Hasil untuk "Mechanics of engineering. Applied mechanics"

Areej Almuneef, Ibrahim Abbas, Alaa El-Bary et al.

This study investigates thermal damage in living tissue during thermotherapy by employing the bioheat equation under fractional derivatives. The Atangana-Baleanu (AB) derivative is taken into consideration in the fractional-order formulation using non-singular and local kernels. Analytical solutions are derived in the Laplace domain, facilitating precise examination of the impacts of fractional derivatives and moving heating source speed on skin tissue temperature and thermal injury. The fractional bioheat model reduces to hyperbolic and Pennes models as the relaxation time approaches zero and the fractional order parameter equals one, according to the results. Thermal damages are quantified using the denatured protein range based on Arrhenius' formulation. Numerical findings on temperature distribution and tissue damage are presented graphically. Finally, a parametric analysis highlights critical design variables for optimizing heating efficiency in hyperthermia treatment.

Sztankovics István, Rodić Dragan

This study compares rotational and longitudinal turning during the machining of normalized medium-carbon steel. The aim is to evaluate differences in energy efficiency and surface quality. Three tools were tested: two rotational turning tools with 30° and 45° inclination angles and a conventional longitudinal turning tool. Thirty-six cutting experiments were performed while varying depth of cut, feed, and cutting speed. Cutting forces were measured in three directions and used to calculate specific cutting forces and total mechanical work. Surface roughness was evaluated using arithmetical mean roughness and maximum peak-to-valley height parameters. The results show that rotational turning, particularly with a 30° inclination, reduces specific cutting forces and enables lower energy consumption at comparable productivity. It also provides better surface finish at medium and high feeds. Longitudinal turning generated acceptable energy levels but produced significantly rougher surfaces. The findings highlight the role of tool inclination in improving energy-surface-quality interactions.

Mayuranath SureshKumar, Hanumanthrao Kannan

Classic problem-space theory models problem solving as a navigation through a structured space of states, operators, goals, and constraints. Systems Engineering (SE) employs analogous constructs (functional analysis, operational analysis, scenarios, trade studies), yet still lacks a rigorous systems-theoretic representation of the problem space itself. In current practice, reasoning often proceeds directly from stakeholder goals to prescriptive artifacts. This makes foundational assumptions about the operational environment, admissible interactions, and contextual conditions implicit or prematurely embedded in architectures or requirements. This paper addresses that gap by formalizing the problem space as an explicit semantic world model containing theoretical constructs that are defined prior to requirements and solution commitments. These constructs along with the developed axioms, theorems and corollary establish a rigorous criterion for unambiguous boundary semantics, context-dependent interaction traceability to successful stakeholder goal satisfaction, and sufficiency of problem-space specification over which disciplined reasoning can occur independent of solution design. It offers a clear distinction between what is true of the problem domain and what is chosen as a solution. The paper concludes by discussing the significance of the theory on practitioners and provides a dialogue-based hypothetical case study between a stakeholder and an engineer, demonstrating how the theory guides problem framing before designing any prescriptive artifacts.

Shaik Sameer Basha, Sachin Thomas, Subastri Ariraman et al.

Abstract Triple-negative breast cancer (TNBC) poses significant therapeutic challenges due to the lack of targetable receptors and the systemic toxicity associated with conventional treatments such as surgery, radiotherapy, and chemotherapy. While phototherapy has emerged as a potential alternative, its clinical translation is hindered by the colloidal instability of photothermal agents and the need for combinatorial strategies. Here, we report the development of a near-infrared (NIR)-responsive theranostic nanoplatform based on archaeal lipid-derived nanoarchaeosomes (NA) co-encapsulating cisplatin (Cis) and PEGylated gold nanorods (AuNRs), forming a multifunctional NA-Cis-AuNRs nanoformulation. Archaeal lipids confer robust colloidal stability to this complex, enabling high drug-loading efficiency. Upon NIR irradiation, the AuNRs embedded within this complex generate localized hyperthermia, facilitating the rapid and controlled release of cisplatin. NA-Cis-AuNRs exhibit excellent biocompatibility in fibroblast cultures and zebrafish larvae, while effectively inducing apoptosis, oxidative stress, and associated DNA damage, and G2/M cell cycle arrest in TNBC cells. In vivo studies using the chick chorioallantoic membrane (CAM) assay confirm significant antiangiogenic activity, marked by downregulation of key angiogenic factors (VEGF, FGF2, and ANG1). Together, these results highlight a minimally invasive, NIR laser-triggered nanotherapeutic strategy with reduced systemic toxicity and establish a potential platform for TNBC treatment, warranting further preclinical validation in mammalian models.

