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Number of results: 54
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Abstract

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.

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Authors and Affiliations

T. Domański
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Abstract

The DiSTFA method (Displacements and Strains using Transformation and Free Adjustment) was presented in Kamiński (2009). The method has been developed for the determination of displacements and strains of engineering objects in unstable reference systems, as well as for examining the stability of reference points. The DiSTFAG (Gross errors) method presented in the paper is the extension of the DiSTFA method making it robust to gross errors. Theoretical considerations have been supplemented with an example of a practical application on a simulated 3D surveying network.
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Authors and Affiliations

Waldemar Kamiński
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Abstract

The paper presents a method of measuring deformations of cylindrical samples on the testing machine for free tube hydroforming experiments. During experiments a sample made of a thin-walled metal tube is expanded by the internal pressure of the working liquid and additionally subjected to axial compression. This results in a considerable circumferential deformation of the tube and its shortening. Analysis of the load cases and their impact on the deformations can be helpful in determining e.g. tube material properties or general limiting conditions in the tube hydroforming process. In connection with the above, the value of deformations and knowledge of their course during experiment has become one of the most important problems related to the issue described above.

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Authors and Affiliations

H. Sadłowska
Ł. Morawiński
C. Jasiński
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Abstract

The paper presents Finite Elements Method numerical analysis of strength of friction pairs most often used in hip and knee joints alloplasty. Analytic solutions are to indicate and define the areas where damages or premature wear of cooperating elements may occur. Analytical-experimental research states complete and thorough analysis. Accurate technical simulation of the joints of the human motor system, is difficult to conduct due to high level of complexity of human bio-bearings. All attempts to simulate the work of human joints, lead only to an approximate reflection of real human joint motion. To properly face the above problems, along with numerical analysis, there have been conducted empirical tests on the simulator of knee joint endoprosthesis
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Authors and Affiliations

M. Nabrdalik
1
ORCID: ORCID
M. Sobociński
1
ORCID: ORCID

  1. Czestochowa University of Technology, Faculty of Mechanical Engineering and Computer Science, Department of Technology and Automation, 21 Armii Krajowej Av ., 42-201 Czestochowa, Poland
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Abstract

The study of the geometry for worm-gearing is much more complicated than that of plane gearing, since worm-gearing is three-dimensional. A numerical method to determine the conjugate profile of worm-gearing tooth is developed. The software, with numerical set-up and graphic display, is an original and special program, and it could be adopted for the geometry of any kind of cylindrical worm-gearings, as well as for spur gearings and bevel gearings.
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Authors and Affiliations

Daniela Ghelase
Luiza Daschievici
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Abstract

In the present paper, the excavation of the energetic approach that estimates the fatigue crack initiation life of metal is conducted for H62 brass. The benefit of the energetic approach is the division of the actual applied strain range Δε into two parts, that is, a damage strain range Δεd that induces fatigue damage within the metal, and an undamaged strain range Δεc, which does not produce fatigue damage of the metal and corresponds to theoretical strain fatigue limit. The brightness of this approach is that the undamaged strain range Δεc can be estimated by the fundamental conventional parameters of metal in tensile test. The result indicated that the fatigue crack initiation life of H62 brass can be estimated by this approach successfully.
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Authors and Affiliations

M. Zheng
1
ORCID: ORCID
S. Zhang
1
ORCID: ORCID
X.J. Peng
1
ORCID: ORCID
Y. Wang
1
ORCID: ORCID

  1. Northwest University, School of Chemical Engineering, Xi’an 710069, P. R. China
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Abstract

