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1

Direct equivalent circuit parameter extraction for a brushless doubly-fed induction machine with a nested-loop rotor winding from a finite element model

Jagieła Mariusz, Łukaniszyn Marian, Wiwatowski Radosław

Archives of Electrical Engineering

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2026

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Vol. 75, nr 2

407--425

EN

The Simplified Equivalent Circuit Model (SECM) is well established as a tool for the performance analysis of the Brushless Doubly-Fed Induction Machine (BDFIM). However, the SECMtypically relies on a constant-parameter approximation, which, in theory, contradicts the machine’s inherent velocity-dependent nature, given its typical nested-loop rotor structure that couples magnetically with a large portion of the air-gap field harmonics’ spectrum. This paper investigates the physics behind this by directly deriving its parameters from rigorous power-balance equations and a time-harmonic finite-element model. The study identifies a self-compensating mechanism: although the extracted rotor leakage reactance and effective turns ratio exhibit significant variations near the natural speed, their combined interaction minimises the impact on terminal quantities. Furthermore, the paper investigates the validity determinants of the constant-parameter SECM in double-feed mode and explains the factors of the conditional accuracy.

2

Effective anchorage stress of prestressed tendons in PC girders under varying tensioning sequences

Xiao Guangqing, Chen Xilong, Xu Lihai, Wu Fucheng, Zeng Liang, He Shaohua

Archives of Civil Engineering

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2025

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Vol. 71, nr 3

217--230

EN

In current design codes, the standardized anchorage stress of prestressed tendons in concrete girders is uniform, which presents a notable challenge in accurately assessing the effective anchorage stress of girders with varying span lengths. This study investigates the impact of prestressed tendons’ span length and tensioning sequences on effective anchorage stress in small-box girders (20 m, 25 m, 30 m) and 40 m T-shaped girders. Comprehensive theoretical approaches for computing the effective anchorage stress of the tendons, accounting for stress losses due to conduit friction, anchor deformation, rebar relaxation, concrete, and joint compression, are presented. The calculated results for prestressed concrete (PC) girders with typical span lengths and cross-sections demonstrate that girder length and tensioning sequence influence the effective anchorage stress of prestressed tendons. The currently recommended standardized effective anchorage stress of 1280 MPa in existing codes, derived solely from a designated length and anchorage retraction, proves inadequate for PC girders of varying lengths. Based on theoretical and numerical findings, refined effective anchorage stress of 1237 MPa, 1244 MPa, and 1251 MPa are proposed for small-box girders with span lengths of 20 m, 25 m, and 30 m, respectively, while the recommended effective anchorage stress for a T-shaped PC girder with a length of 40 m is 1251 MPa. Adoption of the evaluation method effective anchorage stress yields an improved prestressed quality passing rate ranging from 4.0% to 10.9%, thereby effectively reducing the necessity for unnecessary supplementary tensioning or excessive tensioning during on-site construction to meet project requirements.

3

Application of pre-embedded cold water pipe technology in large volume concrete dams

Zhu Yuelu, Chen Yingxing

Archives of Civil Engineering

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2025

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Vol. 71, nr 4

109--122

EN

To address the issue of heat release during the construction of concrete dams, this study employs the approach of embedding water pipes for temperature control. Taking a large-volume concrete gravity dam in China as an example, considering environmental and river water temperatures, inputting concrete thermodynamic parameters, and taking various factors such as pipe layout, calculation parameters, pipe radius, material, spacing, and water temperature into account, the study utilizes finite element software for simulation modeling. It systematically discusses the relationship between cooling effects, costs, and engineering safety. The research results indicate that, under the condition of a rectangular section layout, with a pipe radius of 0.01 m and a spacing of 1.5 × 1.5 m, the comprehensive effect is optimal. The influence of different pipe materials on temperature reduction is minimal. When changing pipe materials, only material costs and their impact on structural safety and durability need consideration. Additionally, excessively low water temperatures during water passage can lead to internal concrete cracking, requiring attention during construction.

