Structural Mechanics Research Articles

Structural response of microtubule and actin cytoskeletons to direct intracellular load.

Microtubule and actin are the two major cytoskeletal polymers that form organized functional structures in the interior of eukaryotic cells. Although the structural mechanics of the cytoskeleton has been extensively studied by direct manipulations in in vitro reconstitution systems, such unambiguous characterizations inside the living cell are sparse. Here, we report a comprehensive analysis of how the microtubule and actin cytoskeletons structurally respond to direct intracellular load. Ferrofluid-based intracellular magnetic tweezers reveal rheological properties of the microtubule complex primarily determined by filamentous actin. The strain fields of the microtubule complex and actin meshwork follow the same scaling, suggesting that the two cytoskeletal systems behave as an integrated elastic body. The structural responses of single microtubules to contact and remote forces further evidence that the individual microtubules are enclosed by the elastic medium of actin. These results, directly characterizing the microtubule and actin cytoskeletons as an interacting continuum throughout the cytoplasm, serve as a cornerstone for the physical understanding of intracellular organization.

Designing Dialogic Peer Feedback in Collaborative Learning: The Role of Thinq Tank

As technology continues to reshape education, the integration of peer feedback (PF) is increasingly recognized as a key element in promoting student collaboration and learning. This design study tracks the development and implementation of the Thinq Tank tool, which is aimed at facilitating dialogic PF within computer-supported collaborative-inquiry learning (CSCiL) environments. The research was conducted through three design iterations, comparing two key experimental conditions: one contrasting non-dialogic PF with dialogic PF, and another comparing dialogic PF with scripted dialogic PF featuring dynamic sentence-starters and defined roles. Utilizing a quasi-experimental design, we assessed the overall impact on scientific (collaborative) learning outcomes, students’ perceptions of PF, and the composition and elements of PF dialogues. The findings suggest that the integration of dialogic PF within a CSCiL lesson series helps to boost scientific collaborative learning outcomes and increases student receptivity to PF. The study demonstrates that integrating structured support mechanisms within PF tools promotes PF dialogues in which students critically evaluate each other’s work and collaboratively think about ways to improve quality. These insights illustrate that structured, technology-supported PF can significantly advance inquiry outcomes and foster deeper collaborative learning in secondary STEM education.

Does Ovariectomy Affect the Mechanics of the Mandibular Alveolar Bone Structure of Wistar Rats Subjected to Tooth Loss and Modified Diet?—A FEA Study

The aim of this study was to evaluate the mechanical effect of ovariectomy, diet, and tooth extraction on the bone structure of the mandible of Wistar rats. Mandibles from 40 female Wistar rats were used, divided into rats with ovariectomy surgery or surgical simulation. Half of the rats had the right upper incisor extracted and a soft diet was introduced for half of the animals for 30 days. After euthanasia, microtomography of the mandibles was performed for bone segmentation to construct three-dimensional models. Each mandible was subjected to a three-point bending test. The simulation by finite element method was configured according to the protocol for positioning the part on the support and force action by the load cell defined in the mechanical tests. Stress dissipation was described qualitatively on a color scale distributed in ranges of stress values. All models showed a higher concentration of stresses in the regions of force action and in the support regions, with differences in stress values and locations. Diet and dental condition interfered in the distribution of stresses, with the lateral surface of the mandible being more influenced by diet and the medial surface of the mandible by diet and dental condition.

Application and Practice of Mathematical Optimization Method in Structural Mechanics Design

Application and Practice of Mathematical Optimization Method in Structural Mechanics Design

Contribution to the Statistical Mechanics of Static Triplet Correlations and Structures in Fluids with Quantum Spinless Behavior