This article describes some selected aspects of a preliminary treatment of measurement cycle results obtained by a new Pen206_18 type hydraulic borehole penetrometer (a borehole jack type), a tool of an in situ determining of mechanical properties of rocks. The pre-treatment of the measurement cycle results is a necessary step to prepare the data for a following appropriate analysis of stress-strain parameters of rocks. Aforementioned aspects are focused mainly on a pre-treatment of hydraulic pressure readouts.
The Pen206_18 type penetrometer is a modified version of a standard Pen206 type penetrometer. The standard version, based on a digital measurement of a critical hydraulic pressure, has been in use in polish hard coal mines for almost 15 years to determine various rock strength parameters. In contrary, the Pen206_18 type penetrometer now provides simultaneous recording of two main measurement cycle parameters (hydraulic pressure and a head pin stroke) during the whole measurement cycle duration. A recent modification of the penetrometer has given an opportunity to look closer at various factors having an influence on the measurement cycle data readouts and, as a consequence, to lay a foundation for a development a new penetrometric method of determining stress-strain parameters of rocks.
In this article it was shown that just before a main stage of the measurement cycle, a transitional stage could occur. It complicates a determination of the beginning of an useful set of measurement cycle data. This problem is widely known also in other static in situ methods of determining stress-strain parameters. Unfortunately, none of various known workouts of this problem were sufficiently adequate to the pre-treatment of the penetrometric measurement cycle results. Hence, a new method of determining the beginning of the useful set of pressure readouts has been developed. The proposed method takes into account an influence of an operational characteristics of the measuring device. This method is an essential part of a new pre-treatment procedure of the Pen206_18 measurement cycle’s pressure readouts.
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Bibliography

[1] A . Kidybiński, J. Gwiazda, Z. Hładysz, Ocena mechanicznych własności skał oraz stateczności górotworu hydraulicznym penetrometrem otworowym. Prace Głównego Instytutu Górnictwa, Seria Dodatkowa. Katowice (1976).
[2] R.E. Goodman, T.K. Van, F.E. Heuze, Measurement of Rock Deformability in Boreholes. In: Proceedings of the 10th U.S. Symposium on Rock Mechanics, University of Texas, Austin, TX, 523-555 (1970).
[3] AS TM D4971-02, Standard Test Method for Determining the In situ Modulus of Deformation of Rock Using the Diametrically Loaded 76-mm (3-in.) Borehole Jack. AS TM International, West Conshohocken, PA, (2002). DOI : https://doi.org/10.1520/D4971-16
[4] R. Pierszalik, S. Rajwa, A. Walentek, K. Bier, 2020. A Pen206 borehole jack suitability assessment for rock mass deformability determination. Arch. Min. Sci. 65 (3), 639-660 (2020). DOI : https://doi.org/10.24425/ams.2020.134135
[5] P.H.V. Nguyen, M. Rotkegel, H.D. Van, Analysis of Behaviour of the Steel Arch Support in the Geological and Mining Conditions of the Cam Pha Coal Basin, Vietnam. Arch. Min. Sci. 65 (3), 551-567 (2020). DOI : https://doi.org/10.24425/ams.2020.134134
[6] A . Walentek, T. Janoszek, S. Prusek, A. Wrana, Influence of longwall gateroad convergence on the process of mine ventilation network-model tests. International Journal of Mining Science and Technology 29, 585-590 (2019). DOI : https://doi.org/10.1016/j.ijmst.2019.06.013
[7] I RB Ogrodzieniec. Penetrometr otworowy typu Pen206. Dokumentacja techniczno-ruchowa + Załącznik A – pulpit Pen206E (2008).
[8] A . Nierobisz, Oznaczanie własności mechanicznych skał za pomocą hydraulicznego penetrometru otworowego nowej generacji. Górnictwo i Geoinżynieria 34 (2), 491-500 (2010).
[9] A . Nierobisz, J. Gawryś, K. Bier, Analiza konstrukcji hydraulicznego penetrometru otworowego i jego modernizacja dla zwiększenia zakresu pomiarowego. Przegląd Górniczy 72 (6), 1-15 (2016).
[10] F .E. Heuze, Estimating the Deformability and Strength of Rock Masses – In-Situ Tests, and Related Procedures. In: STRATCOM Advanced Concept Technology Demonstration (ACTD), Albuquerque (2003). DOI : https://doi.org/10.2172/15005085
[11] M. Rezaei, M. Ghafoori, R. Ajalloeian, Comparison between the In situ Tests’ Data and Empirical Equations for Estimation of Deformation Modulus of Rock Mass. Geosciences Research 1 (1), 47-59 (2016). DOI : https://doi.org/10.22606/gr.2016.11005
[12] A . Palmström, R. Singh, The deformation modulus of rock masses – comparisons between in situ tests and indirect estimates. Tunnelling and Underground Space Technology 16 (3), 115-131 (2001). DOI : https://doi.org/10.1016/S0886-7798(01)00038-4
[13] M. Bukowska, A. Kidybiński, Wpływ czynników naturalnych masywu skalnego na jego wytrzymałość określaną metodami penetrometryczną i laboratoryjną. Prace Naukowe Głównego Instytutu Górnictwa, Research reports mining and environment 1, 35-46 (2002).
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Authors and Affiliations

