Finite Element Modeling Techniques Research Articles

Numerical evaluation of rail track noise and vibration and components optimization

In the context of a project commissioned by the Swiss Federal Office for the Environment, an open-source modelling toolbox was developed to simulate and analyze rail tracks dynamics. In particular, a vibro-acoustic multi-sleeper model, which is based on advanced finite element modelling techniques, was used to investigate the effects of components properties on track noise and vibration. Considering changes around a reference construction (60E2 rail, SBB hard pad, B91 sleeper), parametric studies were performed on the dominant parameters identified for the acoustic and ballast protection performance indicators defined. The following sweet spot for the component properties of the track have been identified as using a rail pad of medium stiffness (1000 kN/mm at 1kHz, 300 kN/mm static stiffness) and high damping (at least 0.5) combined with soft Under Sleeper Pads (250 kN/mm). Based on the present models, such combination could provide both a significant noise reduction and a marked improvement in ballast protection compared to current track construction.

Design and Analysis of Architectural Systems for Earthquake Resilience

This research investigates the impact of wind and gravity loads on the seismic performance of a G+20 reinforced concrete building in Jordan. The study highlights the importance of non-linearities in earthquake-resistant design, with non-linear models showing a 39.66% increase in displacement compared to linear-elastic models. The analysis was conducted using the OpenSees platform. Using a fiber model to account for reinforcement plasticity and inelastic behavior, such as concrete cracking, a single element was used to represent an entire beam or column in the force-based finite element modeling technique. Geometric non-linearities, including large rotations, were addressed through the corotational formulation, and the P-Delta approach was used for result validation. Significant variations in load distribution across floors further highlight the importance of non-linearity in seismic analysis. The results of this study demonstrate how important it is to improve high-rise structures' earthquake resistance through the use of non-linear modeling and real-time electronic monitoring systems. Architects and engineers may greatly decrease structural damage during seismic events by incorporating these cutting-edge solutions into future building designs. This will improve building performance and safety in earthquake-prone areas.

Empirical Punching Shear Capacity Equation for Reinforced Concrete Two-way Slabs with Openings

This study proposes a new equation to estimate the punching shear capacity of Two Way Reinforced Concrete Flat Slab Column (TRFSC) connections with openings. The TRFSC connections with openings in the literature were simulated using the finite element modeling technique. Then, the test results were used to calibrate and verify the finite element model. Next, the number of test data was artificially increased using the finite element model to cover a wide range of critical perimeters. Finally, the effects of several parameters such as the size of the openings in the reinforced concrete slabs, their position, and distance concerning the column on which the punching loading is applied on the variation of punching shear load capacity of TRFSC connections with openings were observed, the results showed that the proposed equation generally gave better results than the several current code equations. For the study used in the verification of the finite element model, it was observed that the ratios of the punching capacity values calculated using the experimental results and the regulations varied between 0.79 and 0.92 on average, and the regulations gave results that were not on the safe side for TRFSC connections with openings. However, with the nonlinear correction coefficient proposed in this study, the ratios of the experimental results and analytically calculated capacity values were calculated as 1.10 on average, and the standard deviation and variant values decreased much more.

Predictive Analysis of Laminated Glass Performance Under Static and Dynamic Loading Conditions

Laminated safety glass is normally used when there is a possibility of human impact or where the glass could fall if shattered. Glass laminate films, the plastic film called an interlayer that is adhered between sheets of glass, are an important component of many glass applications. In an event that causes breakage of the glass, it is held in place by an interlayer, between its two or more layers of glass. The interlayer keeps the glass bonded even when broken, and its high strength prevents the glass from breaking up into large sharp pieces. Various physical tests (standard/non-standard) can be found in the literature to develop and screen the different interlayer materials. In the last several years, we have witnessed extensive growth in computational modeling of complex nonlinear behavior of laminated glass panels with viscoelastic interlayers. To evaluate the mechanical behavior of laterally-loaded interlayer in laminated safety glass, finite element (FE) modeling is widely used in industry. Recently, FE modeling techniques and methods helped to identify selection criterion for proposed materials to be used in the interlayer of laminated glass. The present study aims to develop a numerical model (Finite Element model) verified by experimental results/data given in literature and to utilize the model to examine the mechanical behavior of laterally-loaded interlayer films in laminated safety glass subjected to standard/non-standard tests (four-point bending test and Impact test) conditions. Also, parametric studies (effect of interlayer/glass thickness, impactor speed, soft/stiff interlayer material etc.) are performed through FE analysis to investigate the impact of these parameters on the behavior of the interlayer material.

