Structure Interaction Model Research Articles

Fluid–structure interaction in a follow-up study of arterio-venous fistula maturation

Arteriovenous fistula (AVF) is the preferred vascular access for hemodialysed patients. AVF is created surgically using the patient’s artery and vein. Once the connection (anastomosis) is made, the maturation process begins. Studies have shown that most AVFs do not survive beyond one year. This study presents fluid–structure interaction (FSI) modelling of non-Newtonian blood flow through an end-to-side radio-cephalic AVF, investigated weekly during a 15-week follow-up period and 1.5 years postoperatively using ultrasound methods. The aim was to collect qualitative and quantitative data regarding changes in hemodynamics and alterations in the walls of AVF vasculature. Different material properties were assigned to the artery, suture zone (anastomosis), and vein, while the stiffening of the venous arm over time was also modelled. The proposed FSI methodology can be implemented in future follow-up studies involving groups of patients. The main findings revealed: a) counter-rotating vortices in the anastomosis cross-section affecting local pressure conditions; b) different temporal progression of vorticity, shear strain rate, and turbulent kinetic energy and similarity of the temporal progression of WSS obtained under the assumptions of the rigid-walled and FSI; c) a negligible low-WSS zone in the presented thrombosis-free AVF; d) migration of the zone of maximal temporal wall deformation over time.

Analysis of Resistance in Magnetic Flux Leakage (MFL) Detectors for Natural Gas Pipelines

This study systematically explores the sources and influencing factors of resistance encountered by magnetic flux leakage (MFL) detectors in natural gas pipelines through a theoretical analysis, experimental investigation, and numerical simulation. The research methodology involves the development of a fluid–structure interaction model using ABAQUS 2023 finite element software, complemented by the design and implementation of a pull-testing platform for MFL detectors. This platform simulates detector operation under various interference conditions and quantifies the resulting frictional resistance. The findings reveal that the primary source of frictional resistance is the contact interaction between the MFL detector and the pipeline wall. Key factors influencing the magnitude of this resistance include the detector’s mass, the structural design and materials of the sealing cups and support plates, as well as the surface roughness of the pipeline. Both experimental results and numerical simulations demonstrate a pronounced increase in frictional resistance with heightened interference levels. The theoretical model exhibits strong agreement with experimental data, though deviations are observed under conditions of severe interference. This study provides a detailed understanding of frictional resistance patterns under diverse structural and operational scenarios, offering both theoretical guidance and practical recommendations for the design of low-resistance MFL detectors.

One-way fluid–structure interaction modeling and multi-objective optimization of horizontal-axis wind turbine blades equipped with winglets

ABSTRACT This study aims to investigate the effects of backward-directed winglets applied on the NREL Phase-II reference wind turbine geometry on structural and aerodynamic characteristics and to reveal optimized configurations. The aerodynamic pressure distributions on the blades were imposed as boundary conditions for the FEM analyses since the structural characteristics of the turbine were analyzed by adopting a one-way Fluid Structure Interaction (FSI) approach. The Taguchi analysis with an L27 orthogonal array revealed the descending order of importance of design variables on the coefficient of power ( C P ): height, cant angle, toe angle, curvature radius, and finally twist angle. For von-Mises stress, the descending order of importance is height, cant angle, toe angle, twist angle, and curvature radius. A multi-objective genetic algorithm using artificial neural network (ANN) models was used to optimize the objectives C P and von-Mises stress. Pareto-optimal solutions with off-design points were obtained, and their performances were compared to the reference NREL Phase-II geometry. As a result, it was observed that there was an increase in C P from 8.07% to 15.56% and the von-Mises stress showed a considerable increase up to 231.13%. The study demonstrates the aerodynamic benefits and structural drawbacks of various winglet designs in horizontal axis wind turbines.

Performance analysis and improvement of a novel reed valve in compressors using fluid–structure interaction method

The reed valves used as suction valves in reciprocating compressors are more susceptible to damage due to the limitation of the lift limiter which can't completely block the entire valve plate. This article proposed a novel reed valve featuring a redesigned shape aimed to solve this issue. Compared to conventional reed valves, the proposed valve could effectively mitigate the highest stress occurring at the root of the suction valve. To thoroughly investigate the characteristics of this valve type and improve its performance, a three-dimensional fluid–structure interaction (FSI) model was established and validated using experiments. The leakage through the valve gap in the FSI model was solved using a combination of user-defined function (UDF) and Scheme file in Fluent. Based on this FSI model, the dynamic characteristics and stress distribution of the valve were mainly analyzed. The effect of the lift limiter on the performance of the valve was analyzed, and a suitable lift was determined. Moreover, the influence of thickness and shape parameters, was also analyzed and an efficient improved scheme was subsequently proposed. Through this scheme, the maximum stress of the valve was reduced by 23.77% compared with that of the original valves. This article provides important information for the design and optimization of complex-shaped reed valves.