4

Modelling and analysis of cerebrospinal fluid flow in the human brain – is cerebrospinal fluid an effective protective mechanism during high-impact loading?

Sbriglio Claudia, Ptak Mariusz, Dymek Mateusz, Sawicki Marek, Kwiatkowski Artur

Acta of Bioengineering and Biomechanics

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2025

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Vol. 27, no. 1

144--155

EN

This study investigates cerebrospinal fluid (CSF) flow dynamics to enhance the understanding of brain biomechanics and the importance of CSF during high-impact loading. Methods: Comparative analyses were conducted using the benchmark model with smoothed particle hydrodynamics (SPH), without cerebrospinal fluid, and with an additional element – the arachnoid trabeculae – which functions as rigid connections between the brain and skull. The numerical modelling of cerebrospinal fluid and the derived conclusions were validated and calibrated through experiments performed in the additional research phase. Results: The research emphasises the challenges of accurately modelling cerebrospinal fluid dynamics and brain biomechanics. The results were unexpected in several ways. Initially, a rigid cortex-skull connection was anticipated to yield results nearly identical to those observed in Hardy’s experiments. Even more surprising were the results for the models with cerebrospinal fluid modelled as smoothed particle hydrodynamics and the model without cerebrospinal fluid, which showed almost identical results in comparison to each other. The novel physical experiment with a gelatine insert subjected to controlled loading and numerical model simulations revealed that SPH models exhibited closely resembling fluid displacement, while tetrahedral elements imposed unrealistic rigidity. Conclusions: The simulations and the novel experiment provide key insights into cerebrospinal fluid dynamics during traumatic brain injury. The findings suggest that the protective function of CSF might be less pronounced under extreme conditions than previously assumed. The smoothed particle hydrodynamics method demonstrates clear advantages over tetrahedral finite element approaches by offering superior brain-in-skull flexibility and avoiding the excessive rigidity inherent to traditional finite element models. We concluded that mechanism of brain protection by CSF is performed rather by hydraulic damping than the brain immersion in vast volume of CSF.

5

Characterization of electrically conductive hydrofractures with cross-borehole electromagnetic measurement

Wu Shi-wei, Liu De-jun, Huang Wen-hui, Zhang Cheng-huang

Acta Geophysica

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2025

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Vol. 73, no. 2

1593--1607

EN

Geometric analysis of hydraulic fractures in unconventional shale oil reservoirs is essential for enhancing production efficiency. This paper proposes a new method for evaluating large-scale fractures using cross-borehole electromagnetic measurement technique based on numerical simulation. The three-dimensional finite element method (3D FEM) is used to establish a hydraulic fracture model of horizontal wells, and the accuracy and validity of algorithm are verified using a benchmark model. The relationships between the geometric parameters of fractures and the obtained measurement signals are investigated. To evaluate the effectiveness of our proposed method in complex underground conditions, a case study is conducted. Numerical results indicate that the coaxial component signal (xx,yy,zz) is effective in characterizing hydraulic fractures. The signals exhibit greater sensitivity to the T-R spacing, fracture conductivity, fracture half-length, and fracture number, compared to transmitter frequency and fracture aspect ratio. Furthermore, the opening angle of asymmetrical fractures should be wider than 120° to ensure proper fracturing. In the segmented fracturing monitoring case study, positioning the transmitter source inside the fracturing borehole greatly aids in determining the orientation of fractures, while deploying it in the monitoring borehole conveniently improves the collection of response signals with a more prominent amplitude. This study demonstrates that the cross-borehole measurement method is an effective technique for monitoring hydraulic fracturing in open boreholes and offers promising applications.

6

Concentric magnetic gear structure review

Halim Mohd Firdaus Mohd Ab, Rahman Azhan Abd, Sulaiman Erwan

Przegląd Elektrotechniczny

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2024

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R. 100, nr 8

140--147

EN

The paper presents the evolvement of magnetic gear structure from its inception up to the year of 2023. The output performances (power and torque) of all the structure will be tabled and analyzed in this paper. Among several structures researched in MG, Concentric Magnetic Gear (CMG), is the most researched structure due to its high utilization of the magnetic field compared to other structure. Since many structure evolved from CMG, a classification tree derived from CMG is presented. The classification tree provides an overview of the state of the art in CMG design.

