bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of high-frequency torsion in vibratory pile installation: the Gentle Driving of Piles method
Authors: Tsetas Athanasios , Tsouvalas Apostolos , Metrikine Andrei 
Published: June 2024

Abstract
The Gentle Driving of Piles (GDP) is a new technology for vibratory (mono)pile installation that is based on simultaneous application of low-frequency/axial and high-frequency/torsional vibrations. In this paper, a numerical modelling framework, that has been developed and successfully applied to axial vibratory driving, is employed to study GDP. In that manner, the major driving mechanism of this method is comprehended on the basis of field observations and numerical analyses. As regards the numerical model, the pile is described as a thin cylindrical shell and the soil medium is treated as a linear elastic layered half-space. The pile-soil coupling is realized via a history-dependent frictional interface, that accounts for friction force degradation due to the accumulation of loading cycles at the soil material points. The redirection of the friction force vector due to the high-frequency torsion manifests as the main driving mechanism of GDP. Finally, the soil disturbance during installation is compared for the cases of GDP and axial vibratory driving, showcasing the dissimilar characteristics of the induced soil motion.
Improved double-point material point method for dynamic geotechnical problems
Authors: Chmelnizkij A 
Published: June 2024

Abstract
The Material Point method is a suitable numerical method to simulate large deformations often occurring in geotechnical engineering. The Double-Point MPM (2P-MPM) extends the simulations for water-saturated materials. In the present work, a coupled dynamic formulation is used to account for coupled wave propagation in porous media in addition to large deformations. The computational cost of 2P-MPM is expensive because information between material points and grid nodes must be approximated at each time step. In conventional 2P-MPM formulations, linear shape functions are used for this approximation, leading to well-known grid crossing and loss of contact problems. We use the moving least square approximation for the 2P-MPM to handle these problems better. In addition, a parallelization approach is shown to improve the computation time, especially for large boundary value problems. The developed methods can be combined with non-saturated materials, such as fluids and dry soil, to simulate complex geotechnical issues. The performed computations of wave propagation and large deformations using the proposed methods show improved convergence behavior and increased efficiency.
Recommendations on finite element modelling of non-seismic excitation in soil-structure interaction problems
Authors: Schepers W , Brinkgreve RBJ , Appel S 
Published: June 2024

Abstract
Nowadays geotechnical engineering firms have powerful software tools to extent their consulting business also into dynamic soil-structure interaction, which before has been restricted to a rather small community of specialized experts in this field, and they certainly do. This is particularly true with respect to non-seismic sources, that is all kinds of human induced vibrations. Hence, there is a demand from clients as well as from contractors to have guidance on the requirements as well as the limits of numerical modelling of soil-structure interaction. From the literature as well as from relevant standards, recommendations for the numerical modelling of soil-structure interaction problems involving seismic actions are well known, e. g. ASCE/SEI 4-16. There are, however, some particularities when dealing with human-induced vibrations, which are absent in seismic analyses. For human-induced excitations very little specific guidance has been published in the past. A machine foundation on a homogeneous half space excited by harmonic loads with excitation frequency between 4 Hz and 64 Hz has been analysed by means of several commercially available software packages. Parametric studies have been performed to verify if recommendations for seismic soil-structure analyses are valid for non-seismic analyses as well. This paper provides details on the benchmark example and the most important conclusions from the undertaken parametric studies.
Experimental and numerical analysis of piercing with shaped charge of armor steel
Authors: Pyka Dariusz , Bocian Mirosław , Kurzawa Adam , Jamroziak Krzysztof 
Published: June 2024

Abstract
The tests of resistance to dynamic impact with shaped charge (ŁK) were carried out on a homogeneous armor plate made of Armox 370T Class 1 steel, commonly used in the production of ballistic shields. The chemical composition of the steel was determined in spectrometric tests using a spark discharge spectrometer S1 MiniLab 150 by GNR INDIA and confirmed by a GDS-750-QDP glow discharge spectrometer by LECO. Composition tests confirmed the compliance of the chemical composition of the board with the EN 10029 standard for the Armox 370T grade. Numerical calculations of the considered penetration with a shaped charge were carried out in the ABAQUS program. For this purpose, geometric models were made in the Inventor program and then the geometric models were exported in the .step format to the computing environment. The Johnson-Cook (J-C) mathematical model was used for elastic-plastic materials, including plastic behavior of material. The calculations were based on numerical models separately established for individual elements of the load and cover, assuming material constants appropriate for the materials used for the transition from hybrid methods using the SPH and FEM methods.
Settlement at transition zones in railway tracks – is modelling the soil as a 2-D continuum important?
Authors: Fărăgău Andrei B. , Metrikine Andrei V. , van Dalen Karel N. 
Published: June 2024