Blood flow through a stenosed left anterior descending coronary artery: Evaluation of loss coefficients in one-dimensional fluid–structure interaction model

Coronary arterial flow is affected by conditions such as atherosclerosis and stenosis resulting in coronary artery disease. Quantifying the flow fields across arteries is a key aspect in the functional assessment of occlusive arterial disease. An essential aspect of blood flow modeling is the mechanical interaction between the fluid flow and the arterial vessel wall. The present study focuses on the modeling of blood flow within the left anterior descending artery affected with stenosis. A one-dimensional (1D) model was developed to study the transient blood flow characteristics in the artery. The 1D model is coupled with the material tube law to account for the flexibility of the arterial wall. The loss coefficients that account for the local viscous and turbulent losses across the stenosis region are estimated accurately in terms of the varying local cross-sectional area, instead of empirical constants used in the literature. It was observed that the magnitude of viscous losses decreases with an increase in the severity of stenosis. For lower degree of stenosis (<30%), the local turbulent losses are insignificant compared to the viscous losses. The maximum deformation of the vessel wall is ∼0.12mm at t=0.45s for s=70%. During the cardiac cycle (T=0.9s), the artery is observed to be experiencing dilation (Δr>0) in the upstream region, whereas contraction (Δr<0) in the downstream region for all the values of severity (s). A fractional flow reserve of 58.53% was noticed in a stenosed artery of 70% severity.

Numerical simulation progress of whole-heart modeling: A review

Cardiovascular diseases, characterized by high mortality rates, complex etiologies, and challenging prevention and treatment strategies, have become a major focus of public concern. With the advancement of computational numerical simulation technologies, whole-heart modeling has emerged as a crucial direction in cardiovascular engineering research. This review summarizes the progress in numerical simulations of whole-heart models, with a particular emphasis on the modeling and computation of cardiac-related physical fields. Through a retrospective study, this article covers various modeling approaches, including electrophysiological simulations, cardiac mechanics, and fluid–structure interaction models. Advanced theoretical models and numerical techniques are discussed in depth to enhance the accuracy and relevance of the simulations. Currently, numerical simulation techniques for whole-heart modeling have developed a relatively complete theoretical framework to compute key cardiac functions. However, there remains a need for further exploration in multiphysics coupling and high-performance computing to support clinical applications, requiring additional theories and methods. The integration of multiphysics and multiscale modeling is critical for advancing personalized medicine and improving the diagnosis and treatment of cardiovascular diseases. Future research will focus on enhancing computational efficiency and expanding clinical applications.

Brief communication: Stalagmite damage by cave ice flow quantitatively assessed by fluid–structure interaction simulations

Abstract. Mechanical damage to stalagmites is commonly observed in mid-latitude caves. Former studies have identified thermoelastic ice expansion as a plausible mechanism for such damage. This study builds on these findings and investigates the role of ice flow along the cave bed as a possible second mechanism in stalagmite damage. Utilizing fluid–structure interaction models based on the finite-element method, forces created by ice flow are simulated for different stalagmite geometries. The resulting effects of such forces on the structural integrity of stalagmites are analyzed and presented. Our results suggest that structural failure of stalagmites caused by ice flow is possible, albeit unlikely.