Application of mesh-free and finite element methods in modelling nano-scale material removal from copper substrates: A computational approach

This study explores the modelling methodology using mesh-free smoothed particle hydrodynamics (SPH) and finite element modelling (FE) techniques to simulate the AFM-based nano-scratching processes for advancing precision engineering in nanotechnology. Tip wear in nano machining substantially increases the tip radius, thereby influencing the material removal mechanism and subsequently affecting the quality of machined nanostructures. In this context, this study examines the effects of rake angle (the inclination of the main cutting edge to the plane perpendicular to the scratched surface), tip radius and scratching depth on cutting forces, groove dimensions, and deformed thickness. This was achieved by implementing an in-house SPH method based particle code employing a Lagrangian algorithm, and an FE model incorporating the dynamic explicit algorithm implemented (in ABAQUS) to carry out nano-scratching simulations. The investigation revealed that the cutting mechanism transitioned to ploughing when the scratching depth decreased to 30% of the tip radius for OFHC-Cu workpiece material machined with a diamond tip. The dominance of normal forces over cutting forces during scratching indicated the side flow of material in the vicinity of the tip radius under intense contact pressure. The ploughing mechanism exhibited more sensitivity at a higher negative rake angle of 60°. Increased scratching depth and tip radius led to more significant material deformation owing to the induction of higher cutting forces, with the maximum deformation thickness 3.6 times the tip radius. The simulated results demonstrated favourable concordance with the experimental data.

DESIGN AND ANALYSIS OF PRESSURE VESSEL USING DIFFERENT MATERIALS

This project explores the field of Finite Element Analysis (FEA) in relation to pressure vessels that have different head configurations, while ensuring that the cylindrical volume and thickness remain uniform. The project adheres to ASME standards, specifically Section VIII, Division I, and focuses on designing a pressure vessel that can withstand a pressure of 8 bar within a volume of 24 liters. The main objective of using FEA is to identify areas of stress concentration in each head design. In industrial settings, pressure vessels play a crucial role in containing fluids or gases under varying pressures. The choice of head configuration significantly impacts the distribution of stress and the overall structural strength. This project specifically utilizes ANSYS software for static and thermal analyses to compare stress distribution in pressure vessels with flat heads, elliptical heads, and other common head designs. The goal is to identify configurations that exhibit lower stress levels, with a particular emphasis on practical scenarios that favor elliptical heads. Additionally, the project explores finite element modeling techniques to evaluate pressure vessels made from different materials such as Nimonic 80A and SA516 Gr70 under high-stress conditions

Progress in adhesive-bonded composite joints: A comprehensive review

Among the myriad joining techniques, the adhesive bonding technique is widely used to join complex large-scale composite structures because of its numerous advantages compared to traditional joining techniques. This article profusely analysed the various techniques for ameliorating the performance of composite joints, such as bonding methods (secondary bonding, co-bonding, co-curing, and multi-material bonding), surface modification techniques (plasma, laser surface treatment, surface grinding, etc.), additional reinforcement techniques (Z pin, wire mesh, nanofiller, etc), and different joint geometries (stepped joints, half-stepped joints, balanced joints, and scarf joints). Also, the effect of various adhesives and fabrication techniques on the static and dynamic performance of CFRP and GFRP-based joints was studied in detail. Moreover, this review addresses the finite element modelling and optimisation techniques on adhesively bonded joints. It has been observed that the bonding methods, surface modification to enhance the roughness of the adherend, addition of nanofillers, and variations in joint geometry greatly influence the shear strength, fracture toughness, fatigue, and vibration behaviour of FRP composite joints.

