Analysis Of Structural Behavior Research Articles

Toward enhanced mechanical rigidity: additive manufacturing of auxetic tubes with PU core and comparative analysis of unique structural behaviors

Toward enhanced mechanical rigidity: additive manufacturing of auxetic tubes with PU core and comparative analysis of unique structural behaviors

Incomplete dissolved behavior and mechanical analysis of SnAgCu-SnBi composite solder structures for high-reliable package-on-package techniques

Due to the development of advanced packaging technology such as Package on Package (POP), traditional Sn-Ag-Cu (SAC) solder can no longer meet the demand. Utilizing the differences in temperature and performance of various solder materials to create composite structures for soldering is an effective method to achieve PoP interconnection. In this research, the microstructure of the interface between SAC305 and liquid in the incomplete dissolved solider ball was observed, and the grain orientation after solidification was analyzed. In addition, the effect of SnBi ratios on the microstructure and mechanical properties of SAC305-SnBi composite solder balls, and the fracture mechanism was analyzed according to the fracture morphology. The results show that according to Electron Backscatter Diffraction (EBSD) analysis, the grain size of Sn-Ag-Cu-Bi is small, and the orientation tends to be the same. With the rise in SnBi content, the eutectic structure in the solder ball exhibited a progressive increase and the IMC at the interface gradually changed from uneven rod-like structure to more uniform scallop-like structure. When the weight fraction of SnBi is 66.7%, the shear strength researches a maximum value of 62.2 MPa. As the SnBi content increases, there is an observable shift in the fracture location from the IMC to the solder.

Similitude laws for dynamic response of beam-plate coupled structure

The beam-plate coupled structure is a typical structure in spacecraft solar wings, and the prediction of its mechanical environment is crucial for overall design, structure and mechanism subsystem design. However, it is usually difficult to perform ground simulation tests on spacecraft solar wings with full-size structure. Therefore, a scaled model is established based on similarity theory to forecast the dynamic response of the full-size structure. In this article, finite element (FE) and hybrid finite element-statistical energy analysis (FE-SEA) models of the beam-plate coupled structure are established according to the band division principle. Finite element model allows for detailed analysis of structural behaviour, while hybrid models incorporate statistical energy analysis to account for high-frequency dynamics. By integrating these approaches, a comprehensive understanding of the coupled structure’s response can be achieved, facilitating efficient design and optimisation processes. The scaling laws of the dynamic response are obtained by combining the dimensional analysis and equation analysis methods, respectively. The scaled models are designed for verification, and the natural characteristics and vibration responses predicted by the scaled models are basically consistent with those of the prototype. The findings indicate that the prediction accuracy derived from the FE-SEA model is higher, which provides a novel approach for the dynamic similarity of complicated structures such as the solar wings of spacecraft.

Comprehensive sensitivity analysis of repeated eigenvalues and eigenvectors for structures with viscoelastic elements

The paper discusses systems with viscoelastic elements that exhibit repeated eigenvalues in the eigenvalue problem. The mechanical behavior of viscoelastic elements can be described using classical rheological models as well as models that involve fractional derivatives. Formulas have been derived to calculate first- and second-order sensitivities of repeated eigenvalues and their corresponding eigenvectors. A specific case was also examined, where the first derivatives of eigenvalues are repeated. Calculating derivatives of eigenvectors associated with repeated eigenvalues is complex because they are not unique. To compute their derivatives, it is necessary to identify appropriate adjacent eigenvectors to ensure stable control of eigenvector changes. The derivatives of eigenvectors are obtained by dividing them into particular and homogeneous solutions. Additionally, in the paper, a special factor in the coefficient matrix has been introduced to reduce its condition number. The provided examples validate the correctness of the derived formulas and offer a more detailed analysis of structural behavior for structures with viscoelastic elements when altering a single design parameter or simultaneously changing multiple parameters.