Pouyan Mehryar, Sina Firouzy, Uriel Martinez-Hernandez et al.

<b>Background/Objectives:</b> This study focuses on the motion planning and control of an active ankle–foot orthosis (AFO) that leverages biomechanical insights to mitigate footdrop, a deficit that prevents safe toe clearance during walking. <b>Methods:</b> To adapt the motion of the device to the user’s walking speed, a geometric model was used, together with real-time measurement of the user’s gait cycle. A geometric speed-adaptive model also scales a trapezoidal ankle-velocity profile in real time using the detected gait cycle. The algorithm was tested at three different walking speeds, with a prototype of the AFO worn by a test subject. <b>Results:</b> At walking speeds of 0.44 and 0.61 m/s, reduced tibialis anterior (TA) muscle activity was confirmed by electromyography (EMG) signal measurement during the stance phase of assisted gait. When the AFO was in assistance mode after toe-off (initial and mid-swing phase), it provided an average of 48% of the estimated required power to make up for the deliberate inactivity of the TA muscle. <b>Conclusions:</b> Kinematic analysis of the motion capture data showed that sufficient foot clearance was achieved at all three speeds of the test. No adverse effects or discomfort were reported during the experiment. Future studies should examine the device in populations with footdrop and include a comprehensive evaluation of safety.

Abhishek Patange, Farzam Omidi Moaf, Piotr Fiborek et al.

This study investigates a self-referencing method for damage detection and localization using guided waves (GW) sensed by fiber Bragg grating (FBG) sensors. The research integrates advanced numerical simulations with an innovative configuration of sensors to enhance structural health monitoring (SHM). A self-referencing setup, employing FBG sensors with edge filtering method and remote bonding, enables a baseline-free damage detection approach. The methodology is validated as a proof-of-concept numerical model. The simulation framework incorporates a three-dimensional spectral element method for precise and efficient modelling of GW propagation and interactions with structural anomalies. Three different machine learning (ML) techniques are employed to detect and localize damages, demonstrating effectiveness of ML methods compared to traditional methods. The three techniques employed are decision tree, logistic model tree and random forest. Key findings highlight the effectiveness of random forest models in classifying damage states with a 98.67% accuracy. Different feature selection methods, are used to identify critical features. The proposed methodology reduces sensor requirements, lowers system complexity and cost, and enables efficient SHM solutions in extreme or large-scale environments. This work underscores the potential of ML techniques to perform detection and localization where traditional techniques fail.

Henning Müller, Erik Faust, Alexander Schlüter et al.

This work outlines a Lattice Boltzmann Method (LBM) for geometrically and constitutively nonlinear solid mechanics to simulate large deformations under dynamic loading conditions. The method utilizes the moment chain approach, where the non-linear constitutive law is incorporated via a forcing term. Stress and deformation measures are expressed in the reference configuration. Finite difference schemes are employed for gradient and divergence computations, and Neumann- and Dirichlet-type boundary conditions are introduced. Numerical studies are performed to assess the proposed method and illustrate its capabilities. Benchmark tests for weakly dynamic uniaxial tension and simple shear across a range of Poisson's ratios demonstrate the feasibility of the scheme and serve as validation of the implementation. Furthermore, a dynamic test case involving the propagation of bending waves in a cantilever beam highlights the potential of the method to model complex dynamic phenomena.

