Developed Finite Element Model Research Articles

Simulation of ageing and wear effect on graphene THz passive components using finite element method

In the growing scenario of 2D material-based metamaterials and metasurfaces for Terahertz (THz) applications, assessing the impact of ageing and wear due to environmental stressors on the components’ performance is becoming mandatory to understand the long-term reliability of novel technologies. This paper introduces approaches to assess the ageing and wear effects on THz passive components through numerical simulations. For this purpose, common techniques for introducing 2D materials and thin metal layers in numerical models are discussed. As a case study, this work explores the effects of graphene degradation and reflective metal ageing on the electromagnetic response of a graphene-enhanced reflective grating for THz absorption and modulation by finite element (FE) analysis. The developed FE model is validated against experimental data obtained through THz Time-Domain Spectroscopy. By computing the device’s transmission, reflection, and absorption spectra for degrading graphene and metal conductive properties, this work provides insights into the influence of ageing and wear on THz passive components.

Estimation of load-carrying capacity of cracked RC beams using 3D digital twin model integrated with point clouds and images

Digital twin (DT) is capable of managing, simulating, and future performance prediction of existing infrastructures by integrating three-dimensional (3D) geometric model and finite element (FE) model. This study aims to automatically generate geometric DT of existing RC members using point clouds and incorporate damages detected from images into FE models. An edge-based modeling method was proposed to extract sharp features for geometry reconstruction with incomplete point clouds, and an automated procedure was established for registering images to point clouds, mapping cracks detected in images to FE models, and assigning reduced material properties. Four RC beams were tested in a laboratory to validate the proposed method. Existing cracks were found to have a significant effect on structural capacity and failure mode. The results also showed that the developed FE model produced a good agreement between experimental and predicted failure loads while providing a more efficient and time-saving assessment protocol.

Numerical investigation of bond-slip behaviour between CFRP strips and concrete in shear tests under static and blast loads

The paper is structured into two main sections. In the first part, the focus is on the finite element (FE) analysis of bond slip in a single bond shear test between concrete and carbon fiber reinforced polymer (CFRP) strips under static loads. To model the test set-up, a plastic damage material model and an elastic material model are used for the concrete prism and the unidirectional CFRP strip respectively. Three approaches, including a perfect bond model, a cohesive bond model, and contact algorithms based on recent bond slip models, are employed to simulate the bond interface. The numerical model's validity is confirmed through comparison with experimental results from the literature. The paper predicts the debonding failure mode, the strain evolution along the bond length, and the delamination loads of the CFRP strip. The cohesive bond model exhibits good agreement between numerical and experimental data. In the second part of the paper, the developed FE model is tested under blast loading and compared to the experimental results of the blast tests conducted by the authors. The experimental and numerical findings highlight a significant dynamic enhancement effect on bond-slip properties due to the propagation of the blast wave within the concrete and the high loading rate.

Experimental and numerical investigation on residual stress and deformation of welded I-section curved steel beams

This paper presents an experimental and numerical investigation on welding-induced residual stresses and deformations of in-plane curved welded I-section steel beams. Two welded curved beams with different curvatures were investigated. After welding the curved beam, the residual deformations were measured by a 3D scanner. The residual stresses were subsequently obtained through a high-precision sectioning method. The effects of curvature on the magnitude and distributions of residual deformations and stresses at the specific sections were analysed with the test results. It was found that the residual deformation gradually increased from the weld region to both ends of the flange plate, and the torsion in the web plate became severe with a decrease in curvature of the curved beam. Moreover, the welding process of the curved beam was simulated using the finite element (FE) method. The developed FE model was validated against the test results, and thereafter, parametric analyses were conducted to assess the influence of welding sequence, welding speed, and curvatures of the curved beam on the welding residual stresses and deformations. The numerical results demonstrated that the residual stresses and deformations were significantly influenced by welding speeds, but the influence from curvature of the curved beam was relatively small. Finally, a reasonable welding sequence, welding speed, and curvature of the curved beams were recommended.