The current developments in the theory of quantum static triplet correlations and their associated structures (real r-space and Fourier k-space) in monatomic fluids are reviewed. The main framework utilized is Feynman’s path integral formalism (PI), and the issues addressed cover quantum diffraction effects and zero-spin bosonic exchange. The structures are associated with the external weak fields that reveal their nature, and due attention is paid to the underlying pair-level structures. Without the pair, level one cannot fully grasp the triplet extensions in the hierarchical ladder of structures, as both the pair and the triplet structures are essential ingredients in the triplet response functions. Three general classes of PI structures do arise: centroid, total continuous linear response, and instantaneous. Use of functional differentiation techniques is widely made, and, as a bonus, this leads to the identification of an exact extension of the “classical isomorphism” when the centroid structures are considered. In this connection, the direct correlation functions, as borrowed from classical statistical mechanics, play a key role (either exact or approximate) in the corresponding quantum applications. Additionally, as an auxiliary framework, the traditional closure schemes for triplets are also discussed, owing to their potential usefulness for rationalizing PI triplet results. To illustrate some basic concepts, new numerical calculations (path integral Monte Carlo PIMC and closures) are reported. They are focused on the purely diffraction regime and deal with supercritical helium-3 and the quantum hard-sphere fluid.

Multi-level physics informed deep learning for solving partial differential equations in computational structural mechanics

Physics-informed neural network has emerged as a promising approach for solving partial differential equations. However, it is still a challenge for the computation of structural mechanics problems since it involves solving higher-order partial differential equations as the governing equations are fourth-order nonlinear equations. Here we develop a multi-level physics-informed neural network framework where an aggregation model is developed by combining multiple neural networks, with each one involving only first-order or second-order partial differential equations representing different physics information such as geometrical, constitutive, and equilibrium relations of the structure. The proposed framework demonstrates a remarkable advancement over the classical neural networks in terms of the accuracy and computation time. The proposed method holds the potential to become a promising paradigm for structural mechanics computation and facilitate the intelligent computation of digital twin systems.

Article: The Contribution of the Canadian-European Partnership to the Integration of Sustainable Development Issues into the Multilateral Trading System

In their influential roles within the World Trade Organization (WTO), Canada and the European Union (EU) demonstrate a strong commitment to sustainable development and multilateralism, navigating challenges and opportunities. Plurilateral negotiations, particularly the Joint Statement Initiatives (JSI), underscore their dedication to addressing issues like services regulation and fostering inclusive trade. The institutional framework of their Comprehensive Economic and Trade Agreement (CETA) provides a structured mechanism, with specialized committees like the one on Trade and Sustainable Development, to ensure transparency, regulatory cooperation, and trade promotion aligned with sustainable development goals. However, challenges persist in achieving consensus on binding commitments. The temptation of unilateralism, exemplified by the EU’s carbon border adjustment mechanism (CBAM), raises concerns about its compatibility with WTO principles and the potential prioritization of sustainability over economic development. Despite these challenges, Canada and the EU continue to champion sustainable development in various international forums, emphasizing the importance of the WTO as the primary platform for reconciling trade and sustainability. The forthcoming thirteenth WTO Ministerial Conference in 2024 presents a crucial opportunity for these leaders to demonstrate a significant commitment to a balanced approach between economic development and sustainability in international trade.

TRAINERS CONTINUOUS PROFESSIONAL DEVELOPMENT AND STUDENTS LEARNING OUTCOMES IN TVET INSTITUTIONS

The study sought to establish the influence of Continuous Professional Development (CPD) programs on students learning outcomes in Technical and Vocational Education and Training (TVET) institutions in Ruhango District, Rwanda. The study aimed to determine the influence of CPD programs on course completion rates, acquisition of practical skills and competencies and students participation/engagement among TVET students. Using cross-sectional research design with mixed methods, data were collected from a sample of 427 respondents, including instructors, headteachers, and Sector Education Inspectors (SEIs). Simple random sampling was used for schools and instructors, while headteachers and SEIs were selected through purposive sampling. Quantitative data were analyzed using frequency percentages and correlation analysis, while qualitative data were processed through thematic analysis.The findings revealed that CPD programs significantly enhance student learning outcomes in TVET institutions. A majority of respondents (80%) participated in CPD initiatives, with 65% reporting that CPD had a strong influence on improving course completion rates, and 85% highlighting its positive impact on the acquisition of practical skills and competencies. Additionally, 60% of respondents recognized a substantial influence of CPD on student engagement. Correlation analysis confirmed strong positive relationships between CPD and course completion (r = 0.72), practical skills acquisition (r = 0.85), and student engagement (r = 0.72). The study concluded that CPD programs play a critical role in improving educational outcomes in TVET institutions. Recommendations include tailoring CPD programs to specific technical fields, enhancing hands-on workshops, providing more frequent CPD opportunities, and implementing structured monitoring and evaluation mechanisms. Future research should explore the influence of CPD on specific technical skills and examine its long-term impact on both instructors and students.

