Element Simulation Research Articles

Comprehensive Assessment for Liquefaction Vulnerability in Indonesia: Empirical and Element Simulation Approaches

Historical liquefaction events have occurred at many locations, such as Yogyakarta and Lombok; the most significant flow side is in Palu. The standard Indonesian liquefaction assessment is based on a simplified empirical analysis. However, these methods only occasionally yield appropriate results. Contrastingly, the limited data from the cyclic test ensured that the liquefaction ratio could only partially support the liquefaction vulnerability. This research aims to re-examine the empirical approach that combines the constitutive model using LIQCA with a cyclic triaxial test (CXT) and cyclic simple shear (CSS). The empirical method was arranged using deterministic and probabilistic approaches, and the recommendation of the peak ground acceleration (PGA) threshold was validated. The results show a strong relationship between all calculation methods and the SPT value, which differs in the liquefaction strength ratio. This output offers the PGA recommendation results, reaching a 48% overestimation from the empirical method without considering the cyclic test. This research presents the development of a combination of the empirical method with the element simulation from CXT and CSS. This offers a comprehensive overview of the Indonesian requirement standard assessment for liquefaction vulnerability analysis. Doi: 10.28991/CEJ-2025-011-01-019 Full Text: PDF

Fourier p- element simulation and experimental validation of frequencies for rotating blade in flexure

Fourier p- element simulation and experimental validation of frequencies for rotating blade in flexure

Mechanical properties and failure modes of additively-manufactured chiral metamaterials based on Euclidean tessellations: an experimental and finite element study

PurposeThe “chiralisation” of Euclidean polygonal tessellations is a novel, recent method which has been used to design new auxetic metamaterials with complex topologies and improved geometric versatility over traditional chiral honeycombs. This paper aims to design and manufacture chiral honeycombs representative of four distinct classes of 2D Euclidean tessellations with hexagonal rotational symmetry using fused-deposition additive manufacturing and experimentally analysed the mechanical properties and failure modes of these metamaterials.Design/methodology/approachFinite Element simulations were also used to study the high-strain compressive performance of these systems under both periodic boundary conditions and realistic, finite conditions. Experimental uniaxial compressive loading tests were applied to additively manufactured prototypes and digital image correlation was used to measure the Poisson’s ratio and analyse the deformation behaviour of these systems.FindingsThe results obtained demonstrate that these systems have the ability to exhibit a wide range of Poisson’s ratios (positive, quasi-zero and negative values) and stiffnesses as well as unusual failure modes characterised by a sequential layer-by-layer collapse of specific, non-adjacent ligaments. These findings provide useful insights on the mechanical properties and deformation behaviours of this new class of metamaterials and indicate that these chiral honeycombs could potentially possess anomalous characteristics which are not commonly found in traditional chiral metamaterials based on regular monohedral tilings.Originality/valueTo the best of the authors’ knowledge, the authors have analysed for the first time the high strain behaviour and failure modes of chiral metamaterials based on Euclidean multi-polygonal tessellations.

Effect of cavity radiation on aluminium hollow tubes and facade system subjected to fire

PurposeThis paper numerically investigates the effect of cavity radiation on the thermal response of hollow aluminium tubes and facade systems subjected to fire.Design/methodology/approachFinite element simulations were performed using ABAQUS 6.14. The accuracy of the numerical model was established through experimental and numerical results available in the literature. The proposed numerical model was utilised to study the effect of cavity radiation on the thermal response of aluminium hollow tubes and facade system. Different scenarios were considered to assess the applicability of the commonly used lumped capacitance heat transfer model.FindingsThe effects of cavity radiation were found to be significant for non-uniform fire exposure conditions. The maximum temperature of a hollow aluminium tube with 1-sided fire exposure was found to be 86% greater when cavity radiation was considered. Further, the time to attain critical temperature under non-uniform fire exposure, as calculated from the conventional lumped heat capacity heat transfer model, was non-conservative when compared to that predicted by the proposed simulation approach considering cavity radiation. A metal temperature of 550 °C was attained about 18 min earlier than what was calculated by the lumped heat capacitance model.Research limitations/implicationsThe present study will serve as a basis for the study of the effects of cavity radiation on the thermo-mechanical response of aluminium hollow tubes and facade systems. Such thermo-mechanical analyses will enable the study of the effects of cavity radiation on the failure mechanisms of facade systems.Practical implicationsCavity radiation was found to significantly affect the thermal response of hollow aluminium tubes and façade systems. In design processes, it is essential to consider the potential consequences of non-uniform heating situations, as they can have a significant impact on the temperature of structures. It was also shown that the use of lumped heat capacity heat transfer model in cases of non-uniform fire exposure is unsuitable for the thermal analysis of such systems.Originality/valueThis is the first detailed investigation of the effects of cavity radiation on the thermal response of aluminium tubes and façade systems for different fire exposure conditions.