Seismic performance evaluation of exterior reinforced concrete beam-column connections retrofitted with economical perforated steel haunches

The exterior beam-column joint (BCJ) within reinforced concrete (RC) frame structures is acknowledged as a vulnerable component prone to seismic failure. This article proposes a practical and economical strengthening method for exterior BCJs using a perforated steel haunch system. This method is designed to mitigate damage in BCJs and improve the seismic performance of the structure. Employing finite element modeling (FEM) techniques, the study evaluates the impact of perforated steel haunches on the BCJs’ behavior and performance. The investigation involves creating nine distinct models, each representing a BCJ with a steel haunch system. These models include a control model without any perforations and eight variations with different levels of perforation (ranging from 10% to 50%) within the steel haunch system. Furthermore, the study analyzes the influence of perforation shapes on the connections’ performance, considering square, circular, hexagonal, and triangular shapes. The results reveal that utilizing a steel haunch without perforations significantly increases the load-carrying capacity of a BCJ by about 89%. Additionally, circular or square-shaped perforations, up to 30–35% within the steel haunch, effectively prevent the joints’ failure and promote the ductile behavior. These findings hold the potential to advance the design methodology for RC joints subjected to seismic loads, thereby enhancing the structural resilience in earthquake-prone regions.

Porous versus solid shoulder implants in humeri of different bone densities: A finite element analysis.

Porous metallic prosthesis components can now be manufactured using additive manufacturing techniques, and may prove beneficial for promoting bony ingrowth, for accommodating drug delivery systems, and for reducing stress shielding. Using finite element modeling techniques, 36 scenarios (three porous stems, three bone densities, and four held arm positions) were analysed to assess the viability of porous humeral stems for use in total shoulder arthroplasty, and their resulting mechanobiological impact on the surrounding humerus bone. All three porous stems were predicted to experience stresses below the yield strength of Ti6Al4V (880 MPa) and to be capable of withstanding more than 10 million cycles of each loading scenario before failure. There was an indication that within an 80 mm region of the proximal humerus, there would be a reduction in bone resorption as stem porosity increased. Overall, this study shows promise that these porous structures are mechanically viable for incorporation into permanent shoulder prostheses to combat orthopedic infections.

Performance evaluation of a seismic strengthening applied on a masonry school building by dynamic analyses

With its unreinforced masonry structural system, Münevver Şefik Fergar Primary School has been analyzed and retrofitted by the Istanbul Project Coordination Unit, IPKB in Istanbul. The applied strengthening is mainly composed of the addition of reinforced concrete layers to the masonry walls by shotcreting. This study is performed to monitor the variation of the dynamic properties of the building through the constructional works and evaluate the effects of the performed retrofitting. For this aim, six sets of operational modal analysis type dynamic identification, starting from the original building and ending with the retrofitted building, were performed to extract the dynamic properties of the building. To discuss the effectiveness of retrofitting efficiently, numerical analyses have also been conducted. The original and retrofitted form of the building has been modeled by finite element modeling technique and Eigenvalue analyses were performed to obtain the dynamic properties of the building numerically for both phases. The comparison of the dynamic characteristics of the original and retrofitted building enabled the assessment of the efficiency of the applied seismic strengthening. Moreover, the experimentally and numerically obtained results were compared. It is seen that, while both experimental and numerical results proved the effectiveness of the performed retrofitting to increase the dominant frequencies of the building, the difference in their quantity was worth noting and should be accounted for seismic analysis of similar structures.