Increased stability of short femoral stem through customized distribution of coefficient of friction in porous coating

Stress shielding and aseptic loosening are complications of short stem total hip arthroplasty, which may lead to hardware failure. Stems with increased porosity toward the distal end were discovered to be effective in reducing stress shielding, however, there is a lack of research on optimized porous distribution in stem’s coating. This study aimed to optimize the distribution of the coefficient of friction of a metaphyseal femoral stem, aiming for reducing stress shielding in the proximal area. A finite element analysis model of an implanted, titanium alloy short-tapered wedge stem featuring a porous coating made of titanium was designed to simulate a static structural analysis of the femoral stem's behavior under axial loading in Analysis System Mechanical Software. For computational feasibility, 500 combinations of coefficients of friction were randomly sampled. Increased strains in proximal femur were found in 8.4% of the models, which had decreased coefficients of friction in middle medial areas of porous coating and increased in lateral proximal and lateral and medial distal areas. This study reported the importance of the interface between bone and middle medial and distal lateral areas of the porous coating in influencing the biomechanical behavior of the proximal femur, and potentially reducing stress shielding.

Graphene oxide nanoparticles synthesized from waste tires: A multi-faceted analysis of structure, morphology and antibacterial behavior

In recent years, the sustainable utilization of waste materials has become a significant research area due to environmental concerns and resource scarcity. Graphene oxide nanoparticles (GONPs) are regarded as one of the most important materials due to their capacity to serve as a potentially scalable precursor to graphene and, more recently, as the most promising substance in biomedical research. This study successfully explores the synthesis of GONPs using recovered carbon black (rCB) derived from waste tires. The structural, morphological and antibacterial properties of the synthesised GONPs in this study were highlighted. The intensity ratio (ID/IG) from Raman spectroscopy analysis, obtained at 0.82, with FTIR spectral results shows the functional groups of hydroxyl, carboxyl and epoxy, similar to GO synthesised from pure graphite. TEM analysis showed that the surface morphology of the GONPs contains nanoparticles with a size of 44.95 nm. Despite using waste material, GONPs exhibited potential antibacterial activity towards the gram-positive and gram-negative bacteria tested in this study. The data presented here are novel and show the possibility of GONP synthesis from waste tires as a future cost-effective antibacterial agent.

Research on Modal Behavior of Large Francis Turbine Runner

The water-added-mass can affect the modal behavior of the Francis turbine runner largely. The sealing rings in the band-chamber and the crown-chamber outside of the runner are utilized to prevent leakage of water around the Francis turbine. The sealing rings and the chambers filled with water can also affect the modal behavior of the turbine. When the turbine runner operates in the power plant at various operating conditions, the seal clearances of the band-chamber and the crown-chamber filled with water may change the modal behavior of the large Francis turbine runner. Firstly, the 3D geometrical structure of the studied large-scale Francis turbine runner was constructed, and then the CAD model was meshed to establish the finite-element model for numerical analysis. Next, the modal shapes and the natural-frequencies of runners in the air were calculated, which is the traditional method used for the structural modal behavior analysis of the turbine runners. Finally, this paper investigates the modal behavior of a large-scale Francis runner prototype with the combined effects of sealing rings and water added-mass by direct water-structure coupled analysis via the finite element method (FEM) to obtain more realistic results. The results reveal that the effects of water-added-mass and sealing rings cause a significant decrease in the natural-frequency of the large Francis turbine runner, which may lead to an increase in the amplitude of vibrations and even cracks. Technical suggestions are proposed to improve the monitoring and maintenance in the power stations to maintain the safe and efficient operation of the large Francis turbine units.

Homogenization of rammed earth walls under changing environmental conditions

Construction with rammed earth walls is a technique used for the construction of structures that has been increasing and by its nature requires in-depth knowledge due to the exposure of its materials (soil) to environmental factors, such as precipitation and solar radiation. This causes its structural elements to experience humidity fluctuations that affect the soil that constitutes them, resulting in a structure built with a material with heterogeneous properties, a fact that makes it difficult to understand its behaviour. The use of simulations in numerical models has helped to understand the internal dynamics of these elements. However, these procedures can present challenges in model construction and can also be computationally expensive, depending on the complexity of the model. In this context, the present research focuses on examining the behaviour of rammed earth walls against seismic action, when despite being made up of a single material, its composition is considered heterogeneous due to the humidity variations inherent to its exposure. Next, these models were subjected to a homogenization process of its properties using the Hashin and Shtrikman homogenization bounding theory. The objective is to find equivalent properties that facilitate the analysis of structural behaviour, assuming the homogeneity of the material. This homogenization process was extended to all parameters defined within the Pressure Independent Multi-yield material model employed in OpenSees, encompassing shear modulus, bulk modulus and density. As a result, applying Hashin and Shtrikman's upper bound to homogenize rammed earth walls produces remarkably similar results to those obtained using simulations of heterogeneous walls. This research provides valuable insights to understand rammed earth wall homogenization techniques and their behaviour, with important implications for their design and analysis.

