Structure Interaction Analysis Research Articles

Fluid Structure Interaction Analyses of Elevated Storage Tank under Seismic Load

Elevated storage tanks are used to store fresh and waste water, cereal, oil and petrochemical materials. Therefore they serve in a wide area of utilization in this day and age. Analysis of a half full with water elevated storage tank is performed in the scope of this study. The structure is composed of a steel circular storage tank and frame typed steel stager. The structure is under the effect of earthquake loads as well as operational ones. Numerical model is generated by Finite Elements Analysis (FEA) software including fluid and structure parts. The interaction of the parts is provided by Coupled Eulerian Lagrangian (CEL) technique. While the structure constitutes the Lagrangian part, the fluid constitutes the Eulerian part. Interaction of Eulerian and Lagrangian parts are provided by general contact algorithms. Free surface movement of the water, maximum displacements and natural frequency values with related mode shapes of the structure are obtained after numerical analysis. Numerical results are verified by semi-analytical model, where the structure is modelled as single degree of freedom system. The accordance between results is numerically and visually obtained. The turbulent movement of water under the influence of an earthquake is modelled by utilizing the CEL technique. So, the effect of the dynamic pressure induced by the turbulence on the tank and the structural system has been taken into consideration.

Design and Analysis of the Exhaust Muffler for Two-Wheeler Vehicle

The muffler is an essential part of every type of car. On two-wheelers, however, it disperses flue gases throughout the atmosphere and reduces engine noise to a bearable level. It is occasionally called an exhaust muffler or a muffler. A silencer's main function is to block off noise produced when flue gas rushes past it quickly. Furthermore, the exhaust gases ought to be released into the atmosphere. The primary focus of this work is on two-wheeled vehicle exhaust mufflers. The current exhaust silencer design is subjected to CFD and fluid structure interaction analysis with engine-specific boundary conditions. The specifications will guide the creation of the muffler's design. ANSYS, a finite element analysis tool is used to measure and verify exhaust gas temperatures, velocities, and back pressure. Furthermore, a modal analysis is conducted to figure out how a geometric adaptation affects the fundamental frequency of the system. The actual testing consists of fabricating a customized exhaust silencer and evaluating it for noise and back pressure on a two-wheeler engine test rig.

Influence of Unbalance and Differential Pressure on the Stability of Vertical Rotor-Seal System

Abstract The rotordynamic (RD) fluid force generated in fluid elements such as seals in turbomachinery affects the stability of turbomachinery and causes shaft vibrations. Various studies have been conducted to clarify the effects of seals on the stability of rotor systems. Many studies have investigated the rotor dynamics of horizontal rotating shaft systems, considering the RD fluid force generated in the seals, and in these studies, the stability of horizontal rotating shaft systems has been assessed via eigenvalue analysis using RD coefficients. However, few studies have analyzed vertical rotating shaft systems. The dynamic behavior of vertical rotating shafts differs significantly from that of horizontal rotating shafts because the weight of the rotor does not act on the seal in a vertical rotating shaft system. Vertical rotating shaft systems are generally prone to instability because of the fluid film whirl, and the amplitude of the shaft whirl tends to be large. When the amplitude is large, the RD fluid force cannot be linearized around the equilibrium point using RD coefficients. Therefore, destabilization and stabilization phenomena that appear in vertical rotating shaft systems cannot be predicted using eigenvalue analysis. Fluid–structure interaction (FSI) analysis that considers the interaction between the shaft vibration and the RD fluid force generated in seals is required to predict such phenomena. This study used FSI analysis to investigate the effects of unbalance and differential pressure on the stability of a vertical rotating shaft system subjected to RD fluid force generated in the seal.