Systematic quantification of modeling uncertainties in tank–foundation coupled systems

Traditionally, uncertainty quantification in the context of liquid storage tanks has primarily focused on ground motion record-to-record variability, along with partial consideration of material randomness. This paper presents a comprehensive framework for addressing “modeling uncertainty” in the seismic analysis of rectangular tanks, including the influence of foundation interactions. The framework encompasses uncertainties inherent in both general finite element and mathematical modeling techniques, as well as uncertainty in modeling parameters (e.g., hydrodynamic mass and concrete constitutive model). This is achieved through the implementation of an efficient design of experiments. By employing an innovative intensifying artificial acceleration, over 26,000 transient simulations are conducted, spanning the full spectrum of structural behavior from linear to nonlinear regimes. Through a series of uncertainty quantification and sensitivity analyses, this study assesses bias and dispersion arising from diverse model assumptions. Furthermore, fragility analysis and machine learning post-processing techniques are employed to extract latent insights from the generated data. The outcomes underscore that numerical and mathematical modeling uncertainties can bear comparable significance to ground motion record-to-record variability. The adoption of distinct modeling strategies introduces biases in fragility curves, particularly within higher damage states. Consequently, it is advised to account for modeling randomness directly (via simulation) or approximately (leveraging the insights from this study) in any uncertainty quantification related to storage tanks.

Development of robotic automation solutions for limp flexible material handling leveraging a finite element modelling technique

Development of robotic automation solutions for limp flexible material handling leveraging a finite element modelling technique

Investigation of stair ascending and descending activities on the lifespan of hip implants

Total hip arthroplasty (THA) surgeries among young patients are on the increase, so it is crucial to predict the lifespan of hip implants correctly and produce solutions to improve longevity. Current implants are designed and tested against walking conditions to predict the wear rates. However, it would be reasonable to include the additional effects of other daily life activities on wear rates to predict convergent results to clinical outputs. In this study, 14 participants are recruited to perform stair ascending (AS), descending (DS), and walking activities to obtain kinematic and kinetic data for each cycle using marker based Qualisys motion capture (MOCAP) system. AnyBody Modeling System using the Calibrated Anatomical System Technique (CAST) full body marker set are performed Multibody simulations. The 3D generic musculoskeletal model used in this study is a marker-based full-body motion capture model (AMMR,2.3.1 MoCapModel) consisting of the upper extremity and the Twente Lower Extremity Model (TLEM2). The dynamic wear prediction model detailing the intermittent and overall wear rates for CoCr-on-XLPE bearing couple is developed to investigate the wear mechanism under 3D loading for AS, DS, and walking activities over 5 million cycles (Mc) by using finite element modelling technique. The volumetric wear rates of XLPE liner under AS, DS, and walking activities over 5-Mc are predicted as 27.43, 23.22, and 18.84 mm3/Mc respectively. Additionally, the wear rate was predicted by combining stair activities and gait cycles based on the walk-to-stair ratio. By adding the effect of stair activities, the volumetric wear rate of XLPE is predicted as 22.02 mm3/Mc which is equivalent to 19.41% of walking. In conclusion, in this study, the effect of including other daily life activities is demonstrated and evidence is provided by matching them to the clinical data as opposed to simulator test results of implants under ISO 14242 boundary conditions.

A structural optimization analysis of cable-driven soft manipulator

Cable-driven soft robots hold significant potential for surgical and industrial applications, yet their performance and maneuverability can be further enhanced through design optimization. By optimizing the design, factors such as bending angles, manipulator deformation, and overall functionality can be directly influenced, leading to improved interaction with the environment and more accurate task performance. This article presents a physics-based design optimization approach for cable-driven soft robotic manipulators, aiming to enhance bending performance through structural design enhancements. Four design criteria, namely, cross-sectional shape, material, gap shape, and gap size, are considered in the optimization process. Given the inherent nonlinearity of soft materials, finite element modeling techniques are employed to analyze the effects of modifying each design parameter on displacement and bending angle. The manipulator’s design is evaluated using ABAQUS/CAE, and an analysis of variance test is conducted to identify significant performance differences among the design parameters. The results reveal that material variation has the most substantial impact, followed by gap shape and gap size. Based on subsequent parameter optimization, Dragon Skin 10 is determined to be the optimal material for bending motion, while a trapezoidal gap shape is preferred. In addition, a genetic algorithm is utilized to select a maximum gap size of 8.87 mm. These findings provide valuable insights into key design principles for cable-driven soft manipulators, aiming to enhance flexibility and reduce actuation forces. By establishing a fundamental understanding of the relationship between morphology and motion capability, this methodology demonstrates an effective simulation-driven optimization approach that incorporates the nonlinear elastic behavior of materials to improve performance. Overall, this work establishes a framework for optimizing cable-driven architectures to suit various applications in the field of soft robotics.