Design, control, aerodynamic performances, and structural integrity investigations of compact ducted drone with co-axial propeller for high altitude surveillance

Compact multi-rotor unmanned aerial vehicles (UAVs) can be operated in many challenging environmental conditions. In case the UAV requires certain considerations in designing like lightweight, efficient propulsion system and others depending upon the application, the hybrid UAV comes into play when the usual UAV types cannot be sufficient to meet the requirements. The propulsion system for the UAV was selected to be coaxial rotors because it has a high thrust-to-weight ratio and to increase the efficiency of the propulsion system, a unique propeller was proposed to achieve higher thrust. The proposed propeller was uniquely designed by analyzing various airfoil sections under different Reynolds’s number using X-Foil tool to obtain the optimum airfoil section for the propellers. Since the design with duct increases efficiency, the Hybrid UAV presented in this paper has the modified novel convergent–divergent (C–D)-based duct which is a simplified model of a conventional C–D duct. The yawing and rolling maneuverings of the UAV could be achieved by the thrust vectoring method so that the design is simpler from a structural and mechanical perspective. The use of UAVs has risen in recent years, especially compact UAVs, which can be applied for applications like surveillance, detection and inspection, and monitoring in a narrow region of space. The design of the UAV is modeled in CATIA, and its further performance enactment factors are picked from advanced computational simulations relayed bottom-up approach. The predominant computational fluid dynamics (CFD) and fluid structure interaction (FSI) investigations are imposed and optimized through Computational Analyses using Ansys Workbench 17.2, which includes analysis of structural behaviour of various alloys, CFRP and GFRP based composite materials. From the structural analysis Titanium alloy came out to be the best performing materials among the others by having lower total deformation and other parameters such as normal and equivalent stress. The dynamics control response is obtained using MATLAB Simulink. The validations are carried out on the propeller using a thrust stand for CFD and on the duct through a high-jet facility for structural outcomes to meet the expected outcome.

Cs+ substituted SrZnFe2O4 nanoparticles: analysis of structural, morphological and electrical behavior

Cs+ substituted SrZnFe2O4 nanoparticles: analysis of structural, morphological and electrical behavior

Analysis of Flexible Pavement Structural Behavior Considering Decreased Subgrade Resilient Modulus

This research focuses on the subgrade resilient modulus and its significance in investigating flexible pavements. The study compares results obtained from two distinct flexible pavement structures, utilizing numerical analysis using FLAC3D softawere. Four decreasing levels of subgrade resilient modulus (PF50, PF25, PF10, and PF5) were examined. Our findings reveal that the decrease in subgrade resilient modulus has a more pronounced effect on the GB/GB structure compared to the GB/GNT structure, with the latter demonstrating superior performance. By assessing subgrade resilient modulus, this research contributes to a better understanding and improving road infrastructure investigation not only in Algeria but also in broader contexts

Structural Behavior Analysis of the Beam-Column Connections of Existing Steel Structure Buildings based on Finite Element Modeling-Idea StatiCa

Structural Behavior Analysis of the Beam-Column Connections of Existing Steel Structure Buildings based on Finite Element Modeling-Idea StatiCa

Three-dimensional mechanical characteristics analysis of bolted joints and loosening mechanism

Bolted joints are widely used in various industries. However, in challenging conditions such as shock, vibration, and temperature fluctuations, threads can loosen, leading to equipment damage and accidents. Scholars have introduced self-locking thread designs like wedge-shaped self-locking threads and stepped threads to improve anti-loosening performances. While experiments support their effectiveness, previous research primarily focused on optimizing thread structure parameters, and the studies of loosening mechanism are not in-depth enough, which restricts the development of anti-loosening bolted joints. This paper proposes a parametric modeling approach to create 3D elastic–plastic finite element models of bolted joints with different thread profiles. This approach allows for a comprehensive analysis of structural behavior, stress distribution, and load conditions, enabling the in-depth examination of the mechanical properties for thread loosening. A novel arc-lock anti-loosening threads design is proposed. Arc-lock threads are found to provide superior load distribution uniformity, increased normal force, and enhanced frictional resistance. Furthermore, the correctness of the finite element results is validated through photoelastic experiments and transverse vibration experiments. Results show that under a preload force of 225.5kN, the assembly of M24 Grade 10.9 bolts with Grade 10 nuts exhibit RMSE (Root Mean Square Error) values of 11.25, 9.02, and 8.76 for regular threads, wedge-shaped threads and arc-lock threads, respectively. Arc-lock threads demonstrate a more uniform stress distribution. In transverse vibration experiments under fully tightened conditions, regular threads loosened at the 2326th vibration cycle, while wedge-shaped self-locking threads and arc-lock threads maintained the preload percentages of 91.24% and 93.51%, respectively. These findings offer a scientific basis for understanding anti-loosening mechanisms in bolted joints and inform anti-loosening thread design.

