Hasil untuk "Mechanics of engineering. Applied mechanics"

J. Barber, M. Ciavarella

R. Chhabra, J. F. Richardson

Shixing Chen, Jingchuan Zhu, Tingyao Liu et al.

This study deploys an integrated computational materials engineering (ICME) workflow to elucidate how aging schedules govern the microstructure and mechanical properties of a novel ultra-high-strength maraging steel. Thermodynamic calculations identify precipitate species and contents, while kinetic modeling captures nucleation and growth; in parallel, a machine-learning model tuned by the Sparrow Search Algorithm (SSA) assesses model accuracy, examines the normality of residuals, and delivers global predictions of mechanical properties across the design space. A vacuum-arc-melted martensitic steel was aged between 380 and 680 °C. Strength increases and then decreases with aging temperature, whereas ductility shows the opposite trend. The 480 °C condition provides the optimal overall balance, with a yield strength of 2160 MPa, ultimate tensile strength of 2220 MPa, elongation of 3.85 %, reduction of area of 33.7 %, and hardness of 62.2 HRC. In contrast, the 680 °C condition yields maximum plasticity, characterized by an elongation of 15.5 % and a reduction of area of 62.2 %. EBSD reveals an increase in characteristic grain size with temperature and a gradual decrease in the fraction of low-angle boundaries; XRD and SEM corroborate the formation of reverted austenite at higher temperatures. The SSA-assisted model achieves absolute prediction errors within ±10 % across all tested conditions, supporting its reliability. Integrating thermodynamics, kinetics, and data-driven prediction yields a coherent process–structure–property map and offers practical guidance for heat-treatment design in new maraging steels.

Daoping Liu, Jingna Guo, Qiang Li et al.

IntroductionGas migration in low-permeability buffer materials is a crucial aspect of nuclear waste disposal. This study focuses on Gaomiaozi bentonite to investigate its behavior under various conditions.MethodsWe developed a coupled hydro-mechanical model that incorporates damage mechanisms in bentonite under flexible boundary conditions. Utilizing the elastic theory of porous media, gas pressure was integrated into the soil's constitutive equation. The model accounted for damage effects on the elastic modulus and permeability, with damage variables defined by the Galileo and Coulomb-Mohr criteria. We conducted numerical simulations of the seepage and stress fields using COMSOL and MATLAB. Gas breakthrough tests were also performed on bentonite samples under controlled conditions.ResultsThe permeability obtained from gas breakthrough tests and numerical simulations was within a 10% error margin. The experimentally measured gas breakthrough pressure aligned closely with the predicted values, validating the model's applicability.DiscussionAnalysis revealed that increased dry density under flexible boundaries reduced the damage area and influenced gas breakthrough pressure. Specifically, at dry densities of 1.4 g/cm3, 1.6 g/cm3, and 1.7 g/cm3, the corresponding gas breakthrough pressures were 5.0 MPa, 6.0 MPa, and 6.5 MPa, respectively. At a dry density of 1.8 g/cm3 and an injection pressure of 10.0 MPa, no continuous seepage channels formed, indicating no gas breakthrough. This phenomenon is attributed to the greater tensile and compressive strengths associated with higher dry densities, which render the material less susceptible to damage from external forces.

Sunith Babu Loganathan, Ashok Kumar Krishnappa, Jaya Christiyan Kumaravelu Grace Jesu Bai et al.

Composites are widely used for different applications in engineering mainly due to their tailored benefits, durability, reduced maintenance, and enhanced performance. GFRP is a synthetic material that has revolutionized the aerospace industry, offering a high strength-to-weight ratio, fuel efficiency, and enhanced performance for advanced applications. In structures like aircraft components, holes or notches are often present due to design requirements or secondary joining processes through rivets or bolted connections, which leads to wear and tear. Further, how these materials behave under tensile loads near these openings is critical for ensuring the safety and reliability of such structures. In the present study, GFRP/Epoxy composite laminates are subjected to open hole tensile test under ON and OFF axis orientations. The effect of loading under different sequences was studied. The nature of failure near the hole region was reviewed and presented. It is noted that the dominant failure was LGM type under the ON-axis and different under the OFF-axis which is not limited to shear failure, interlaminar delamination, and mixed mode failures. These trends are noted for different hole dia, namely 6,9,12 and 18mm. The study also presents the nature of the stress-strain curve for both configurations. The OFF-axis specimens displayed a non-linear behavior to failure as compared to the On-axis type. While, the on-axis specimens showed a marked reduction in peak load and tensile strength as hole dia increased with reductions up to 65.23% and 63.57%, respectively relative to hole-less specimens. The inclined failure in off-axis specimens varied between 500 - 550. Further, the damage tolerance in OFF-axis samples was higher as compared to ON-axis specimens.