PL

W artykule przedstawiono ewolucję konstrukcji przekładni magnetycznej od jej powstania do roku 2023. W artykule zostaną zestawione i przeanalizowane parametry wyjściowe (moc i moment obrotowy) wszystkich konstrukcji. Spośród kilku struktur badanych w MG, koncentryczna przekładnia magnetyczna (CMG) jest najczęściej badaną strukturą ze względu na wysokie wykorzystanie pola magnetycznego w porównaniu z innymi strukturami. Ponieważ wiele struktur wyewoluowało z CMG, przedstawiono drzewo klasyfikacyjne wywodzące się z CMG. Drzewo klasyfikacyjne zawiera przegląd stanu techniki w projektowaniu CMG.

7

Compressive behavior of fiber-reinforced concrete strengthened with CFRP strips after exposure to temperature environments

Abadel Aref A., Alharbi Yousef R.

Materials Science Poland

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2024

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Vol. 42, No. 3

17--38

EN

Reinforced concrete constructions are extremely vulnerable to fire damage over their lifespan. Despite its non-flammability, concrete is nonetheless affected by fire exposure, which impacts its stress–strain characteristics and durability. Therefore, developing strengthening methods is an economical option compared to the costs of demolishing and rebuilding constructions. This article aims to experimentally and numerically examine the strengthening of fiber-reinforced concrete cylinders by using carbon fiber-reinforced polymer (CFRP) strips after exposure to 600°C. Four different concrete mixtures have been investigated. A total of 48 cylinders were subjected to axial compression testing. The testing program primarily focused on three variables: (i) exposure temperature (600°C); (ii) the effect of using various types of fibers (steel fiber, polypropylene, and hybrid fibers); and (iii) CFRP strengthening. Finite element (FE) models were created using the ABAQUS program to conduct numerical analysis of concrete cylinders in exposure to heating scenarios and strengthen them with CFRP strips. The results show that when subjected to a temperature of 600°C, the compressive strength decreased significantly, ranging from 23.7 to 53.3%. The presence of fibers significantly impacted compressive strength, regardless of the fiber type, leading to an enhanced ratio of up to 34.7% in comparison to the control cylinders (i.e., unheated and unstrengthened cylinders). The suggested strengthening procedures using CFRP strips effectively repaired the heat-damaged cylinders, surpassing the initial compressive strength of unheated cylinders. The FE prediction shows satisfactory, consistent results in comparison to experimental data.

8

Fully discrete approximations and an a priori error analysis of a two-temperature thermo-elastic model with microtemperatures

Baldonedo Jacobo, Fernández José R., Quintanilla Ramón

International Journal of Applied Mathematics and Computer Science

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2024

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Vol. 34, no. 1

93--103

EN

In this paper, we consider, from a numerical point of view, a two-temperature poro-thermoelastic problem. The model is written as a coupled linear system of hyperbolic and elliptic partial differential equations. An existence result is proved and energy decay properties are recalled. Then we introduce a fully discrete approximation by using the finite element method and the implicit Euler scheme. Some a priori error estimates are obtained, from which the linear convergence of the approximation is deduced under an appropriate additional regularity. Finally, some numerical simulations are performed to demonstrate the accuracy of the approximation, the decay of the discrete energy and the behaviour of the solution depending on a constitutive parameter.

9

Frequency-based crack effect study on beams under free vibration using finite element analysis

Sahu Ompriya, Das Priyadarshi, Muni Manoj Kumar, Pradhan Nibedita, Basa Bidyadhar, Sahu Shishir Kumar

Engineering Transactions

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2024

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Vol. 72, iss. 1

95--114

EN

A numerical computation-based analysis of the free vibration analysis of uniform beams with rectangular cross-sections is presented in this work using finite element analysis. The approach involves dividing the beam into segments at the crack section, which is then modelled for simulation for eigenfrequencies on the ABAQUS platform. The numerical simulation results are in excellent agreement with the findings of previous research, confirming the efficacy and applicability of the developed beam model. A sequential comprehensive approach towards analysis of the effects of the position and depth of the cracks on the natural frequencies are addressed in numerical results. The research findings confirm that the simulation model is suitable for the vibration analysis of beams or beam-like elements with different cross-sections.