Comprehensive Evaluation of Lateral Performance of Innovative Post in Sand

Under environmental loads such as wind and earthquakes, piles are subjected to large lateral loads. A foundation system denoted Innovative Post (IP) that is composed of an H-pile shaft and one or two steel plates (paddles) welded to its flanges, has been developed to resist large lateral loads on sound wall systems. The present study evaluates the performance of IP installed in layered cohesionless soils through a comprehensive full-scale lateral load testing program and finite element (FE) analysis considering various pile and plate configurations. The developed FE model was validated employing the field test data and was then employed to conduct a parametric study to evaluate the performance of IP considering different paddles geometry (i.e., number of paddles, single or double, width, and length). The results demonstrated that adding the plates significantly increased the lateral capacity of H-piles. A positive relationship was identified between paddle’s width and length and the load efficiency. Optimal parameter values for paddles are established based on the experimental and numerical results proposed.

Sustainability and Resiliency Investigation of Grouted Coupler Embedded in RC ABC Bridge Pier at Vehicle Impact

Increased occurrences of natural and man-made dynamic loading caused by high strain rate dynamic impact load have been recently reported. Different statistical results indicate that vehicular impacts occur more frequently compared to the other dynamic loads. However, existing literature primarily focuses on enhancing survivability and determining damage levels specifically in relation to faster bridge construction methods used as an accelerated bridge construction (ABC). In this context, the present study investigates the dynamic behavior of a commonly used connection type in ABC, namely grouted coupler that connects pre-cast elements like bridge piers and foundations. To execute the research, both the static and dynamic performance of grouted couplers embedded in pier foundation subjected to high strain rate loading incurred by high velocity vehicular impact are examined. A representative non-traditional reinforced concrete (RC) bridge pier is selected for the study with the standardized geometry and selected material properties. The use of splice sleeves as coupler materials and specified cross-sectional hollow cast iron cylinders filled with high strength concrete grout is employed for developing Finite Element (FE) modeling, extracting data from published journals. A commercial software, ANSYS, has been utilized to develop FE models to capture post impact respective static and dynamic behaviors, and the simulation results are then compared with the analytical. This also includes determining material performance via FE simulations. By considering dynamic loading, the dynamic impact factor (DIF) has been evaluated for the reinforcing steel bar adjacent and embedded into the coupler. In addition, dynamic simulations, and material modulus in demand to sustain impact are determined. Thus, the research necessitates mesh-independent sensitivity studies to investigate DIF corresponding to the precise outcomes. The findings of this study manifests valuable information that aids to opt for the suitable coupler connections, considering material properties, and adequate post impact execution. Consequently, it will serve as a useful design tool for design offices, structural practitioners, and forensic structural engineers.

Custom orthotic design by integrating 3D scanning and subject-specific FE modelling workflow.

The finite element (FE) foot model can help estimate pathomechanics and improve the customized foot orthoses design. However, the procedure of developing FE models can be time-consuming and costly. This study aimed to develop a subject-specific scaled foot modelling workflow for the foot orthoses design based on the scanned foot surface data. Six participants (twelve feet) were collected for the foot finite element modelling. The subject-specific surface-based finite element model (SFEM) was established by incorporating the scanned foot surface and scaled foot bone geometries. The geometric deviations between the scaled and the scanned foot surfaces were calculated. The SFEM model was adopted to predict barefoot and foot-orthosis interface pressures. The averaged distances between the scaled and scanned foot surfaces were 0.23 ± 0.09mm. There was no significant difference for the hallux, medial forefoot, middle forefoot, midfoot, medial hindfoot, and lateral hindfoot, except for the lateral forefoot region (p = 0.045). The SFEM model evaluated slightly higher foot-orthoses interface pressure values than measured, with a maximum deviation of 7.1%. These results indicated that the SFEM technique could predict the barefoot and foot-orthoses interface pressure, which has the potential to expedite the process of orthotic design and optimization.