Abstract
While most recent models of railway tracks include the nonlocal nature of the foundation reaction force, few studies have investigated the influence of its nonlocal nature on the response. Accounting for the nonlocal nature of the foundation force is computationally expensive and increases the complexity of the model, thus, knowing when and when not to account for it is important. This paper aims to shed light on the influence of the nonlocal, both in time and space, reaction force provided by the foundation on the transient response at railway transition zones. To this end, a 2-D system in which the soil layer is modelled as a visco-elastic continuum is compared to an equivalent 1-D system with a local foundation reaction force (i.e., Winkler foundation). Results show that, in general, the response of the 2-D system with shallow and/or stiff soil layers can be well captured by the equivalent 1-D model. However, for medium-to-deep and/or soft soil layers, the nonlocality of the foundation reaction force is influential and the transient response at transition zones cannot be satisfactorily captured by 1-D models. Finally, the ballast settlement is also poorly captured for medium-to-deep and/or soft soil layers, with the main cause being the inability of the 1-D model to separate between ballast and soil stresses, and not the locality of the reaction force.
Seismic soil-structure interaction analysis considering a layered half space subjected to geothermal induced seismicity
Authors: Taddei Francesca , Yuan Shihao , Freisinger Julian , Müller Gerhard 
Published: June 2024

Abstract
In the near future, geothermal energy is bound to play a critical role in the transition to sustainable energy sources. Micro-earthquakes may be induced by the underground operations performed at the geothermal power plants. In most cases, these vibrations are considered a general nuisance similar to the vibrations resulting from railway track operations. However, given the heightened public concern regarding induced seismicity, it is crucial to identify and analyze the effects of these micro-seismic events on the built environment. In this contribution, we present a numerical technique for the simulation of buildings subjected to geothermal induced seismicity. We apply a substructure method, where the soil is represented as a continuum using the integral transform method (ITM) and the building as a discrete structure using the finite element method (FEM). For the semi-analytical elastodynamical solution, as in the ITM case, the seismic excitation can be converted to an equivalent load acting at the interaction nodes between soil and structure. To obtain these equivalent loads, one has to compute in advance the free field displacements at these interaction nodes. We apply the presented approach to a plate underlain by a layered half space that is subjected to a geothermal-induced earthquake with characteristics typical for the Greater Munich Area in Germany.
Further Dynamic-integrity-based Reliability Analysis
Authors: Provasi Rodrigo , Mazzilli Carlos E. N. , Franzini Guilherme R. 
Published: June 2024

Abstract
Non-linear dynamical systems of different areas of engineering and technology are subject to parameters that should most of the times be realistically modelled as random variables, although they are usually considered to be deterministic. This paper addresses in a simple, almost naïve fashion, the reliability analysis of those systems, starting from a deterministic analysis, but then bringing into it the statistical properties of input variables. Although the concept of dynamical integrity has greatly contributed to establishing safe thresholds in dynamical systems, requiring that the basins of attraction should be robust, a reliability measure is still missing in that respect. In fact, supposing that the erosion curve of a dynamic integrity measure I (for instance, the integrity factor) has been obtained in terms of a system parameter A (for instance, a load amplitude, a load frequency, or still an imperfection parameter) using a deterministic approach, one can estimate the output statistical properties for I, in terms of those of the input parameter A, now considered as a random variable in its own right. Hence, once reference values for the integrity measure I
ref and the system parameter A
ref have been established, and assuming that increase of A beyond A
ref may prove to be dangerous, the probability that I ≥ I
ref, provided that A ≤ A
ref, would give a sound reliability assessment. A very simple approach towards this aim is proposed and applied herewith to an archetypal model of a rigid column asymmetrically constrained by a linear spring, subject to a conservative axial compression and a small dynamical transversal load, playing the role of a random dynamical imperfection. It should be said that this work is a continuation of another one, with the same archetypal model, yet taking into account only the effect of a statical imperfection. A versatile in-house code is used to obtain the basins of attraction and the erosion curves that give support to the proposed methodology. The reliability assessment is carried out in two different scenarios, namely varying either the dynamical imperfection amplitude or its frequency. The influence of nearness to either buckling, or to external resonance or even parametric resonance can be studied according to the proposed methodology. It is simple and easy to be applied. Therefore, one hopes that it can be absorbed in engineering design practice without its traditional resistance to incorporate new trends.
Nonlinear dynamic analysis of a cylindrical panel with a discontinuous unilateral elastic base
Authors: Morais Jordana L , Silva Frederico M A , Gonçalves Paulo B 
Published: June 2024