10

Estimation of adhesive joint failure initiation using FEM

Derewonko Agnieszka, Maruschak Pavlo, Prusko Paweł

Biuletyn Wojskowej Akademii Technicznej

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2024

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Vol. 73, nr 1

33--42

EN

In adhesive joints, the integrity of the adhesive and the joined parts results from intermolecular forces. The determination of the total elastic energy at the interface of two different bodies is possible by introducing the contact problem in the numerical model of the system. The paper presents the optimization of a single lap adhesive joint by estimating the tensile force causing the joint failure initiation and its location based on the calculated elastic energy. This approach limits the number of experimental tests. Limitation of the estimation, resulting from dimension of the applied finite element mesh, is also considered. The application is demonstrated through a numerical analysis of a quasi-static tension test on a single-lap adhesive joint without spacers. Two models, created based on the described limitations, are analyzed. The calculated surface energy values are presented as three-dimensional graphs in the Matlab environment for one of the bonding surfaces. The selection of this surface is justified by a brief theoretical analysis.

PL

W połączeniach klejowych integralność kleju i połączonych części wynika z sił międzycząsteczkowych. Określenie całkowitej energii sprężystej na styku dwóch różnych ciał jest możliwe poprzez wprowadzenie problemu kontaktu do modelu numerycznego układu. W artykule przedstawiono optymalizację pojedynczego zakładkowego połączenia klejowego poprzez oszacowanie siły rozciągającej powodującej inicjację uszkodzenia połączenia i jego lokalizację na podstawie obliczonej energii sprężystej. Takie podejście ogranicza liczbę testów eksperymentalnych. Uwzględniono również ograniczenia estymacji wynikające z wymiarów zastosowanej siatki elementów skończonych. Aplikacja została zademonstrowana poprzez analizę numeryczną quasi-statycznego testu rozciągania na pojedynczym połączeniu klejowym bez przekładek. Analizowane są dwa modele utworzone w oparciu o opisane ograniczenia. Obliczone wartości energii powierzchniowej są prezentowane jako trójwymiarowe wykresy w środowisku Matlab dla jednej z powierzchni klejenia. Wybór tej powierzchni uzasadniono krótką analizą teoretyczną.

11

Effect of fatigue behaviour on fracture in the 4th gear of a pick-up truck

Janmanee P., Saodaen R., Thanadngarn C., Kumnorkaew T., Jamkamon K., Utjimajiratthitikarn K.

Archives of Materials Science and Engineering

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2024

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Vol. 126, nr 1

5--14

EN

Purpose: This paper aims to investigate the effect of fatigue behaviour on fracture in the 4th gear (helical gear) of a pick-up truck. Design/methodology/approach: Fracture on the failed helical gear is characterised through metallographic and fractographic analyses. Mechanical testing and finite element simulation are employed to assess the factors contributing to the gear failure. Findings: The microstructure observed in the case layer was martensite, leading to a hard and brittle surface due to carburising. Failure initiated at the crack origins and then propagated to the instant fracture zone in the core of the gear tooth. Multiple crack origins accelerated the development of ratchet marks, attributed to the high intensity of stress exerted on the workpiece and ultimately leading to a substantial final overload zone. Hardness decreased with increasing depth of the gear surface due to the effects of carburising and hardening treatments. Stress was initiated from the contact stress on the gear tooth surface and transformed into bending stress along the central axis of the gear. The contact stresses became critical when the torque surpassed the contact strength of the material. Research limitations/implications: Simulation samples must be experimentally validated to improve the results. Practical implications: Metallographic and fractographic analyses are crucial in elucidating the wear mechanisms in mechanical components. Additionally, finite element analysis can indicate the influence of stress on the mechanical part, providing insights that can effectively guide the limiting transmission power to ensure extended service life. Originality/value: Cost reduction, time for analysis, and finding the root causes of the problem should be conducted to improve the implementation process, leading to high product quality.