A comparison of modeled and measured impedance of brass instruments and mouthpieces

The impedance of a brass instrument has an important influence on its playability and sound timbre. The geometry of the mouthpiece has various features, such as the cup volume and shape, opening diameter, and length, that determine the characteristics of the overall impedance of the instrument-mouthpiece combination. Brass instruments, and especially mouthpieces, are designed for specific purposes, and horns or mouthpieces are chosen depending on the musical requirements. In order to investigate the relationship between the physical parameters and the impedances of instruments and mouthpieces, they have been modeled with transfer matrix and finite element model techniques, and the results are compared with impedance measurements of instruments, mouthpieces, and combinations of instruments and mouthpieces. Trumpets, flugelhorns, (French) horns, trombones, and the corresponding mouthpieces have been used. A detailed analysis of the estimation of the viscothermal losses has been performed, as the loss estimation in the narrow throat of the mouthpiece and in the flaring part of the brass instrument bell departs from the ordinary transfer matrix calculations. The effect of varying the physical parameters of mouthpieces and instruments is investigated by means of impedance considerations and sound synthesis, and the resulting influences on intonation, playability, and timbre are presented.

Unreinforced masonry walls under two-way out-of-plane bending: Comparison of FE model predictions with analytical models

Four existing design guidelines based on the virtual work method have been compared to predict the out-of-plane (OOP) bending capacities of unreinforced masonry (URM) walls to one-way and two-way actions. The two-way OOP bending design equation as per the Australian masonry standard (AS 3700) and the three subsequent models developed by other researchers are based on specific wall geometries, support conditions, dimensions and strengths of masonry units and mortar. Due to limited experimental data available on URM walls under two-way bending, it is difficult to carry out a detailed investigation of the performance of these two-way design models against all the design parameters. This paper applies the finite element (FE) modelling technique to generate data and extensively investigate the influence of support conditions, pre-compression and aspect ratio on the two-way OOP bending capacity of URM walls. An explicit FE model previously developed by the authors where masonry is macroscopically modelled as an anisotropic composite material, is used for this purpose. Performances of three key parameters (i.e., moment capacity under horizontal bending and diagonal bending and torsional shear strength of masonry) that differentiate the four design models are investigated against varying levels of vertical pre-compression and flexural tensile strength of masonry. The OOP bending capacity predicted by the FE model is compared with the predictions of the design models. Results show that three out of four design models generally overpredict the two-way OOP bending capacities of square and taller walls. Further refinement to the AS 3700 design equation has been proposed in a modified model. The outcomes of this research will help to improve the design of masonry walls under OOP bending.

Structural Condition Assessment of Reinforced Concrete Bridge Using Operational Modal Analysis and Finite Element Model

The integration of Operational Modal Analysis (OMA) and Finite Element Model (FEM) techniques has proven to be a valuable approach for evaluating and maintaining the health of such structures. OMA extracts dynamic characteristics from a bridge's responses to ambient vibrations, while FEM employs computational models to simulate and compare these dynamic behaviours. This comprehensive methodology ensures an accurate representation of the bridge's behaviour and its correlation with real-world conditions. However, a significant challenge arises in assessing the Ultra High Performance Fiber Reinforced Concrete (UHPFRC) pedestrian bridge in Klang, Selangor, launched in October 2022, due to limited available information about OMA and FEM on UHPFRC. This research aims to develop FEM and conduct ambient vibration tests to obtain modal parameters. Moreover, the study investigates OMA techniques in the context of weak excitation sources, filling a critical knowledge gap. By comparing experimental results with FEM, this research provides insights into the feasibility and reliability of OMA under challenging environmental conditions. The principal results reveal significant percentage differences in natural frequencies between FEM and OMA, with the most notable disparities occurring in the first mode. Nevertheless, the mode shapes extracted from OMA closely resemble those from FEM. In conclusion, this research enhances the understanding of UHPFRC pedestrian bridge behaviour and modal analysis techniques.