Well-posedness of a Nonlinear Acoustics – Structure Interaction Model

Well-posedness of a Nonlinear Acoustics – Structure Interaction Model

MODEL OF SPARE PARTS INVENTORY MANAGEMENT IN THE SUPPLY SYSTEM: THE CASE OF THE ‘OLL TRAK PARTS’ COMPANY

The article identifies the relevance of the problem of optimisation of material reserves of a company and their effective management, as the state of existing reserves has a decisive impact on the competitiveness of the company, its financial condition, and the corresponding performance results. It allows the formulation of the research objective in this development. It is a given that inventory management technology is an integral part of the management system of any manufacturing and trading company. The efficiency of these companies depends on such critical criteria as the number of costs incurred for inventory management. Traditional indicators, such as inventory volume, resource turnover, and continuity of supply, cannot be used in isolation to accurately measure the extent to which an inventory management system is improving since they are part of the overall cost criterion. The article examines scientific developments of theoretical foundations for implementing rational solutions in the supply chain, where the authors use modern research methods and approaches. After analysing these studies, we identify the main problematic issues: determining a rational way of servicing orders by the core production warehouse systems, organising an efficient product supply form, and developing rational inventory management technologies throughout the entire product supply chain. We create a structural model of interaction between the warehouse system of the ‘OLL TRAK PARTS’ company and suppliers and customers, formed with the participation of certain parties in all relevant operations. The structure of stocks accounts for the customer’s needs in a multi-nomenclature offer of spare parts for trucks, cars, and agricultural machinery supplied by ‘OLL TRAK PARTS’. The authors build a mathematical model of spare parts inventory management under limited demand conditions, which considers the following parameters of influence: the period for ordering spare parts, the cost of supplying ordered spare parts, and the cost of storing one unit of spare parts inventory. To achieve maximum measurement accuracy with a minimum number of trials and to maintain the statistical reliability of the results, we develop a full-factor experiment plan for three input parameters with three levels of values, consisting of 27 series of trials. The experiment allowed us to model the change in minimum costs with different order volumes of spare parts. Based on the results of the regression analysis of the obtained values of the estimated indicator, we determined the type of regression model – a linear form with a non-zero coefficient. Keywords: model, warehouse, system, logistics, interaction.

Dynamic Characteristics of Pressure-Balanced Metal Bellows in Fluid–Structure Interaction

As a flexible component in high-pressure vessels and pipeline systems, bellows experience significant fluid–structure interaction effects under high-speed internal fluids and external vibrations. Nevertheless, their dynamic response mechanisms coupled with fluid–structure interaction mentioned below have not yet been clarified so far. In this work, a novel pressure-balanced metal bellow (PBMB) for low-stiffness and high-pressure resistance is firstly proposed. Several fluid–structure interaction models were considered to study the dynamic response characteristics of the PBMB. An experimental platform associated with fluid–structure interaction was established to validate the effectiveness of its vibration attenuation performance. The results indicate that the PBMB has an obvious vibration attenuation effect in the range of 5–90[Formula: see text]Hz, and super-harmonic and sub-harmonic resonance phenomena occur in the range of 90–200[Formula: see text]Hz. Under constant fluid conditions, fluid density, viscosity, flow velocity, and pressure are positively correlated with the response amplitude of the PBMB. The response of the PBMB oscillates at the fluid entry point due to both pulsating flow velocity and pulsating pressure. After several cycles, the response caused by pulsating flow velocity gradually decays and stabilizes. Thus, the impact of pulsating frequency on the stability of the response of bellows is insignificant during the initial cycles.

Simplified soil–structure interaction modeling techniques for the dynamic assessment of end shield bridges

In this paper, the dynamic behavior of four railway bridges with integrated retaining walls, considering the effect of soil–structure interaction (SSI), is investigated both numerically and experimentally. Among these bridges, two are single-span, and the remaining two are three-span. Each bridge is equipped with numerous accelerometers and is excited by a hydraulic actuator across various frequencies. Full 3D solid Finite Element (FE) models incorporating the railway bridges and surrounding soils are developed and calibrated using the Frequency Response Functions (FRFs) from each accelerometer. Furthermore, simplified 3D solid and 2D beam models are created for each railway bridge, incorporating springs and dashpots to account for the effect of surrounding soils. The values for these springs and dashpots are obtained from simple equations, except for the impact of the backfill soil in the simplified 2D beam models, which are derived from the impedance functions of the soil medium. The performance of these simplified models is then compared to the calibrated 3D models in terms of modal properties of the first bending mode and the maximum acceleration response during high-speed train passages. The results indicate that the simplified models closely align with the calibrated models in terms of modal properties and high-speed train passage response and can be used as simple and efficient alternatives for practical usage in bridge design.

Shear stress identification in plate rubber bearing using surface-bonded piezoelectric transducer: A feasibility study

This paper presented a preliminary study on the feasibility of shear stress identification in plate rubber bearings using surface-bonded piezoceramic (PZT) transducers. A PZT-rubber bearing structural dynamic interaction model was developed to analyze the shear stress effect on the electromechanical admittance (EMA, inverse of impedance) by introducing a mechanical impedance system consisting of parallel mechanical elements. 3D finite element (FE) model of a full-sized plate rubber bearing was generated to detect shear stress using the EMA signatures. Proof-of-concept experiment was finally conducted on two plate rubber bearings subjected to shearing force, during which the process was monitored by three PZT sheets arranged at different loci. Theoretical, numerical and experimental results demonstrated that identification results of PZT transducers were closely related to the PZT location, shear stress in rubber bearings were generally in linear relationship with the peak values of EMA spectrum and its statistically quantifiable indicators.

