Connective Elements Research Articles

Bio-based connections and hybrid planar truss: A parallel genetic algorithm approach for model updating

Bolted steel to laminated bio-based material connections experience significant performance challenges due to the nonlinear response and high stress concentrations at their joints. This paper introduces an innovative 3D plasticity-fracture continuum Finite Element (FE) model that significantly advances the simulation of such truss joints by integrating Hill's yielding criteria with an element removal methodology for fracture simulation. This novel approach captures both plastic and fracture behaviors simultaneously, a capability not sufficiently addressed in existing models. We detail the theoretical framework for these models, including the derivation of constitutive equations and the algorithms necessary for their implementation in ABAQUS. Additionally, it is provided a low-fidelity modeling of truss joints, offering a comprehensive analysis of connector elements, joint models, and parametric modeling via Python scripting. The model's efficacy is demonstrated through identification of connection and of hybrid planar trusses under cyclic loading, which validates the practical applicability of the method. To optimize computational efficiency, we developed a Parallel Genetic Algorithm (PGA) that integrates seamlessly with ABAQUS and Python to facilitate parameter calibration. This integration not only enhances the model's accuracy but also reduces computational load, making it feasible for complex engineering applications. Our findings illustrate a significant improvement in modeling accuracy and efficiency, establishing a robust methodology for analyzing truss joints in bio-based construction materials.

A Novel Connection Element Method for Multiscale Numerical Simulation of Two-Phase Flow in Fractured Reservoirs

Summary This paper presents a novel approach to the numerical simulation of fractured reservoirs, called the connection element method (CEM), which differs from traditional grid-based methods. The reservoir computational domain is discretized into a series of nodes, and a system of connection elements is constructed based on the given connection lengths and angles. The pressure diffusion term is approximated using generalized finite difference theory. Meanwhile, the transmissibility and volume of the connection elements are determined, and pressure equations are solved discretely to obtain pressure at nodes to approximate the upstream flux along connection elements. Then, we solve the transport equation to obtain oil saturation profiles with low numerical diffusion, utilizing the discontinuous Galerkin (DG) method. Moreover, the flow path tracking algorithm is introduced to quantify the flow allocation factors between wells. In all, the pressure equation can be solved at a global coarse-scale point cloud and the saturation equation is calculated at a local fine-scale connection element. In other words, CEM is of multiscale characteristics relatively. Finally, several numerical examples are implemented to demonstrate that CEM can achieve a relatively better balance between computational accuracy and efficiency compared with embedded discrete fracture modeling (EDFM). Furthermore, CEM adopts flexible meshless nodes instead of grids with strong topology, making it more practical to handle complex reservoir geometry such as fractured reservoirs.

The concept of the Indo-Pacific region: role and significance of India

The term ‘Indo-Pacific region’ (IPR) was first used in international studies by the Indian researcher G.S. Khurana, who included in this concept the maritime space that unites the Indian Ocean and the Western Pacific, all Asian (up to the Middle East) and even North African countries, highlighting the connecting elements of ‘energy routes’. Therefore, this article is devoted to the concept of the Indo-Pacific region (IPR), which is a new geopolitical concept in which India is being introduced. This Asian country is now seen as one of the most important elements of the region because of its enormous potential. Therefore, Western countries are trying to ‘win’ it over and bring it into the ‘leading four’ of the ITR (the United States, Japan, India, and Australia). To understand how India has become a "key element" of the RIIT, the authors analyse the main factors that influenced this. It is shown that the US views interaction with India as a ‘bearing axle’ in the American strategy in the Asia-Pacific region. The concept of the Indo-Pacific region has a clear anti-Chinese orientation and is created as a counterweight to the main initiative of the People’s Republic of China ‘One Belt, One Road’. As for India’s participation in the new format, Delhi’s difficult relations with Beijing, the rivalry of the two countries on the Asian continent, and the concerns of India, the United States, Japan and many Asian countries about China’s actions in the South China Sea are taken into account here. The role of the concept of IPR as a key element of the modern India’s foreign policy strategy is considered, the importance of economic, security, civilizational and cultural factors in this process is analyzed.