Comprehensive Numerical Modeling of Prestressed Girder Bridges under Low-Velocity Impact

Accidental collisions involving over-height trucks that exceed vertical clearance limits and bridge superstructures frequently happen, resulting in compromised girders and potential threats to structural safety and performance. The numerical simulation of large-scale prestressed girder bridge collisions poses challenges due to the associated nonlinearities, as well as the limited availability of large-scale experimental testing data in the literature due to cost and complexity constraints. This study introduces a numerical modeling approach to efficiently capture the response of prestressed girder bridges under lateral impact loads. A finite element (FE) model was developed using LS-DYNA and meticulously validated against experimental data from the literature. The study explored four methods for applying prestressing forces and evaluated the performance of four concrete material constitutive models, including the Continuous Surface Cap Model (CSCM), Concrete Damage Plastic Model (CDPM), Karagozian & Case Concrete (KCC) model, and Winfrith concrete model, under impact loads. Furthermore, an impact study was conducted to investigate the influence of impact speed, impact mass, and prestressing force on the behavior of prestressed girder bridges. Utilizing the dynamic relaxation (DR) approach, the developed FE model precisely captured the response of prestressed girders under impact loads. The CSCM yielded the most accurate predictions of impact forces, with an error of less than 8%, and demonstrated a strong ability to predict damage patterns. Impact speed, mass, and the presence of prestressing force showed a significant influence on the resulting peak impact force experienced by the girder. Furthermore, the study underscores the composite nature of the bridge’s response and emphasizes the importance of analyzing the bridge as a whole rather than focusing solely on individual girders.

Ground response of rolling dynamic compaction—a finite element modelling approach

Rolling dynamic compaction (RDC) technology utilises a heavy non-circular module (impact roller) to compact the underlying soil dynamically. The stresses imparted to the soil through this technique and the resulting vibrations, have been the subject of investigation in the field. A finite element (FE) model predicting the settlement and densification of a coarse-grained fill material subject to RDC with a BH-1300 4-sided 8 tonne impact roller has been shown to provide good agreement with that observed in the field. This paper presents estimates using the developed FE model for the peak particle velocity and acceleration, and the maximum stresses applied through each impact upon a coarse-grained soil. Distributions of the results and their empirical formulae are presented herein.

Numerical Study on the Axial Compressive Behavior of Steel-Tube-Confined Concrete-Filled Steel Tubes.

To improve the concrete confinement and mechanical properties of concrete-filled steel tube (CFST) columns, a new configuration of steel-tube-confined concrete-filled steel tube (T-CFST) columns has recently been developed, in which an outer steel tube is employed externally, and the additional tube does not sustain the axial load directly. This preliminary experimental study revealed that, due to the effective concrete confinement by the outer steel tube, the T-CFST column achieves higher compressive strength and more ductile deformation compared to the CFST columns of the same steel ratio. In this study, two finite element (FE) models were developed for the T-CFST cross-section and stub column, respectively. The numerical study results revealed that the concrete can be constrained by the outer steel tube at the beginning of loading and the outer steel tube hoop stress can reach its yield strength at the column's compressive strength, showing its effective confinement to the concrete. Numerous data were generated by the developed FE model to cover a wide range of parameters. Based on that, the calculation methods for the stress components of the inner and outer steel tubes are proposed. Finally, a suitable prediction method is proposed, utilizing the superposition method to determine the compressive strength of the T-CFST stub column, and the results of the calculation method and FE model agree well with each other. This research is the basis for promoting further research of T-CFST columns.

An experimental and numerical study on the rotational behavior of bolted glulam beam-to-column connections reinforced by double U-shaped welded steel sections

The study presented the results of the experimental and numerical study on the rotational behavior of the bolted glulam beam-to-column connections reinforced by double U-shaped welded steel sections. To demonstrate the enhancement efficiency of double U-shaped steel sections on the performance of bolted glulam beam-to-column connections, both unreinforced and reinforced bolted glulam connections were tested under the monotonic pure bending scenario and the cyclic loading scenario with combined shear and bending, respectively. Besides, detailed finite element (FE) models of the reinforced bolted glulam beam-to-column connections were developed and then validated by the experimental results. The rotational behavior of the unreinforced connections and that of the reinforced connections were compared in terms of damage modes, performance parameters, stiffness degradation, and cumulative energy dissipation, respectively. The effects of two configurational parameters on the rotational behavior of the reinforced connections were analyzed, which were the diameter of the holes predrilled in the beams and the width-to-thickness ratio of the top plates of the U-shaped steel sections. In the monotonic pure bending tests, the rotational stiffness of the reinforced connections is 1.20–2.22 times that of the unreinforced connections. The rotational stiffness of the reinforced connections is enhanced as the width-to-thickness ratio of the top plates is reduced. Furthermore, when the diameter of the holes predrilled in the beams is enlarged from 22 mm to 30 mm, the rotational stiffness and the ultimate moment resisting capacity of the reinforced connections are reduced by 27.8% and 16.6%, respectively. As for the cyclic loading tests, when reinforced with U-shaped steel sections, the ultimate moment resisting capacity and the rotational stiffness of the bolted glulam connections are enhanced by 26.7% and 17.0%, respectively. The degradation of the secant stiffness of the unreinforced connection is more severe, indicating that the reinforcement with double U-shaped steel sections is an efficient damage-resistant technique for both new and existing bolted glulam connections. based on the developed FE models, both the failure modes and the moment-rotation curves of the reinforced connections under the monotonic pure bending scenario can be predicted.