Su-Xiang Guo, Meng-Tian Song, Jie-Chao Lei et al.

This study employs a force element analysis to investigate vortex-induced vibrations (VIV) of three side-by-side circular cylinders at Reynolds number <i>Re</i> = 100, mass ratio <i>m</i>* = 10, spacing ratios <i>S</i>/<i>D</i> = 3–6, and reduced velocities <i>Ur</i> = 2–14. The lift and drag forces are decomposed into three physical components: volume vorticity force, surface vorticity force, and surface acceleration force. The present work systematically examines varying <i>S</i>/<i>D</i> and <i>Ur</i> effects on vibration amplitudes, frequencies, phase relationships, and transitions between distinct vortex-shedding patterns. By quantitative force decomposition, underlying physical mechanisms governing VIV in the triple-cylinder system are elucidated, including vortex dynamics, inter-cylinder interference, and flow structures. Results indicate that when <i>S</i>/<i>D</i> < 4, cylinders exhibit “multi-frequency” vibration responses. When <i>S</i>/<i>D</i> > 4, the “lock-in” region broadens, and the wake structure approaches the patterns of an isolated single cylinder; in addition, the trajectories of cylinders become more regularized. The forces acting on the central cylinder present characteristics of stochastic synchronization, significantly different from those observed in two-cylinder systems. The results can advance the understanding of complex interactions between hydrodynamic and structural dynamic forces under different geometric parameters that govern VIV response characteristics of marine structures.

Nazanin Ahmadi, Qianying Cao, Jay D. Humphrey et al.

Physics-informed machine learning (PIML) is emerging as a potentially transformative paradigm for modeling complex biomedical systems by integrating parameterized physical laws with data-driven methods. Here, we review three main classes of PIML frameworks: physics-informed neural networks (PINNs), neural ordinary differential equations (NODEs), and neural operators (NOs), highlighting their growing role in biomedical science and engineering. We begin with PINNs, which embed governing equations into deep learning models and have been successfully applied to biosolid and biofluid mechanics, mechanobiology, and medical imaging among other areas. We then review NODEs, which offer continuous-time modeling, especially suited to dynamic physiological systems, pharmacokinetics, and cell signaling. Finally, we discuss deep NOs as powerful tools for learning mappings between function spaces, enabling efficient simulations across multiscale and spatially heterogeneous biological domains. Throughout, we emphasize applications where physical interpretability, data scarcity, or system complexity make conventional black-box learning insufficient. We conclude by identifying open challenges and future directions for advancing PIML in biomedical science and engineering, including issues of uncertainty quantification, generalization, and integration of PIML and large language models.

Georgi Markov, Jon G. Hall, Lucia Rapanotti

Many organisational problems are addressed through systemic change and re-engineering of existing Information Systems rather than radical new design. In the face of widespread IT project failure, devising effective ways to tackle this type of change remains an open challenge. This work discusses the motivation, theoretical foundation, characteristics and evaluation of a novel framework - referred to as POE-$Δ$, which is rooted in design and engineering and is aimed at providing systematic support for representing, structuring and exploring change problems of a socio-technical nature, including implementing their solutions when they exist. We generalise an existing framework of greenfield design as problem solving for application to change problems. From a theoretical perspective,POE-$Δ$ is a strict extension to its parent framework, allowing the seamless integration of greenfield and brownfield design to tackle change problems. A Design Science Research methodology was applied over a decade to define and evaluate POE-$Δ$, with significant case study research conducted to evaluate the framework in its application to real-world change problems of varying criticality and complexity. The results show that POE-$Δ$ exhibits desirable characteristics of a design approach to organisational change and can bring tangible benefits when applied in practice as a holistic and systematic approach to change in socio-technical contexts.