Eirenias of Miletus’ Career between the Attalids and the Seleucids

The role played by Eirenias of Miletus in the mid-2nd century B.C. between his city and the Attalids and Seleucids demonstrates the vitality of his polis, which had de facto the status of a free city after the Treaty of Apamea of 188. A small corpus of Milesian inscriptions shows that Eirenias, known only from epigraphy, dedicated most of his political activity to relations with external powers, playing numerous times the role of ambassador in favour of his city, for which he was able to obtain many privileges from the Attalids and, to a lesser extent, from the Seleucids. Notables such as Eirenias, who used their external relations for the benefit of their own cites, constituted the connecting element between the euergetism of kings and powerful outsiders and that of private citizens.

Культурный код: определение понятия и практическая проблематика феномена: теоретический обзор

The aim of the study is to form a theoretical core of understanding of this phenomenon within the framework of theoretical review of modern concepts of cultural code. The article considers different definitional, structural and functional aspects of the cultural code, reveals its psychic roots and significance in human behavior, structure, sign-symbolic, figurative and value content, the role of a connecting element between the psyche and culture, the function of a communicative element and an interpreter of cultural texts and a cipher encapsulating the main meanings of culture. The significance of the cultural code in ethnic and national forms of human existence, in the construction of social and cultural identity is established. The key problems and risks associated with the defragmentation of the cultural code are outlined: standardization and unification of cultural codes within the framework of globalization, ideological and cultural wars and propaganda, excessive subordination of culture to market and materialistic principles, erosion of traditional values and meanings and at the same time imbalance between traditional and innovative principles in culture, conflictogenicity and disharmony of socio-cultural space as factors of intergroup and international conflicts, destructive processes, and the emergence of new cultural codes. Based on the generalization and synthesis of the obtained knowledge, a new theoretical and conceptual core of the cultural code is formulated as a structure that determines the image-symbolic and value content of culture, its ethnic and national peculiarities, the prospects of development of the sociocultural environment or the mechanisms slowing down this development, as well as the specificity of unconscious thinking and behavior of the people-expressor of the culture and its codes. In the framework of the proposed concept, the cultural code appears as a kind of “genome” of culture, laying the foundations of its development, determining the nature of interaction and human assimilation of its products, serves as a basic mechanism of specific cultural mastering and transformation of the world around people, as well as a decoder that allows (if correctly interpreted) to read the mental characteristics of social groups and influence them in the mental and behavioral sense.

Navigating the Legal Landscape: LGBTQ+ Rights in Family Law

Family regulation assumes an urgent part in characterizing the freedoms as well as certain limitations of people inside familial connections. With changing cultural mentalities and legitimate changes, the acknowledgement of LGBTQ+ privileges inside family regulation has been a subject of developing significance. This article investigates the advancing legitimate scene of LGBTQ+ freedoms in family regulation, including issues connected with reception, marriage fairness, and youngster guardianship. In the steadily advancing embroidered artwork of current culture, the convergences of regulation and basic liberties ceaselessly shape the elements of familial connections. One of the most extraordinary and extensive developments in this domain is the quest for LGBTQ+ privileges inside family regulation. As people embrace their different characters and love has no limits, the lawful scene should adjust to mirror these changing accepted practices and guarantee impartial treatment for all. This article sets out on an excursion through the moving shapes of LGBTQ+ privileges inside family regulation, looking at the significant effects on issues going from reception and marriage balance to kid guardianship and nurturing freedoms. In doing so, we enlighten the way ahead in the continuous quest for equity, uniformity, and acknowledgement for LGBTQ+ people and families inside the core of our overall sets of laws.

