Dynamic Finite Element Analysis Research Articles

Energy-absorbing limitations of hard hat safety helmets in mitigating trauma from falling objects

The aim of the study was to analyze the effectiveness of hard hat helmets in mitigating head injuries from high-energy falling objects through a real-world case study, advanced numerical simulations and an uncertainty study. The study aims to answer the following research questions: (a) to what extent would the use of the protective helmet limit the kinetic energy of the falling construction prop, (b) whether the hard hat helmet would be damaged, and if so, to what extent, according to the helmet standards? A fatal construction accident involving a falling prop impact on the victim’s head was reconstructed using multi-body dynamics simulations and finite element analysis (FEA) based on uncertainty-based determination of initial conditions. The study quantified the impact energy, helmet damage and its energy-absorbing capabilities, and potential injury reduction compared to scenarios without a helmet. While the helmet absorbed significant energy (245% of the standard requirement) and reduced the Head Injury Criterion by 8–11%, the high impact energy ultimately proved fatal. This study highlights the limitations of hard hat helmets in extreme scenarios with high kinetic energy impacts. While helmets offer valuable protection, unrealistic expectations should not be placed on their ability to prevent all head injuries. The study not only enhances our understanding of the biomechanics of head injuries in such incidents but also provides practical implications for safety protocols and regulations.

Motion reconstruction and finite element analysis of the temporomandibular joint during swallowing in healthy adults

There is a close physiological connection between swallowing and the temporomandibular joint (TMJ). However, a shortage of quantitative research on the biomechanical behavior of the TMJ during swallowing exists. The purpose of this study was to reconstruct the movement of the temporomandibular joint (TMJ) based on in vivo experiment and analyze the biomechanical responses during swallowing in healthy adults to investigate the role of the TMJ in swallowing. Motion capture of swallowing, computed tomography (CT), and magnet resonance images (MRI) were performed on six healthy subjects. The movements of the TMJ during swallowing were reconstructed from the motion capture data. The three-dimensional finite element model was constructed. The dynamic finite element analysis of the swallowing process was performed based on the motion data. The range of condylar displacement was within 1 mm in all subjects. The left and right condyle movements were asymmetrical in two-thirds of the subjects. The peak stresses of the discs were relatively low, with a maximum of 0.11 MPa. During swallowing, the condylar displacement showed two trends: slow retraction and slow extension. The tendency to extend could lead to a gradual increase in stress on the disc.

Mechanistic insight into the Janus Green B on electrochemical roughening layer of copper foil

This study explores the impact of the electroplating additive JGB the surface characteristics and peel strength of electrolytic copper foils used in printed circuit boards. Utilizing Scanning Electron Microscopy and Atomic Force Microscopy, we found that optimal JGB concentrations enhance the morphology and roughness of the copper foil roughening layer while maintaining high peel strength. The ideal concentration of 3 mg/L achieved an average roughness of 0.953 µm and a peel strength of 0.946 N/mm. JGB's effectiveness in inhibiting copper deposition was confirmed through cyclic voltammetry, linear sweep voltammetry, and electrochemical impedance spectroscopy. Density Functional Theory calculations and in situ infrared spectroscopy elucidated JGB's adsorption and coordination actions, which have a synergistic effect on its inhibitory performance. Further investigations with molecular dynamics simulations and finite element analysis demonstrated JGB's preferential adsorption in areas of high electric field intensity, effectively controlling the copper grain morphology in the roughening layer. This research highlights the potential of dye-type additives in improving copper foil roughening for printed circuit boards applications. Future research should explore the long-term stability and environmental impact of JGB in industrial applications, while investigating other dye-type additives may further optimize the roughening process to meet diverse printed circuit boards manufacturing needs.

