Jesús D. Villalba-Morales, Sandra Jerez, Ricardo Parra
et al.
Recent developments in higher education have transformed teaching–learning processes across disciplines, including structural mechanics in civil engineering programs. However, reports on innovative teaching practices in structural engineering are scattered, hindering their application in other contexts. This study consolidates and analyzes global research trends in structural mechanics education (from 2014 to 2023), complemented by insights obtained from surveys applied to students, instructors, and senior structural engineers in Colombia. The sample literature comprises 150 Scopus-indexed English articles analyzed with Bibliometrix. Eight guiding questions serve to characterize the literature, identify predominant pedagogical strategies, and outline future research directions. Results reveal limited collaboration networks, inconsistent keyword usage, and a strong concentration of U.S.-based authors and institutions. Most papers appear in engineering education journals, and the recurrent topics (active learning strategies, digital and virtual resources, and assessment methods) confirm the prevalence of experiential, student-centered approaches. Based on the findings, eight emerging areas should guide future research: sustainability, educational research, non-disciplinary competencies, digital resources, artificial intelligence, innovation, disciplinary competencies, and digital competencies. Also, it is recommended that engineering faculties focus efforts on clarifying competency frameworks, strengthening pedagogical and faculty development, investing in educational technologies and laboratory infrastructure, fostering collaborative networks, and enhancing the visibility of structural mechanics education research.
Sebastian Levin, Jendrik-Alexander Tröger, Hagen Lukas-Kock
et al.
While laser powder bed fusion enables rapid and resource-efficient production, challenges such as microstructural defects, porosity, and unfavourable residual stresses compromise the durability of components under dynamic loading. Thus, we investigated methods to enhance fatigue life of AlSi10Mg produced by laser powder bed fusion. To do so, we explore the effects of manual polishing, heat treatment, and deep rolling on the mechanical properties and fatigue performance of AlSi10Mg.Specimens were fabricated and divided into five groups: as-built, as-built with manual polishing, heat-treated and manually polished, as-built with deep rolling, and heat-treated with deep rolling. These groups underwent surface roughness measurements, residual stress analysis, hardness testing, and microscopy. The primary evaluation of fatigue performance was conducted using a rotating bending test rig under a load ratio of R = −1, following the high-cycle fatigue string-of-pearl method.The fatigue tests revealed significant differences among the treatment groups. The as-built specimens exhibited the lowest fatigue life, with cracks initiating from surface defects. While polishing and heat treatment provided moderate improvements, specimens treated with deep rolling exhibited the highest bearable stress amplitudes and the flattest S–N curves, indicating a significant improvement in fatigue resistance. The slope of the S–N curve in this condition is 7.8 times flatter compared to the untreated as-built condition. At a defined number of load cycles of 1E+06, the bearable stress in the “as-built + deep rolling” condition reaches 251 MPa, which is ∼8.5 times the stress amplitude tolerated in the untreated as-built condition. Interestingly, combining heat treatment with deep rolling resulted in a decrease in performance compared to deep rolling alone.Our results indicate that surface treatment is critical for improving the fatigue life of additively manufactured AlSi10Mg components. It has turned out that deep rolling is an effective and economical method, as it reduces surface roughness and induces beneficial compressive residual stresses that counteract crack initiation. Furthermore, deep rolling eliminates the need for subsequent heat treatment, which may even be counter-productive, thus saving both time and energy costs. Our results help to exploit the potential of laser powder bed fusion of AlSi10Mg by combining near-net-shape production with effective surface enhancement.
Skyler R. St. Pierre, Ethan C. Darwin, Divya Adil
et al.