Mechanical Properties of Two-Dimensional Metal Nitrides: Numerical Simulation Study.

It is expected that two-dimensional (2D) metal nitrides (MNs) consisting of the 13th group elements of the periodic table and nitrogen, namely aluminium nitride (AlN), gallium nitride (GaN), indium nitride (InN) and thallium nitride (TlN), have enhanced physical and mechanical properties due to the honeycomb, graphene-like atomic arrangement characteristic of these compounds. The basis for the correct design and improved performance of nanodevices and complex structures based on 2D MNs from the 13th group is an understanding of the mechanical response of their components. In this context, a comparative study to determine the elastic properties of metal nitride nanosheets was carried out making use of the nanoscale continuum modelling (or molecular structural mechanics) method. The differences in the elastic properties (surface shear and Young's moduli and Poisson's ratio) found for the 2D 13th group MNs are attributed to the bond length of the respective hexagonal lattice of their diatomic nanostructure. The outcomes obtained contribute to a benchmark in the evaluation of the mechanical properties of AlN, GaN, InN and TlN monolayers using analytical and numerical approaches.

Analysing Flexural Response in RC Beams: A Closed-Form Solution Designer Perspective from Detailed to Simplified Modelling

This paper presents a detailed analytical approach for the bending analysis of reinforced concrete beams, integrating both structural mechanics principles and Eurocode 2 provisions. The general analytical expressions derived for the curvature were applied for the transverse displacement analysis of a simply supported reinforced concrete beam under four-point loading, focusing on key limit states: the initiation of cracking, the yielding of tensile reinforcement and the compressive failure of concrete. The displacement’s results were validated through experimental testing, showing a high degree of accuracy in the elastic and crack propagation phases. Deviations in the yielding phase were attributed to the conservative material assumptions within the Eurocode 2 framework, though the analytical model remained reliable overall. To streamline the computational process for more complex structures, a simplified model utilising a non-linear rotational spring was further developed. This model effectively captures the influence of cracking with significantly reduced computational effort, making it suitable for serviceability limit state analyses in complex loading scenarios, such as seismic impacts. The results demonstrate that combining detailed analytical methods with this simplified model provides an efficient and practical solution for the analysis of reinforced concrete beams, balancing precision with computational efficiency.

Elevational patterns of bird alpha and beta diversity in Haba Snow Mountain, Southwestern China: Implication for conservation

Understanding environmental patterns of species diversity is essential for nature reserve planning and biodiversity conservation. In this study, we explored the birds’ alpha and beta diversity along the elevational gradients in Haba Snow Mountain Nature Reserve (hereafter, HBSM), a global biodiversity hotspot, and studied which environmental factor is the main driver in explaining alpha and beta diversity patterns. Our results indicated that taxonomic, functional, and phylogenetic alpha diversity consistently exhibited hump-shaped patterns with similar peaks. After controlling for species richness, both functional and phylogenetic alpha diversity increased with elevation, and the peaks at 3400–3700 m. Mean pairwise functional distance remained nearly constant along the elevation band, whereas mean pairwise phylogenetic distance shown hump-shaped pattern, and the predicted MPD peaked at the fifth band (3100–3400 m a.s.l). The functional and phylogenetic structure of bird communities in HBSM were more clustered along the elevation gradients, suggesting environmental filtering likely drove the assembly processes. Additionally, primary productivity (NDVI and/or habitat heterogeneity) and/or precipitation were robust predictors of variation in most diversity metrics. For multiple-site beta diversity, we observed that high turnover component in taxonomic, functional, and phylogenetic dimensions, indicating distinct bird assemblages across various elevational bands. In pairwise beta diversity, the spatial turnover of taxonomic and phylogenetic aspects was higher than nestedness, revealing species replacement occurs relatively frequently between evolutionarily related species with similar niche and functional traits. Overall, our findings highlight the importance of considering both different dimensions and multifaceted diversity when assessing elevational patterns of bird diversity. This study also provides valuable insights into the structuring mechanisms of bird communities and informs conservation planning along elevational gradients in HBSM, and offers a comprehensive case on species richness along elevational gradients.