Rafał Pierszalik
1
ORCID: ORCID

  1. Central Mining Institute (GIG ), 1 Gwarków Sq., 40-166 Katowice, Poland
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Abstract

The purpose of the paper was to design geometric models of the movable connection made of brass for three different attachment options and three different loads. The numerical analysis of the mechanical properties, stresses, strains and displacements using the finite element method was carried out in SolidWorks 2020 and their comparative analysis was performed. The computer simulations performed will allow the boundary conditions that directly affect the mechanical properties of the engineering materials to be optimised.
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Authors and Affiliations

Amadeusz Dziwis
1
ORCID: ORCID
Tomasz Tański
1
ORCID: ORCID
Marek Sroka
1
ORCID: ORCID
Agata Śliwa
1
ORCID: ORCID
Rafał Dziwis
1
ORCID: ORCID

  1. Silesian University of Technology, Department of Engineering Materials and Biomaterials, 18A S. Konarskiego Str., 44-100 Gliwice, Poland
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Abstract

Reliable evaluation of stress-strain characteristics can be done only in the laboratory where boundary conditions with respect to stress and strain can be controlled. The most popular laboratory equipment is a triaxial apparatus. Unfortunately, standard version of triaxial apparatus can reliable measure strain not smaller than 0.1 %. Such accuracy does not allow to determine stiffness referred to strain range most often mobilized in situ i.e. 10-3 ÷ 10-1%, in which stiffness distribution is highly nonlinear. In order to overcome this problem fundamental modifications of standard triaxial apparatus should be done. The first one concerns construction of the cell. The second refers to method of measurement of vertical and horizontal deformation of a specimen. The paper compares three versions of triaxial equipment i.e. standard cell, the modified one and the cell with system of internal measurement of deformation. The comparison was made with respect to capability of stiffness measurement in strain range relevant for typical geotechnical applications. Examples of some test results are given, which are to illustrate an universal potential of the laboratory triaxial apparatus with proximity transducers capable to trace stress-strain response of soil in a reliable way.

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Authors and Affiliations

Mirosław J. Lipiński
Małgorzata K. Wdowska
Anna Wudzka
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Abstract

A DIRECT APPROACH to the problem of the separation of elastic strain energy in the case of generally anisotropic materials is described in the present work. It is based on a simple analysis of the strain tensor into a spherical and a deviatoric one. A definition of dilatational and distortional elastic strain densities is introduced, based on the consideration of the geometrical response of a material. Through the generalized Hooke's law, analytic expressions are obtained for the generally anisotropic materials. The present results coincide with the only available in the literature data for anisotropic materials with cubic symmetry. In addition, an application for transversally isotropic materials is presented.
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Authors and Affiliations

N. P. Andrianopoulos
V. C. Boulougouris
A. P. Iliopoulos
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Abstract

The paper shows the hybrid method of stress and strain distributions analysis. In the method, the results of displacement measurement were used as boundary conditions in the numerical analysis of the tested objects. The numerical analysis was performed with the use of the finite element method (FEM), whereas measurements of displacement were made by laser grating interferometry technique (moire interferometry). Examples of tests presented in the paper show good efficiency of the method in the analysis of stress and strain distribution in the areas of their heterogeneous distribution. Mutual completion of laser grating interferometry and finite element method makes it possible to exclude their disadvantages creating broader' possibilities for research impossible to achieve in separate use.
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Authors and Affiliations