Comparative morphological and morphometric analysis of the structure of the wall of the calf venous collectors

Introduction. Development of venous pathology of the lower extremities is based on morphological changes in the vascular wall. Further structural restructuring of the vein wall in chronic venous insufficiency will depend on the initially present differences in the structure of their walls.Aim. To conduct a comparative analysis of morphological and morphometric features of the structure of the walls of the main venous collectors of the lower leg: the great saphenous vein, intramuscular veins, posterior tibia veins and poplitea vein.Materials and methods. Histological studies were carried out on autopsy material of the veins of 32 people who died from various causes aged 35 to 50 years and 10 amputated limbs. Morphological studies of the venous wall were carried out by light microscopy with digital photo processing.Results. A quantitative comparative analysis of morphological changes with the determination of the volume fraction of smooth muscle and connective tissue elements of various membranes of the venous wall, as well as measurement of the total thickness of the vascular wall and its ratio to the lumen of the veins showed statistically significant differences at a significance level of p < 0.05.Discussion. Despite the similarity of the general morphological picture of the structure of various venous collectors of the lower leg, structural differences were established, which concerned the volume fraction of the presence of both smooth muscle and connective tissue elements.Conclusion. The comparative qualitative and quantitative statistical analysis of morphological and morphometric features of the structure of the walls of the main venous collectors of the lower leg allows us to make an assumption about the unequal role of individual main venous collectors in the work of the muscular-venous pump of the lower leg as a whole.

Ecological Requirements for Abundance and Dispersion of Brazilian Yellow Fever Vectors in Tropical Areas.

In the Americas, wild yellow fever (WYF) is an infectious disease that is highly lethal for some non-human primate species and non-vaccinated people. Specifically, in the Brazilian Atlantic Forest, Haemagogus leucocelaenus and Haemagogus janthinomys mosquitoes act as the major vectors. Despite transmission risk being related to vector densities, little is known about how landscape structure affects vector abundance and movement. To fill these gaps, we used vector abundance data and a model-selection approach to assess how landscape structure affects vector abundance, aiming to identify connecting elements for virus dispersion in the state of São Paulo, Brazil. Our findings show that Hg. leucocelaenus and Hg. janthinomys abundances, in highly degraded and fragmented landscapes, are mainly affected by increases in forest cover at scales of 2.0 and 2.5 km, respectively. Fragmented landscapes provide ecological corridors for vector dispersion, which, along with high vector abundance, promotes the creation of risk areas for WYF virus spread, especially along the border with Minas Gerais state, the upper edges of the Serra do Mar, in the Serra da Cantareira, and in areas of the metropolitan regions of São Paulo and Campinas.

Seismic performance of recentering energy dissipation bracing with pendulum in prefabricated steel frame structure systems

This research introduces the recentering energy dissipation bracing with a pendulum in prefabricated steel frame (REBP-PSF) structures. The primary objective of this study is to mitigate potential severe damage to steel frames during seismic events and to expedite postearthquake rehabilitation. This innovative system harnesses energy dissipation through friction between structural members and facilitates recentering through the cable pretensioning force. Consequently, this may make postearthquake repairs minimal or even unnecessary. Three REBP-PSF structures and a prefabricated steel frame with cantilever beam splices (PSF-CBS) were meticulously modeled using the ABAQUS finite element method to evaluate the seismic performance of this novel system. The study investigated the effects of pretensioning parameters and varied structural morphologies on seismic performance metrics, including failure modes, hysteresis performance, energy dissipation capacity, and residual displacements. This paper introduced a simplified method to simulate the restoring force model of REBP using the connection element method. Subsequently, a model for the REBP-RSF overall structure was established, enabling nonlinear dynamic time-history analysis, which was then compared with the rigid steel frame (RSF) structure. The results showed that the REBP-PSF structure outperformed the PSF-CBS in terms of initial stiffness, yield load, ultimate load, and energy dissipation capability. The bearing and energy dissipation capacities of the REBP-PSF structure were enhanced by augmenting the cable pretensioning force within this structure. The proposed connection element method could accurately simulate the hysteretic behavior of REBP. Compared with the RSF structure, the REBP-RSF demonstrated superior seismic performance, characterized by small story drift and residual displacements during seismic activities. Furthermore, a notable augmentation was observed in the lateral stiffness and torsional rigidity of the proposed structure.