Semi-Analytical Results for the Linear Nonaging Viscoelastic Contact Behaviors

This paper investigates the importance of creep and relaxation functions in modeling the Hertzian contact problem between linear nonaging viscoelastic materials and viscoelastic rough surfaces. We provide novel analytical and semi-analytical solutions to these functions for various materials, including Generalized Maxwell, Generalized Kelvin, and Burgers’ rheological materials. Closed-form and semi-analytical solutions are developed for several specific cases with high practical applications, such as the contact between incompressible solids, a rigid material and an incompressible material, and two solids with no volumetric viscous strain. They are extensions of existing solutions given in the literature. A simple computation procedure based on the discretized integral technique is proposed for the general case of contact between linear nonaging viscoelastic materials. This proposed method is easy to implement in practical applications such as the interpretation of viscoelastic indentation tests for material characterization and the implementation of viscoelastic contact in finite/discrete element simulations.

Design and manufacture of a forelimb prosthesis prototype for a dog

The objective of this writing is to develop a methodology for the design and selection of materials that allows for the manufacturing of a canine prosthesis prototype based on anthropometric measurements, element simulation, and finite analysis. The canine prosthesis aims to restore mobility to a missing limb of a dog due to amputation and/or congenital malformation. The methodological approach for this study has been determined based on the analysis of a series of parameters, such as the dimensions of the animal leg, as well as its weight and the location of the amputation, to mention just a few points. As a contribution, a prototype of an exoprosthesis is proposed for a missing front limb, where it should fit within the range of the leg length, from 35 cm to 45 cm, and its weight should range between 30 kg and 40 kg. Additionally, the amputation should be located starting from the elbow region, and the optimal design should be able to adapt to different anthropometric measurements and the needs of the dogs.

Machine learning-driven stress integration method for anisotropic plasticity in sheet metal forming

This study proposes a machine learning-based constitutive model for anisotropic plasticity in sheet metals. A fully connected deep neural network (DNN) is constructed to learn the stress integration procedure under the plane stress condition. The DNN utilizes the labeled training data for feature learning, and the respective dataset is generated numerically based on the Euler-backward method for the whole loading domains with one element simulation. The DNN is trained sufficiently to learn all the incremental loading paths of the input-output stress pair by using advanced anisotropic yield functions. Its performance with anisotropy is evaluated for the predictions of r-values and normalized yield stress ratios along 0–90 ° to the rolling direction. In addition, the trained DNN is then incorporated in user material subroutine UMAT in ABAQUS/Implicit. Thereafter, the DNN-based anisotropic constitutive model is tested with a cup drawing simulation to evaluate earing profile. The obtained earing profile is compatible with the one from the trained anisotropic yield function.

Quasi-Stable, Non-Magnetic, Toroidal Fluid Droplets in a Ferrofluid with Annular Magnetic Field

A relatively stable, non-magnetic, torus-shaped fluid droplet within a linearly magnetizable surrounding ferrofluid medium, and subject to the annular magnetic field induced by an electric current in a wire passing perpendicularly through its centre, has been found through the use of coupled finite element/boundary element computer simulations.

Modeling the Impact of the Variation in Peripheral Nerve Anatomy on Stimulation.