Integrated behavioural analysis of FRP-confined circular columns using FEM and machine learning

This study investigates the structural behaviour of double-skin columns, introducing novel double-skin double filled tubular (DSDFT) columns, which utilise double steel tubes and concrete to enhance the load-carrying capacity and ductility beyond conventional double-skin hollow tubular (DSHT) columns, employing a combination of finite element model (FEM) and machine learning (ML) techniques. A total of 48 columns (DSHT+DSDFT) were created to examine the impact of various parameters, such as double steel tube configurations, thickness of fibre-reinforced polymer (FRP) layer, type of FRP material, and steel tube diameter, on the load-carrying capacity and ductility of the columns. The results were validated against the experimental findings to ensure their accuracy. Key findings highlight the advantages of the DSDFT configuration. Compared to the DSHT columns, the DSDFT columns exhibited remarkable 19.54 % to 101.21 % increases in the load-carrying capacity, demonstrating improved ductility and load-bearing capabilities. Thicker FRP layers enhanced the load-carrying capacity up to 15 %, however at the expense of the reduced axial strain. It was also observed that glass FRP wrapping displayed 25 % superior ultimate axial strain than aramid FRP wrapping. Four different ML models were assessed to predict the axial load-carrying capacity of the columns, with long short-term memory (LSTM) and bidirectional LSTM models emerging as superior choices indicating exceptional predictive capabilities. This interdisciplinary approach offers valuable insights into designing and optimising confined column systems. It sheds light on both double-tube and single-tube configurations, propelling advancements in structural engineering practices for new constructions and retrofitting. Further, it lays out a blueprint for maximising the performance of the confined columns under the axial compression.

Application of machine learning technique for dynamic analysis of confined geomaterial subjected to vibratory load

Computer programming-based numerical programs are firmly established in geotechnical engineering, with rapid growth of finite element modeling and machine learning techniques gaining much attention both in practice and academia. This study is intended to expedite the dissemination of advanced computer applications in terms of finite element simulation and machine learning models by investigating the dynamic response of geomaterials subjected to vibratory loads. Several trial models were built to perform the experimental investigations with a vibratory shaker, signal generator, several accelerometers, a data collection system, and other ancillary devices. The implicit integration techniques in commercialized software were adopted for numerical simulations. After data collection from numerical simulation, models were chosen, trained, and assessed to produce predictions that were then used in this study. Several technologies, including the ensemble boosted tree, squared exponential Gaussian Process Regression (GPR), Matern 5/2 GPR, exponential GPR, and decision tree architectures (fine and medium), were used to forecast the displacement of confined geomaterial. The displacement-depth ratio was found rising to 80% in the frequency range of 5 to 25 Hz, suggesting a considerable change in the behavior of the geomaterial. The Matern 5/2 GPR model showed better accuracy with an R2 value of 0.99, indicating an outstanding predictive ability. The Matern 5/2 GPR and boosted tree models could help better understand the links between displacement and its distribution along the direction of load application. The outcomes of this study based on computer-aided finite element programs can be effectively implemented in machine learning to develop computer programs. In conclusion, the computational machine learning models adopted in this study offer a new insight for uncovering hidden intrinsic laws and creating new knowledge for geotechnical researchers and practitioners.

Numerical investigation and design of lightweight aggregate concrete-filled cold-formed built-up box section (CFBBS) stub columns under axial compression

Cold-formed built-up box sections (CFBBS) have emerged as a promising solution for applications in light gauge steel framing systems and modular construction. However, they suffer from the inherent local buckling effect. Concrete infill has proven effective in mitigating this issue, yet existing codified provisions lack specific guidelines for the design of concrete-filled CFBBS stub columns. This paper proposed a design methodology that aims to predict the ultimate compressive strength of lightweight concrete-filled CFBBS stub columns. Leveraging finite element (FE) modelling techniques, this study augmented the existing test database and shed light on parametric influences, considering practical considerations, on the structural performances and axial compressive behaviour. The proposed design approach demonstrated superior prediction accuracy and consistency compared to other evaluated design approaches in this study.