F. M. Hanapiah, Irnie Azlin Zakaria, S. R. Makhsin et al.

The miniaturization in the design of the electronic system became inevitable due to the rapid advancement and development of technology. This has imposed challenges to the thermal management capability as the heat flux density has increased tremendously due to a smaller heat transfer surface. Nanofluids adoption in electronic cooling seems to be an alternative way for better heat dissipation. This research explores the feasibility of ternary hybrid nanofluids GO: Al2O3: SiO2 in water with different volume concentrations and mixture ratios in a serpentine cooling plate. In this research, 0.01% GO + Al2O3: SiO2, 0.006% GO + Al2O3: SiO2, and 0.008% GO + Al2O3: SiO2 in mixture ratios of 10:90 and 20:80 (Al2O3: SiO2) were studied. The result showed that 0.01% GO + Al2O3: SiO2 (10:90) nanofluids displayed the highest enhancement of heat transfer coefficient with 1.1 times higher as compared to the base fluid. This was then followed by 0.008% GO + Al2O3: SiO2  (10:90) and  0.006% GO + Al2O3: SiO2 (10:90) with 1.03 times and 0.87 times higher heat transfer coefficient enhancement consecutively as compared to the base fluid. In term of mixture ratios, GO in 10:90 (Al2O3: SiO2) performed better than 20:80. To assess the feasibility of adoption, the advantage ratio (AR) was conducted to measure both heat transfer enhancement and pressure drop effect. The AR analysis showed that at the lower Reynolds, Re number region, the 0.01% GO + Al2O3: SiO2  (10:90) ternary hybrid nanofluids was proven to be the most feasible due to a higher ratio of heat transfer enhancement over the pressure drop penalty.

Marvin Wyrich, Justus Bogner

LinkedIn is the largest professional network in the world. As such, it can serve to build bridges between practitioners, whose daily work is software engineering (SE), and researchers, who work to advance the field of software engineering. We know that such a metaphorical bridge exists: SE research findings are sometimes shared on LinkedIn and commented on by software practitioners. Yet, we do not know what state the bridge is in. Therefore, we quantitatively and qualitatively investigate how SE practitioners and researchers approach each other via public LinkedIn discussions and what both sides can contribute to effective science communication. We found that a considerable proportion of LinkedIn posts on SE research are written by people who are not the paper authors (39%). Further, 71% of all comments in our dataset are from people in the industry, but only every second post receives at least one comment at all. Based on our findings, we formulate concrete advice for researchers and practitioners to make sharing new research findings on LinkedIn more fruitful.

James S. Wheaton, Daniel R. Herber

Traditional requirements engineering tools do not readily access the SysML-defined system architecture model, often resulting in ad-hoc duplication of model elements that lacks the connectivity and expressive detail possible in a SysML-defined model. Without that model connectivity, requirement quality can suffer due to imprecision and inconsistent terminology, frustrating communication during system development. Further integration of requirements engineering activities with MBSE contributes to the Authoritative Source of Truth while facilitating deep access to system architecture model elements for V&V activities. The Model-Based Structured Requirement SysML Profile was extended to comply with the INCOSE Guide to Writing Requirements updated in 2023 while conforming to the ISO/IEC/IEEE 29148 standard requirement statement templates. Rules, Characteristics, and Attributes were defined in SysML according to the Guide to facilitate requirements definition and requirements V&V. The resulting SysML Profile was applied in two system architecture models at NASA Jet Propulsion Laboratory, allowing us to explore its applicability and value in real-world project environments. Initial results indicate that INCOSE-derived Model-Based Structured Requirements may rapidly improve requirement expression quality while complementing the NASA Systems Engineering Handbook checklist and guidance, but typical requirement management activities still have challenges related to automation and support with the system architecture modeling software.