Abstract
This work evaluates the nonlinear dynamic behavior and dynamic instability of an imperfect cylindrical panel with a discontinuous unilateral elastic base. The cylindrical panel is described by Donnell’s nonlinear shallow shell theory, being discretized by the Galerkin method, using a previous reduced order model obtained by a perturbation method. It is shown that an efficient modal solution with two degree-of-freedom is sufficient to describe the non-linear softening behavior of the cylindrical panel with a discontinuous elastic base. The Heaviside and the Signum function are used to describe the elastic base domain and the unilateral contact force respectively. The obtained results, using the fourth order Runge-Kutta method, demonstrate the influence of the discontinuous unilateral elastic base and initial geometrical imperfection on the bifurcation diagrams, phase portraits and resonance curves of the cylindrical panel. They demonstrate the important changes in the stable and unstable regions of the nonlinear equilibrium paths and dynamics instability regions due to the unilateral contact constraint and the localized foundation.
Nonlinear dynamics of a 3D-printed pre-compressed beam structure: an experimental investigation
Authors: Anastasio D , Daga A P , Fasana A , Garibaldi L , Marchesiello S , Cheng P 
Published: June 2024

Abstract
Engineering applications have conventionally aimed to avoid phenomena related to mechanical instabilities or buckling, as they can bring undesired nonlinear effects or even failure. In recent years however the research in this field has experienced an inversion of direction making use of such phenomena to improve the performance of solids and structures. In this context, the adoption of pre-compressed slender beam elements is one of the most common solutions. A typical application is the development of quasi-zero stiffness (QZS) vibration isolators, that bring a high static stiffness and an extremely low dynamic stiffness. As a general rule, the QZS characteristics can be obtained by coupling a negative stiffness effect with a positive one. When considering beam elements, the application of a compressive axial force can lead to a mechanical instability and to a negative stiffness region in the force-displacement characteristics. This paper studies the dynamical behaviour of such elements by comparing experimental measurements with a mathematical model. To this end, a 3D-printed V-shaped structure is considered, comprising two pre-compressed beam elements and a controllable pre-load. The regulation of the pre-load allows the V-structure to undergo tensile or compressive forces, thus altering its characteristics. In particular, the restoring force of the system can show regions of negative or quasi-zero stiffness when compressive forces are applied. The system is excited with an electromagnetic shaker considering different pre-loads, and the nonlinear dynamic behaviour is estimated from the measured responses. A comparison between experimental measurements and model predictions is eventually carried out to strengthen the understanding of the observed dynamical phenomena.
Advancing Steel Component Repair by Investigating the Surface Properties of Mild Steel Plates Coated with Alumina Using Metal Inert Gas Welding
Authors: Mwema F M , Shagwira H , Jen T C , Wambua J M , Bodunrin M O , Akinlabi E T 
Published: June 2024

Abstract
Arc-welding coatings are extensively employed within the informal sectors of many African countries to repair various machine components, such as gear teeth, machine shafts, bushings, and many others. In the pursuit of advancing steel component repair techniques, this study investigates the surface properties of mild steel plates coated with alumina using the Metal Inert Gas (MIG) welding process. Mild steel wire of diameter 1.6 mm, alumina particles of size 1 µm, and mild steel plates were used. The prepared samples were analysed for microstructural, hardness, wear, and corrosion properties. For the first time, and through a traditional welding process, it is demonstrated that the hardness, wear, and corrosion resistance of steel parts can be improved by the inclusion of alumina particles on their surfaces. As such, this work will have an impact on the informal engineering sector (Jua Kali sector as known in Kenya) involved in the surface repair of steel components.
Experimental study on dynamic characteristics of wall pressure in supersonic combustor of kerosene fuel
Authors: Jiao Guiqian , Song Wenyan , Zeng Xianglong 
Published: June 2024

Abstract
In order to study the rationality and feasibility of kerosene-fueled supersonic combustor wall pressure as the controlled parameter of scramjet, a series of supersonic combustor ground direct-connected tests were carried out on the ground direct-connected test bench of Northwestern Polytechnical University. The test simulated the actual process of ignition and combustion in a double-cavities supersonic combustor under the conditions of inlet total pressure of 800 kPa and 900 kPa, total temperature of 810 K, and Mach number 2.0. The characteristics of pressure distribution and sensitivity on the wall of the combustor were measured and analyzed. The results show that the combustor wall pressure fluctuates obviously in steady state, and the fluctuation is positively correlated with the oil-gas ratio. The relative variation of wall pressure difference value and equivalent oil-gas ratio can reflect the sensitivity of wall pressure change under different oil-gas ratios. The wall sensitivity at X=370 mm is the largest, which is most suitable as the controlled parameter of the engine kerosene flow.
An Energy Stable Alternative WENO Scheme with a New Smoothness Indicator for Hyperbolic Conservation Laws
Authors: Lou Shuai , Ren Yi-peng , Yang Xue-jun , Wang Zhao-wei , Zhong Kang , Yan Chao 
Published: June 2024