Coaxial one-side resistance spot welding for cross-lap joints of Al5052 and CFRP: Thermal process and strength evaluation

Coaxial one-side resistance welding (COS-RSW) is an advanced joining technology for the metal-plastic hybrid structure, which has great application potential in the lightweight design of body-in-white. In the present research, the Al5052-CFRP cross-lap joints were fabricated by COS-RSW with different welding conditions. The author-developed finite element (FE) code JWRIAN-RSW was employed to reproduce the multi-physics coupled phenomena of COS-RSW and predict thermal history. The influence of welding current and welding time on molten zone generation and joining strength was discussed in detail. The results showed that the developed FE model can predict temperature distribution and variation effectively, which were verified by the bonding zone observation and infrared thermal image measurement. Both welding current and welding time had a significant contribution to the Joule heat generation. While their influence on the molten zone growth during heating and cooling stage was distinct. The maximum joining strength of COS-RSW cross-lap joints can reach about 1380 N. The static tensile strength was improved significantly when the maximum interface temperature exceeded 340 °C and the failure mode altered into staged fracture. The strength degradation induced by significant CFRP decomposition was appeared when the predicted interface temperature reached 410 °C. For the COS-RSW joint of Al5052 and CFRP, it was better to improve the joining strength using longer welding time rather than higher welding current, which led to sufficient heat generation, persistent thermal conduction and elongated melting duration for sound joining.

Seismic performance of precast multi-segment columns with grouted sleeves: Experimental and numerical investigations

This research explores the seismic performance of multi-segment columns, which are gaining attention due to their segmented prefabrication and assembly that address transportation and installation challenges. The main objective is to investigate the effective use of grouted sleeves as connections, both between column segments and to the foundation, in order to achieve satisfactory seismic behavior. To achieve this objective, an experimental program involving reversed cyclic tests was conducted on three precast specimens, which were compared to a reference conventional cast-in-place (CIP) column. The precast specimens featured grouted sleeve connections, with variations in the number of column segments and the connection types. The test results showed higher peak strength but reduced ductility in the grouted sleeve specimens compared to the CIP column. Moreover, multi-segment columns displayed significant improvements in ductility (12.8%), deformation capacity (27.0%), and energy dissipation (14.8%) compared to the single-segment column. Transferring grouted sleeves to the foundation further improved ductility by 18.0%. In parallel, a finite element (FE) modeling method was developed, with simplified representations of cushions and grouted sleeves. The FE results exhibited satisfactory agreement with the experimental findings, validating the accuracy of the developed FE models in terms of hysteresis curves, residual displacement, peak strength, and energy dissipation.

Influences of the bond-slip on the flexural performance of CFRP plate-strengthened damaged steel beams with intermediate debonding: A numerical study