Abstract Eating less meat is associated with a healthier body and planet. Yet, we remain reluctant to switch to a plant-based diet, largely due to the sensory experience of plant-based meat. Food scientists characterize meat using a double compression test, which only probes one-dimensional behavior. Here we use tension, compression, and shear tests–combined with constitutive neural networks–to automatically discover the behavior of eight plant-based and animal meats across the entire three-dimensional spectrum. We find that plant-based sausage and hotdog, with stiffnesses of 95.9 ± 14.1 kPa and 38.7 ± 3.0 kPa, successfully mimic their animal counterparts, with 63.5 ± 45.7 kPa and 44.3 ± 13.2 kPa, while tofurky is twice as stiff, and tofu is twice as soft. Strikingly, a complementary food tasting survey produces in nearly identical stiffness rankings for all eight products (ρ = 0.833, p = 0.015). Probing the fully three-dimensional signature of meats is critical to understand subtle differences in texture that may result in a different perception of taste. Our data and code are freely available at https://github.com/LivingMatterLab/CANN
Nutrition. Foods and food supply, Food processing and manufacture
The paper is concerned with the mathematical modelling and numerical solution of unilateral problems for viscoelastic-plastic structural systems. A new material model is proposed in which the viscoelastic and plastic strains are governed by different constitutive laws. The model is restricted to isothermal quasistatic deformation processes under conditions of geometric linearity. The mechanical problem is posed in the format of piecewise linear plasticity and the unilateral contact conditions are described by means of the clearance function. The linear viscoelastic laws are integrated by a creep approach method, which allows for jump-discontinuities in the history of stress. For the evolution of plastic strains an implicit method is used. The problem is formulated and solved as a sequence of nested (mixed) linear complementarity problems. The question of existence and uniqueness of a solution to the problem is discussed. A numerical algorithm based on the pivotal transformations is devised and its stability is shown numerically. Results of numerical experiments for several illustrative examples of a beam/foundation system subjected to nonproportional loading histories are presented . The results clearly demonstrate the impact of the history of loading and the unilateral constraints upon the current state of the structural system.
Computer engineering. Computer hardware, Mechanics of engineering. Applied mechanics
Due to structural limitations, the processes of boring holes are performed in a low-rigidity machining system, which predetermines their susceptibility to vibrations. The article is devoted to the study of the process of boring holes on CNC machines, and the subject of the study is the effect of the cutting mode on the stability of the machining. The mathematical model of the machining system is presented in the form of a two-mass dynamic system, which forms a closed loop structure with negative feedback by elastic displacement. In addition, positive feedback is taken into account through the delay argument function, which represents machining along traces. It has been proven that this process provokes the emergence of regenerative oscillations in the machining system. The application of the system’s approach made it possible to obtain a mathematical model in the form of state variables, which is acceptable for the use of numerical modeling methods in both time and frequency space. An applied engineering program for determining the stability diagram in "cutting depth - spindle speed" coordinates has been created. The program uses a new criterion of stability of systems closed through positive feedback loop with a delay argument function. For the first time, the validity of such a criterion was proved for systems described by differential equations of the fourth order. The importance of taking into account the results of the study in the form of a stability lobes diagram when assigning a cutting mode, especially in the area of high speeds, is proven. Thus, according to the results of the experiments, a change in speed of only 7% from 2150 rpm to 2320 rpm with the same cutting depth of 0.4 mm allows the process to become stable. The use of the created program is possible in the system of automatic control of the online cutting mode when the machine is equipped with vibration sensors with appropriate systems for identifying the dynamic parameters of the machining system, which will significantly increase the machining efficiency.
Current trends in the transportation industry prioritize competitive rivalry, compelling manufacturers to prioritize concepts such as quality and reliability. These concepts are closely associated with public expectations of safety, vehicle lifespan, and trouble-free operation. However, the public must recognize that a vehicle weighing several hundred kilograms, moving at a non-zero speed, only contacts the road surface through a few points (depending on the number of wheels), each no larger than a human palm. Therefore, it is imperative to operate the vehicle in a manner that optimizes the behavior of these contact points. There are situations where drivers find themselves requiring dynamic vehicle handling, often unpredictable with a high degree of uncertainty. Rapid changes in direction become necessary in these cases. Such maneuvers can pose a significant risk of rollover for three-wheeled vehicles. Hence, the vehicle itself should contribute to increased ride safety. This paper presents key findings from the development of an unconventional three-wheeled vehicle utilizing the delta arrangement. Rollover safety for three-wheeled vehicles is currently well-managed, thanks to the utilization of electronic or mechatronic systems in delta-type vehicles to enhance stability. However, these systems require additional components. In contrast, the proposed control system operates solely on a mechanical principle, eliminating operational costs, energy consumption, maintenance expenses, and similar factors. The study also explores the absence of equivalent suspension and steering systems for front-wheel steering. Such designs are lacking in both practical applications and theoretical realms. Analytical and simulation calculations are compared in this study, highlighting the effectiveness of the newly proposed control system in enhancing stability and safety compared to conventional front-wheel suspension systems. Simulation programs provide more realistic results than analytical calculations due to their ability to account for dynamic effects on vehicle components and passengers, which is practically unfeasible in analytical approaches. Furthermore, this study focuses on investigating the fatigue life of material frames subjected to dynamic loading, which is a crucial aspect of ensuring safety. It is essential to have various testing devices to examine the fatigue life of materials under both uniaxial and multiaxial loading conditions. However, obtaining experimental results for fatigue life measurements of specific materials, which can be directly applied to one’s research, poses significant challenges. Hence, the proposed testing device plays a vital role in measuring material fatigue life and advancing the development of unconventional transportation methods. The information about the original testing device aligns perfectly with the article’s emphasis on dynamic analysis. The ultimate objective of all these efforts is to put the vehicle into practical operation for commercial utilization.