Dynamics of interdomain rotation facilitates FtsZ filament assembly

FtsZ, the tubulin homolog essential for bacterial cell division, assembles as Z-ring at the division site, and directs peptidoglycan synthesis by treadmilling. It is unclear how FtsZ achieves its kinetic polarity that drives treadmilling. To obtain insights into fundamental features of FtsZ assembly dynamics independent of peptidoglycan synthesis, we carried out the structural and biochemical characterization of FtsZ from the cell wall-less bacteria, Spiroplasma melliferum (SmFtsZ). Interestingly the structures of SmFtsZ, determined in GDP and GMPPNP bound form, were captured as domain swapped dimers. SmFtsZ was found to be a slower GTPase and has higher critical concentration (CC) for polymerization compared to Escherichia coli FtsZ (EcFtsZ). In FtsZs, a conformational switch from R-state (close) to T-state (open) favors polymerization. We identified a residue, Phe224, located at the interdomain cleft of SmFtsZ, which is crucial for R- to T-state transition. The mutation F224M in SmFtsZ cleft resulted in higher GTPase activity and lower CC, whereas the corresponding M225F in EcFtsZ resulted in cell division defects in E. coli. Our results demonstrate that relative rotation of the domains is a rate-limiting step of polymerization and that the dynamics of the interdomain rotation is important for the assembly of FtsZ filament. Our structural analysis of interdomain interactions suggests that this step is plausibly triggered upon addition of a GTP-bound monomer to the filament through interaction of the preformed N-terminal domain (NTD). Hence, the addition of monomers to the NTD-exposed end of filament is slower in comparison to the C-terminal domain (CTD) end, thus explaining kinetic polarity. In summary, the study sheds light on the molecular mechanisms underlying FtsZ assembly dynamics and highlights the importance of interdomain interactions, conformational changes, and specific residues in regulating FtsZ polymerization, which are crucial for bacterial cell division.

Multi-objective optimization and correlation development of HPD-type perforated fins based on fluid–structure interaction analysis

In this study, in combination with the flow behavior of HPD-type fins, an HPD-type perforated fin is proposed, which reduces the flow resistance by an average of 55.9% and improves the comprehensive performance by an average of 22.3%. Subsequently, the thermal–hydraulic performance and stress analysis of HPD-type perforated fins are numerically investigated based on fluid–structure interaction analysis. The findings indicate that the performance of HPD-type perforated fins is highly influenced by the fin width Fw. Moreover, the correlations were established using the RSM concerning the j, f-factor, and the maximum stress, with maximum prediction errors of 8.9%, 19.1%, and 5.8%, respectively. Ultimately, the optimized parameter combination for HPD-type perforated fins was determined through GRA, considering maximum JF-factor and minimal maximum stress as the optimization objectives. The outcomes revealed a notable enhancement in the JF-factor by 96.4% and a concurrent reduction in maximum stress by 3.7% under identical conditions. In conclusion, perforating HPD-type fins proves to be an effective strategy for enhancing both thermal–hydraulic performance and stress distribution.

Mechanistic Insight into the Mechanical Unfolding of the Integral Membrane Diacylglycerol Kinase.

The essential forces stabilizing membrane proteins and governing their folding and unfolding are difficult to decipher. Single-molecule atomic force spectroscopy mechanically unfolds individual membrane proteins and quantifies their dynamics and energetics. However, it remains challenging to structurally assign unfolding intermediates precisely and to deduce dominant interactions between specific residues that facilitate either the localized stabilization of these intermediates or the global assembly of membrane proteins. Here, we performed force spectroscopy experiments and multiscale molecular dynamics simulations to study the unfolding pathway of diacylglycerol kinase (DGK), a small trimeric multispan transmembrane enzyme. The remarkable agreement between experiments and simulations allowed precise structural assignment and interaction analysis of unfolding intermediates, bypassing existing limitations on structural mapping, and thus provided mechanistic explanations for the formation of these states. DGK unfolding was found to proceed with structural segments varying in size that do not correlate with its secondary structure. We identified intermolecular side-chain packing interactions as one of the major contributions to the stability of unfolding intermediates. Mutagenesis creating packing defects induced a dramatic decrease in the mechano-stability of corresponding intermediates and also in the thermo-stability of DGK trimer, in good agreement with predictions from simulations. Hence, the molecular determinants of the mechano- and thermo-stability of a membrane protein can be identified at residue resolution. The accurate structural assignment established and microscopic mechanism revealed in this work may substantially expand the scope of single-molecule studies of membrane proteins.