Theoretical and numerical study on the bond behavior between reinforcing steel and concrete

The bond-slip interaction between reinforcing steel and concrete plays a crucial role in transferring stress and the synergistic mechanical behavior of reinforced concrete members. Based on the interface tensile mechanism of reinforcing steel and concrete, a novel simple bond-slip model was developed to consider the tensile fracture behavior of the interface in different stress stages. According to the influencing factors including concrete strength, cover thickness, reinforcing steel rib spacing, stirrup arrangements, reinforcing steel diameter and anchorage length, characteristic points are established. The results show that the calculated results of this model agree well with the experimental results under monotonic loading. Finally, the different stages of slip behavior are simulated with the elastic, plastic and damage behavior of the connector elements according to a three-dimensional modeling method. Comparisons that were performed between the nonlinear numerical simulations and theoretical results have clearly shown that the connector element can predict the interface behavior of reinforcing steel and concrete.

ВПЛИВ РАДИАЛЬНОГО НАТЯГА БОЛТІВ НА ХАРАКТЕРИСТИКИ НДС МОДЕЛЕЙ З'ЄДНАНЬ ЕЛЕМЕНТІВ КОНСТРУКЦІЙ ЛІТАКА

To study the effect of radial bolt tension on the VAT characteristics of the bolted connection elements of aircraft structures, calculations are carried out using the finite element method, which is based on experimental verification using a model of the bolted connection design with tension. The constructed model is verified by the test of bolted connections, based on the reliability of the three-dimensional model of elastoplastic analysis by the finite element method. A model of the analysis of the influence of the design parameters of the bolted connection for six different tension values was created. A comparative analysis of the influence of different tension values on the nature of the VAT distribution, the initial stiffness and the load-bearing capacity of the bolted connection design was carried out. The results of the study showed that the stress distribution and their concentration can be changed when applying the appropriate fit with tension. At a tension value of 1.5 % of the bolt diameter, the initial stiffness and bearing capacity increase by 14.1 % and 9.33 %, respectively.

On Pseudo-Coordination in the province of Catania

This paper discusses the preliminary results of an exploratory study based on acceptability judgments about Pseudo-Coordination (PseCo) as found in the province of Catania (Sicily). PseCo is a monoclausal verbal periphrasis where an inflected verb (V1), usually of motion, is followed by another inflected verb (V2) with an optional connecting element between them (cf. Giusti, Di Caro and Ross 2022). In western Sicilian varieties, the V1 GO can occur as an invariable form (i.e., va-, vo-, uo-, o- as in Oppigghju u pani ‘I go and fetch the bread’) prefixed to the V2. An online anonymous questionnaire was administered to 295 participants (180 female, 115 male; Age M: 20,95 years, Age SD: 2,73 years) to assess whether (i) PseCo with V1 GO in the present indicative is productive among younger speakers; (ii) different forms of invariable V1 GO can cooccur in one and the same variety. The results show that PseCo in the province of Catania is still vital among younger generation of speakers and that invariable V1 GO generally occurs in at least two different forms but with no particular semantic specialization.

Bifenox induces hepatotoxicity and vascular toxicity in zebrafish embryos via ROS production and alterations in signaling pathways