Eduardo A. Oliveira, Leon Sterling

This paper describes how motivational models can be used to cross check agile requirements artifacts to improve consistency and completeness of software requirements. Motivational models provide a high level understanding of the purposes of a software system. They complement personas and user stories which focus more on user needs rather than on system features. We present an exploratory case study sought to understand how software engineering students could use motivational models to create better requirements artifacts so they are understandable to non-technical users, easily understood by developers, and are consistent with each other. Nine consistency principles were created as an outcome of our study and are now successfully adopted by software engineering students at the University of Melbourne to ensure consistency between motivational models, personas, and user stories in requirements engineering.

Cristiana Lara Nunes, Kateřina Mlsnová, Zuzana Slížková

Paints are the protective and aesthetic skin of buildings, so (re) painting is one of the most recurrent maintenance actions. Limewashes have been used since antiquity and are currently of high interest for both conservation and new construction, majorly thanks to their eco-friendly and antiseptic features, and ability to improve the performance of the materials in relation to water transport. Linseed oil is a traditional water-repellent additive that can enhance the water-shedding properties of the limewashes. However, it has the risk of altering the drying kinetics of the substrate if an improper dosage is used. In this work, limewashes with the addition of varying dosages of linseed oil have been applied on two types of natural stone to study the effect of the paints in respect to water and salt transport. The water absorption by capillarity was reduced in both stones coated with pure limewash and limewash with oil, while the drying rate was slightly accelerated. The effect of the paints on the drying of the salt-laden stones varied. The salt damage developed during drying also diverged in both stones, damaging the coats and stone surface of the less porous stone and mainly promoting salt efflorescence in the most porous one.

Michał Nowak, Marek Morzyński

In the paper the structure optimization system based on the surface remodeling is presented. The base of algorithm formulation was the trabecular bone surface remodeling phenomenon leading to optimization of the trabecular net in the bone as well as the design with optimal stiffness principle. The closed system including Finite Element mesh generation, decision criterion for structure adaptation and Finite Element Analysis in parallel environment are presented. The issues concerning the use of the tool for the mechanical design are discussed. Some results of computations, using special prepared software are presented.

Vahisht K. Tamboli, Priti V. Tandel

Abstract ‘‘The time-fractional generalized Burger–Fisher equation (TF-GBFE)” is used in various applied sciences and physical applications, including simulation of gas dynamics, financial mathematics, fluid mechanics, and ocean engineering. This equation represents a concept for the coordination of reaction systems, as well as advection, and conveys the understanding of dissipation. The Fractional Reduced Differential Transform Method (FRDTM) is used to evaluate “the time-fractional generalized Burger–Fisher equation (TF-GBFE).” To determine the method’s validity, when the solutions are obtained, they are correlated to exact solutions of α = 1 order, and even for various values of α . Three-dimensional graphs are used to depict the solutions. Additionally, the analysis of exact and FRDTM solutions indicates that the proposed approach is very accurate.

Ca Bernard, D George, S Ahzi et al.

Numerous models have been developed in the literature to simulate the thermomechanical behavior of amorphous polymer at large strain. These models generally show a good agreement with experimental results when the material is submitted to uniaxial loadings (tension or compression) or in case of shear loadings. However, this agreement is highly degraded when they are used in the case of combined load cases. A generalization of these models to more complex loads is scarce. In particular, models that are identified in tension or compression often overestimate the response in shear. One difficulty lies in the fact that 3D models must aggregate different physical modeling, described with different kinematics. This requires the use of transport operators complex to manipulate. In this paper, we propose a mechanical model for large strains, generalized in 3D, and precisely introducing the adequate transport operators in order to obtain an exact kinematic. The stress strain duality is validated in the writing of the power of internal forces. This generalized model is applied in the case of a polycarbonate amorphous polymers. The simulation results in tension/compression and shear are compared with the classical modeling and experimental results from the literature. The results highly improve the numerical predictions of the mechanical response of amorphous polymers submitted to any load case.