Seismic responses of a fuel assembly in nuclear heating reactor

The fuel assembly (FA) stands as a pivotal component within nuclear reactors, impacting safety, reliability, and economic viability of the entire facility. In the 200 MW nuclear heating reactor (NHR200-II), the FA embodies a novel structural configuration, characterized by a 9 × 9 fuel bundle arrangement enclosed within a singular channel. During seismic events, challenges like potential FA damage and control rod insertion failures can pose safety risks. Therefore, a comprehensive structural integrity assessment is essential. The seismic responses of the NHR200-II FA unidirectionally and bidirectionally under different boundary conditions, using a time-compressed El-Centro N-S earthquake (1.5 times amplification, ∼0.36 g peak acceleration), are analyzed in detail. We examine stress distribution, channel-spacer grid interactions, dynamic clamping, acceleration responses, and response spectra. Results confirm the robust seismic performance of NHR200-II FA, with potential for future seismic fluid–structure interaction analysis based on the model used in this work.

Supramolecular complexes of Co(II), Zn(II) and Mn(II) based on a pyridazine dicarboxylic derivative: Synthesis, crystal structures and properties

Three supramolecular complexes of Co(II), Zn(II) and Mn(II) based on a pyridazine dicarboxylic derivative, namely, {M(H2O)2[H(4-CPCA)]2}·2H2O (M = Co (SNUT-16), Zn (SNUT-17), Mn (SNUT-18), H2(4-CPCA) = 1-(4-carboxyphenyl)-4-oxo-1,4-dihydropyridazine-3-carboxylic acid, have been successfully obtained by the solvothermal method. Single crystal X-ray crystallography reveals that SNUT-16, SNUT-17 and SNUT-18 are isostructural, which exhibit same 3D supramolecular network. Density Functional Theory (DFT) calculations were carried out to ascertain the optimum geometry structures of three complexes with the DFT/B3LYP method at the 6–311Gcomputational level and the calculated HOMO and LUMO energies were presented. Theoretical modeling on the electronic structure properties was performed, quantitative analysis of intermolecular interactions in crystal structures has been conducted using Hirshfeld surface analysis. In addition, the fluorescence, molecular docking and antibacterial properties also had been investigated at room temperature.

Fluid–Structure Interaction Simulations of Wind Turbine Blades with Pointed Tips

The aerodynamic shapes of the blades are of great importance in wind turbine design to achieve better overall turbine performance. Fluid–structure interaction (FSI) analyses are normally carried out to take into consideration the effects due to the loads between the air flow and the turbine structures. A structural integrity check can then be performed, and the structural/material design can be optimized accordingly. In this study, three different tip shapes are investigated based on the original blade of the test wind turbine (Phase VI) from the National Renewable Energy Laboratory (NREL). A one-way coupled simulation of FSI is conducted, and results with a focus on stresses and deformations along the span of the blade are investigated. The results show that tip modifications of the blade have the potential to effectively increase the power generation of wind turbines while ensuring adequate structural strength. Furthermore, instead of using more complicated but computationally expensive techniques, this study demonstrates an effective approach to making quality observations of this highly nonlinear phenomenon for wind turbine blade design.

Investigation on the performance of a torque-driven undulatory swimmer with distributed flexibility

The locomotion of fish provides insight for the design of efficient swimming robotic devices. The current study presents a systematic investigation of the locomotion performance of a fish-like swimmer with a wide range of parameter settings. Two-dimensional simulations with the immersed boundary method in the framework of Navier–Stokes equations are employed for the fluid–structure interaction analysis. Unlike most previous studies where the kinematics of the swimmer is predetermined, the locomotion of the current swimmer is the response of a single periodic torque applied to the anterior part. In addition, current simulations applied a direct correspondence between code units and real-world units, providing more engineering-related guidance for the future design of microrobotic swimmers. The effect of the distribution of body stiffness on swimming performance and propulsion generation is discussed with different pitch frequencies and amplitudes. It was shown that swimmers with a more flexible posterior part have an advantage in undulatory swimming performance when the pitch angle is low or moderate. However, such an advantage disappears when the pitch angle or actuating frequency exceed a certain level. An analysis of the phase-averaged vorticity field and thrust sequence is given to clarify the change in performance due to the variation of flexibility.