The peripheral nervous system has a complex anatomical structure. Stimulation of nerve fibers in the peripheral nervous system depends on the fiber diameter and myelination as well as its location within the nerve, packing fraction and fascicle distribution within the nerve bundle. This paper analyzes the impact of the variation in peripheral nervous system anatomy and the distance of the stimulating electrodes on the probability of generating an action potential. A mathematical model for effective fascicle conductivity has been developed to capture the variation in the packing fraction and fiber diameter. A linear activating function is utilized to analyze the impact of this effective conductivity and fascicle distribution as an indicator of generating an action potential. Finite element simulations are performed for the nerve-electrode configuration to evaluate the electric field. The simulation results are used to analyze the activating function for different packing fractions and type of nerve fibers. The effect of electrode distance on activating function and the total current through a nerve bundle has also been studied. The simulation results indicate that the peripheral nerve anatomy and electrode distance have a significant effect on the action potential generation.

Sizing by SQP optimization of an electrical drive: Application to a switched capacitor connected to a permanent magnet synchronous generator

The paper deals with the design by optimization in pre-sizing step of a drive system that combines a switched capacitor system and a permanent magnet synchronous machine (PMSM). The sizing of the converter and the machine are considered strongly dependent due to the series quasi-resonant topology. The system modelling is based on a semi-analytical approach validated by finite element (FE) simulations. It involves an analytical modelling of the electrical machine and a numerical time solving of the electrical circuit sub-model because of the natural switching events of diodes. The optimization is carried out by SQP (Sequential Quadratic Programming). The model gradients are computed combining mathematical laws, symbolic derivation and automatic differentiation. Finally, trade-offs and gains on the machine power density, the magnet volume and the efficiency are investigated through a Pareto approach.

Effects of Automated Emergency Braking and Seatbelt Pre-Pretensioning on Occupant Injury Risks in High-Severity Frontal Crashes

In high-severity crashes, occupant protection is challenging. Automated Emergency Braking (AEB) and seatbelt pre-pretensioning (PPT) are means to improve occupant protection; the purpose of this study was to quantify their effects on occupant injury risks in high-severity full-frontal crashes by Finite Element (FE) simulations. The SAFER Active average male Human Body Model was used as an occupant substitute. The crash pulses used were from separate full-frontal crash simulations using a Honda Accord FE model. The vehicle interior model comprised a seat, an instrument panel, a three-point pretensioned seatbelt system with a load-limiter of 3.1 kN force level, and a frontal passenger airbag. The effects of AEB and PPT were evaluated by simulating a 1 g pre-crash braking scenario for 0.5 s, with and without AEB, for three different PPT force levels: 0, 300, and 600 N. The impact speed of 80 km/h was reduced to 69 km/h by AEB. When neither system was activated, the predicted risk for an occupant to sustain two or more fractured ribs (NFR2+) was 100% for both 45- and 65-year-old male occupants. The risks were reduced when the AEB was activated, particularly for the 45-year-old occupant. When the AEB was activated, the risks of concussion and rib fractures were reduced; upper neck tension forces, pelvis Anterior Superior Iliac Spine (ASIS) forces, and lower extremity forces were also reduced. Increasing the PPT forces reduced the rib fracture risk further (to about 48% for a 45-year-old occupant with 600 N PPT force). The reduced speed due to AEB resulted in a lower concussion risk (from 71.3% to 31%). However, the concussion risk increased slightly with increased PPT forces.

Numerical Analysis of TGU Windows Under Blast – GLASS-SHARD Outlook

The analysis of load-bearing capacity and the determination of blast protection levels for ordinary glass windows and façade components in buildings is known to represent a design and research issue of crucial importance. In the same way, reliable methods to address this issue are mostly based on cost and management expensive experimental investigations on full-size samples. According to the tendency of recent years, this paper presents some of major outcomes of Finite Element (FE) numerical methods and simulations that have been explored in the framework of the GLASS-SHARD research project for glass windows and facades under explosion or soft-body impact. The attention is focused on the analysis of a Triple Glass Unit (TGU), so as to address the blast performance of a rather ordinary glass window for buildings characterized by the presence of multiple laminated glass (LG) layers, on one side, and by the presence of two interposed gas cavities. The TGU blast performance is investigated in terms of load-bearing capacity of single components, with respect to variations in the input blast loads (stand-off distance R, charge W, etc).