Existing evidence shows that currently used pesticides pose toxicological risks to exposed wildlife. Chemically, bifenox belongs to diphenyl ethers, a well-known group of herbicides. Its mechanism of action primarily involves inducing lipid peroxidation and blocking protoporphyrinogen oxidases. Toxicity of diphenyl ether herbicides has been elucidated in animal cells; however, in vivo toxicological evaluations of bifenox are required to determine its unexpected effects. This study aimed to determine the negative effects of bifenox, and its effects on higher eukaryotes. We found that early stages of zebrafish embryo exposed to bifenox demonstrated increased mortality and physiological defects, based on the LC50 value. Bifenox severely inhibited blood vessel growth by reducing key elements of complex connectivity; fluorescently tagged transgenic lines (fli1a:EGFP) showed morphological changes. Additionally, transgenic lines that selectively identified hepatocytes (fabp10a:DsRed) showed reduced fluorescence, indicating that bifenox may inhibit liver development. To evaluate the level of oxidative stress, we used 2′,7′-dichlorofluorescein diacetate (DCFH-DA) probes in zebrafish embryos to identify the underlying mechanisms causing developmental damage. Our findings demonstrate that exposure to bifenox causes abnormalities in the hepatic and cardiovascular systems during zebrafish embryogenesis. Therefore, this study provides new information for the evaluation of toxicological risks of bifenox in vertebrates.

The Use of PVD Coatings for Anti-Wear Protection of the Press-In Connection Elements

Press-in connections are the commonly used methods for connecting machinery components. In relation to that wide use, those connections are liable to various types of damage and wear. Therefore, this article proposes one of the methods which may improve the life of the press-in connection. CrN+OX, TiN, and ZrN coatings made in the PVD technology were used. The coatings were applied on shafts mating with sleeves and subjected to a rotational bending moment. Tests and observations were conducted that enabled the assessment of the influence of those coatings on the development of wear, in particular fretting, in the tribological kinematic pair. The tests showed the development of wear on all the observed shaft surfaces, with a lower intensity of damage recorded on coated shafts compared to uncoated ones. The traces of fretting wear were noted each time at the edges of the connection, which is due to the mechanism of wear development under rotational bending conditions. In the case of uncoated shafts, wear occurs at the entire circumference of the axle seat in the form of a 3–4 mm wide ring; however, that width is different on either side. In the case of coated shafts, wear occurs on the circumference of the axle seat in the form of a thin ring 1–3 mm wide, depending on the coating. In the case of a ZrN coating, fretting wear appears locally. The largest surface area occupied by wear is 0.75 cm2. Fretting wear comprises mainly material build-ups, pits, and surface scratches. In addition to fretting wear, damage resulting from the process of forcing the sleeve onto the shaft was observed on the tested surfaces.

Retraction Note: Dynamic analysis of structures installed hysteretic dampers with hardening post-yielding stiffness using connection element method

Retraction Note: Dynamic analysis of structures installed hysteretic dampers with hardening post-yielding stiffness using connection element method

Towards the realization of composite metastructures: A failure analysis of connections

Metastructures hold significant potential for applications such as adaptive structures and soft robotics. Architectures of fiber-reinforced polymer metastructures may relate to modular arrangement of straight and curved laminates, with their connections to resemble perfect cracks, thus susceptible to delamination. This study investigated geometrical effects on the load-carrying capabilities of these connections upon a global tensile deformation, as well as lean modeling tools to facilitate the development of architected composite metastructures. Numerical fracture mechanics approach on different connection geometries and thicknesses showed that connection delamination is a critical failure mode, but crack-driving-force has low dependence on connection shape for given ligament thickness (and stiffness). Adopted analytical models could capture either moment or force-driven delamination failure, while the intermediate regime necessitates numerical tools. First-ply failure may precede depending on shape and ligament stiffness. These trends were also verified on an exemplary rotating chiral composite geometry. Furthermore, interface load-carrying capability improvements were studied via design considerations including connection filler material and element variable thickness. Indicatively, the latter showed a 157 % increase in bending deflection (and global deformations), while reducing crack driving force by 38 % for a given load case. The conducted analysis offers valuable insights into the design of lightweight, load-carrying composite metastructures.

Nonlinear dynamic collapse analysis of space semi-rigid frames using finite particle method

Based on the finite particle method, this work presents a general numerical method to perform the nonlinear dynamic collapse analysis of space semi-rigid structures. A space connection element composed of two particles and six zero-length springs is proposed to simulate the space semi-rigid connection. Geometrical nonlinearity is addressed through fictitious motion, while material and connection behavior nonlinearities are captured by updating the element stiffness matrix and the connection stiffness matrix, respectively. Member and connection fracture models are convenient for simulating fracture behaviors during collapse processes. To verify the effectiveness of the proposed method, the numerical results are compared with those from previous studies, and energy conversion analyses are adopted. The analysis results indicate that only member fractures occur at beam ends in the rigid and linear semi-rigid frames, while only connection fractures occur at beam ends in the nonlinear semi-rigid frame.