Dariusz Boroński
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Abstract

Filler surface modification has become an essential approach to improve the compatibility problem between natural fillers and polymer matrices. However, there is limited work that concerns on this particular effect under dynamic loading conditions. Therefore, in this study, both untreated and treated low linear density polyethylene/rice husk composites were tested under static (0.001 s –1, 0.01 s –1 and 0.1 s –1) and dynamic loading rates (650 s –1, 900 s –1 and 1100 s –1) using universal testing machine and split Hopkinson pressure bar equipment, respectively. Rice husk filler was modified using silane coupling agents at four different concentrations (1, 3, 5 and 7% weight percentage of silane) at room temperature. This surface modification was experimentally proven by Fourier transform infrared and Field emission scanning electron microscopy. Results show that strength properties, stiffness properties and yield behaviour of treated composites were higher than untreated composites. Among the treated composites, the 5% silane weight percentage composite shows the optimum mechanical properties. Besides, the rate of sensitivity of both untreated and treated composites also shows great dependency on strain rate sensitivity with increasing strain rate. On the other hand, the thermal activation volume shows contrary trend. For fracture surface analysis, the results show that the treated LLDPE/RH composites experienced less permanent deformation as compared to untreated LLDPE/RH composites. Besides, at dynamic loading, the fracture surface analysis of the treated composites showed good attachment between RH and LLDPE.
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Authors and Affiliations

Mohd Firdaus Omar
1 2
ORCID: ORCID
Mohd Mustafa Al Bakri Abdullah
1 2
ORCID: ORCID
Sam Sung Ting
1 2
ORCID: ORCID
B. Jeż
3
ORCID: ORCID
M. Nabiałek
3
ORCID: ORCID
Hazizan Md Akil
4
ORCID: ORCID
Nik Noriman Zulkepli
1
ORCID: ORCID
Shayfull Zamree Abd Rahim
1
ORCID: ORCID
Azida Azmi
2
ORCID: ORCID

  1. Universiti Malaysia Perlis (UniMAP),Centre of Excellent Geopolymer & Green Technology (CeGeoGTech), Perlis, Malaysia
  2. Universiti Malaysia Perlis (UniMAP), Faculty of Chemical Engineering Technology, Perlis, Malaysia
  3. Częstochowa University of Technology, Faculty of Mechanical Engineering and Computer Science, 42-200 Częstochowa, Poland
  4. Universiti Sains Malaysia, School of Materials and Mineral Resources Engineering, Pulau Pinang, Malaysia
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Abstract

The present research deals with the effect of pre-strain on the hydrogen embrittlement behavior of intercritically annealed medium-Mn steels. A slow strain-rate tensile test was conducted after hydrogen charging by an electrochemical permeation method. Based on EBSD and XRD analysis results, the microstructure was composed of martensite and retained austenite of which fraction increased with an increase in the intercritical annealing temperature. The tensile test results showed that the steel with a higher fraction of retained austenite had relatively high hydrogen embrittlement resistance because the retained austenite acts as an irreversible hydrogen trap site. As the amount of pre-strain was increased, the hydrogen embrittlement resistance decreased notably due to an increase in the dislocation density and strain-induced martensite transformation.
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Authors and Affiliations

Sang-Gyu Kim
1
ORCID: ORCID
Young-Chul Yoon
1
ORCID: ORCID
Seok-Woo Ko
1
ORCID: ORCID
Byoungchul Hwang
1
ORCID: ORCID

  1. Seoul National University of Science and Technology, Department of Materials Science and Engineering, Seoul, 01811, Republic of Korea
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Abstract

Pseudorabies (PR) outbreaks have devastated many swine farms in several parts of China since late 2011. The outbreak-associated pseudorabies virus (PRV) variant strains exhibited some typical amino acid changes in glycoprotein E (gE), a diagnostic antigen used for discriminating between PRV-infected and vaccinated animals (DIVA). To counteract the potential impact of epitope variations on current serological diagnostics of PRV, we produced monoclonal antibodies (mAbs) against gE protein of one representative PRV variant strain and developed a blocking immunoperoxidase monolayer assay (b-IPMA) for DIVA. The b-IPMA was based on the inhibition of binding between PRV-infected cells and mAb by PRV-specific antibodies present in clinical swine sera and was validated by comparison with a commercial PRV gpI Antibody Test Kit (IDEXX Laboratories, USA). The diagnostic sensitivity, diagnostic specificity and agreement were determined to be 99.25%, 98.18% and 99.02% respectively upon testing 509 serum samples. b-IPMA detected only PRV-specific antibodies and showed no cross- -reactivity with antibodies elicited by gE-deleted vaccine or other common swine pathogens. Thus, b-IPMA has the potential to be used for high-throughput screening of PRV-infected animals in veterinary clinics.