12

Rational steel mesh layout influence on plate utilization of large span corrugated steel structure

Bareikis Nerijus

Archives of Civil Engineering

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2024

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Vol. 70, nr 3

561--578

EN

Corrugated steel structures buried in the surrounding soil are currently used worldwide in road and railway engineering as culverts, pedestrian and animal crossings, tunnels and bridges. The need of large span corrugated steel structures is rapidly growing however their behavior analysis is still understudied. There is also a lack of discussion about the impact of additional strengthening elements for the behavior of corrugated steel structures. This study analyses the influence of rational steel mesh layout on the behavior of a large span deepest corrugation steel structure. The numerical two-dimensional model of two-radius 17.5 m span profile with corrugation of 237 mm depth and 500 mm pitch was developed to replicate the ongoing project in Lithuania. Originally the stiffness of the structure from both sides was increased by six layers of steel meshes as lateral support. Nevertheless, the current study was looking for rational steel mesh layout. Also, the influence of different layouts of steel mesh on corrugated steel plate utilization to buckling failure in the peaking, dead load and in the most unfavorable live load location phase was analyzed. The finite element model results indicated that steel meshes could be used to control structure deformations and internal reactions. Vertical displacement of the crown of the structure could be reduced by 45% in the peaking phase when using proper steel meshes layout. Furthermore, steel meshes could be a decisive factor for the bearing capacity of corrugated steel structure in a positive sense.

13

Modeling and numerical simulation of eddy current sensors for electromagnetic characterization of fluids

Miloudi Khaled, Moulai Hocine, Azizi Hakim

Przegląd Elektrotechniczny

|

2023

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R. 99, nr 10

88--92

EN

This work aims to model a device enabling a useful and accurate electromagnetic characterization of fluids. The device developed is based on a non destructive testing (NDT) control technique evolving the eddy currents induced in the fluid to be characterized. The finite element method was used in the modeling to determine the conductivity of the fluid from the induced eddy current. In addition, an experimental device has been built. It consists of an absolute probe where the fluid control is made by determining its electrical conductivity by measuring the variations of the fluid impedance as a function of the applied voltage frequency. Good agreements are found between modeling results and experimental measurements. An inverse model that converges after only 7 iterations has been also proposed for the determination of the conductivity of fluids by the use of theoretical and experimental measurements.

PL

Niniejsza praca ma na celu zamodelowanie urządzenia umożliwiającego użyteczną i dokładną charakterystykę elektromagnetyczną płynów. Opracowane urządzenie opiera się na technice kontroli badań nieniszczących (NDT), która rozwija prądy wirowe indukowane w scharakteryzowanym płynie. W modelowaniu wykorzystano metodę elementów skończonych do wyznaczenia przewodności płynu z indukowanych prądów wirowych. Ponadto zbudowano eksperymentalne urządzenie. Składa się z sondy absolutnej, w której kontrola płynu odbywa się poprzez określenie jego przewodności elektrycznej poprzez pomiar zmian impedancji płynu w funkcji przyłożonej częstotliwości napięcia. Stwierdzono dobrą zgodność między wynikami modelowania a pomiarami eksperymentalnymi. Zaproponowano również model odwrotny, który zbiega się już po 7 iteracjach, do wyznaczania przewodnictwa płynów za pomocą pomiarów teoretycznych i eksperymentalnych.

14

Comparison of Monte Carlo and bootstrap analyses for residual life and confidence interval

Husnain M. M. N., Akramin M. R. M., Shaari M. S., Takahashi Akiyuki, Bashiri Abdullateef H., Alshoaibi Abdulnaser M.