Seismic fragility assessment of embankment: A displacement-based approach using dynamic finite element model analysis

Abstract The assessment of seismic fragility of highway embankments is a key component of seismic risk modeling for traffic infrastructure. This study examines the seismic fragility of an embankment using advanced finite element dynamic analysis, contrasting findings with prior research to validate results. Based on established methodologies, an incremental dynamic analysis (IDA) was executed, with the Probabilistic Seismic Demand Analysis (PSDA) for the development of fragility curves. A comparative study was conducted between two modeling methods; one employing finite difference (FD) method and other employing finite element (FE)method. The analysis revealed that, selection of inputs like the nature of earthquake time history and number of records selected along with the analysis method influences the seismic fragility assessment of embankments. The choice between finite difference and finite element methods can yield differing results, with FD, being grid-based, can face challenges with complex geometries and boundary conditions, on the other hand, FE’s mesh-based approach offers flexibility in modeling intricate domains, handles complex boundary conditions more adeptly, and provides a more continuous representation of material behavior. A distinct dynamic stability test based on Newmark sliding block principles showed the embankment slope’s inherent resilience, with no permanent deformation, underscoring the requirement for further research.

Advanced analysis and construction techniques for long-span spatial structures in steel engineering

This paper explores advanced analysis methods and construction techniques for long-span spatial structures in steel engineering. It delves into the principles of the Direct Analysis Method (DAM), emphasizing equilibrium, compatibility, plasticity, and stability, as well as load path and redundancy considerations. The DAM provides a robust framework for analyzing complex steel structures, ensuring stability, resilience, and efficiency. Furthermore, the paper discusses modeling techniques, including Finite Element Analysis (FEA), dynamic analysis, and nonlinear analysis, highlighting their significance in optimizing design solutions and predicting structural behavior under diverse loading conditions. Practical considerations in material selection, connection design, and construction are addressed, focusing on enhancing performance, durability, and constructability. Prefabrication and modular construction techniques are explored as effective strategies for accelerating project schedules, improving quality control, and enhancing site safety. Through a comprehensive review of literature and case studies, this paper provides valuable insights for engineers and researchers involved in the design and construction of long-span spatial structures in steel engineering.

A Simulation-Based Investigation on Thermal Responses of Suspension Bridge Tower Under Different Fire Scenarios

AbstractRecords of bridge fire incidents illustrate that bridge fires can have catastrophic consequences. The severity of these fires can be influenced by various factors such as bridge type, vehicle size, and wind. Contrary to building fires that have been extensively studied, scant attention has been paid to bridge fires and more specifically fire exposure to the suspension bridges. In addition, existing bridge fire literature is mostly concentrated on fire exposure to girders or cables of suspension bridges. Therefore, this study focused on the post-fire condition of a fire-exposed suspension bridge tower using computational fluid dynamics (CFD) modeling techniques and finite element analysis (FEA). The impacts of the main bridge fire parameters including vehicle size, exposure duration, distance between the fire source and tower, and wind effects were also evaluated. Initially, fire dynamic simulator (FDS) was used to simulate 12 different fire scenarios. The time–temperature histories obtained from each scenario were transferred to the ABAQUS finite element (FE) software to conduct transient thermal analysis and obtain the temperature development within the steel tower of the bridge. The post-fire evaluation was performed with respect to the temperature-induced reduction in the yield strength of steel. The results show that fire exposure from a fuel truck in the proximity of a steel tower could significantly reduce the strength of the tower and lead to severe damage. Early control of the fuel truck fire is crucial in reducing the severity of the damage and preventing temperature development in higher areas of the tower. Although a wind toward the tower can significantly increase the fire-induced damage to the bottom parts of the tower, it considerably reduces the temperature exposure to the higher parts of the tower. Fire exposure from a normal vehicle does not put the tower at risk of failure, and an unprotected steel tower can withstand it. However, a bus fire may lead to minor damage. The thermal strengthening of the first 20 m of the tower can help in preventing the potential fire damage.