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Authors and Affiliations

Y.B. Wang
Y.H. Li
Q.M. Li
W.T. Xie
C.L. Guo
J.Q. Guo
R.G. Deng
G.P. Zhang
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Abstract

In 2017, the Central Mining Institute (GIG), Jastrzębska Spółka Węglowa SA (JSW SA), the largest producer of coking coal in Europe, and JOY KOMATSU, the producer of mining machinery, signed a consortium. The project’s main goal was to reduce the costs of driving mine workings by reintroducing the rock bolt support. The works began in November 2019, and for the first time in the history of Polish coal mining, a Bolter Miner machine was used for the purpose. The paper presents the results of measuring the axial forces in rock bolts at the measurement base and their analysis with numerical modelling.
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Bibliography

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[15] V. Kajzar, R. Kukutsch, P. Waclawik, P. Konicek, Coal pillar deformation monitoring using terrestrial laser scanner technology in room and pillar panel – A case study from the Ostrava-Karvina Coal Field. Rock Mechanics and Rock Engineering: From the Past to the Future – Ulusay et al. (Eds.), Taylor & Francis Group, London, 951-956 (2016).
[16] H. Kang, Support technologies for deep and complex roadways in underground coal mines: a review. Int. J. Coal Sci. Technol. 1 (3), 261-277 (2014). DOI: https://doi.org/10.1007/s40789-014-0043-0
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Authors and Affiliations

Wojciech Masny
1
ORCID: ORCID
Łukasz Nita
2
ORCID: ORCID
Jerzy Ficek
3

  1. Central Mining Institute, 1 Gwarków Sq., 40-166 Katowice, Poland
  2. Jastrzębska Spółka Węglowa SA, KWK „Budryk”, Poland
  3. „Geofic“ Scientific and Technical Office, Poland
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Abstract

The paper presents the results of research on the DiSTFA method (Displacements and Strains using Transformation and Free Adjustment) for the determination of displacement and strains of a surface determined in unstable reference systems. Additionally, covariance matrices were introduced to assess the accuracy of estimation results. The theoretical discussion includes an example of its application in a simulated, three-dimensional geodetic network. The obtained results encourage further, more detailed analysis of real geodetic networks.
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Authors and Affiliations

Waldemar Kamiński
ORCID: ORCID
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Abstract

Safety and reliability are primary concerns in launch vehicle performance due to the involved costs and risk. Pressure vessels are one of the significant subsystems of launch vehicles. In order to have minimal weight, high strength material viz. maraging steel M250 grade is used in realizing the pressure vessel casing hardware. Despite the best efforts in design methodology, quality evaluation in production and effective structural integrity assessment is still a farfetched goal. The evolution of such a system requires, first, identification of an appropriate technique and next its adoption to meet the challenges posed by advanced materials like maraging steels. In fact, a quick survey of the available Non-Destructive Evaluation (NDE) techniques suggests Acoustic Emission (AE) as an effective structural integrity assessment tool capable of identifying any impending failure or degradation at an earlier stage. Experience shows that the longitudinal welds in the pressure vessels are quite vulnerable to failure due to the fact that they experience the maximum stress (i.e. hoop stress). Loading welded tensile samples are quite synonymous to the hoop stress experienced by longitudinal welds. An attempt is made to compare the Acoustic Emission data acquired during tensile deformation of maraging steel welded specimens. A total of 16 welded specimen’s with known defects were studied for their tensile behaviour is in connection with Acoustic Emission data. The lowest failure load was 70.5 kN and the highest being 84.8 kN. AE activity graphs viz. cumulative AE activity, hit rate, energy rate, count rate, AE amplitude history, AE count history, AE energy history, amplitude-count correlation and hit amplitude distribution have been investigated and salient features with respect to the data have been critically studied and relevant correlations are arrived at.

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Authors and Affiliations

Gowri Shankar Wuriti
Somnath Chattopadhyaya
Grzegorz Krolczyk
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Abstract

In this paper, detailed theoretical investigation on the frequency response and responsivity of a strain balanced SiGeSn/GeSn quantum well infrared photodetector (QWIP) is made. Rate equation and continuity equation in the well are solved simultaneously to obtain photo generated current. Quantum mechanical carrier transport like carrier capture in QW, escape of carrier from the well due to thermionic emission and tunneling are considered in this calculation. Impact of Sn composition in the GeSn well on the frequency response, bandwidth and responsivity are studied. Results show that Sn concentration in the GeSn active layer and applied bias have important role on the performance of the device. Significant bandwidth is obtained at low reverse bias voltage, e.g., 200 GHz is obtained at 0.28 V bias for a single Ge0.83Sn0.17 layer. Whereas, the maximum responsivity is of 8.6 mA/W at 0.5 V bias for the same structure. However, this can be enhanced by using MQW structure.

