized by a significant measurement accuracy of up to 1 mm, a service life of up to 30 years, the possibility of measuring large deformations of up to 8%, significant fatigue life, the possibility of building measurement networks and, something extremely important in mining – intrinsic safety, because the operating medium is white light. The entire measurement system based on the optical interrogator was also discussed. It enables conducting both static and dynamic measurements. The results of the strain research for an engineering machine, in which the loads had exceeded 800 T, were reported.

4

Temperature and pressure dependent creep stress analysis of spherical shell

Pathania D. S., Verma G.

International Journal of Applied Mechanics and Engineering

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2019

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Vol. 24, no. 1

105--115

EN

In the present paper, we have studied the temperature and pressure dependent creep stress analysis of spherical shell. The review is critical to enhance the warm resistance of spherical shells in high-temperature conditions. The effect of different parameters was studied and it was noticed that the parameter n has a significant influence on the creep stresses and strain rates. Creep stresses and strain rates are ascertained on the premise of summed up strain measures and Seth’s transition hypothesis. This investigation is completed to demonstrate the impacts of temperature on the creep stresses and strain rates in the spherical shell. The resulting quantities are computed numerically and depicted graphically. It has been watched that the spherical shell made of an incompressible material is on more secure side of configuration when contrasted with the shell made of a compressible material.

5

Numerical Analysis of Thermo-Mechanical Phenomena of the Progressive Hardening Elements Made of Tool Steel for Cold Work

Domański T.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 1

329--338

EN

The numerical algorithm of thermal phenomena is based on the solution of the heat conduction equations in Petrov-Galerkin’s formula using the finite element method. In the modeling of phase transformation in the solid state, the models based on the diagrams of continuous heating and continuous cooling (CHT and CCT). In the modeling of mechanical phenomena, equations of equilibrium and constitutive relationships were adopted in the rate form. It was assumed that the hardened material is elastic-plastic, and the plasticizing can be characterized by isotropic, kinematic or mixed strengthening. In the model of mechanical phenomena besides thermal, plastic and structural strains, the transformations plasticity was taken into account. Thermo-physical size occurring in the constitutive relationship, such as Young’s modulus and tangential modulus, while yield point depend on temperature and phase composition of the material. The modified Leblond model was used to determine transformation plasticity. This model was supplemented by an algorithm of modified plane strain state, advantageous in application to the modeling of mechanical phenomena in slender objects. The problem of thermoelasticity and plasticity was solved by the FEM. In order to evaluate the quality and usefulness of the presented numerical models, numerical analysis of temperature fields, phase fractions, stresses and strains was performed, i.e. the basic phenomena accompanying surface layer of progressive-hardening with a movable heat source of slender elements made of tool steel for cold work.

6

Numerical analysis of strains and stresses in the hot cogging process

Kukuryk M.

Journal of Applied Mathematics and Computational Mechanics

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2018

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Vol. 17, nr 3

45--52

EN

In this paper, the analysis of the three-dimensional strain state for the hot cogging process of a steel tool with the application of the finite element method is presented. The results of work connected with the simulation of metal flow scheme, and fields of stress, strain and temperature in the material deformation process in the hot forging conditions are presented. The distribution of the effective strain, the effective stress, mean stresses and temperature on the surface of forging cross sections are determined. The numerical analysis was performed with the application of the programme DEFORM-3D. The theoretical results are subjected to experimental verification.

7

Weryfikacja modelu obliczeniowego stanu konstrukcji nawierzchni drogowej bazującego na sprężystych warstwach skończonych wykorzystanego w programie MWS Pavement Design

Szczepankiewicz P.

Drogownictwo

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2018

|

nr 6

191--195

PL

W artykule przedstawiono weryfikację narzędzia do obliczeń stanu konstrukcji nawierzchni drogowej (tj. naprężeń, odkształceń i przemieszczeń) MWS Pavement Design poprzez porównanie do modelu wielowarstwowej półprzestrzeni sprężystej. Przedstawiono różnicę między modelami, a następnie porównano dwie konstrukcje nawierzchni drogowych. W pierwszej kolejności porównano różnice wyników odkształceń w krytycznych punktach konstrukcji nawierzchni. Dokonano obliczeń trwałości zmęczeniowej obu konstrukcji na podstawie wyliczonych odkształceń. Ostatecznie podsumowano obliczenia porównaniem wyników.

