Proposed Finite Element Model Research Articles

Study on seismic behavior of prefabricated shear wall with pressed cone sleeves (PCSs)

Current prefabricated shear walls predominantly utilize grouting sleeves for connection, whereas an in-depth review and summary of the current state of research have indicated a 26.7 % construction defect rate in these sleeves due to present construction techniques. To solve the problem of defects, this study introduced a novel prefabricated shear wall design using vertical rebars connected via pressed cone sleeves (PCSs). Three reinforced concrete (RC) prefabricated shear walls with different vertical rebars connected and tested under cyclic horizontal load and constant vertical load to study the seismic performance, including cast-in-situ shear wall (specimen SW1), partial sleeve grouting defects shear wall (specimen SW2) and shear wall with vertical rebars connected via PCSs (PCSs-SW, specimen SW3). Key performance indicators such as failure modes, hysteresis curves, shear capacity, stiffness, ductility, energy dissipation capacity and stress characteristics were evaluated. The results of the tests revealed that SW1 and SW3 failures resulted from a combination of bending moment and shear force, whereas SW2 failure in the area of grout sleeve defects connection. Compared to the specimen SW2, the SW3 owns better shear bearing capacity, ductility, stiffness, energy dissipating capacity and reliable seismic performance. Meanwhile, SW3 and SW1 exhibited the similar seismic performance, can primarily achieve the effect of “equivalent cast-in-situ”. Finite element (FE) model of specimen SW3 were developed by using software ABAQUS, and the precision and utility of FE models verified by testing data. Using proposed FE models, an extensive parametric study was conducted to investigate the influencing factors on the seismic performance of precast fabricated RC shear wall, including axial compression ratio, concrete strength, vertical rebar strengths and vertical rebar diameters.

A Numerical Study on Predicting Bond-Slip Relationship of Reinforced Concrete using Surface Based Cohesive Behavior

Overall structural integrity and load transfer between concrete and reinforcement enabling composite action relies on the bond between concrete and reinforcement. Bond strength determination of reinforced concrete is an essential task that a pullout test can determine. Experimental pullout behaviour can be affected by various parameters, such as concrete and steel strength, boundary conditions, etc. Therefore, a parametric study on pullout tests is time-consuming. In addition, measurements of internal stress-strain components and damages of constitutive materials are also difficult in experimental endeavours. In this context, finite element (FE) models should be developed to perform a parametric study with cost and time-saving. This study proposes a finite element modeling strategy of reinforced concrete under pullout force by using the expected failure mechanism to predict bond-slip behaviour in ABAQUS. In FE models, surface-to-surface cohesive interaction behaviour was used to assign interaction between reinforcement and concrete. The proposed modelling strategy was validated with available experimental data from four reference specimens, having all possible failures (i.e., pullout, splitting, and splitting-pullout) under pullout loading. The finite element analysis showed that the proposed FE modeling strategy performed well in predicting bond-slip behaviour in elastic regions. Additionally, maximum bond stresses were predicted satisfactorily, except for the splitting failure pattern, using the proposed FE modelling strategy.

Shaking Table Tests and Numerical Analysis Conducted on an Aluminum Alloy Single-Layer Spherical Reticulated Shell with Fully Welded Connections

Aluminum alloy offers the advantages of being lightweight, high in strength, corrosion-resistant, and easy to process. It has a promising application prospect in large-span space structures, with its primary application form being single-layer reticulated shells. In this study, shaking table tests were conducted on a 1/25 scale aluminum alloy single-layer spherical reticulated shell structure. A finite element (FE) model of the reticulated shell structure was established in Ansys. Compared with the experimental results, the deviation in natural frequency, acceleration amplitude, and displacement amplitude was less than 20%, confirming the validity of the model. An extensive analysis of the various rise–span ratios and connection constraints of a single-layer spherical reticulated shell structure was carried out using the proposed FE model. The experimental and simulation results showed that as the rise–span ratio of the aluminum alloy reticulated shell increases, the natural frequency of the reticulated shell structure also increases while the dynamic performance decreases. The connection of the circumferential members changes from a rigid connection to a hinged connection. The natural frequency of the reticulated shell structure is reduced by about 40% while the acceleration and displacement response values are decreased by approximately 15%.