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Authors and Affiliations

P. Pareek
M.K. Das
S. Kumar
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Abstract

This paper presents a simulation study of the simultaneous reconstruction of the non-smooth strain distribution of an optical fiber Bragg grating and its temperature, which is based on the reflection spectrum of the reflected beam of the grating. The transition matrix method was used to model the reflection spectrum of the grating, and the nonlinear Nelder- Mead optimization method was used to simultaneously reconstruct the strain distribution along the grating and its temperature. The results of simulations of simultaneous reconstruction of the strain profile and temperature indicate good accord with the strain profiles and temperature set. The reconstruction errors of the strain profiles are less than 1.2 percent and the temperature change errors are less than 0.2 percent, with a noise level of 5 percent.
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Authors and Affiliations

Małgorzata Detka
1
Cezary Kaczmarek
2

  1. Faculty of Electrical Engineering, Automatic Control and Computer Science, Kielce University of Technology, Poland
  2. Faculty of Electrical Engineering and ComputerScience, Lublin University of Technology, Poland
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Abstract

The austenitic stability and strain-induced martensitic transformation behavior of a nanocrystalline FeNiCrMoC alloy were investigated. The alloy was fabricated by high-energy ball milling and spark plasma sintering. The phase fraction and grain size were measured using X-ray diffraction. The grain sizes of the milled powder and the sintered alloy were confirmed to be on the order of several nanometers. The variation in the austenite fraction according to compressive deformation was measured, and the austenite stability and strain-induced martensitic transformation behavior were calculated. The hardness was measured to evaluate the mechanical properties according to compression deformation, which confirmed that the hardness increased to 64.03 HRC when compressed up to 30%.
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Authors and Affiliations

Jungbin Park
1
ORCID: ORCID
Junhyub Jeon
1
ORCID: ORCID
Namhyuk Seo
1
ORCID: ORCID
Gwanghun Kim
1
ORCID: ORCID
Seung Bae Son
1
ORCID: ORCID
Jae-Gil Jung
1
ORCID: ORCID
Seok-Jae Lee
1
ORCID: ORCID

  1. Jeonbuk National University, Research Center for Advanced Materials Development, Division of Advanced Materials Engineering, Jeonju 54896, Republic of Korea
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Abstract

In this paper, the microstructural and texture changes in polycrystalline CuZn30 alloy, copper, and AA1050 aluminium alloy have been studied to describe the crystal lattice rotation during shear bands formation. The hat-shaped specimens were deformed using a drop-hammer at the strain rate of 560 s –1. Microstructure evolution was investigated using optical microscopy, whereas texture changes were examined with the use of a scanning electron microscope equipped with the EBSD facility. The microstructural observations were correlated with nanohardness measurements to evaluate the mechanical properties of the sheared regions. The analyses demonstrate the gradual nature of the shear banding process, which can be described as a mechanism of the bands nucleation and then successive growth rather than as an abrupt instability. It was found that regardless of the initial orientation of the grains inside the sheared region, a well-defined tendency of the crystal lattice rotation is observed. This rotation mechanism leads to the formation of specific texture components of the sheared region, different from the one observed in a weakly or non-deformed matrix. During the process of rotation, one of the {111} planes in each grain of the sheared region ‘tends’ to overlap with the plane of maximum shear stresses and one of the <110> or <112> directions align with the shear direction. This allows slip propagation through the boundaries between adjacent grains without apparent change in the shear direction. Finally, in order to trace the rotation path, transforming the matrix texture components into shear band, rotation axis and angles were identified.
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Authors and Affiliations

I. Mania
1
ORCID: ORCID
H. Paul
1
ORCID: ORCID
R. Chulist
1
ORCID: ORCID
P. Petrzak
1
ORCID: ORCID
M. Miszczyk
1
ORCID: ORCID
M. Prażmowski
2
ORCID: ORCID