Holistic Exploration of Structural, Electronic, Magnetic, Transport, Mechanical, and Thermodynamic Characteristics, Including Curie Temperature Analysis.

Through intricate calculations, the density functional theory (DFT) implemented in the Wien2k code was employed to comprehensively investigate a wide range of material characteristics. Our study encompasses an exhaustive analysis of structural stability, electronic properties, magnetic behaviors, transport phenomena, mechanical responses, and thermodynamic profiles of two notable instances of filled Skutterudites, namely, CeNi4P12 and DyCo4Sb12, which have been thoroughly explored. These computations were performed using the WIEN 2K code, combining local orbitals and the full-potential linearized augmented plane-wave approach. The findings provided insight into the wide range of properties of these materials. In this methodology, the exchange-correlation potential relies on the local-density approximation. We conducted the calculations with and without incorporating spin-orbit interactions. The results obtained provide information about the lattice constant, bulk modulus, and pressure derivative. The stability, as indicated by the P-V graphical plot, suggests that there are no structural phase transitions from the cubic symmetry structure. Notably, our work includes an examination of Curie temperatures, which are pivotal in understanding magnetic phase transitions. The validated elastic properties further support the material's stability and corroborate its ductile nature. These alloys should be considered for spintronic and thermoelectric applications due to their estimated transport characteristics and the observed ductile nature. To enhance our understanding of the thermal stability of antimony-based compounds, we have made reliable estimations of the thermophysical characteristics. By integrating theoretical insights with practical implications, we bridge the gap between fundamental understanding and material design applications. Using DFT in the Wien2k framework, we discover connections and patterns among different properties, showing how to create materials with specific functions and better performance. This approach not only advances our fundamental comprehension of materials but also promises innovation across various technological domains.

Assessment of shear capacity in NSM prestressed FRP strengthening with anchorage conditions

Efforts to achieve a defect-free flat groove in near-surface-mounted prestressed fiber-reinforced polymer (FRP) strengthening systems have proven challenging. Despite attempts, attaining an ideal groove remains formidable. In this system, anchorage device installation involves injecting epoxy resin into groove defects to achieve planarity. Structural behavior analysis and optimization of the anchorage device were conducted based on device type, anchor type, and defect depth through shear loading tests. The mechanical anchor demonstrated an ultimate load of 261 kN, with failure modes including concrete cracking, concrete compression failure, and anchor tensile failure. The chemical anchor exhibited an ultimate load of 390 kN, with its final failure attributed to anchor tensile failure. The ultimate load capacity of anchorage device surpassed that of a carbon FRP(CFRP) bar by up to 62.5%. In a parametric study, the shear strength of the anchorage device was explored concerning concrete compressive strength and anchor diameter. The ultimate load of the proposed model with low concrete compressive strength proved insufficient compared to the strength of CFRP rebar.

Analysis of structural behavior of thin wall façade using textile reinforced concrete

Recently, textile reinforced concrete has been increasingly used in the production of precast thin wall facade. This type of material has advantages such as lightweight and corrosion resistance. The purpose of this paper is to analyze the flexural behavior of thin wall panels using textile reinforced concrete through experimental and numerical simulation methods. The experimental study was conducted to determine the load capacity, stiffness, and failure mode of the wall panels. The numerical simulation study showed similar results to the experimental study. Therefore, the results demonstrate the potential of numerical simulation methods in the design of thin wall panels using textile reinforced concrete.