EN

The article presents the verification of the tool for calculating the pavement construction condition (stresses, strains and displacements) that is MWS Pavement Design Software, by comparing it to the well-known multilayer elastic half-space model. The difference between the models was presented, and further two road pavement constructions were compared. First, the differences in deformation at critical points in the pavement construction were compared. Next, the fatigue life of both constructions was calculated on the basis of calculated deformations. Finally, the calculations were summarized by comparing the results.

8

System monitorowania mostów kompozytowych z wykorzystaniem światłowodowych czujników odkształceń

Siwowski T., Sieńko R., Bednarski Ł.

Mosty

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2017

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nr 5

50--53

PL

Wysoka wytrzymałość i trwałość kompozytów FRP powodują, że materiał ten coraz częściej jest stosowany w budownictwie mostowym. Istnieje jednak ryzyko powstania uszkodzeń konstrukcyjnych (np. pęknięcia międzywarstwowe, degradacja matrycy). W artykule opisano wykorzystanie technologii światłowodowej do rozłożonych pomiarów odkształceń mostu FRP w czasie obciążenia próbnego, zrealizowanych przy współpracy Politechniki Rzeszowskiej i firmy SHM System.

EN

High strength and durability of FRP (fibre reinforced polymer) composites make this material increasingly applied in bridge construction. However, there is a risk of structural damage (e.g. cracks between layers, matrix degradation). The paper describes the application of optical fibre technology for distributed strain measurements of an FRP bridge during its load test, conducted in cooperation between the Rzeszów University of Technology and the SHM System company.

9

Uproszczone modele deformacji frezu walcowego poddanego obciążeniom pochodzącym od sił skrawania podczas frezowania stopu aluminium Al 7075

Kawalec A., Szałęga K.

Mechanik

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2017

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R. 90, nr 11

968--970

PL

Omówiono zagadnienie geometrycznego modelowania frezu walcowego oraz obliczania jego ugięć pod wpływem obciążeń odwzorowujących siły skrawania występujące podczas frezowania powierzchni wyrobu ze stopu Al 7075. W modelowaniu uwzględniono 2 modele przestrzenne frezu walcowego: z prostoliniowymi krawędziami skrawającymi oraz ze śrubowymi krawędziami skrawającymi. Wzięto pod uwagę oddziaływanie sił skupionych i różnych rozkładów obciążeń odwzorowujących siły skrawania. Wyciągnięto wnioski dotyczące wpływu kąta nachylenia sił względem wybranej osi układu współrzędnych na generowane naprężenia zredukowane i deformacje frezu. Do obliczenia pól przemieszczeń, odkształceń i naprężeń wykorzystano metodę elementów skończonych.

EN

The problem of geometric modeling of the plain milling cutter and its deflection under the influence of loads mapping forces occurring during the milling of the Al 7075 alloy surface is discussed. In modeling, 2 types of plain milling cutters are included: with rectilinear cutting edges and with helical cutting edges. The influence of concentrated forces and different distributions of loads mapping the cutting forces, is considered. Conclusions are drawn regarding the influence of the force inclination angles relative to the selected axis of the coordinate system on the generated effective stresses and cutter deformations. The finite element method was used to calculate the displacements, deformations and stresses.

10

The impact of food on the growth of clones of Lecane inermis, a potential bulking control agent

Kowalska E., Paturej E., Zielińska M.