Materials Science Poland

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2023

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Vol. 41, No. 1

15--26

EN

Failure starts with creation of a crack, then the propagation of the crack and eventually the fracture of the material. Furthermore, material selection, geometry, processing and residual stresses are critical factors that may contribute to uncertainty and prospective failure mechanisms in engineering. These issues may also arise in computational analysis, a problematic model, for instance, a three-dimensional surface fracture that may necessitate numerous degrees of freedom during analysis. However, considering the multiple incidents of material failure, detailed analysis and efforts to prevent premature material failure for safety and engineering integrity can be carried out. Thus, the objective of this study is to model crack growth in a surface-cracked structure. Aluminium alloy 7075-T6 was the material of interest in this study. The S-version finite element method (SFEM) was used to study fracture propagation. The numerical approach developed in this research was the probabilistic SFEM. Instead of mesh rebuilding, a typical finite element approach, the SFEM uses global–local element overlay method to create a fatigue crack growth model, which was then used for crack research. Empirical computation and previous experimental data were used to evaluate the stress intensity factor (SIF), surface crack growth and fatigue life. The SIF was determined using a virtual crack closure method (VCCM). In addition, the probabilistic approach is also a critical method to generate random parameters, such as Monte Carlo and bootstrap methods. The SIF, fatigue life and surface crack growth were validated and deemed to be within the acceptable range.

15

A parametric study of higher-mode natural frequencies of composite stiffened cylindrical shell with cut-out

Chaudhuri Puja Basu, Sahoo Sarmila, Mitra Anirban

Engineering Transactions

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2023

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Vol. 71, iss. 1

81--109

EN

A finite element-based dynamic study of cut-out borne composite cylindrical shells reinforced with stiffeners is conducted. Isoparametric shell element with eight nodes and beam element with three nodes are used to study the mode-frequency behavior of shells with varied edge conditions. Anti-symmetric angle-ply laminates of two, four and ten layers with varying lamination angles are considered. Ten-layer laminates are investigated further as they exhibit better performance in fundamental frequency than two and four-layer laminates. The reduced integration method is adopted to find the shell element’s stiffness and mass matrices and the subspace iteration method is used for the eigenvalue solution of free vibration formulation. Natural frequencies for the first five modes are considered. The effects of fiber orientation angle (θ), degree of orthotropy (E11/E22), and width/thickness ratio (b/h) on the natural frequency are determined through numerical studies. It is revealed that vibration behavior strongly depends on both the number and arrangement of boundary constraints.

16

Numerical failure analysis of laminated beams using a refined finite element model

Layachi Maroua, Khechai Abdelhak, Ghrieb Abderrahmane, Layachi Safa

Advances in Materials Science

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2023

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Vol. 23, nr 1(75)

32--57

EN

In the present investigation, laminated composite beams subjected to a bending static loading are studied in order to determine their failure mechanisms and the first ply failure (FPF) load. The FPF analysis is performed using a refined rectangular plate element. The present element is formulated based on the classical lamination theory (CLT) to calculate the in-plane stresses. To achieve this goal, several failure criterions, including Tsai-Wu, Tsai-Hill, Hashin, and Maximum Stress criteria, are used to predict failure mechanisms. These criterions are implemented within the finite element code to predict the different failure damages and responses of laminated beams from the initial loading to the final failure. The numerical results obtained using the present element compare favorably with those given by the analytic approaches. It is observed that the numerical results are very close to the analytical results, which demonstrates the accuracy of the present element. Finally, several parameters, such as fiber orientations, stacking sequences, and boundary conditions, are considered to determine and understand their effects on the strength of these laminated beams.

17

Numerical analysis of the effects of canal wall-up and canal wall-down mastoidectomy on the sound transmission characteristics of human ears