Bilen Emek Abali

Physical systems are modeled by field equations; these are coupled, partial differential equations in space and time. Field equations are often given by balance equations and constitutive equations, where the former are axiomatically given and the latter are thermodynamically derived. This approach is useful in thermomechanics and electromagnetism, yet challenges arise once we apply it in damage mechanics for generalized continua. For deriving governing equations, an alternative method is based on a variational framework known as the extended Noether's formalism. Its formal introduction relies on mathematical concepts limiting its use in applied mechanics as a field theory. In this work, we demonstrate the power of extended Noether's formalism by using tensor algebra and usual continuum mechanics nomenclature. We demonstrate derivation of field equations in damage mechanics for generalized continua, specifically in the case of strain gradient elasticity.

Mertcan Cihan, F. Aldakheel, B. Hudobivnik et al.

This work provides an efficient virtual element scheme for the modeling of nonlinear elastodynamics undergoing large deformations. The virtual element method (VEM) has been applied to various engineering problems such as elasto-plasticity, multiphysics, damage and fracture mechanics. This work focuses on the extension of VEM towards dynamic applications. Within this framework, we employ low-order ansatz functions in one, two and three dimensions that having arbitrary convex or concave polygonal elements. The formulations considered in this contribution are based on minimization of potential function for both the static and the dynamic behavior. While the stiffness-matrix needs a suitable stabilization, the mass-matrix can be calculated using only the projection part. For the implicit time integration scheme, Newmark-Method is used. To show the performance of the method, various numerical examples in 1D, 2D and 3D are presented.

G. Urbikain, L. N. L. D. Lacalle

Abstract Today requirements by machine-tool users point towards knowing more about the machining processes. In a globalized and competitive market as manufacturing is, future engineers will be urged to develop transversal skills on diverse science domains such as Mechanics, Mechatronics or Electrics. Monitoring of machining processes allows determining possible errors and deviations from the desirable conditions (aged machine-tools, bad machining conditions, most energetically / cost-effective conditions) as well as saving historical data of the workpieces manufactured by the same machine. In order to strengthen students’ skills, the Department of Mechanical Engineering of the University of the Basque Country (UPV/EHU) developed a monitoring tool using Labview© programming. The application, built from the combination of reconfigurable Input/Output (I/O) architecture and Field Programmable Gate Arrays (FPGA), was applied to practical classes in the machine shop to improve students’ skills.

N. Milovanović, A. Sedmak, M. Arsić et al.

Abstract Failures of rotating equipment often cause severe consequences, so it is necessary to study their integrity and life as detailed as possible, especially when crack is detected. In the case studied here, hydro power plant turbine shaft is analysed by using fracture mechanics parameters both for static and dynamic loading in order to assess its structural integrity and life. In both cases classical engineering approach and Finite Element Method have been applied to evaluate stress state and number of cycles from a given initial crack length to its critical value. Results of analytical and numerical modelling are compared to verify both approaches.

Jingyu Liu, Yanan Xu, Hong Yang et al.

Nacre is a natural composite featuring exceptional mechanical properties such as high strength and high toughness. Its unique structure is now universally applied in engineering bioinspired materials. On the other hand, it is still a technical challenge to investigate its interfacial strength and fracture mechanisms at micro or nano-scale. In this work, the interfacial strength and fracture mechanism of the 'brick-mortar' structure in nacre are investigated using micro-sized cantilever beam and bend samples. As compared to previous works, a high aragonite/biopolymer interfacial strength is observed (~298 MPa). The crack propagation path is investigated via experiment and finite element modelling and compared with the fracture mechanics analysis. It is confirmed that crack deflection to the aragonite/biopolymer interface contributes to a high overall toughness. This work provides a better understanding of the toughening mechanism in nacre and other bioinspired composites.