Environment Protection Engineering

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2017

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Vol. 43, nr 1

49--57

EN

Excessive growth of filamentous bacteria, inducing activated sludge bulking, presents a serious problem in many wastewater treatment plants (WWTPs). The idea of using Lecane inermis rotifers as a tool for controlling the filamentous bacteria density in activated sludge requires developing a method of culturing rotifers at high concentrations. The objective of this work was to determine the effect of two culture media on the growth of three Lecane inermis strains. The growth of rotifers from a single individual (parthenogenetic female) fed the tested culture media was observed for 10 days. The rotifers showed different individual growth, depending on the strain and type of culture medium. The results of the studies suggest that by using the tested culture media, it may be possible to select a Lecane inermis strain with the highest culturing capacity at high density of rotifers in order to inoculate activated sludge with these organisms in wastewater treatment plants.

11

Verification of the method of estimating bending moments in soil-shell structures on the basis of shell deformation

Korusiewicz L.

Roads and Bridges - Drogi i Mosty

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2016

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Vol. 15, no. 3

221--230

EN

The paper concerns soil-shell bridge structures of arch cross-section made from corrugated plates. During backfilling the shell crown is deflected upwards and the sides move inwards at the shoulder (haunch) level. The measured displacements are used to represent the arch deformation. With large displacements that typically occur during backfilling it is possible to measure them with surveying instruments. This enables monitoring the changes in the shell deformations on site as the work proceeds. This study analyses the accuracy of the method to estimate the bending moments induced in the structure - the main factor influencing the values of normal stresses in the shell – on the basis of the deformation of curvature at the crown, determined by measuring the displacements. The measurements and calculations carried out for an existing structure were used for comparative analysis. The structure identified for this purpose is an arch shell made of single, deep-corrugated metal plate (Super Cor). The experimental study included measurement of unit strain of the shell to determine the bending moments used for independent verification of the computed values.

PL

Praca dotyczy mostowych obiektów gruntowo-powłokowych o łukowym kształcie przekroju poprzecznego powłok, wykonanych ze stalowej blachy falistej. Podczas układania zasypki gruntowej powłoka o takim kształcie ulega wypiętrzeniu w kluczu i zwężeniu w pachwinie. Na podstawie pomiarów tych przemieszczeń odwzorowuje się jej deformację. Dzięki znacznym wartościom przemieszczeń występującym podczas zasypki pomiary te mogą być realizowane z użyciem technik geodezyjnych. Umożliwia to śledzenie na budowie zmian deformacji powłoki wraz z postępem robót na obiekcie. W pracy poddano analizie dokładności metodę szacowana momentów zginających – głównego czynnika wpływającego na wartość naprężeń normalnych w powłoce – na podstawie zmiany krzywizny w jej kluczu, określonej z pomiarów przemieszczeń. Analizę porównawczą oparto na wynikach pomiarów i obliczeń uzyskanych na wybudowanym obiekcie. Wykorzystano do tego celu powłokę o kształcie łukowym, wykonaną z pojedynczej blachy o wysokim profilu (Super Cor). W badaniach tych dokonano jednocześnie pomiarów odkształcenia jednostkowego powłoki, które wykorzystano do określenia momentów zginających, pozwalających na niezależną weryfikację wyników obliczeń.

12

High biomass producers and promising candidates for biodiesel production from microalgae collection IBASU-A (Ukraine)

Tsarenko P., Borysova O., Blume Y.

Oceanological and Hydrobiological Studies

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2016

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Vol. 45, No. 1

79--85

EN

A comparative study was carried out on the growth characteristics of 33 strains of 12 species belonging to genera Acutodesmus (7), Botryococcus (1), Chlorella (5), Chloroidium (2), Desmodesmus (8), Euglena (2), Monoraphidium (2), and Parachlorella (6) from the Microalgae Culture Collection of the Institute of Botany, NAS of Ukraine (IBASU-A). All high biomass-producing strains considered as promising candidates for biofuel production demonstrated active growth (high maximum cell concentration, specific growth rate and productivity). The most promising strains included Acutodesmus dimorphus IBASU-A 251, 252, Desmodesmus magnus IBASU-A 401, D. multivariabilis var. turskensis IBASU-A 398, Chlorella vulgaris IBASU-A 189, 192, and Parachlorella kessleri IBASU-A 444. Their productivity varied from 0.58 g d.w. -1 to 1.6 g d.w. -1 per day. In general, the cultivation of these strains is considered both as a potential bioresource of feedstock for biodiesel production and other industrial demands.