Application of a shear cell for the simulation of extrusion to test the structurability of raw materials

The required raw material properties and the mechanisms behind fibrous structure formation during high moisture extrusion cooking (HMEC) to produce plant-based meat analogues are not sufficiently understood. The implementation of new raw materials is therefore a labour-intensive, empirical endeavour. Hence, this research explores the potential of a high-pressure shear cell (HPSC) as a tool for rapid screening of raw materials for HMEC suitability. During these texturisation tests, material viscosity was monitored to gain deeper mechanistic insights. For that, hydrated pea protein isolate (PPI) and soy protein concentrate (SPC) were sheared at 5-40 s−1 in the HPSC with a cone-plate or plate-plate geometry under extrusion-like conditions at 140–160 °C and 20 bar. Fibrous structures were successfully generated with both tested plant proteins, but reproducibility was limited to trials with SPC. Monitoring of viscoelastic properties revealed an onsetting polymerisation, followed by a decrease in viscosity, indicating fracturing of the forming network as underlying structuring mechanism. The suggested fracturing of an emerging network aligns with an observed increase in fibrousness in the plate-plate geometry compared to the cone-plate geometry due to the radial shear rate gradient. Finally, this research showcased a high similarity of the process-structure response pattern for SPC between the applied HPSC process and HMEC. Yet, further modifications, such as increasing the mechanical energy input capacity, are required to effectively apply HPSC processing for the prediction of the structuring behaviour in HMEC for the broad range of existing raw materials.

A Finite Element Analysis for Investigating the Effects of Moving Loads on Flexible Pavements

To assist researchers in solving challenging structural mechanics engineering problems, finite element modeling (FEM) has grown to be a very popular technique. The several layers of various materials that make up a pavement's complicated structure and affect how it responds to stress have an impact on how it behaves. In this study, finite element analysis is done on a real existing road which is named Nowhata-Chowmasia road, situated in Rajshahi, Bangladesh. FEM is used to study this flexible pavement, which consists of 7 layers (surface, binder, base type-1, base type-2, sub-base, enhanced subgrade, and subgrade). The effect of the depth of the base layer on vertical stresses and displacements is examined using the ABAQUS/CAE 2017 modeling and simulation program. The base layer of the real existing road is 150 mm provided by the Roads and Highways Department (RHD) Rajshahi, Bangladesh. The analysis is done by measuring stress and displacement under wheel load by decreasing the base layer thickness to 100 mm and further increasing it to 200 mm. The modeling approach assumes that all materials function in a linear elastic manner. The Poisson's ratio, layer thickness, and material elastic modulus are the major inputs used in the modeling procedure. In this work, flexible pavement is simulated using a conventional axle load of 100 kN, which corresponds to a single four-wheeled axle. Finally, FEM analysis showed that the maximum stresses are 0.35 MPa, 0.27 MPa, and 0.21 MPa and maximum displacements are 0.52 mm, 0.34 mm, and 0.21 mm for 100 mm, 150 mm, and 200 mm base layer thickness respectively. So, for the increase of base layer thickness the stress and displacement are decreased.