Coupling a nonlinear finite element mooring model with an overset CFD solver for dynamic analysis of floating structures in waves

An accurate prediction of motion responses of a moored floating structure requires high-fidelity coupled analysis between the structure and its mooring system in waves, which involves both mooring line dynamics and fluid dynamics. In this paper, we develop a nonlinear finite element dynamic mooring analysis module that allows large axial stretching of mooring lines under the open source CFD framework OpenFOAM, and couple it with an Overset CFD solver to establish a fully coupled finite element mooring-CFD analysis model for floating structures. The coupled model is advantageous over existing models in that it is able to deal with large axial mooring stretching and complex mesh motions induced by significant structure responses under severe operating conditions. The developed dynamic mooring analysis method is firstly validated against publicly available data. In order to validate the coupled model, a series of experimental tests were carried out for a semi-submersible platform moored by eight catenary lines under different operating conditions, including free decay, regular and irregular wave tests. The dynamic responses of the floating structure and mooring tension are analyzed and compared with experimental data. Results show that numerically predicted structure responses and mooring tension are generally in good agreement with experimental measurements. Meanwhile, the strongly nonlinear large-amplitude resonant motions generated by the interaction of irregular waves with the moored floating structure are also investigated. Comparisons reveal that the coupled model can accurately predict the resonant spectral peaks of the structure responses, indicating that the it is capable of simulating large-amplitude motions of moored floating structures. The coupled model developed in this paper can be further applied to study the survivability of moored floating structures under harsh sea conditions.

Influence of modelling approach for reinforced concrete underground structures, with application to the CMS cavern at CERN

Representative modelling of reinforced concrete (RC) components in underground structures is essential for accurate assessment of structural performance (deformations and internal forces) within numerical simulations. This paper examines the implications of selecting different structural modelling approaches within the seismic (dynamic) finite element analysis of a buried structure of complex shape, using the CMS (Compact Muon Solenoid) Detector Cavern of the Large Hadron Collider in Geneva, Switzerland, as a case study. Two alternate modelling approaches were employed to model the cavern lining: (i) a composite continuum approach, with the concrete and embedded reinforcement being explicitly modelled; and (ii) the use of a nonlinear elasto-plastic plate element. The pre-earthquake ground initial conditions were determined through simulation of the construction and detector installation operations consistent with field measurements from extensometers and internal survey of floor deformations. The results demonstrate the importance of adopting a non-linear continuum modelling approach in representing the RC lining under strong shaking events to avoid under-prediction of seismic actions at locations of potential seismically induced damage. Such an approach will be essential in 3D problems where multi-axial dynamically varying stresses are applied on the RC section. Finally, it offers a realistic approach in representing structures of complex shape and that contains volume and thick elements.

Uncertain pedestrian load modeling for structural vibration assessment in footbridge design

The request of material savings in bridge constructions leads to the development towards slender and lightweight structures, which are more sensitive to human-induced vibrations caused by walking pedestrians. The resulting accelerations do not endanger the structural safety, but can be perceived as unpleasant for the user and must therefore be restricted within the limit state of serviceability. For this purpose, the guidelines define acceleration intervals, called as “comfort levels” (CL), which evaluate the comfort of the pedestrians, given the maximum acceleration of the bridge. The model for human-induced loads in the design guideline is based on conservative and deterministic simplifications. In particular, the uncertainties in the human gait parameters are neglected. The main objective of this paper is to develop an uncertain load model for walking pedestrians based on Fourier series. The aleatory and epistemic uncertainties in the human gait parameters are quantified with appropriate uncertainty models relying on available data. In a dynamical finite element analysis, the model is used to simulate groups of pedestrians randomly walking over a bridge to calculate the resulting acceleration amplitudes. The approach is applied to a single span beam and to a real world footbridge using a 3D finite element model. The results are then evaluated within the CLs, enabling new assessment methods.