13

Uproszczony dwuwymiarowy model ugięć cienkiej ścianki wywołanych siłą odporową od frezu

Kawalec A., Płodzień M.

Mechanik

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2016

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R. 89, nr 10

1524--1525

PL

W artykule omówiono zagadnienie numerycznego modelowania ugięć cienkiej ścianki półwyrobu kształtowanego w procesie frezowania frezem walcowym. Opracowany model obliczeniowy jest dwuwymiarowy i uwzględnia zjawiska przenoszenia nacisków w obszarze styku między frezem a obrabianą ścianką. Do obliczenia przemieszczeń, odkształceń oraz naprężeń zastosowano metodę elementów skończonych.

EN

In the paper there is described the problem of numerical modeling of deflections of thin wall in the process of milling using plain milling cutter. Developed numerical model is two-dimensional and takes into consideration the distribution of pressure phenomena between the milling cutter and manufactured wall. For computing displacements, strains and stresses the finite element method was used.

14

Rehabilitation of Prestressed Concrete Bridges by FRP Composites in the Light of in Situ Testing

Mordak A., Mańko Z.

Logistics and Transport

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2016

|

Vol. 29, No. 1

57--64

EN

The article presents the analysis of FRP composite materials strengthening systems for pre-stressed bridge structure elements. Displacements and strains of main beams of bridges were investigated before and after the strengthening executed by FRP composite materials. Test load field and theoretical analysis were performed after bridge structure repair. The results of bridge structures after strengthening in field load tests allowed for an assessment of the efficiency of the strengthening, as well as establishment of guidelines for future reference concerning this type of maintenance in the engineering practice.

15

Niejednoznaczność deformacyjno-wymiarowa wynikająca z dyrektywy UE dotyczącej gięcia rur dla dużych i małych odkształceń

Śloderbach Z.

Energetyka

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2016

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nr 11

706--710

PL

Wyprowadzono zależności dla obliczania maksymalnych wielkości odkształceń w miarach odkształceń logarytmicznych, które są słuszne dla przypadku dużych i małych deformacji, jakie powstają w procesie gięcia rur na giętarkach w warstwach rozciąganych i ściskanych i są oparte na Dyrektywie UE. Dyrektywa dotyczy wytwarzania urządzeń ciśnieniowych zgodnie z europejsko-unijnymi i polskimi wymaganiami. Wykazano, że dla przypadku dużych deformacji, jakie zachodzą podczas gięcia rur na kolana wartości odkształcenia liczone w miarach odkształceń logarytmicznych (rzeczywistych) i względnych dają różne wartości obliczeniowe, lecz równe grubości ścianki w strefie gięcia i zgięcia. W przypadku użycia miar odkształceń względnych słusznych dla małych odkształceń, wówczas różne są zarówno wartości składowych i intensywności odkształcenia, a także grubości ścianki. Obliczono także wymagane grubości początkowych-wyjściowych ścianek rur przeznaczonych do gięcia, aby po zgięciu otrzymać żądaną grubość ścianki kolana. Obliczeniowe rezultaty przedstawiono w postaci odpowiednich wykresów.

EN

In paper the relations to calculate the maximum value of relative strains valid for the case of large and small deformations, which occur in a process of bending of tubes on benders, in stretched layers of tubes, are presented in this work on the basis of EU-Directive concerning production of pressure equipment. It has been shown that for large deformations that occur during bending of the pipes on knees, logarithmic strain measures (real) and relative strain measures give different values of strain but equal wall thicknesses in the bending zone. For the case of relative measures of deformations valid for small deformations different are both values of components and intensities of the deformation and thicknesses of the partition wall. Logarithmic measures are frequently used in engineering practice and are valid for large and small deformations. Reverse expressions were also derived to calculate the required initial wall thickness of the tube to be bent, in order to obtain the desired wall thickness of knee after bending. Computational results were presented in the form of graphs.