The Intriguing Mystery of RPA Phosphorylation in DNA Double-Strand Break Repair.

Human Replication Protein A (RPA) was historically discovered as one of the six components needed to reconstitute simian virus 40 DNA replication from purified components. RPA is now known to be involved in all DNA metabolism pathways that involve single-stranded DNA (ssDNA). Heterotrimeric RPA comprises several domains connected by flexible linkers and is heavily regulated by post-translational modifications (PTMs). The structure of RPA has been challenging to obtain. Various structural methods have been applied, but a complete understanding of RPA's flexible structure, its function, and how it is regulated by PTMs has yet to be obtained. This review will summarize recent literature concerning how RPA is phosphorylated in the cell cycle, the structural analysis of RPA, DNA and protein interactions involving RPA, and how PTMs regulate RPA activity and complex formation in double-strand break repair. There are many holes in our understanding of this research area. We will conclude with perspectives for future research on how RPA PTMs control double-strand break repair in the cell cycle.

Homology Modeling, Molecular Dynamics Simulation, and Prediction of Bovine TLR2 Heterodimerization.

Toll-like receptor 2 (TLR2) is a major membrane-bound receptor with ligand and species specificity that activates the host immune response. Heterodimerization of TLR2 with TLR1 (TLR2/1) or TLR6 (TLR2/6), triggered by ligand binding, is essential to initiating the signaling pathway. Bovine TLR2 (bTLR2) heterodimerization has not been defined yet compared with human and mouse TLR2s (hTLR2 and mTLR2). The aim of the present study was to model bovine TLRs (TLRs 1, 2 and 6) and create the heterodimeric forms of the bovine TLR2 using molecular dynamics (MD) simulations. We compared the intermolecular interactions in bTLR2/1-PAM3 and bTLR2/6-PAM2 with the hTLR2 and mTLR2 complexes through docking simulations and subsequent MD analyses. The present computational findings showed that bTLR2 dimerization could have a biological function and activate the immune response, similar to hTLR2 and mTLR2. Agonists and antagonists that are designed for hTLR2 and mTLR2 can target bTLR2. However, the experimental approaches to comparing the functional immune response of TLR2 across species were missing in the present study. This computational study provides a structural analysis of the bTLR2 interaction with bTLR1 and bTLR6 in the presence of an agonist/antagonist and reveals the three-dimensional structure of bTLR2 dimerization. The present findings could guide future experimental studies targeting bTLR2 with different ligands and lipopeptides.

Machine learning-based soil–structure interaction analysis of laterally loaded piles through physics-informed neural networks

Machine learning-based soil–structure interaction analysis of laterally loaded piles through physics-informed neural networks

Whole-heart modelling with valves in a fluid–structure interaction framework

Computational modelling of whole-heart function is a useful tool to study heart mechanics and haemodynamics. Many existing heart models focus on electromechanical aspect without considering physiological valves and use simplified fluid models instead. In this study we develop a four-chamber heart model featuring realistic chamber geometry, detailed valve modelling, hyperelasticity with fibre architecture and fluid–structure interaction analysis. Our model is used to investigate heart behaviours with different modelling assumptions including restricted/free valve annular dynamics, and with/without heart-pericardium interactions. Our simulation results capture the interactions between valve leaflet and surrounding flow, typical left ventricular flow vortices, typical venous and transvalvular flow waveform, and physiological heart deformations such as atrioventricular plane movement. The improvement of ventricular filling and atrial emptying at early diastole is evident with free annulus. In addition, we find that the added pericardial forces on the heart have a predominant effect on atrial wall deformation especially during atrial contraction, and further help with the atrial filling process. Most importantly, the current study provides a framework for comprehensive multi-physics whole-heart modelling considering all heart valves and fluid–structure interactions.