Abstract Lightweight, ultra-flexible, and robust crosslinked transition metal carbide (Ti3C2 MXene) coated polyimide (PI) (C-MXene@PI) porous composites are manufactured via a scalable dip-coating followed by chemical crosslinking approach. In addition to the hydrophobicity, anti-oxidation and extreme-temperature stability, efficient utilization of the intrinsic conductivity of MXene, the interfacial polarization between MXene and PI, and the micrometer-sized pores of the composite foams are achieved. Consequently, the composites show a satisfactory X-band electromagnetic interference (EMI) shielding effectiveness of 22.5 to 62.5 dB at a density of 28.7 to 48.7 mg cm−3, leading to an excellent surface-specific SE of 21,317 dB cm2 g−1. Moreover, the composite foams exhibit excellent electrothermal performance as flexible heaters in terms of a prominent, rapid reproducible, and stable electrothermal effect at low voltages and superior heat performance and more uniform heat distribution compared with the commercial heaters composed of alloy plates. Furthermore, the composite foams are well attached on a human body to check their electromechanical sensing performance, demonstrating the sensitive and reliable detection of human motions as wearable sensors. The excellent EMI shielding performance and multifunctionalities, along with the facile and easy-to-scalable manufacturing techniques, imply promising perspectives of the porous C-MXene@PI composites in next-generation flexible electronics, aerospace, and smart devices.
Друга частина статті виходить з відправних положень в задачі прийняття рішень (ЗПР), зазначених на першому етапі досліджень [1,п.2.].Тут продовжено зіставлення за превалюванням (ефективністю)альтернативних автоклавних та безавтоклавних технологій виготовлення вуглепластикових авіаконструкцій (АК) типу високонавантажених стрингерних панелей кесона крила (ВСП) магістральних літаків В787, А350, МС – 21, CSeries. За методологічну основу взяті головні положення теорії прийняття рішень та системно – процесний підхід з залученням результатів практики. З початку представлені:схема оцінювання відносної якості об’єктів технологічного процесу;концептуальна модель предметної області прийняття рішень (ПОПР)блокового типу та її базис; склад критеріїв вибору та показників. Виходячи з вище приведеного та з залученням положень автономних динамічних систем (АДС) з дискретним часом, а також теорії параболи (квадратична функція), приведена формалізована модель системно згрупованих процесів при оцінюванні альтернатив. На цій основі продовжено дослідження суттєвих відмінностей альтернатив з інтерпретацією ідей топології(групи гомології) для підтримки прийняття в подальшому обґрунтованого заключного рішення,як мета моделювання цієї окремої сторони функціонування технічної системи.
Despite the increasing importance of strain localization modeling (e.g., failure analysis) in computer-aided engineering, there is a lack of effective approaches to capturing relevant material behaviors consistently across multiple length scales. We aim to address this gap within the framework of deep material networks (DMN) -- a machine learning model with embedded mechanics in the building blocks. A new cell-division scheme is proposed to track the scale transition through the network, and its consistency is ensured by the physics of fitting parameters. Essentially, each microscale node in the bottom layer is described by an ellipsoidal cell with its dimensions back-propagated from the macroscale material point. New crack surfaces in the cell are modeled by enriching cohesive layers, and failure algorithms are developed for crack initiation and evolution in the implicit DMN analysis. Besides studies on a single material point, we apply the multiscale model to concurrent multiscale simulations for the dynamic crush of a particle-reinforced composite tube and various tests on carbon fiber reinforced polymer composites. For the latter, experimental validations on an off-axis tensile test specimen are also provided.