Numerical investigation on mechanical behavior of 3D orthogonal woven composites in hygrothermal environments

3D orthogonal woven composites (3DOWCs) are increasingly utilized in various engineering applications due to their superior mechanical properties. However, their mechanical properties and damage mechanisms could be significantly influenced by the environmental factors such as temperature and moisture. This study aims to investigate the mechanical behavior of 3DOWCs under hygrothermal conditions through meso-scale finite element (FE) simulations. The proposed FE model is validated using existing experimental results under standard temperature and humidity conditions, and subsequently applied to predict the performance in hygrothermal environments. The effects of temperature, humidity, and loading conditions on the mechanical properties of 3DOWCs are analyzed and the corresponding failure mechanisms are revealed. This study offers significant insights into the hygrothermal behavior of 3DOWCs, thereby facilitating their optimal design and implementation in various engineering applications.

Numerical simulation of temperature profile during laser cladding of nickel powder for in situ repairing

A 3-D Finite Element (FE) model was established to simulate the laser cladding of nickel powder for in situ repairing AISI 410 stainless steel. The temperature distribution field was estimated at six different points using low laser power of 450 W and a scanning speed of 2 mm/s. This study used a moving laser heat source in COMSOL to simulate the laser cladding process. The proposed FE model investigated the temperature field in two cases: (1) in situ repairing the defect by laser cladding without preheating and (2) in situ repairing the defect by laser cladding technique after preheating the cavity made on the substrate. A time-temperature profile was obtained after the simulation in both cases. The results of both cases were compared and analyzed. When the cladding material is poured into the preheated cavity, its temperature rises due to the heating effect obtained from the cavity, resulting in a higher maximum temperature after the cladding process. It was observed that after the cladding process, the maximum temperature was higher in the case of laser cladding after preheating the substrate (2400.49 K) compared to the maximum temperature in cladding without preheating the substrate (1770 K). Therefore, a molten pool is formed, solidifying rapidly to form a clad coating with better metallurgical bonding and enhanced surface properties.

Numerical investigation on orthogonal cutting and damage response of CFRP/Ti6Al4V stacks

CFRP/Ti6Al4V stacks are widely employed in aerospace, automotive and marine applications owing to their superior properties. However, machining these stacked structures pose challenges due to the intrinsic difference in the mechanical properties of CFRP and Ti6Al4V. Such difference can induce distinct failure mechanisms and chip formation processes compared to those observed in individual materials. This paper presents an explicit finite element (FE) modeling to predict the cutting forces and analyze the induced damage during the orthogonal cutting process. The proposed FE model is validated using available experimental data for separate CFRP and Ti6Al4V conditions before being applied to simulate the cutting behavior of CFRP/Ti6Al4V stacks. The effects of fiber angles, cutting sequences and cutting parameters on the cutting performance and damage mechanism of CFRP/Ti6Al4V stacks are investigated in detail. This work provides insights into the cutting behavior of CFRP/Ti6Al4V stacks and facilitates the optimization of machining process for such composite system.

Numerical simulation of corroded circular hollow section steel columns: A corrosion evolution approach

This study introduces a numerical simulation method for corroded circular hollow section steel columns, utilising a newly developed corrosion evolution model. This model was formulated by characterising the corrosion morphology and calibrating parameters throughout the entire corrosion process. An interpolation method was implemented to estimate the number of corrosion pits, based on experimentally measured corrosion ratios. Consequently, this allowed for the numerical prediction of the time-varying corrosion morphologies. Finite element (FE) models, incorporating this corrosion evolution model, were constructed. These corroded column models underwent validation through comparison with experimental findings. To further establish the effectiveness of the proposed FE models in predicting the structural behaviour of corroded members, FE models were also developed using the traditional uniform thickness reduction approach for comparative analysis. The results revealed that the proposed FE models for corroded structures offer a more accurate prediction of mechanical performance, particularly in instances of severe corrosion damage.