GIS-BASED REAL-TIME GAS LEAK DETECTION SYSTEM AT BASKENT NATURAL GAS DISTRIBUTION COMPANY

Abstract. Natural gas has been used for heating and production purposes in Turkey since 1987, and every passing year, the natural gas pipeline network continues to expand with investments. The distribution of natural gas within urban areas is achieved through a complex network structure formed by the joining of Polyethylene (PE) and Steel (ST) pipes using various connection elements. This complex structure is susceptible to deformation over time due to various reasons such as corrosion in steel lines, manufacturing errors in connection elements in PE lines, and other factors. As a result, natural gas leaks occasionally occur in these pipelines. The leakage control process in natural gas pipelines is carried out using specially designed equipment and vehicles equipped for this purpose. However, while these systems may be sufficient for collecting the necessary data for leak detection, the complex structure of the distribution network and the necessary data for leak detection, the complex structure of the distribution network and the necessity of performing this process with multiple teams bring about many challenges in terms of tracking, management, and reliability of the operation. At this point, the advancement of GIS (Geographic Information System), mobile, and communication technologies has made it possible to overcome these challenges. In this study, a real-time GIS-supported leak detection system developed using these technologies for Başkent Natural Gas Distrubition Inc. (Başkentgaz), which provides natural gas distribution services in Ankara, has been described. The study discusses the benefits brought by this system to the natural gas leak detection process.

Nonlinear Dynamic Analysis for a Jeffcott Rotor Considering Varying Connection Stiffness of Bolted Joint

Bolted joints have been widely used in rotor assemblies of aircraft engines. A typical bolt joint is composed of two metal parts connected mechanically with pre-tensioned bolts. During operations, the bolting pretensions can vary with the changing contacting relationship between the parts, which makes the connection stiffness of the joint nonlinear on the macroscopic scale. The fundamental problems of the dynamical analysis for bolted joints are (1) to identify the transition of the change of the connection stiffness and properly model the overall connection stiffness and (2) to investigate the influence of such variable stiffness on the rotor vibration. In this paper, an analytical model is proposed considering the effect of bolted joints. The bolt of the joint is simplified as a two-node spring-like connection element considering different axial tension and compression stiffness, non-uniform preload of bolts and the contact interface friction described based on Coulomb friction. The dynamic equations of the rotor system are established based on the lumped mass modeling and the proposed connection element, and numerically solved through the Runge–Kutta method. The results indicate that the rotor system exhibits a variety of states, such as period-1 motion, multi-period motion, quasi-periodic motion and chaotic motion. The effects of friction coefficient and preload of the bolts on the nonlinear dynamic behaviors of the bolted rotor system are demonstrated in detail.

Preliminary experimental tests of a novel friction damper for seismic retrofit of RC precast structures

Precast RC structures have been widely adopted for industrial and commercial buildings since the ’60 s in the most developed countries. For this structural typology, connections between structural elements set a crucial point in the presence of lateral loads, such as earthquakes, since the deficiency, or lacking, of connection elements is the main responsible for their structural collapse. This paper shows the preliminary mechanical testing of an innovative damping device conceived to be installed in beam-to-column joints of precast RC structures, with a bidirectional dissipative potential due to its geometry. This new Bidirectional Rotation Friction Damper (BRFD) has been designed and optimised after a tribological campaign, which led to the selection of the two different friction interfaces investigated in this work. The mechanical tests have been performed considering the guidelines of EN15129 and the previous tribological investigation findings, showing the influence of sliding frequency and bolt torque increment on the steadiness of the BRFD hysteresis cycle.