Revolutionizing tire engineering: Finite element analysis and design of an X-shaped spoke structure for non-pneumatic military tires

In this study, we developed a non-pneumatic tire (NPT) specifically designed for military vehicles, such as the Humvee. Our aim was to enhance performance on challenging terrains crucial for mission success. We selected a novel X-shaped polygonal structure for the spoke design owing its exceptional load-carrying capacity and durability. The equivalent modulus, which is the key factor in spoke design, was analytically derived and formulated. This calculated modulus served as a benchmark for achieving the desired vertical stiffness of the NPT. We manufactured a prototype NPT and evaluated its mechanical properties by using a polyurethane (PU) spoke structure. Multiple finite element models of the novel NPT, considering different parameters such as the number of spoke sections, thickness, and modulus of elasticity, were developed while maintaining a consistent equivalent modulus value. Dynamic finite element analysis was then performed to assess the rolling performance of the NPT. We found that the maximum dynamic stress at the spoke was 2.387 MPa, which is 0.398 times the allowable yield strength of the PU spoke. This finding confirms the durability of the novel NPT under dynamic usage in military vehicles, with promising implications for overcoming challenging terrains.

Numerical Study on the Dynamic Response and Damage Cumulative of Bolt-Supported Cavern under Adjacent Cyclic Explosion

Adjacent cyclic explosions significantly impact the stability of underground anchored caverns. Based on the similar model test of the vault explosion of the anchored cavern, the dynamic analysis finite element software ANSYS/LSDYNA(18.0) was used to establish a model of the straight wall side explosion of the underground anchored cavern and conduct a numerical simulation. When the total amount of explosion load is the same, we compared the stress time history curve, displacement time history curve, tunnel wall displacement, and circumferential strain curve of the surrounding rock in the underground anchored cavern (under both a high-level single-side blast and a low-level cyclic side blast). We obtained the dynamic response rules of the surrounding rock. By comparing the damage evolution process of the surrounding rock in the two situations, the damage accumulation law of the surrounding rock was analyzed. At the same time, the axial stress distribution characteristics of underground anchor cavern anchors under the action of cyclic explosion were studied. The findings demonstrate that when the total level of blast load adjacent to the cavern is the same, the displacement and circumferential peak strain of surrounding rock and the axial stress of rock bolt in the high-level single explosion are greater than those in the low-level cyclic explosion. However, compared to a single explosion, the rock mass suffers more damage in the cyclic explosion. This study will provide engineers with information that will assist them with a better understanding of the cumulative damage mechanisms of surrounding rock, as well as the stress characteristics of rock bolts under dynamic loads near the explosion site, which will be used to design underground caves with anti-blast features.

Seismic intensity measures and predictive equations for the evaluation of earthquake—induced crest settlements of earth dams

AbstractIn this paper the results of 2D dynamic finite element analyses of a zoned earth dam are presented and discussed with the aim of detecting proper intensity measures able to describe the variation of the crest permanent settlement with the characteristics of the input ground motion. A large set of horizontal components of earthquake records has been selected and used as input motion considering both upstream and downstream directions. This allowed to explore the activation of plastic mechanisms in the dam embankment and the amplification of the horizontal accelerations. Starting from the analysis results, two original intensity measures, related to the amplitude, energy and frequency content of the input motion, have been detected and original empirical predictive formulas have also been derived to estimate the permanent crest settlement of the dam. The effectiveness of the proposed intensity measures and the reliability of the novel relationships between these intensity measures and earthquake‐induced permanent crest settlements have been checked against (i) numerical results of further dynamic analyses carried out for the same dam using additional sets of input motions, (ii) numerical results available in the literature for two other earth dams and (iii) field data relative to the crest settlements induced in four earth dams by two recent large earthquakes. The whole set of analysis results allowed defining an empirical equation that appears as a promising general predictive tool for the earthquake‐induced crest settlement of earth dams.