Flexibility evaluation of psammophytes using Young’s modulus based on 3D numerical simulation

Flexible psammophytes play an important role in controlling soil wind erosion and desertification, owing to their characteristics. Although flexibility of psammophytes has been considered in previous studies, the interaction between flexible psammophytes and the surrounding airflow field still remained unclear. In this study, we used the Young’s modulus to describe plant flexibility and conducted a 3D computational fluid dynamics simulation using a standard k-ε model and a fluid–structure interaction model. Taking Caragana korshinskii (Caragana), a typical psammophyte, as the research object, we constructed 3D geometric models with different diameters to simulate the airflow field around the flexible psammophytes. By comparing with the simulation results of rigid plants and simulation results of flexible plants at different wind speeds, we could verify the rationality of the simulation method. Based on the simulation results, the maximum swing amplitude of the model and the Young’s modulus were found to have a negative correlation, presenting an exponential functional relationship with good fitting. The relationship between the actual Young’s modulus of the plant branches and that of different diameter models in the numerical simulation was also established. This study is expected to improve our basic understanding of the interaction between flexible psammophytes and the surrounding airflow field, and provide some qualitative reference for the numerical simulation of the airflow field around flexible psammophytes.

Different Soil-Structure Interaction Modelling Strategies for Seismic Analysis of a Masonry Church

ABSTRACT Masonry structures can be damaged different external reasons such as war, flood, earthquake etc. For protecting and transfer to the next generations, these structures can be examined detailed. Finite element analysis has generally been used for the seismic evaluation of masonry structures. The fixed base assumption has been used in traditional finite element analysis of masonry structures. Interacting with the surrounding soil and structure was generally ignored. The seismic behavior of masonry structures is significantly influenced by the soil-structure interaction (SSI). There are various soil structure interaction modelling strategies in the recent studies. In this paper, the dimensions, mechanical properties and material model of the soil are considered constant. One of them had no soil-structure interaction. The others, roller support case, fixed support case, absorbing boundary case, free field columns and Winkler supports. Variations in the seismic response of a historical masonry church were investigated using 4 different SSI models and a fixed base (SSI ignored) model. Nonlinear time history analyses were employed for the finite element analysis. The soil borehole provided the material characteristics of the surrounding soil. According to the analysis results, higher response amplitudes were obtained when SSI was considered.

A coupled high-accuracy phase-field fluid–structure interaction framework for Stokes fluid-filled fracture surrounded by an elastic medium

In this work, we couple a high-accuracy phase-field fracture reconstruction approach iteratively to fluid–structure interaction. The key motivation is to utilise phase-field modelling to compute the fracture path. A mesh reconstruction allows a switch from interface-capturing to interface-tracking in which the coupling conditions can be realised in a highly accurate fashion. Consequently, inside the fracture, a Stokes flow can be modelled that is coupled to the surrounding elastic medium. A fully coupled approach is obtained by iterating between the phase-field and the fluid–structure interaction model. The resulting algorithm is demonstrated for several numerical examples of quasi-static brittle fractures. We consider both stationary and quasi-stationary problems. In the latter, the dynamics arise through an incrementally increasing given pressure.

Nonlinear Spatial Dynamic Panel Data Models with Endogenous Dominant Units: An Application to Share Data

This article develops a nonlinear spatial dynamic panel data model with one particularly interesting application to a structural interaction model for share data. To account for effects from dominant (popular) units, the spatial weights matrix in our model can allow for unbounded column sums. To account for heterogeneity, our model includes two-way fixed effects and heteroscedastic errors. We further consider the potential endogeneity of the spatial weight matrix constructed from socioeconomic distance. We investigate the quasi-maximum likelihood estimator (QMLE), generalized methods of moments estimator (GMME), and root estimator (RTE), and establish their consistency and asymptotic normality based on the near epoch dependence (NED) framework. The RTE can derive a relatively computationally simple and closed-form solution without evaluating the QMLE’s Jacobian matrix as well as the iterations by GMME. We consider both n , T → ∞ , and the strength of the dominant units is equal to 1 when T → ∞ . For the purpose of empirical analysis, we derive the marginal effects and their limiting distributions based on the proposed estimators. In an empirical application, we apply our model to China’s prefecture city-level data, revealing significant spillover effects of the tertiary industry share. These findings suggest that the development of the tertiary sector in large cities can foster its growth in small cities.