Sensitivity Analysis of Underwater Structural-Acoustic Problems Based on Coupled Finite Element Method/Fast Multipole Boundary Element Method with Non-Uniform Rational B-Splines

For the direct differentiation technique-based modeling of acoustic fluid–structure interaction and structural-acoustic sensitivity analysis, a coupling algorithm based on the finite element method (FEM) and the fast multipole boundary element method (FMBEM) is suggested. By bypassing the challenging volume parameterization process in isogeometric finite element techniques and the laborious meshing process in traditional FEM/BEM, non-uniform rational B-splines (NURBS) isogeometric analysis (IGA) is utilized to immediately perform numerical analysis on CAD models. The matrix-vector products in the boundary element analysis are accelerated using the fast multipole method (FMM). To hasten the solution of the linear system of equations, the iterative solver GMRES is used. The numerical prediction of the effects of arbitrarily shaped vibrating structures on the sound field is made feasible by the FEM/FMBEM technique. A number of numerical examples are provided to show the applicability and effectiveness of the suggested approach.

O USO DAS FERRAMENTAS DA ANÁLISE DA SUPERFÍCIE DE HIRSHFELD NO ESTUDO DAS LIGAÇÕES NÃO-COVALENTES EM COMPLEXOS CORRELATOS

THE USE OF HIRSHFELD SURFACE ANALYSIS TOOLS IN THE STUDY OF NON-COVALENT BONDS IN RELATED COMPLEXES. The analysis of non-covalent interactions in crystalline structures through the Hirshfeld surface method using the CrystalExplorer® software has been widely used by the global scientific community over the past few decades. Although widely recognized, as far as we know, there has been no publication on this subject in the Química Nova journal. Therefore, in this work, we intended to demonstrate how these tools could be employed to study and compare the non-covalent bonds in 21 mononuclear complexes of the type [MY2(o-XPy)2], [MY2(m-XPy)2], and [MY2(p-XPy)2], where M = Zn2+ or Co2+, Y = Cl-, Br-, or I-; Py = pyridinic ligand ortho-, meta-, or para-monosubstituted by X, where X = Cl-, Br-, or I-. With a main emphasis on halogen bonds and π···π stacking interactions, the study demonstrates how Hirshfeld analysis can be used for a qualitative and quantitative comparison of non-covalent bonds, proving to be an important tool for a comprehensive understanding of the forces that stabilize these complexes in the solid-state. The study demonstrates the potential of Hirshfeld surface analysis as a valuable resource for synthetic chemists to select chemical species for rational synthesis and achieve desired properties or supramolecular arrays.

Numerical analysis of inflow turbulence intensity impact on the stress and fatigue life of vertical axis hydrokinetic turbine

The present study aims to analyze the effect of upstream turbulence intensity on the hydrodynamic and structural performance of the straight-blade vertical axis turbine. To achieve this, a one-way fluid structure interaction analysis is conducted within the ANSYS workbench environment. Initially, computational fluid dynamics (CFD) simulation is performed at different values of upstream velocity values. Additionally, the impact of upstream turbulence intensity is also analyzed. The CFD simulation results were validated against published experimental work. Once CFD simulation is performed then computed fluid loads are transferred to the ANSYS mechanical structural module. Finite element modeling is performed to compute the stresses and the fatigue life. The study reveals that increasing the upstream turbulence intensity from 5% to 20% leads to 8.6% improvement in the turbine's power performance. However, turbulence intensity also results in 35.6% increase in Von-Mises stresses produced within the designed turbine. However, even with this increase, the Von-Mises stresses remain below a critical threshold, measuring at 173.34 MPa when the upstream water velocity is 1.4 m/s, and the inflow turbulence intensity is at 20%. This stress level is well within the material's yield strength, ensuring the turbine's structural integrity. Moreover, the simulation results emphasize that turbulence intensity has a significant impact on the turbine's fatigue life. Further, it is predicted that an increase in turbulence intensity from 5% to 20% leads to a significant 40% reduction in the turbine's fatigue life. The stress analysis results reveal that struts, strut–blade joints, and strut–shaft joints are the key stress concentration areas. The results suggested that an increase in upstream turbulence intensity has favorable impact on turbine performance, however, for highly turbulent flows turbine should have higher strength and key areas should be focused on designing turbine for such flow conditions.