Board Games and Entrepreneurial Skills Acquisition: A Mixed-Methods Study on the Efficacy of the EntreComp Framework in Higher Education

The landscape of higher education has witnessed a paradigmatic shift towards methodologies that are more interactive and engaging. The integration of gamification and board games as active learning methodologies in higher education, as well as the instruction in entrepreneurial competencies, has garnered significant interest for its potential to engage and motivate students, thereby enhancing learning outcomes. Gamification, characterized by the incorporation of game design elements into non-game contexts, offers a captivating and novel learning experience that fosters intrinsic motivation and active participation among students. One of the main ways of applying gamification is through board games, providing hands-on opportunities for students to apply theoretical knowledge in practical scenarios. A critical aspect of this educational innovation is its contribution to the instruction of entrepreneurial competencies, a domain gaining traction within higher educational settings. The European Entrepreneurship Competence Framework (EntreComp) stands at the forefront of this educational endeavor, offering a comprehensive blueprint for cultivating entrepreneurial skills and mindsets. This study is anchored in the context described above, with a focused aim to delineate which entrepreneurial competencies, as outlined by the EntreComp framework, are most effectively developed through these novel educational interventions. To facilitate this investigation, the "Game It Away!" project was initiated, encompassing three pilot studies. These pilots innovatively employed board games as the medium through which participants could acquire and hone their entrepreneurial skills. A key component of the learning process within these pilots was the maintenance of a learning journal by the students. This journal, filled with various reflective questions, provided a structured mechanism for participants to document and reflect upon their learning journey throughout the project. In this way, by using qualitative and quantitative methodologies, it is possible to verify the evolution of certain competences. The integration of gamification and board games within educational settings, particularly through the lens of the "Game It Away!" project, represents a pioneering approach to fostering entrepreneurial competencies among students. This study, leveraging both qualitative and quantitative methodologies, has illuminated the substantial potential of these innovative pedagogical strategies to revolutionize the teaching and acquisition of entrepreneurial skills as outlined by the EntreComp framework.

Research on the cross-sectional geometric parameters and rigid skeleton length of reinforced concrete arch bridges: A case study of Yelanghu Bridge

To investigate the influence of cross-sectional parameters and the rigid skeleton length on the structural mechanics behavior of reinforced concrete arch bridges, this study focused on the Yelanghu Bridge with a span of 210 m. The sensitivity of the main arch rib's instability mode to cross-sectional parameters such as width, spacing between adjacent webs, height, and concrete thickness was examined by combining the finite element method and the theoretical derivation. Subsequently, research was conducted on the impact of the rigid skeleton length during construction on the static and dynamic performance of the structure relying on the Midas Civil software. The findings indicate that for the Yelanghu Bridge, the risk of in-plane instability is greater than that of out-of-plane and local instabilities. In-plane instability is most sensitive to the section height and the out-plane instability is most sensitive to the thickness of the roof and floor concrete. Under ultimate load-bearing conditions, the axial force in the critical sections of the bridge increases with the length of the rigid skeleton. The fundamental frequency of the Yelanghu Bridge is approximately 0.32, which is significantly lower than that of more rigid arch bridges but higher than those of structurally softer structures such as cable-stayed or suspension bridges. This indicates that large-span reinforced concrete arch bridges exhibit unique dynamic characteristics and belong to moderately flexible structures.

A comparative experimental study on the compressive mechanical properties of honeycomb structural mechanics made of different materials via selective laser melting additives

A comparative experimental study on the compressive mechanical properties of honeycomb structural mechanics made of different materials via selective laser melting additives

Free vibrations of a Continuous-discrete multi-span Beam taking into account inertial Rotation Forces

Objective. The aim of the study is to estimate free vibrations of a continuousdiscrete multi-span beam taking into account the inertial forces of rotation. The goal is to determine the spectra of natural frequencies, damping coefficients and natural modes. Method. The study is based on the methods of linear mechanics of structures; numerical and numericalanalytical calculation methods. The solution to the problem is found using the method of separation of variables. Rotational movements of particles of continuous sections are taken into account according to one of the models of the Timoshenko beam. The D'Alembert principle and hypotheses on the smallness of displacements and angles of rotation of sections are used. Result. A system of equations in matrix-vector form is obtained. The mathematical model of transverse vibrations consists of three systems of differential equations. The equation includes transverse forces, external concentrated forces, d'Alembert inertial forcesi, and linear-viscous resistance forces. The inertial forces of rotation of concentrated masses are taken into account. The boundary and other additional conditions to the equations correspond to the calculation scheme. The left end of the beam is hinged. The conjugation conditions are met at the junction of the sections. Conclusions. This random process of disturbances is very close to the processes used in deterministic problems. The amplitudes and standard deviations of displacements in the deterministic and stochastic problems almost coincide, which confirms the reliability of the proposed calculation theory. Analysis of the curves shows that the standard deviations significantly depend on the degree of correlation of the components of the vector random process of disturbances. The use of modern computing computer systems such as Matlab allows us to successfully combine the advantages of both numerical and graphical methods.