The interfacial intermediate debonding between the steel beam and CFRP (carbon-fiber-reinforced polymer) is a considerable issue for a CFRP plate-strengthened damaged steel beam. The interfacial bond-slip property determines the interfacial debonding and thus affects the strengthening efficiency. To comprehend the influence laws of the bond-slip behavior, this study conducted a finite element (FE) modelling to assess the strengthening efficiency of the damaged steel beam using CFRP plates. The triangular and trapezoidal cohesive zone models were considered in parametric investigations. The comparisons of FE and experimental results verify the developed FE models. The FE modelling shows that the interfacial fracture energy is the most important bond-slip parameter affecting the flexural strengthening efficiency, relative to the maximum bond stress, elastic and plastic slips. The flexural capacity, ultimate deflection, and debonding load of the damaged steel beam are significantly increased with an increase in the interfacial fracture energy. However, changing the maximum bond stress, elastic slip or plastic slip only produce a minor influence under the same interfacial fracture energy. The selection of the adhesive type is critical for strengthening the damaged steel beam using CFRP plates. In this study, the debonding load, flexural capacity, and ultimate deflection are increased by 75.0%, 51.0%, and 131.1%, respectively, when Araldite-2015 adhesive with the trapezoidal bond-slip model is used instead of Sikadur-30 adhesive with the triangular bond-slip model. Moreover, the debonding load and flexural capacity are hardly increased but the ductility can be considerably improved with an increasing CFRP plate length.

A DFT-based finite element model to study the elastic, buckling and vibrational characteristics of monolayer bismuthene

PurposeIn this paper, based on the density functional theory (DFT) and finite element method (FEM), the elastic, buckling and vibrational behaviors of the monolayer bismuthene are studied.Design/methodology/approachThe computed elastic properties based on DFT are used to develop a finite element (FE) model for the monolayer bismuthene in which the Bi-Bi bonds are simulated by beam elements. Furthermore, mass elements are used to model the Bi atoms. The developed FE model is used to compute Young's modulus of monolayer bismuthene. The model is then used to evaluate the buckling force and fundamental natural frequency of the monolayer bismuthene with different geometrical parameters.FindingsComparing the results of the FEM and DFT, it is shown that the proposed model can predict Young's modulus of the monolayer bismuthene with an acceptable accuracy. It is also shown that the influence of the vertical side length on the fundamental natural frequency of the monolayer bismuthene is not significant. However, vibrational characteristics of the bismuthene are significantly affected by the horizontal side length.Originality/valueDFT and FEM are used to study the elastic, vibrational and buckling properties of the monolayer bismuthene. The developed model can be used to predict Young's modulus of the monolayer bismuthene accurately. Effect of the vertical side length on the fundamental natural frequency is negligible. However, vibrational characteristics are significantly affected by the horizontal side length.

Tests and finite element modeling of concrete beams reinforced with reused steel bars

AbstractThis paper presents the experimental study and finite element modeling of the flexural behavior of concrete beams reinforced with reused steel bars as longitudinal reinforcements. The experimental program and results of eight reinforced concrete (RC) beams constructed with and without reused steel bars are described in detail. The replacement percentages of brand‐new bars with reused steel bars in the tested beams were 50% and 100%. The reused steel bars were coated with and without epoxy. Steel fibers with fractions of 0.5% and 1.0% of the concrete volume were added to the concrete mixes. The load‐deflection relationship, ductility index, toughness, and failure modes of the tested beams are presented and discussed. It is shown that utilizing reused steel bars decreases the ultimate load of RC beams but increases their deflection at the ultimate load compared with the control beam. Increasing the steel fiber ratio increases the ultimate load and the deflection at the ultimate load of RC beams incorporating reused steel bars. However, the zinc‐rich epoxy used to coat the reused steel bars does not affect the behavior of the beams. Three‐dimensional nonlinear finite element (FE) models of the tested beams were developed using ABAQUS and validated against the test results. The developed FE models are capable of accurately simulating the experimentally observed behavior of RC beams with reused steel bars.

Numerical modelling of 3D concrete printing: material models, boundary conditions and failure identification

3D concrete printing (3DCP) attracts significant attention as an innovative manufacturing technology for the construction industry. As one of the challenges in 3DCP, failure mechanisms of 3D printed concrete structures were not well understood yet and hard to predict. The three-dimensional finite element (FE) method is an effective method to simulate such a layer-by-layer process. However, some existing technical issues in FE modelling, including additional initial deformations, failure identification, selection of material models, concrete foundation interactions and initial imperfections, need to be addressed for accurate simulation of 3DCP. In this study, FE models using a novel tracing element approach are developed to capture mechanical behaviours and failure modes of typical 3D printed concrete structures. The developed FE models was validated by comparing the obtained numerical results with those data available in literature. Furthermore, four material constitutive models are investigated analytically and numerically to compare their applicability in modelling 3D printed concrete structures. The obtained results show that the Mohr-Coulomb and Concrete Damage Plasticity (CDP) models can accurately predict failure behaviours of 3D printed concrete structures.