Seismic capacity models for earth dams and their use in developing fragility curves

This article develops seismic capacity models for earth dams and demonstrates how the proposed seismic capacity models may be used to develop seismic fragility curves that predict the probability of damage as a function of ground shaking intensity. Developing earth dam fragility curves requires two major components: (1) a seismic capacity model that predicts the probability of a damage state given the relative settlement (RS) and (2) an engineering demand model that predicts the RS as a function of ground motion intensity. While seismic demand models for earth dams have been studied by various researchers, there is a scarcity of seismic capacity models. This article focuses first on developing seismic capacity relationships using a dataset of earthquake case histories of dam performance. Different from previously developed relationships, only the damage description for each dam is used when assigning the damage state, which results in statistical variability in the capacity relationship between the damage state and RS. The fragility curve development is demonstrated by combining the seismic capacity relationships with a seismic demand model for RS derived from nonlinear, dynamic finite element analyses for a 20-m generic dam geometry subjected to a suite of earthquake motions from the NGA-West2 database.

The effect of Kahramanmaraş earthquakes on historical Malatya Yeni Mosque

The earthquakes that occurred on February 6, 2023, in Kahramanmaraş, Turkiye, caused extensive damage, particularly in historical mosques built with traditional methods. This study aims to investigate the collapse mechanism of Malatya Yeni Mosque, which underwent a strengthening operation before the Kahramanmaraş Earthquakes. The primary objective of this study is to offer insights into the rehabilitation of similar structures. Post-earthquake field surveys, combined with finite element modeling and dynamic analysis using city center acceleration data from Malatya, were utilized to assess structural vulnerabilities. The results of numerical analyses and field studies have indicated that seismic damages generally occurred in specific Mosque areas, particularly in the domes, minarets, columns (elephant feet), and arch systems supporting the central dome. The observed damage patterns in these areas signify the zones where the structural inadequacies generally coincide. The main findings of this study shed light on the necessity of strengthening these unique structures exposed to seismic forces and offer an essential step in minimizing the adverse effects of such disasters in the future. This study guides the planning and implementation of efficacious engineering interventions to preserve historical buildings.

Lightweight design of steel sprocket for roller chain drive using explicit dynamic simulation

Roller chain drives are frequently applied in a variety of machinery for mechanical motion and power transmission. The roller engagement location on the sprocket tooth contour and the resulted contact behavior is governed by the wear of components and pretension of the chain. Therefore, the influence of extension of chain resulted from wear and pretension of chain on contact behavior was investigated numerically using explicit dynamics module of ABAQUS software. The contact angles evaluated from the numerical simulation were assessed relative to those obtained from the basic rigid body analytical formulation. The chain elongation of 3% increased the maximum contact force up to 52% during engagement with the driver sprocket. The contact force raised to 400% when the pretension in the chain drive was increased from 200 to 1000 N, leaving the force distribution pattern unaltered. The optimal design of a steel sprocket is realized through equivalent static finite element contact analysis of a sprocket engaged with 3% extended roller chain. The dynamic finite element analysis in conjunction with topology optimization reduced the weight of the sprocket by 24%.

Seismic performance of shared suction caisson anchors installed in liquefiable sand for floating offshore wind turbines

Shared anchors will reduce the levelized cost of energy for floating offshore wind (FOW) arrays currently under active development in various seismically active regions. This study investigates the seismic performance of a shared suction caisson anchor installed in liquefiable sand for a FOW array using a nonlinear dynamic 3D finite element analysis. The advanced UBC3D-PLM constitutive model was calibrated against cyclic element tests then validated with centrifuge experimental data. Strong ground motions with orthogonal horizontal and vertical components were applied to the model with varying frequency content, peak ground acceleration (PGA), and orientation. The model captured the stress–strain response of the soil and evolution of excess pore pressure to the onset of liquefaction, which occurred after application of a PGA of 0.2 g and above. Despite significant liquefaction caused by a PGA of 0.8 g, displacement of the anchor remained within around 10% of anchor diameter. The results suggest some resilience to pull-out during seismic loading in liquefiable soils, even with vertical tensile loading on the anchor developed by the inverse catenary. Further investigation could be carried out under specific site conditions and serviceability criteria to optimize the size of the caisson and reduce costs while ensuring anchor performance during seismic loading.