A Structural Analysis of Host-Parasite Interactions in Achatina fulica (Giant African Snail) Infected with Angiostrongylus cantonensis.

Angiostrongylus cantonensis is a nematode parasite that resides in the pulmonary arteries of rodents, serving as its definitive hosts. The life cycle involves several species of non-marine gastropods as intermediate hosts, and the African giant snail Achatina fulica is considered one of the most important around the world. Experimental data concerning A. cantonensis infection in the African giant snail remains notably limited. This helminth causes eosinophilic meningitis or meningoencephalitis in humans, representing an emergent zoonosis in Brazil. Understanding the host-parasite relationship through the application of new tools is crucial, given the complex interaction between zoonosis and the intricate mechanisms involving wild/human hosts, parasite adaptation, and dispersion. The objective of this study was to employ SEM as a novel methodology to understand the structural organization of the host tissue, particularly the granuloma formation. This sheds light on the complex balance between A. fulica and A. cantonensis. Nine three-month-old snails were randomly selected and exposed for 24 h to a concentration of 2000 L1/dose of A. cantonensis. A necropsy was performed 37 days after the infection, and the samples were examined using light and scanning electron microscopy (SEM). The histopathological results revealed third-stage larvae of A. cantonensis associated with granulomas distributed throughout the head-foot mass, mantle, and kidney. Scanning electron microscopy of the histological section surface showed that the granuloma is surrounded by a cluster of spherical particles, which are distributed in the region bordering the larvae. This reveal details of the nematode structure, demonstrating how this methodology can enhance our understanding of the role of granulomas in molluscan tissue. The structural characteristics of granuloma formation in A. fulica suggest it as an excellent invertebrate host for A. cantonensis. This relationship appears to provide protection to the parasite against the host's immune defense system while isolating the snail's tissue from potential exposure to nematode antigens.

Soil–Structure Interaction Analysis Using the Finite Element Method in Thin-Walled Steel Pipes Buried under Haul Roads

This paper addresses the challenges associated with steel pipes used for transporting liquid fluids within buried sections of mining facilities, specifically in areas with heavy mining vehicles. While existing design standards, such as AW-WA M11, and manufacturer recommendations largely consider loads from vehicles like the AASHTO HS20 or Cooper E-80, both weighing below 35 tons, these guidelines inadequately represent the actual loads experienced on certain mining roads, notably those accommodating heavy vehicles, like haul roads. The research presented here focuses on the interaction between soil and buried steel pipes under the substantial loads exerted by mining vehicles with a maximum gross load of up to 612 tons, inclusive of hauled material weight. Utilizing a parametric study with the finite element method, the paper identifies critical variables influencing efforts and deflections calculations in these facilities. The analysis of 108 models, varying parameters related to trench pipe installation conditions, offers insights that empower designers to refine soil trench parameters in mining facilities, mitigating pipe failures and optimizing installation costs. Ultimately, the key influential variables affecting pipe deflection and stress are identified as the trench backfill height and the elasticity modulus of the trench lateral fill.

Two-way coupling fluid–structure interaction analysis on dynamic response of offshore wind turbine

The monopile-supported offshore wind turbines (OWTs) are subjected to the wave and current loadings. Affected by currents and waves, monopile-supported OWTs are also vulnerable to scour. However, the effect of scour and currents on the dynamic behavior of the monopile are not fully appreciated. This study conducted the model tests to evaluate the effect of scour depth and flow velocity on the lateral responses of support structure. Furthermore, the two-way (T-W) coupling fluid–structure interaction (FSI) method was proposed to evaluate the dynamic responses of piles in sand. The support structure is modeled using ABAQUS, a finite-element models software package, by considering the nonlinear soil–structure interaction effects, STAR-CCM + tools has been employed to model the FSI which are fed into ABAQUS to predict the structure’s dynamic response. Using the proposed method, a parametric study has been conducted to evaluate the effects of scour depths, flow velocities on the dynamic responses of OWTs. The results indicate that scour altered the fundamental frequency of OWT, causing resonance. An increase in scour depth and flow velocity increased the dynamic responses of support structure, which are detrimental for the safety and stability of the OWT system.