Human–structure interaction effects on lightweight footbridges with tuned mass dampers

The aim of the work is to explore how the interaction between pedestrians and a bridge deck could affect the effectiveness of tuned mass dampers (TMD) in suppressing the vibrations of lightweight footbridges. To this end, a human–structure interaction (HSI) model is built in a modal dynamic analysis framework, and it is applied to a lightweight footbridge subject to a large number of pedestrian arrangements with near-resonant walking frequencies. Compared with the response ignoring HSI, the results show that the interaction between the dynamic response of the pedestrians and the structure can reduce the vibrations in the deck, but they exceed comfort limits based on peak and root mean square (RMS) acceleration criteria. In order to reduce the oscillations to a comfortable level, a TMD located at midspan has been designed following classical optimisation methods that neglect HSI. The efficiency of the damper in resonant conditions is demonstrated in the time and frequency domains, even under a large number of synchronised pedestrians interacting with the structure, suggesting that crowds do not introduce important detuning effects in the TMD.

Vertical Crowd–Structure Interaction Modeling: Numerical and Experimental Assessment of a Cable-Stayed Footbridge

Vertical Crowd–Structure Interaction Modeling: Numerical and Experimental Assessment of a Cable-Stayed Footbridge

A Combined Paddy Field Inter-Row Weeding Wheel Based on Display Dynamics Simulation Increasing Weed Mortality

Weeds compete with rice for sunlight and nutrients and are prone to harboring pathogens, leading to reduced rice yields. Addressing the issues of low weeding efficiency and weed mortality rates in existing inter-row weeding devices, the study proposes the design of a combination paddy field inter-row weeding wheel. The device’s operation process is theoretically analyzed based on the weed control requirements in the northeastern region of China, leading to the determination of specific structural parameters. This research conducted experiments on the mechanical properties of weed cutting to obtain geometric parameters for paddy field weeds. It was found that the range for the cutting gap of the dynamic–fixed blade is between 0.6 mm to 1.4 mm and the cutting angle is between 5° to 15°, resulting in the lowest peak cutting force for weeds. Using LS-DYNA R12.0.0 dynamic simulation software, a fluid–structure interaction (FSI) model of the weeding wheel–water–soil system was established. By employing the central composite experimental design principle and considering the soil stir rate and coupling stress as indicators, the optimal structural parameter combination for the device is obtained: a dynamic–fixed blade cutting gap of 1.4 mm, a cutting angle of 10.95°, and a dynamic blade install angle of −3.44°. Field experiments demonstrated that the device achieved an average weeding rate of 89.7% and an average seedling damage rate of 1.9%, indicating excellent performance. This study contributes to improving weed mortality rates and provides valuable guidance for inter-row mechanical weeding technology.

The interdisciplinary approach as tool of pharmaceutical education of children: from theory to practice

The pharmaceutical literacy is a necessary element of ensuring quality of human life that is to be formed at early age. The article demonstrates that key direction of development of health literacy is pharmaceutical education involving pharmaceutical workers. The necessity of development of pharmaceutical literacy in children through involvement into process of pharmaceutical education pedagogues and parents/legal representatives of child. The article presents analysis of normative legal documents regulating strategic directions of state and international policy in the field of protection of health and rights of minor citizen/children that regulate organization of pharmaceutical and educational activities and requirements to pharmaceutical and pedagogical workers within the framework of their professional role. The problematic zones in organization of pharmaceutical counseling of minors citizen were discovered. The necessity to improve professional competence of pharmaceutical and pedagogical workers in organization of pharmaceutical education of children of preschool and school age is established. The results of sociological survey of minor citizen and their parents demonstrated inadequate level of pharmaceutical literacy of respondents. On the basis of research results structural model of interaction of participants of pharmaceutical education of children (pharmaceutical workers - parents - pedagogues). The communication relations at the stage of transferring pharmaceutical knowledge to minor personality were revealed. The main result of the study is original structural functional model of organization of pharmaceutical education of children implementing interdisciplinary approach in forming pharmaceutical knowledge in children of preschool and school age. The stages of interaction of participants and professional tasks of pharmaceutical and pedagogical specialists in process of teaching children skills of pharmaceutical safety are determined.