Finite element method studying the reliability of taper steel frame with semi-rigid connected impact wind load

This article studies the application of the Stochastic Finite Element Method (SFEM) to analyze beveled frames with semi-rigid connections subjected to wind loads when the connection and load parameters are random quantities. The structural behavior analysis algorithm is a combination of the SFEM method and Monte-Carlo simulation. The calculation program was then used to evaluate the reliability of the semi-rigidly connected beveled steel frame subjected to wind loads.

A real-time quantitative acceleration monitoring method based on triboelectric nanogenerator for bridge cable vibration

Real-time monitoring of vibration acceleration of civil infrastructure is imperative for effective management and safe operation of structures. Although the triboelectric nanogenerator (TENG) shows potential for self-powered sensing, it faces challenges in correlating limited experimental electrical amplitudes to structural responses, thereby hindering comprehensive performance analysis of civil infrastructure. Herein, a self-driven acceleration TENG sensor (A-TENG) is designed and manufactured, comprising an outer shell and an inner mass-spring-damper system. By establishing a sensing model based on vibration theory and the TENG mechanism, the electrical signals generated by the sensors can be correlated with structural acceleration, enabling self-driven real-time quantitative characterization. Indoor and on-site experiments demonstrate that the A-TENG sensor is capable of continuously monitoring the acceleration profile with excellent consistency compared to commercial sensors. The non-contact free-standing sliding mode design and ultra-lightweight construction of the A-TENG sensor (∼8 g) enhance its start-up sensitivity (∼0.1 m/s2), long-term stability (∼30,000 loading cycles) while minimizing mass interference. The proposed sensing theory renders a novel approach to offering complete time-domain information, which is vital for the precise analysis of structural behavior. This work facilitates understanding of self-driven sensors utilizing TENG technology and provides a useful tool for long-term real-time quantitative structural health monitoring.

Machine learning prediction of structural dynamic responses using graph neural networks

Prediction of structural responses is essential for the analysis of structural behaviour subjected to dynamic loads. Existing approaches are limited in different ways. Experimental tests are expensive due to the requirement of intensive labour hours and specialised equipment. Numerical models can provide high-fidelity and labour-effective simulation of impact tests after proper validation, but it comes with high computational costs, which prohibit the usage of numerical methods for intensive and large-scale simulations in a design office. Data-driven machine learning approaches are also applied to structural response predictions, but they often exploit direct input–output mapping schemes that predict static field variables without capturing the dynamic response process. To close these gaps, we propose a novel machine learning approach based on graph neural networks (GNN) for full-field structural dynamics prediction. Our approach adopts a discretised representation of structures with an iterative rollout prediction scheme, and therefore it can simulate comprehensive spatiotemporal structural dynamics, providing the full potential for structural dynamics analysis. With several benchmark tests, it is demonstrated that our approach can generate accurate predictions of related field variables, e.g., displacement, strain, and stress, for different structures with a wide range of input parameters, such as structure geometry, impact speed and location. Additional interpolation and extrapolation tests are also conducted to show that our approach enjoys inherent generalisability and can produce satisfactory prediction even when all inputs are sampled outside of the training distribution. Our approach is also efficient and runs an order of magnitude faster than the commonly used numerical competitors. As the first attempt of using GNN for structural dynamics prediction and the result is promising, it is believed that GNN is well-suited for effective and efficient prediction of dynamic structural responses.

Burnout resistance of concrete‐filled steel tubular (CFST) columns under realistic fire conditions

AbstractIn this paper, we investigate the structural behaviour of concrete‐filled steel tubular (CFST) columns under various fires. Our contribution is based on two fire scenarios in modelled FDS with subsequent 3D FE numerical analysis (Abaqus), where material properties are defined for heating and cooling using user subroutines. Our goal is to examine the burnout resistance of CFST columns under different realistic fire scenarios involving varying number of burning cars.The loss of compressive strength of concrete due to high temperature is irreversible. Hence, the burnout resistance is affected by the field of the highest temperatures reached inside the column. Moreover, the pre‐existing load affects the deformation of the column during heating and influences the post‐fire behaviour. The analysis is performed in several steps: first, results from the CFD models are extracted and appropriately mapped, then the heat transfer analysis between fire and solid is performed, and the resulting temperature history of the CFST column is calculated. Subsequently, a mechanical analysis is performed, where (1) the column is loaded, (2) the analysis of the column's structural fire behaviour is carried out, (3) if the column sur‐vives burnout, then in the last step, it is loaded until failure.