Abstract
An energy stable alternative weighted Essentially Non-Oscillatory (WENO) scheme with a new smoothness indicator (EAWN) is proposed in this paper. The developed EAWN scheme is stable for linear problems by adding a correction operator and can recover the designed order of accuracy at critical points with no dependency on user-defined parameter for smoothness indicators. Application of EAWN in one-dimensional and two-dimensional hyperbolic conservation laws also indicates the superiority of the new method over its non-modified version in terms of shock-capturing and vorticity-resolving.
Structural and electrical conductivity studies of Polyaniline - WO3 hybrid nanocomposites for gas sensing applications
Authors: Jaiswal Rohan , Chandra Joshi Manish , Ramadurai Ranjith , Sunkara Manorama , Kannan Vijayanandhini 
Published: June 2024

Abstract
Conducting polymer – metal oxide based hybrid nanocomposites are a fascinating class of materials for miniaturized and flexible gas sensor devices. They exhibit enhanced physiochemical properties such as sensitivity, selectivity towards various volatile and hazardous chemical and bioanalytes. Our study focuses on conducting polyaniline (PANI) and WO3 nanocomposites, where different weight percentages (wt.%) of WO3 nanoparticles are embedded within the conducting PANI matrix using an in-situ oxidation polymerization synthesis technique. The surface morphology analysis indicated that the WO3 nanoparticles with an average grain size of ~200 nm are homogeneously distributed within the PANI nanofibers. The Fourier Transform Infra-Red (FTIR) spectrum analysis showed that the absorption peaks at 1111,1291, 1385, 1474, and 1560 cm−1 are typical of the conducting PANI emeraldine phase. We attribute the additional broad peak ranging between 840 to 720 cm−1 in the spectrum to WO3 phase, wherein, the intensity of the peak increases with WO3 content in case of hybrid composites. Current-voltage (I-V) characteristics for all our samples showed linear behaviour up to 1.2 volts. Temperature-dependent DC electrical conductivity (σ) studies measured from room temperature to 120°C for pure PANI, and PANI-WO3 composites showed an enhanced electrical conductivity of values up to 0.12 S/cm for PANI as compared to WO3 with σ ~ 1.4 x 10−3 S/cm. Pure PANI exhibits semiconducting behavior with an increase in electrical conductivity with temperature due to the charge carrier delocalization within the dispersed PANI backbone. The addition of higher concentrations of WO3 in composites leads to a metallic-like behavior, characterized by a decrease in electrical conductivity with temperature. These observations are attributed to the field-assisted band bending effects at the interfaces of PANI and WO3. Our composites show desired electrical characteristics suitable for gas sensing applications.
Impact of sol-gel and co-precipitation synthesis methods on structural properties of lithium ferrite
Authors: Sai Santoshi T , Bharadwaj S , Choudary G S V R K , Chaitanya Varma M 
Published: June 2024

Abstract
In the present study, lithium ferrite is synthesized by both sol-gel and chemical coprecipitation methods and then annealed at 700°C for 2 hrs. The variation in the phase transition and weight loss (%) is clearly evident from the thermo-gravimetric analysis for the lithium ferrite prepared using two different synthesis routes indicating the formation of structural changes. The lattice parameter (a), average crystallite size (D) are calculated using the cubic phase formula and Debye-Sherrer’s equation respectively and the values are in good agreement with literature. Higher value of saturation magnetization is observed in the case of lithium ferrite synthesized by sol-gel method when compared with co-precipitation method highlights the importance of phase formation.
Spectroscopic Studies of CuO-incorporated PEO Nanocomposite Films for Flexible Optoelectronic Devices
Authors: Sudhakar K. , Venugopal R. , Narsimlu N. , Srinivas CH. 
Published: June 2024

Abstract
Polymer nanocomposites is a promising area of research due to polymers’ unique properties and potential applications in various fields such as automotive, aerospace, defense, and biomedicine. In present work, we report preparation and characterization of copper oxide nanoparticles (CuO NPs)-incorporated polyethylene oxide (PEO) nanocomposites. CuO nanoparticles (5, 10 and 15 wt. %) were incorporated into PEO matrix, and preparation method of solution casting had been employed. These films were characterized by XRD, FTIR, SEM and UV–Vis spectroscopy. SEM Morphological studies revealed the original structure of the CuO nanoparticles in PEO matrix. The crystallinity of composite films decreases with increasing CuO weight percentage. The SEM images confirmed uniform distribution of CuO nanoparticles in composite films. UV–Vis spectroscopy of composite films revealed that absorption is more in UV region with increasing CuO wt.%. This property can be used in preparation of UV filters for glass windows to protect them from UV radiation. With addition of CuO NPs to PEO matrix, optical direct and indirect band gaps decreased from 5.32eV to 5.28eV and from 5.28 to 5.03eV, respectively. These results reveal that PEO-CuO nanocomposite films are useful for UV-shielding devices, tunable bandgap devices, photo sensors, and next-generation flexible optoelectronic devices.