Experimental and Modelling of Lightning Damage to Carbon Fibre-Reinforced Composites under Swept Stroke

Lightning swept stroke creates multiple lightning attachments along an aircraft in flight. This introduces distinct structural damage compared to that from a single-point lightning current injection test in laboratory. This study presents both experimental and numerical studies on lightning damage in carbon fibre-reinforced polymer (CFRP) composites under swept stroke. Coupled electrical–thermal finite element (FE) models were proposed to predict lightning damage to CFRP composites under single-point current injection and swept stroke, respectively. A lightning swept stroke testing method was proposed by embedding a copper wire inside the composites to simulate multiple lightning attachments on the composites. The FE-predicted damage from single-point current injection and swept stroke were comparable to those obtained from the experiments with a deviation less than 23%, demonstrating the effectiveness of the proposed FE model. Finally, the FE model was further utilised to gain insights into the failure mechanism of CFRP composites under swept stroke associated with different skip distances and peak currents. This paper provides an experimental method and a FE model for obtaining the LS damage of CFRP composite by swept stroke.

Hysteretic behavior of prestressed high-strength bolt joint subject to combined flexure and axial forces for prefabricated prestressed spatial structures

A novel prestressed high-strength bolt (PHSB) joint applied in the prefabricated large-span ridge tube cable dome with annular struts (PLRTCDAS) was proposed. Firstly, the hysteretic behavior of the PHSB joint under combinations of bending moment and axial compression was studied by experiments. Four parameters of the PHSB joint, including the disc thickness, perforated cross plate thickness, perforated angle steel thickness, and outer sleeve height, were considered in the test. The effects of these parameters on the hysteretic curves, skeleton curves, bearing capacity, failure modes, energy dissipation behavior, and ductility were analyzed and discussed in detail. Secondly, a three-dimensional finite element (FE) model of the PHSB joint considering geometric, material, and interaction nonlinearities was established by ABAQUS. The accuracy of FE model was verified by comparing the test and numerical results. Finally, the hysteretic behavior of the PSHB joint under different combinations of axial forces and bending moments was investigated by the proposed FE model. The research indicates that the PHSB joint exhibits perfect energy dissipation capacity and higher ductility. Reducing the perforated angle steel thickness or increasing the outer sleeve height can improve the hysteretic behavior of the PHSB joint without significantly reducing its bearing capacity. The verified FE model is an effective method to simulate PHSB joint hysteretic behavior.

Flexural vibration of elastic composite beams using a third-order deformation kinematics

The present study introduces a one-dimensional finite element (FE) model that utilizes third-order deformation kinematics to analyze the flexural vibration of two-layered composite beams with partial shear slip. The proposed model incorporates a three-node straight beam element, utilizing the field-consistent approach and full numerical integration of the stiffness matrix. This approach is adopted to effectively address stress oscillation and shear locking issues, ensuring accurate and reliable results. The analysis focuses on the third-order deformation kinematics of longitudinal displacement within the beam depth, examining each of the two layers individually. The interface between the two material layers is joined using deformable shear connectors, which are represented as dispersed shear springs over the length of the beam. This study focuses on conducting a flexural vibration analysis of two-layered composite beams. The analysis includes the examination of both free vibration and forced vibration responses while considering or omitting the influence of damping under various loading conditions. The validity of the proposed FE model is assessed by the utilization of a two-dimensional model developed within the ABAQUS software. Additionally, the suggested model is evaluated through the process of verification by comparing it with previously published results.

Behavior of CFRP strengthened concrete-filled steel tubes with spherical-cap gap under axial compression

Carbon fiber-reinforced polymer (CFRP) strengthening can be considered as an effect approach to compensate the unfavorable influence caused by the spherical-cap gap on concrete-filled steel tube (CFST) structures. In the present study, the influence of CFRP wrapped on the mechanical behavior of CFST with spherical-cap gap (CFST-G) is examined. Sixteen CFST stub columns are experimentally tested under axial compression loads, considering the gap ratio and the number of CFRP layers (nCFRP) as the main parameters for analysis. The test results show that the bearing capacity decreases with increasing gap ratio, and the wrapped CFRP effectively improves the axial bearing capacity of CFST-G. Notably, the strengthening effect increases as nCFRP increases. Meanwhile, finite element (FE) models are established and verified against the test results. The proposed FE model is then used to conduct behavior analysis, and the working mechanism of CFST-G with CFRP strengthened is revealed. Parametric studies are also carried out by the FE model. The results show that, under the same gap ratio, the strength index decreases with increasing steel strength, steel ratio, and nCFRP, whereas it increases as the concrete strength increases. Based on the test and numerical analysis results, a simplified formula to calculate the bearing capacity of CFRP-strengthened CFST-G is proposed, providing a basis and reference for practical engineering and design codes.