Carolyn Seaman, Rashina Hoda, Robert Feldt

The paper entitled "Qualitative Methods in Empirical Studies of Software Engineering" by Carolyn Seaman was published in TSE in 1999. It has been chosen as one of the most influential papers from the third decade of TSE's 50 years history. In this retrospective, the authors discuss the evolution of the use of qualitative methods in software engineering research, the impact it's had on research and practice, and reflections on what is coming and deserves attention.

Yu-an Jin, Chaoqi Xie, Qing Gao et al.

Abstract Melt electro writing (MEW) provides three-dimensional (3D) printing porous scaffolds with well-defined geometrical features of ultrafine fibers in the tissue engineering. Scaffolds with adjustable Poisson's ratio are more suitable in certain biological applications for mimicking the behavior of native tissue mechanics. However, it is still a challenging issue to tune the Poisson's ratio. In order to resolve this problem, a new method is proposed in the present study to design and fabricate tunable auxetic scaffolds through altering the printing configurations in the MEW. Patterns with thick fibers are designed using specific geometries and then these patterns are utilized to tune the Poisson's ratio based on the intended deformation mechanism. Moreover, the electrospun thin fibers are used to fill the unit cell of auxetic lattice structures for promoting the cell growth. Investigating the mechanical characteristics of the fabricated scaffolds demonstrates that the Poisson's ratio of the scaffold can be effectively tuned. Furthermore, cell sense and response to the fabricated scaffolds are studied. Obtained results indicate that the proposed approach can potentially be applied in a wide variety of biomedical applications.

T. Nasu, T. Tokuzawa, M. Nakata et al.

Electron-scale turbulence, whose wavelength is the electron Larmor radius, is thought to have the potential to cause stiffness in an electron temperature gradient and degrade the confinement of future burning plasma in which the electron heating by alpha particles is dominant. The dependence of electron-scale turbulence and electron heat flux on the electron temperature inverse gradient length $R_\textrm{ax}/L_{T_\textrm{e}}$ , were investigated. The electron temperature gradient was successfully varied in the range of $-3 \lt R_\textrm{ax}/L_{T_\textrm{e}} \lt 12$ by controlling the injection power of on/off-axis electron cyclotron heating. The results show a significant increase in the electron-scale turbulence with increasing $R_\textrm{ax}/L_{T_\textrm{e}}$ , especially in conditions where Electron Temperature Gradient (ETG) instability is linearly unstable, suggesting the presence of ETG turbulence at high $R_\textrm{ax}/L_{T_\textrm{e}}$ . The electron heat flux also increases steeply with increasing $R_\textrm{ax}/L_{T_\textrm{e}}$ . In addition, the electron-scale turbulence is observed even at $R_\textrm{ax}/L_{T_\textrm{e}} \sim 0$ , which is stable in linear GKV calculations. Finding the cause of this phenomenon is an interesting task for the future.

Svetlana A. Kovaliova, Viktor I. Zhornik, Pyotr A. Vityaz et al.

The article considers the mechanochemical preparation of TiC-Ni composites in reaction mixtures of Ti-C-Ni powders and the formation of the structure of materials during their sintering under pressure. The synthesis was carried out in an AGO-2 planetary ball mill with a mixture processing time of 12 and 20 min; their subsequent sintering was performed at a temperature of 950 °C and a pressure of 130 MPa. The results of diffraction studies are presented for structural-phase transformations in mixtures of equimolar composition of titanium and carbon depending on the nickel content in the range of 50–70 wt.%. It is established that an increase in the Ni concentration leads to a decrease in the size of the formed TiCx crystallites from 29 ± 1 to 16 ± 1 nm. A high carbon content TiC0.88–0.98 carbide is formed in Ti-C-(50 and 60 %)Ni compositions and non-stoichiometric TiC0.62–0.78 at 70 % Ni. The microstructure of dispersion-strengthened grains of the nickel solid solution is formed during sintering of TiC/(50–60 %)Ni mechanocomposites. Titanium carbide inclusions have a spherical shape and a diameter of 60–100 nm. When sintering TiC/70%Ni, depleted titanium carbide has a grain boundary distribution with the formation of large (~400 nm) agglomerates. The microhardness of sintered materials is in the range of 850–900 HV.