  1. Polish Academy of Sciences, Institute of Metallurgy and Materials Science, 25 Reymonta Str., 30-059 Krakow, Poland
  2. Opole University of Technology, Faculty of Mechanics, 76 Prószkowska Str., 45-758 Opole, Poland
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Abstract

A π-phase-shifted fiber Bragg grating (π-FBG) shows high sensitivity to the ultrasonic (US) wave as compared to the conventional FBG due to the strong slow-light phenomenon at the resonance peak. However, its sensitivity is limited by the interrogation schemes. A combination of π-FBG and unbalanced fiber Mach– Zehnder interferometer (F-MZI) are theoretically analyzed and optimized for the highly sensitive acoustic sensor. The coupled-mode theory (CMT) and transfer matrix method (TMM) are used to establish the numerical modelling of π-FBG. For the optimized grating parameters of π-FBG, the proposed sensing system shows the high strain sensitivity of 1.2 × 108/ε, the highest dynamic strain resolution of 4.1fε/√Hz, and the highest wavelength shift resolution of 4.9 × 10−9 pm. Further, the proposed sensing system strongly supports both time andwavelength division multiplexing techniques. Therefore, the proposed sensing system shows extreme importance in single as well as quasi-distributed US acoustic wave sensing networks.

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Authors and Affiliations

Krishna Mohan Dwivedi
Gaurav Trivedi
Sunil K. Khijwania
Tomasz Osuch
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Abstract

Severe Plastic Deformation (SPD) techniques have been used by researchers for last three decades in order to obtain Ultra-Fine Grained (UFG) materials. Equal Channel Angular Pressing (ECAP) is preferred more than other SPD techniques thanks to its high performance and practicability. Hexa Equal Channel Angular Pressing (Hexa-ECAP) – modified ECAP technique which enables to apply ECAP routes for cylindrical samples properly – was preferred in this study. Within the objective of this study, the effects of coefficient and ram velocity on the mean effective strain and strain inhomogeneity of Hexa-ECAP processed Al7075 aluminium alloy were investigated. Also, the effects of ram velocity and friction coefficient on hardness homogeneity were investigated benefitting from the similarity between the hardness distribution and the strain distribution.
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Authors and Affiliations

Serkan Öğüt
1
ORCID: ORCID
Hasan Kaya
2
Aykut Kentli
1
Kerim Özbeyaz
1
Mehmet Şahbaz
3
Mehmet Uçar
4

  1. Marmara University, Faculty of Engineering, Mechanical Engineering Department, Istanbul – Turkey
  2. Kocaeli University, Asım Kocabıyık Vocational School, Machine and Metal Technology Department, Kocaeli – Turkey
  3. Karamanoğlu Mehmetbey University, Faculty of Engineering, Mechanical Engineering Department, Karaman, Turkey
  4. Kocaeli University, Faculty of Technology, Automotive Engineering Department, Kocaeli – Turkey
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Abstract

Dual-phase steels have received extensive attention in autobody frame manufacturing due to the resulting characteristics of an interesting combination of ductile ferrite and hard martensite. Moreover, the ductile ferrite and hard martensite lead to heterogeneous deformation in the boundary between the two phases. Then, geometrically necessary dislocations (GNDs) are created to accommodate a lattice mismatch due to the deformation incompatibility of the boundary in straining. In this study, a new empirical GND model is developed, in which the GND density is a function of local plastic deformation; the GND density is distributed in the phase boundary in accordance with an “S” model of material plastic strain. The boundary conditions are applied to define the parameters. The proposed model is verified with DP600 steel. The effects of the GNDs and the width between ferrite and martensite on the strain hardening of DP600 steel are evaluated.
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Authors and Affiliations

Gou Rui-Bin
1
Dan Wen-Jiao
1
Xu Yong-Sheng
2
Yu Min
3
Li Tong-Jie
1

  1. Anhui Science and Technology University, College of Mechanical Engineering, Fengyang 233100, Anhui, China
  2. Shanghai Jiao Tong University, Department of Engineering Mechanics, School of Naval Architecture, Ocean and Civil Engineering, Shanghai 200240, China
  3. Anhui Science and Technology University, College of Architecture, Bengbu 233000, Anhui, China

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