An improved method for monitoring the junction temperature of 1200V / 50A IGBT modules used in power conversion systems

Abstract Insulated gate bipolar transistor (IGBT) is one of the most used devices for high-power-density and high-voltage applications such as wind turbines, electric vehicles, and smart grids. However, the field of IGBT research is still in its infancy owing to the failures that can happen to the module due to its temperature rise. Hence, the junction temperature T j measurement of the active region is essential for analyzing and predicting the degradation state of the IGBT device. In this paper, an overall study, including uses of the governing thermal equation to estimate the junction temperature T j, experimental analysis of the IGBT component during operation, and a numerical finite element (FE) study, was conducted. The thermal management FE model is conducted to predict temperature variation along time and heat spreading inside the IGBT layers. To investigate the material’s properties and structure change during operation impacting the junction temperature, scanning electron microscopy (SEM) and energy X-ray dispersive spectroscopy (EDS) were performed on the IGBT power module. Results were used to interpret the difference between the experimental and the predicted temperature values. For effectiveness validation purposes, results obtained from the proposed FE model are compared with the results of the experimental thermo-sensitive electrical parameters (TSEP) method. Good agreement was found between the experiment and the proposed FE model.

Numerical and theoretical studies for the shear behavior of CFRP plate-ECC-concrete composite interface

The shear behavior of the single-shear specimen with CFRP plate-ECC-concrete (CEC) composite interface was investigated using the finite element (FE) and theoretical calculation methods. The proposed FE model was established to simulate the entire loading process of the single-shear specimen under actual experimental conditions, and the newly developed CFRP-ECC interface model was incorporated. The FE model was calibrated and verified by comparing it with the experimental results. The results showed good agreement between the simulated and measured values for debonding load, shear stress, and interface damage. The proposed FE model was further adopted to perform parameter analyses of ECC thickness, CFRP bonding length, and CFRP plate width. This paper also proposed a calculation model for the debonding load of CEC composite interface considering the high tensile strength and the thickness of ECC. The results show that the proposed model shows a high accuracy for the prediction of debonding load.

Ballistic performance and damage behavior of three-dimensional angle-interlock woven composites under high velocity impact: Experimental and numerical studies

Three-dimensional angle-interlock woven composites (3DAWCs) are usually employed as exposed components in aerospace and other high-tech areas due to their superior impact resistance. In this work, the experimental characterization and numerical modeling are combined together to study the ballistic performance and damage behavior of 3DAWCs under high velocity impact (HVI). The initial-residual velocity relation is examined by ballistic impact test and the penetration process is recorded by high-speed camera. A nonlinear finite element (FE) model based on a multi-scale modeling framework is established to simulate the ballistic impact response and damage behavior of 3DAWCs. The proposed FE model is verified by comparing the predicted initial-residual velocity curve and penetration propagation with the experimental data. Parameter analysis is conducted to address the influences of projectile diameter and impact angle on the impact performance of 3DAWCs and the corresponding damage mechanisms are revealed in detail. The present work provides a transferable approach for studying the HVI problems of other textile composite structures.

Self-Piercing rivet joining of multi-material including CFRP: Experiments and FE modeling

In this study, finite element (FE) analyses based on the arbitrary Lagrangian–Eulerian technique were used to investigate the complex deformation behavior and numerous process variables that arise during the self-piercing riveting (SPR) joining of multi-materials, including carbon-fiber-reinforced polymer, GA590DP, and Al5052-H32 sheets in two- and three-layer combinations. Tensile tests and inverse analysis were conducted to determine the mechanical responses of each joining material, including the rivet, and equivalent strain-based fracture modeling approaches were adopted for a simple but effective crack initiation prediction during the mechanical joining process. The damage distribution and joining characteristics during the SPR joining were then numerically investigated by considering different die profiles. The high predictability of the proposed FE modeling approach in terms of the cross-sectional profile with joint quality indicators, such as the interlock, residual distance between the rivet leg and die, minimum thickness of the bottom sheet, load history, and peak load during mechanical joining, was validated through comparisons between the experiments and FE simulations.