16

Carrying capacity of strengthened reinforced elements on action of bending moments

Mazurak A., Kovalyk I.

ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes

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2016

|

Vol. 5, No 3

197--204

EN

The article proposes methods of calculation of carrying capacity of strengthened reinforced elements on action of bending moments. Basing on the experimental research, we have carried out analysis of calculated data with the investigated results.

17

Derivation of relations and analysis of tube bending processes using discontinuous fields of plastic strains. Part II. Discussion and analysis of the obtained results

Śloderbach Z.

International Journal of Applied Mechanics and Engineering

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2015

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Vol. 20, no. 1

427--435

EN

This paper presents the calculation results obtained on the basis of three formal simplifications (derived in Part I) gradually led into the main components of the generalized model of strain where suitable simplifications of the 1st, 2nd and 3rd type have been obtained. The paper also presents the results of considerations on the Wall thickness distribution in the vertex point of the elongated layers of the bent elbow, and values of main components of the strain state and intensity of the strain (equivalent strain) depending on the bending angle for the generalized strain scheme and three simplified methods. The results are shown in the form of graphs and table.

18

Derivation of relations and analysis of tube bending processes using discontinuous fields of plastic strains. Part II. Discussion and analysis of the obtained results

Śloderbach Z.

International Journal of Applied Mechanics and Engineering

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2015

|

Vol. 20, no. 2

427--435

EN

This paper presents the calculation results obtained on the basis of three formal simplifications (derived in Part I) gradually led into the main components of the generalized model of strain where suitable simplifications of the 1st, 2nd and 3rd type have been obtained. The paper also presents the results of considerations on the wall thickness distribution in the vertex point of the elongated layers of the bent elbow, and values of main components of the strain state and intensity of the strain (equivalent strain) depending on the bending angle for the generalized strain scheme and three simplified methods. The results are shown in the form of graphs and table.

19

Derivation of relations and analysis of tube bending processes using discontinuous fields of plastic strains. Part I. Derivation of geometric-analytic relationships

Śloderbach Z.

International Journal of Applied Mechanics and Engineering

|

2015

|

Vol. 20, no. 2

417--426

EN

The generalized strain scheme in bending metal tubes at bending machines with the use of a mandrel presented in Śloderbach (1999; 2002; 20131,2; 2014) satisfies initial and boundary kinematic conditions of bending, conditions of continuity and inseparability of strains. This paper introduces three formal simplifications gradually imposed into forms of principal components of the generalized strain model giving suitable simplifications of the 1st, 2nd and 3rd types. Such mathematical simplifications cause that the obtained strain fields do not satisfy the condition of consistency of displacements and strain continuity. The simplified methods determine safer values of the wall thickness than those from the generalized continuous strain scheme. The condition of plastic incompressibility was used for the derivation of an expression for distribution of Wall thickness of the bent elbow in the layers subjected to tension and compression for three examples of discontinuous kinematic strain fields.

20

Determination of the initial thickness of tubes subjected to bending. Part II. Discussion and analysis of obtained results

Śloderbach Z.

Engineering Transactions

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2015

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Vol. 63, iss. 4

497--507

EN

In this second part of the paper, applying epressions derived in Part I, the exemplary calculations of the initial thickness of a metallic tube subject to bending at bending machines are presented. The expressions for calculating of the initial thickness were presented for a suitable measure of the big actual radius Ri in the bending zone for an exact (general) solution and for three formal simplifications of the 1st, 2nd, and 3rd order. In the calculations the external or internal diameter of the tube subjected to bending is applied as a parameter. In this paper, the author shows that the calculated initial thickness of the tube (for the same parameters of bending) depending on the external diameter is lower than that calculated depending on the internal diameter. For example, the expression for calculation of deformations included in the UE Directive [1], contains dependence on dext not on dint. The results of the calculations are presented in the graphs and tables enclosed.