Effect of porosity gradient on fracture mechanics of bi-directional FGM structures: Phase field approach

This research aims to develop a computational model that can accurately predict the fracture behavior of porous bi-directional Functionally Graded Materials (FGMs). The Voigt model for homogenization, is established to account the effects of porosity fraction and gradient distribution within the FGMs, providing valuable insights about the brittle crack propagation. The study employs the UMAT subroutine in ABAQUS software and establishes an analogy between the phase field evolution law and the heat transfer equation, enabling efficient analysis of complex fracture problems. To validate the model, 2D fracture benchmark cases are analyzed, demonstrating its ability to capture different failure modes and the intricate material behavior of porous FGMs under fracture conditions. Furthermore, newly parametric analyses, that highlights the impact of various values of porosity’s volume fraction and FGM’s power law indexes on the brittle fracture path, are conducted to further validate the effectiveness of the newly developed phase field model in predicting the fracture behavior of bi-directional porous FGMs.

Improving dynamic energy absorption performance and stability loss prediction of an all-PET sandwich structure through artificial neural networks

Abstract One key characteristic that is frequently studied in composite sandwich structure mechanics is low-velocity impact performance. Single polymer composites present higher ductility when compared to traditional glass fibre and carbon fibre reinforced plastic composites (GFRP, CFRP), which makes them strong candidates for impact energy absorption. These lightweight structures are also fully recyclable due to their all-PET constituents, an important aspect when considering possible applications. In this paper an existing second order composite SrPET and PET foam sandwich structure (self-reinforced poly-ethylene terephthalate matrix and fibre) is numerically investigated for optimal structural design configuration under out-ofplane, low velocity, dynamic loading. The study explores the parametric geometry interdependencies of the structure’s configuration with respect to its energy absorption potential. The results are then compared to the quasi-static loading performance behaviour studied by M.N. Velea et all [1]. This work provides a deeper understanding of how geometry configurations can influence energy absorption capabilities highlighting structural strengths and weaknesses while exploring non-equilateral triangle configurations. The Design Space Exploration (DSE) is carried out by using an optimization algorithm for a dynamic out of plane 3D impact simulation based on the finite element (FE) method software. The synergy between DSE and FE generates a guided simulation loop that can successfully be used to train a neural network to predict the dynamic behaviour of different geometric configurations from the exploration space. Based on the data samples obtained, an artificial neural network (ANN) is built to predict the energy absorption capacity for a given set of structural design parameters, useful in experimental validation test cases.

INTEGRATING ENVIRONMENTAL CONSIDERATIONS INTO INDUSTRIAL ENTERPRISE OPERATIONS

This article addresses the development and implementation of a framework for integrating environmental considerations into the core operations of industrial enterprises. As industries contribute significantly to environmental degradation, there is an urgent need for sustainable approaches that minimize their ecological footprint. This study examines existing environmental management practices and identifies gaps where integration with industrial activities can be enhanced. Drawing on current literature and recent case studies, the article introduces a structured mechanism designed to align industrial operations with environmental objectives, including pollution control, resource efficiency, and waste reduction. The proposed framework incorporates environmental impact assessments, adherence to international standards, and sustainable resource management strategies to promote environmental accountability within industrial settings. The results demonstrate that implementing these practices not only reduces environmental harm but also offers economic benefits, such as cost savings from efficient resource usage and improved regulatory compliance. By providing a comprehensive model for environmental integration, this study contributes valuable insights into the transformation of industrial enterprises towards sustainability, benefiting both the industry and the broader environment.