Akuro Big-Alabo, Joseph Chukwuka Ofodu

This article presents a theoretical investigation of the problem of free fall of a spherical particle in a viscous fluid. The classic Boussinesq-Basset-Oseen (BBO) model for particle motion in laminar flow was modified for generalized flow by using a drag law that is applicable for 0<Re≤2.0 x 10^5. By assuming that the acceleration in the Basset force integral is constant, the Basset force effect was approximated to form an integrated added mass coefficient. Consequently, the integro-differential equation of the BBO model was transformed to a first-order nonlinear ordinary differential equation that accounts for the Basset force effect and was solved using the continuous piecewise linearization method (CPLM). The CPLM algorithm was developed based on the jerk-velocity relationship and is applicable to zero and non-zero initial conditions, steady motion, increasing or decreasing velocities and the corresponding acceleration and jerk responses. The CPLM algorithm was shown to predict published experimental results accurately and compared very well with numerical solutions and existing analytical solutions. Examination of the fall response under varying parameters showed that the fall distance, fall time and terminal velocity depend strongly on the sphere diameter, sphere density, and the density and viscosity of the fluid medium. Also, an analytical solution for the power dissipated in the fluid medium as the sphere falls to reach its terminal velocity was derived. The power dissipated was found to increase exponentially as the initial velocity deviates positively from the terminal velocity.

Monge Joao Carlos, Mantari Jose Luis, Llosa Melchor Nicolas et al.

An unavailable semi-analytical non-local 3D solution for functionally graded nanoshells with constant radii of curvature is presented. The small length scale effect is included in Eringen’s nonlocal elasticity theory. The constitutive and equilibrium equations are written in terms of curvilinear orthogonal coordinates systems which are only valid for spherical and cylindrical shells, and rectangular plates. The stresses and displacements are assumed in terms of the Navier method which is applicable for simply supported structures. The derivatives in terms of thickness are approximated by the differential quadrature method (DQM). The thickness domain is discretized by the Chebyshev–Gauss–Lobatto grid distribution. Lagrange interpolation polynomials are considered as the basis function for DQM. The correct free surface boundary condition for out-of-plane stresses is considered. Several problems of isotropic and functionally graded shells subjected to different types of loads are analyzed. The results are compared with other three-dimensional solutions and higher-order theories. It is important to emphasize that the radii of curvature are crucial at nanoscale, so it should be considered in the design of nanodevices.

Afreen Nishat, Mohammad Yusuf, Abdul Qadir et al.

Over the past few decades, there has been a significant increase in population and unsustainable urbanization, resulting in the exploitation of water and energy resources on a large scale. This has led to a rise in the demand for freshwater, which, in turn, has caused water pollution due to the improper disposal of wastewater from various sources such as industries, agriculture, and households. The wastewater from industries often contains toxic heavy metals and harmful emerging contaminants (ECs), which can harm living beings and cannot biodegrade. Hence, it is a severe issue that needs to be addressed. To combat this problem, wastewater treatments are necessary for two main reasons: firstly, to recycle and reuse wastewater to meet future human demand and reduce water scarcity, and secondly, to ensure compliance with wastewater discharge standards for environmental sustainability while minimizing groundwater and soil contamination. In this review, several wastewater treatment technologies comprising physical, chemical, and biological methods have been discussed critically. The state-of-the-art discussion on different existing wastewater treatment techniques and their limitations has been deliberated. Finally, the limitations of the various existing wastewater treatment techniques and contemporary trends in wastewater treatment have been highlighted.

Aurel M. Alecu, Mihail I. Boiangiu, Viorel I. Anghel

The paper presents a semi-analytical method for the study of a linear differential system with variable coefficients. The solution is given in terms of real positive integer powers; it is obtained in terms of independent functions which are computed numerically. The paper extended the semi-analytical method from [5] (for one differential equation only), to the study of a linear differential system. The differential system became a system with recurrent expressions between the coefficients of the power series in a matrix form. The strength of this method is shown by application to the dynamic analysis of typical rotor blades. The frequencies and mode shapes are calculated. The results are compared with theoretical results for the degenerate cases and with results obtained through other methods.

Lihua Lou, Tanaji Paul, Brandon A. Aguiar et al.