Effect of masonry infill on the response of reinforced concrete frames subject to in-plane blast loading

This paper presents a numerical study investigating the effect of masonry infill on the response of reinforced concrete (RC) frames subject to in-plane blast loading. Three-dimensional single-bay single-story masonry infilled reinforced concrete (MIRC) frames were modeled, in which a simplified micro-modeling approach was adopted for the masonry infill. The surface-based cohesive model was employed between the expanded brick units by adopting the traction-separation law. A non-integral modeling approach was considered with an appropriate contact algorithm between the infill wall and bounding RC frame. The dynamic material models with explicit dependency on strain rate were incorporated in the finite element (FE) models and validated against the experimental test data. The developed FE models of bare RC and MIRC frames were subjected to surface blasts with variable scaled distances representing the far-field, near-field, and close-in blasts. The effect of masonry infill on the response of RC frames subject to in-plane blast loading was investigated using the general-purpose FE software ABAQUS without employing user-defined subroutines. The blast response was characterized using displacements, energy dissipation, strain localization and accumulation, stiffness degradation, and damage modes. Results highlight the beneficial influence of masonry infill in reducing the local deformation and altering the failure modes of RC frames subject to in-plane blasts. However, results suggest that the effects of infill on the overall structural response, including axial, flexural, and shear demands, must be considered during the design of bounding RC frames. Furthermore, parametric studies were carried out based on varying masonry bonding patterns and wall thickness, number of bays and stories, and masonry infill heights, and provided conclusive remarks.

Behaviour, finite element modelling and design of high strength steel homogeneous and hybrid welded I‐section beams

AbstractThe behaviour and design of homogeneous and hybrid high strength steel (HSS) beams are addressed in the present study. Six in‐plane three‐point bending tests on three different welded I‐sections were first conducted. Following the experimental investigation, a finite element (FE) modelling programme was performed, which included a validation study confirming the accuracy of the developed FE models in replicating the flexural behaviour of HSS welded I‐section beams, and a parametric study generating additional FE data on HSS welded I‐section beams over a broader range of cross‐sectional slendernesses, steel grades and loading configurations. Then, the suitability of the current Eurocode 3 cross‐section slenderness limits for HSS homogeneous and hybrid welded I‐sections in bending were evaluated. It is shown that the current Eurocode Class 2 and Class 3 slenderness limits are suitable for the classification of the outstand flange (in compression) and internal web (in bending) elements of both HSS homogeneous and hybrid welded I‐sections subjected to major axis bending, while stricter Class 1 slenderness limits are considered necessary to achieve sufficient rotation capacity for plastic design. The findings indicate that plastic design can be used for HSS structures, provided the proposed stricter Class 1 slenderness limits are employed. Further work is underway to develop advanced design approaches using second‐order inelastic analysis with strain limits for HSS welded I‐section members.

Numerical and analytical investigations on the flexural behaviours of composite beams of inverted-T steel section and ultra-high-performance concrete (UHPC) slab

This study numerically and analytically investigates the flexural performance of a new form of steel–concrete composite beam, where an inverted-T section is connected to ultra-high-performance concrete (UHPC) slab that serves as the compression chord. Such arrangement eliminates the necessity for the top flange and absorbs the compressive stresses when the beam is under construction. Thus, the aim of this study is to develop a comprehensive finite element (FE) model for the proposed inverted-T steel-UHPC composite beam in ABAQUS by considering both geometric and material nonlinearities. The developed FE model was validated against the existing experimental results, and afterwards the validated FE model was employed to conduct an extensive parametric study. In the parametric study, the effects of different design parameters including slab thickness, concrete compressive strength, stud spacing, stud diameter, effective width of slab and web penetration depth were investigated in terms of the load–deflection, bond-slip, and damage patterns. Furthermore, the load–deflection and load-slip behaviors of the proposed beam were compared with the conventional steel–concrete composite beam. Finally, an analytical procedure was developed to determine the flexural resistance of the inverted-T steel-UHPC composite beam. The results of this study will pave the way toward a practical application that is expected to decrease the construction time and cost.