Evaluation of stability of fixation using conventional miniplate osteosynthesis in comminuted and non-comminuted Le Fort I, II, III fractures – A dynamic finite element analysis

Purpose: The purpose of the present study was to evaluate and compare the stability of fixation using conventional miniplate osteosynthesis in comminuted and non-comminuted Le Fort I, II, and III fractures in open and closed jaw movements under masticatory loading conditions.Materials and Methods: About 23 dimensional models of comminuted and non-comminuted Le Fort I, II, and II with traditional miniplate fixation were simulated virtually using a CT scan of the patient and analyzed using ANSYS Workbench 2020 R1 software. The dynamic finite element method was applied by the simulation of the forces of the muscles of mastication upon the fractured midface. The von Mises stress was analyzed and collated for each model; thereby, the stability of conventional miniplate fixation was interpreted.Results: The von Mises stress over the regions of fixation were compared and the tabulated data was interpreted. Considerable von Mises stress was generated on the bone and deformation over the hardware was noted on the pyriform rim in the Le Fort I model, infraorbital rim in the Le Fort II model, and frontonasal region in the Le Fort III model in the closing phase of jaw movement.Conclusion: The findings implicated that the biomechanical stability of conventional miniplate osteosynthesis is insufficient to secure the midface fractured bone under masticatory load.

Multiple objective optimal design for an electrically assisted bicycle under dynamic finite element analysis

ABSTRACT Electrically assisted bicycles have become increasingly popular in modern cities. This article presents an optimization design process to enhance the strength of an electrically assisted bicycle frame (EABF) model. This process includes several techniques such as uniform design (UD), Kriging interpolation (KGI), entropy weighting analysis (EWA), gray relational analysis (GRA), and genetic algorithm (GA). The EN 15,194 test standard is used to calculate the maximum deformation of the fork in an EABF, through falling mass (FM) and falling frame (FF) impact simulations with ANSYS/LS-DYNA software. Six geometry characteristics of an EABF are selected as control factors. The UD generates multiple simulation tests, as each control factor in the design space is continuous. Dynamic finite element analysis (FEA) is conducted to determine the maximum impact deformation (ID) of each experiment in the UD. Applying a multiple objective optimization process, the best design for an EABF is obtained. The newly designed model offers a maximum improvement of 4.20% over the original design for the largest distortion. In conclusion, the multiple objective optimization technique improves the maximum ID of an EABF.

Dynamic recrystallization behavior and finite element analysis of a low-alloy high-strength steel

Dynamic recrystallization behavior and finite element analysis of a low-alloy high-strength steel

Dynamic Response of Offshore Wind Turbine with a New Monopile Foundation under Different Lateral and Seismic Loadings

Using a monopile foundation due to a reliable and simple technology has a wide application in engineering structures. This paper investigates numerically the performance of an offshore wind turbine with a monopile foundation equipped with a restriction plate at a middle inside height of the monopile under the wind, wave, and seismic loadings. Different parameters, including wind velocity, wave period, wave height, soil characteristics, and combination of loadings, are considered in nonlinear finite element dynamic analyses. Results are given in terms of the distribution of displacement and bending moment over the turbine height and frequencies. The results reveal that by increasing the wind velocity, the responses of the tower increase, and the wind load acting on the hub has the most important effect on the turbine behavior rather than the wind load acting on the tower body. Furthermore, the values of maximum displacement and bending moment under wind and wave loading decrease with the increase of the shear strength of the soil, whereas the responses of the tower under earthquake loading increase. Generally, it is necessary to consider the effect of a combination of wind, wave, and earthquake loadings on the design of the turbine tower.