Nanometer- and submicrometer-sized fiber have been used as scaffolds for tissue engineering, because of their fundamental load-bearing properties in synergy with mechano-transduction. This study investigates a single biodegradable poly(lactic-co-glycolic acid) (PLGA) fiber's load-displacement behavior utilizing the nanoindentation technique coupled with a high-resolution in situ imaging system. It is demonstrated that a maximum force of ∼3 μN in the radial direction and displacement of at least 150% of fiber diameter should be applied to acquire the fiber's macroscopic mechanical properties for tissue engineering. The adhesion behavior of a single fiber is captured using a high-resolution camera. The digital image correlation (DIC) technique is adopted to quantify the adhesion force (∼25 μN) between the fiber and the tip. Adhesion force has also been quantified for the fiber after immersing in phosphate-buffered saline (PBS) to mimic the bioenvironment. A 4-fold increase in adhesion force after PBS treatment was observed due to water penetration and hydrolysis on the fiber's surface. A high similarity between mechanical properties of a single fiber and native tissues (elastic modulus of 10-25 kPa) and superior adhesion force (25-107.25 μN) was observed, which is excellent for promoting cell-matrix communication. Overall, this study examines the mechanics of a single fiber using innovative indentation and imaging processing techniques, disclosing its profound and striking roles in tissue engineering.

Ogul Esen, Miroslav Grmela, Michal Pavelka

This paper contains a fully geometric formulation of the General Equation for Non-Equilibrium Reversible-Irreversible Coupling (GENERIC). Although GENERIC, which is the sum of Hamiltonian mechanics and gradient dynamics, is a framework unifying a vast range of models in non-equilibrium thermodynamics, it has unclear geometric structure, due to the diverse geometric origins of Hamiltonian mechanics and gradient dynamics. The difference can be overcome by cotangent lifts of the dynamics, which leads, for instance, to a Hamiltonian form of gradient dynamics. Moreover, the lifted vector fields can be split into their holonomic and vertical representatives, which provides a geometric method of dynamic reduction. The lifted dynamics can be also given physical meaning, here called the rate-GENERIC. Finally, the lifts can be formulated within contact geometry, where the second law of thermodynamics is explicitly contained within the evolution equations.

N. Lauber, O. Tichacek, R. Bose et al.

Physical mechanisms of phase separation in living systems can play key physiological roles and have recently been the focus of intensive studies. The strongly heterogeneous and disordered nature of such phenomena in the biological domain poses difficult modeling challenges that require going beyond mean field approaches based on postulating a free energy landscape. The alternative pathway we take in this work is to tackle the full statistical mechanics problem of calculating the partition function in these systems, starting from microscopic interactions, by means of cavity methods. We illustrate the procedure first on the simple binary case, and we then apply it successfully to ternary systems, in which the naive mean field approximations are proved inadequate. We then demonstrate the agreement with lattice model simulations, to finally contrast our theory also with experiments of coacervate formation by associative de-mixing of nucleotides and poly-lysine in aqueous solution. In this way, different types of evidence are provided to support cavity methods as ideal tools for quantitative modeling of biomolecular condensation, giving an optimal balance between the accurate consideration of spatial aspects of the microscopic dynamics and the fast computational results rooted in their analytical tractability.

Bo Yang, E. Klineberg, G. O’Connell

Painful herniated discs are treated surgically by removing extruded nucleus pulposus (NP) material (nucleotomy). NP removal through enzymatic digestion is also commonly performed to initiate degenerative changes to study potential biological repair strategies. Experimental and computational studies have shown a decrease in disc stiffness with nucleotomy under single loading modalities, such as compression-only or bending-only loading. However, studies that apply more physiologically relevant loading conditions, such as compression in combination with bending or torsion, have shown contradicting results. We used a previously validated bone-disc-bone finite element model (Control) to create a Nucleotomy model to evaluate the effect of dual loading conditions (compression with torsion or bending) on intradiscal deformations. While disc joint stiffness decreased with nucleotomy under single loading conditions, as commonly reported in the literature, dual loading resulted in an increase in bending stiffness. More specifically, dual loading resulted in a 40% increase in bending stiffness under flexion and extension and a 25% increase in stiffness under lateral bending. The increase in bending stiffness was due to an increase and shift in compressive stress, where peak stresses migrated from the NP-annulus interface to the outer annulus. In contrast, the decrease in torsional stiffness was due to greater fiber reorientation during compression. In general, large radial strains were observed with nucleotomy, suggesting an increased risk for delamination or degenerative remodeling. In conclusion, the effect of nucleotomy on disc mechanics depends on the type and complexity of applied loads.