Parametric Study of PEKK Based Fiber Metal Laminates Used in Aerospace Applications

Numerical analyses offer a cost-effective and efficient alternative to experimental investigations, and Finite Element (FE) models have become a popular tool to simulate the behavior of Fiber metal laminates (FMLs) under impact loads. This study verified the reliability of the proposed FE models to predict the perforation response of ‎the FMLs investigated under low-velocity impact loadings. The validation of ‎the FE models was assessed through comparison with the corresponding results of the ‎experimental work. The results showed that the proposed simulations are capable of predicting the dynamic response of the laminates investigated with a high degree of success. The parametric studies were conducted on 2/1 titanium FMLs based on 2-ply composite cores and 2/1 aluminum FMLs based on 4-ply composite cores under impact with a variety of loading conditions. The developed FE models were then used to explore the structural behavior of the fiber metal laminates investigated with an extended variation of parameters, i.e., projectile striking angle, impact locations, the geometry of the projectile, and velocity. The results of the FE models are presented in terms of load-displacement traces, energy absorption, and failure modes. The findings of this study contribute to the understanding of the structural behavior of FMLs under impact loads and can inform the design and optimization of FMLs for various engineering applications. The use of FE models provides a cost-effective and efficient means of exploring the structural behavior of FMLs under different impact conditions, which can reduce the need for costly and time-consuming experimental investigations.

Computational modeling and simulations for predicting the nonlinear responses of reinforced concrete beams

PurposeThe ultimate capacity and ductility behavior of a reinforced concrete (RC) beam generally depends on its constituent material properties. This study aims to use ANSYS to accentuate the nonlinear parametric finite element (FE) simulations of RC sections under monotonic loading.Design/methodology/approachThe concrete matrix and steel reinforcement are the primary constituent materials of RC beams. The material properties such as tensile reinforcement area, tensile bars yield strength, concrete compressive strength and strain rate in tensile reinforcement at nominal strength have significantly influenced the ultimate response of RC beams. Therefore, these intensive parameters are considered in this study to ascertain their effect on the RC beam's ultimate behavior. The nonlinear response up to the ultimate load capacity and the crack evolutions of RC beams are predicted efficiently.FindingsThe parametric study reveals that increasing the tensile steel reinforcements (from Ast = 213–857 mm2) significantly improves the ultimate load capacity by 229% and yield deflections by 20%. However, it declines the ultimate deflection by 47% and ductility by 56% substantially. Varying the strain limit (?tn = 0.010–0.0015) of tensile reinforcement has proficiently increased the ultimate load-resisting capacity by 20%, whereas the ductility declined by 62%. When the concrete strength increases (from fck = 25–65 MPa), the cracking load increases profoundly by 51%, whereas the ultimate capacity has found an insignificant effect.Originality/valueThe load-deflection response plots extracted from the proposed numerical model exhibit satisfactory accuracy (less than 9% deviation) against the experimental curves available in the literature, which emphasizes the proficiency of the proposed FE model.

Numerical and Experimental Behavior Analysis of Slabs Strengthened Using Steel Plates and Slurry-Infiltrated Mat Concrete (SIMCON) Laminates