Analytical Study on Profiled Steel Sheet – Concrete Composite Sandwich Panel under Axial Load

Steel-concrete composite panels have been proposed and developed for applications in various types of structures A sandwich panel is a typical structural form with good structural performance and excellent material advantages, such as high-specific strength, stiffness, light weight, high thermal insulation, and better performance under shock absorption. The project investigated the response of profiled steel sheet – concrete composite sandwich panel subjected to axial loading. Steel-concrete-steel sandwich structures consisting of two steel face plates infilled with concrete composite material has been developed. Sandwich panel consists of profiled steel sheet as the outer skins(face) and concrete as the infill, connected by using through bolts and the concrete portion is called core. Further, numerical study has been conducted to assess the integrity of the connection between skin and core and to find the effectiveness of connection on overall strength of the panel. Three-dimensional finite element (FE) simulation model is created for the parametric study to investigate the effect of several parameters on overall strength of the panel. Parametric studies are performed and numerical analysis using ANSYS Workbench results are analysed including failure mode, load–deflection curves and strength capacity.

Finite Element Simplifications and Simulation Reliability in Single Point Incremental Forming.

Single point incremental forming (SPIF) is one of the most promising technologies for the manufacturing of sheet metal prototypes and parts in small quantities. Similar to other forming processes, the design of the SPIF process is a demanding task. Nowadays, the design process is usually performed using numerical simulations and virtual models. The modelling of the SPIF process faces several challenges, including extremely long computational times caused by long tool paths and the complexity of the problem. Path determination is also a demanding task. This paper presents a finite element (FE) analysis of an incrementally formed truncated pyramid compared to experimental validation. Focus was placed on a possible simplification of the FE process modelling and its impact on the reliability of the results obtained, especially on the geometric accuracy of the part and bottom pillowing effect. The FE modelling of SPIF process was performed with the software ABAQUS, while the experiment was performed on a conventional milling machine. Low-carbon steel DC04 was used. The results confirm that by implementing mass scaling and/or time scaling, the required calculation time can be significantly reduced without substantially affecting the pillowing accuracy. An innovative artificial neural network (ANN) approach was selected to find the optimal values of mesh size and mass scaling in term of minimal bottom pillowing error. However, care should be taken when increasing the element size, as it has a significant impact on the pillow effect at the bottom of the formed part. In the range of selected mass scaling and element size, the smallest geometrical error regarding the experimental part was obtained by mass scaling of 19.01 and tool velocity of 16.49 m/s at the mesh size of 1 × 1 mm. The obtained results enable significant reduction of the computational time and can be applied in the future for other incrementally formed shapes as well.

Low Frequency Anti-Interference Mechanism of Axial Stretching Fiber Laser Hydrophones

For the axial stretching fiber laser hydrophone, a fiber laser is often exposed to flexural interference. A theoretical model for the flexural vibration of a fiber laser was therefore constructed in this paper to explore the low frequency anti-interference mechanism for the frequency response of an axially tensioned fiber laser hydrophone (FLH). A specific packaging structure was used for finite element comparison and simulation. Packaged FLHs were tested for frequency response. The simulation and test results reveal that the flexible attachment at both ends of a fiber laser leads to lower amplitude of flexural vibration compared with rigid attachment, which therefore promotes a flat acoustic response curve of an FLH. The analysis given in this paper can be taken as a basis for improving the packaging technique.

Influence of the model parameters for the finite element simulation of bone conduction in the human head

Bone conduction (BC) describes the transmission of vibrations via osseous, cartilage, and soft tissue pathways that contribute to the hearing sensation. It is important, e.g., in the context of BC hearing aids as well as for the occlusion effect and one’s own voice perception when using hearing protection or hearing devices. Finite element (FE) simulations of BC allow to overcome practical and ethical limitations of measurements with real heads and help to gain insights into underlying mechanisms. However, FE models inevitably require substantial simplifications due to the assignment and definition of volumetric domains and corresponding materials. Additionally, the material parameters are often only known within certain ranges. In this presentation, an overview on FE models of human heads used for BC research is given, and similarities and differences are discussed. The influence of the FE-inherent simplifications and the challenges in determining the model parameters are illustrated by varying the geometry and the material properties of a simple ellipsoidal model. The variability of the model predictions is compared to simulation results obtained with more realistic geometries and to the inter-subject variability observed in measurements with real human heads reported in the literature.