Liu Peihan, Liu Wen, Zhao Yu, Yan Shanshan, Jiang Wen, Liu Houguang, Wan Jin

Acta of Bioengineering and Biomechanics

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2023

|

Vol. 25, no. 2

133--145

EN

The aim of this work was to study the effect of canal wall-up (CWU) and canal wall-down (CWD) and mastoid obliteration in conjunction with CWD (CWD-MO) mastoidectomy on the sound transmission characteristics of the human ear. Methods: Three mastoidectomy surgical methods, CWU, CWD and CWD-MO, were simulated on the freshly dissected cadaver heads. Then, the finite element (FE) models corresponding to these surgical methods were established by micro-computed tomography (Micro-CT) and reverse engineering technology, and the accuracy of the models was verified. Finally, the FE Models were used to analyze the effects of different surgical methods on the sound transmission characteristics of the human ear. Results: For CWU, since the integrity of the outer wall of the ear canal is ensured, the sound pressure (SP) gain of the ear canal and the stapes footplate displacement (FPD) gain after this operation are close to normal values. For CWD, due to severe damage to the outer wall of the ear canal, a negative gain of the ear canal SP occurs in the high-frequency range, and the resonance frequency is significantly reduced. For CWD-MO, the frequency range of SP negative gain in the ear canal is reduced due to the addition of fillers in the ear canal to reduce the degree of damage, and the resonance frequency is increased compared to CWD. Conclusions: The impact of three types of mastoidectomy, including CWU, CWD, and CWDMO, on the sound transmission characteristics of the human ear after surgery is relatively small.

18

Studies on the performance of impact resistant structure of hydraulic support in fully mechanized mining face under rock burst

Zhang Qiang, Zhang Runxin

Journal of Theoretical and Applied Mechanics

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2022

|

Vol. 60 nr 4

649--658

EN

In order to solve the support problem of a fully mechanized coal face under rock burst and with the goal of safe and efficient coal mining, the present study hasenvisaged a hexagon periodic arrangement energy absorption structure. Based on the shell theory, the mechanical model of the impact resistant structure and hydraulic support was constructed using the finite element method. The mechanical properties of the hydraulic support under a full impact and a partial load impact of the roof were analysed, and the impact resistant structure was designed to prove the reliability of the structure. The results showed that the anti-impact structure reduced the stress and stress fluctuation of the column and effectively reduced the shape variable of the weak link of the hydraulic support. Furthermore, a delay in the time was observed, when the pressure of the hydraulic cylinder reached the yield strength, and there was a gain in the time for the opening of the large flow safety valve. Especially, under the action of partial load, the column did not bend, and the hydraulic cylinder was in the elastic range. Our results can provide new insights in the support of rock burst working face, which is of great significance concerning safety in the coal mining.

19

Numerical investigation of static behavior of bolted joints

Hammami Chaima

Journal of Theoretical and Applied Mechanics

|

2022

|

Vol. 60 nr 3

385--394

EN

This paper investigates the static behavior of bolted joints and the extent of its control in the design of assembled structures. An analysis method is thus first developed highlighting stresses distribution in the junction to dimension the functional performance area. A description of the joint characteristics is presented. Numerical simulations, comparing the complete and simplified finite element models relevance, are then carried out. The integration of results of this analysis in the design of multiple bolted joints structures in finally presented. Experiments on a testbed, where a viscoelastic material is introduced in joints interfaces to enhance global damping, validate the approach developed.

20

A conceptual sector-scale numerical modeling of a landslide in an open pit mine

Koca Tümay Kadakci

Archives of Mining Sciences

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2022

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Vol. 67, no. 2

275--287

EN

In this study, an old rotational landslide that has reactivated in the NW sector of an open-pit mine operated within the gneiss rock unit was evaluated for geological and hydrogeological properties. The pit slopes were susceptible to mass movement when there were variations in water inflows. Considering this fact, a conceptual numerical model concerning geostructural features, rainfall infiltration, and varying hydrological conditions was constructed. Initially, finite element (FE) groundwater seepage analyses were performed to evaluate the effect of water flow on stability in the dry and rainy seasons. The rainy season was simulated by vertical infiltration. Since the dewatering measures are of importance in open pit slope instability mitigation, pumping wells were designed to control water flow through the disturbed zone to improve the stability of the sector that can be triggered again with changing environmental conditions. The performance and organization of the pumping wells were also simulated in the FE model. This FE model was part of a dewatering plan. From this, the effect of the pumping rate from the wells on the stability of the sector was revealed. It was also found that there should be an increase in the pumping rate in the rainy season.