This study has two main aims; firstly, investigating the behavior of slabs that are strengthened with different types of reinforcements and with Slurry-Infiltrated Mat Concrete (SIMCON) laminates, having different dimensions and thicknesses and subjected to static and dynamic (impact) loads. Secondly, the development of a non-linear finite element (FE) model to simulate the behavior of the tested slabs utilizing the ABAQUS/Standard package. The modeling of the NSC slabs strengthened with either SIMCON or steel plates involves using three-dimensional solid elements that are partially integrated with the modeling of concretes using the 8-node brick element (C3D8R). The results of the experimental and numerical investigations are compared to examine whether the slab modeling is sufficient. The comparison includes the element type, material characteristics, real constants, and convergence study. The predicted ultimate load-carrying capacity versus vertical deformation response is compared with the lab results that correspond with it, as obtained via the FE analysis of all tested slabs. In addition, the results of the FE analysis of slab specimens that are strengthened with steel plates were compared to the results of the ones strengthened using SIMCON laminates. The obtained results have led to a number of significant observations. Considering the punching shear strength, it was found that using SIMCON strengthening in different dimensions increased the slab’s punching shear capacity and outperformed steel-strengthened slabs. As for the plate stiffness, SIMCON-strengthened slabs presented higher stiffness rates than steel-strengthened slabs, to the extent that even 20 mm SIMCON strengthening outperformed the steel plate-strengthened slabs of any thickness or dimensions. The axial load-displacement relationships indicate that all the numerical models show a stiffer behavior when compared with the experimental axial load-displacement relationships. The slab thickness of SIMCON significantly affects the load-carrying capacity, and it increases with the increase in thickness. Likewise, using strengthening from steel plates gives a higher load-carrying capacity. Finally, since the results of the yield line analyses for these slabs are found to match the experimental results closely, this method is considered to be suitable for practical use in determining the strength of plated slabs. Therefore, the conclusion is drawn that the proposed FE model can be sufficiently used in evaluating the dynamic responses of slabs strengthened with SIMCON or steel plates and subjected to cyclic and impact load.

Finite Element Modeling of Interface Behavior between Normal Concrete and Ultra-High Performance Fiber-Reinforced Concrete

The behavior at the interface between normal strength concrete (NSC) and Ultra-High Performance Fiber-Reinforced Concrete (UHPFRC) plays a crucial role in accurately predicting the capacity of UHPFRC for strengthening and repairing concrete structures. Until now, there has been a lack of sufficient finite element (FE) models for accurately predicting the behavior at the interface between NSC and UHPFRC. This study aims to investigate the structural behavior of composite members made of NSC and UHPFRC by developing a model that accurately simulates the interface between the two materials using a linear traction-separation law. Novel parameters for the surface-based cohesive model, based on the traction-separation model, were obtained and calibrated from prior experiments using analytical methods. These parameters were then integrated into seven FE models to simulate the behavior at the interface between NSC and UHPFRC in shear, tensile, and flexural tests. The accuracy of the FE models was validated using experimental data. The findings revealed that the proposed FE models could effectively predict the structural behavior of composite NSC-UHPFRC members under various working conditions. Specifically, the maximum deviations between EXP and FEA were 6.8% in ultimate load for the shear test and 15.9% and 2.8% in ultimate displacement for the tensile and flexural tests, respectively. The model can be utilized to design the use of UHPFRC and ultra-high performance fiber-reinforced shotcrete (UHPFRS) for repairing and strengthening damaged concrete structures.

FE-assisted investigation for mechanical behaviour of connections in offshore wind turbine towers

The overall competitiveness of offshore wind turbine towers is significantly influenced by the selection of the connection. The following three types of connections: a conventional bolted ring flange (RF) connection, ring flange connection with defined contact surfaces (RFD), and C1 wedge connection (C1-WC) are considered. A quantitative comparison is made to enhance performance in a specific condition and enable further optimization of these connections in engineering practices. The study compares the tensile behaviour and fatigue performance of these connections by validated finite element (FE) simulation and analysis. The proposed FE modelling is based on a realistic geometry including all contacts present in the connections, steel full-range stress–strain relationship and ductile damage model. The efficiency and accuracy of the FE models are validated through the comparison with the performed tests. Then, a series of parametric FE analyses are carried out to examine the impact of the applied boundary conditions, bolt pretension level, and steel grade on the behaviour of connections. Load-displacement curves, bolt evolution curves, and stress responses are analysed to compare their tensile behaviour. The effectiveness of conventional segment specimen testing is evaluated thoroughly. For the fatigue performance of connections, the results indicate that the segment specimen testing substantially underestimates the fatigue performance of C1-WCs. This discrepancy is essential to be considered in the tower design. It is also noted that C1-WCs are rather insensitive to the variation of pretension force level, which show superiority to avoiding the difficulties associated with typically bolted joints. This research provides in-depth knowledge for the practical application of such connections and further optimization.