Vibration frequencies of meta-material plates based on the numerical calibration of shape factor for various cell patterns

In this paper, the material properties of architected meta-material plates (MMP) with different cell patterns have been obtained through numerical calibration of natural frequencies. The meta-material plate has been a single layer and like sandwich with cylindrical and cubic unit cells. The effective material properties of the meta-material have been obtained based on open-cell assumption, including a shape factor that depends on cell geometry and deformation. An artificial neural network (ANN) with three layers has been developed to derive a meta-material shape factor for all possible cell geometries. Therefore, this study presents a novel class of meta-material plates (MMP) with arbitrarily periodic webbing. Finite element (FE) simulations have verified the theoretical model, and satisfactory agreements have been obtained. Parametric studies have examined the influences of the periodic design patterns on the natural frequencies of MMP. The theoretical model introduced in this paper can be used to predict the vibration behavior of architected MMP with arbitrarily periodic patterns, and derived shape factors and frequencies can be used as benchmark results for future studies.

Approximation Method for Stress–Strain Using Metamodel Parameter Updating

The properties of the material applied to the finite element (FE) simulation can be expressed by constitutive models, and simple constitutive and complex constitutive models can be used to show the actual phenomenon. The technology to improve the accuracy of the constitutive model applied to FE simulation is the inverse method. The inverse method is a method to curve fit the FE simulation result to the test data by utilizing finite element model updating (FEMU). Inverse methods are general approaches to update material properties. The inverse method can iteratively run many FE simulations for constitutive model optimization and consider metamodel-based simulation optimization (MBSO) to reduce this resource waste. With MBSO, one can obtain significant results with fewer resources. However, the MBSO algorithm has the problem in that the optimization performance deteriorates as the number of parameters increases. The typical process of the inverse method is to adjust these factor values individually. If there are many factors in the constitutive model, the optimization result may deteriorate owing to the performance limit of the MBSO when the structural method is used. This paper proposes a method of fitting a stress–strain constitutive model with a scaling factor to improve the efficiency of the inversion method using MBSO. For this purpose, a process was performed to determine the curve characteristics during the pretreatment stage. The results show that the proposed method significantly improved the prediction efficiency of the combination function. Thus, we conclude that initializing the combination function and setting the parameters of the inverse method by applying the proposed approach improves the efficiency of large deformation analyses.

Scattering analysis of linear and nonlinear symmetric Lamb wave at cracks in plates

ABSTRACT This paper presents a detailed study on detecting defects in isotropic plates by studying scattering analysis of first and second harmonics of symmetric Lamb wave (S0 ) at cracks in aluminium plates induced by Contact Acoustic Nonlinearity (CAN) using experimental and 3D Finite Element (FE) simulation approaches. In this study, a set of models with different crack sizes and orientations are studied. The effects of crack size and crack orientation on scattering behaviour of first and second harmonics of Lamb waves are investigated . The results show that the Scattering Directivity Pattern (SDP) of Lamb wave around the cracks is significantly influenced by crack size and crack orientation. It is also shown that the largest amplitude of scattered S0 wave is acquired from forward scattering waves for linear waves while the largest amplitude of scattered S0 Lamb wave is obtained from backward scattering waves for nonlinear waves. Therefore, it is expected that pulse-echo sensor configuration enhances nonlinear wave damage detection while pitch-catch configuration may suit better when linear wave is used. It is shown that selecting proper propagation direction for incident wave and proper geometry and angle for monitoring points are the key factors to achieve successful damage detection in isotropic plates.

Impact Behavior of High-Strength Engineered Cementitious Composite and Concrete Layered Slabs

High strength Engineered Cementitious Composite (HS-ECC) is a promising material to be used in protective structures. Due to its high manufacturing efforts and cost compared to conventional concrete, nonlinear finite element (FE) simulation is performed to study the influence of replacing HS-ECC layers with concrete under drop weight impact load. Both materials are simulated using the MAT_72R3 material model impeded in LS-DYNA and verified with experimental results. Several FE slab models were developed to compare the impact responses of different configurations. This study as a whole will provide a guideline for researchers to carry out a performance and cost optimization for protective structure elements.