ABAQUS Model Research Articles

Dynamic Response of Transmission Tower-Line Systems Due to Ground Vibration Caused by High-Speed Trains

With the continuous expansion of the scale of power grid and transportation infrastructure construction, the number of crossovers between transmission lines and high-speed railways continues to increase. At present, there is a lack of systematic research on the dynamic characteristics of transmission tower-line structures crossing high-speed railways under vehicle-induced ground vibration. This article focuses on the phenomenon of accidents such as line drops when crossing areas in recent years and establishes a high-speed train track foundation soil finite element model in ABAQUS that considers track irregularity. The three-dimensional vibration characteristics and attenuation law of train ground vibration are analyzed. Acceleration data for key points are also extracted. A separate finite element model of the transmission tower-line system is established in ANSYS, where acceleration is applied as an excitation to the transmission tower-line system, and the coupling effect between the tower and the line is considered to analyze its dynamic response. Subsequently, modal analysis is conducted on the tower-line system, providing the vibration modes and natural frequencies of the transmission tower-line structure. The effects of factors such as train speed, soil quality, and distance from the tower to the track on the dynamic response of the transmission tower-line system under vehicle-induced ground vibration are studied. The results show that the speed range (300 km/h–400 km/h) and track distance range (4.5 m–30 m) with the greatest impacts are obtained. The research results can provide a reference for the reasonable design of transmission tower-line systems in high-speed railway sections.

Numerical modeling on the deformation features of expansive soil slopes under moisture variations based on Fractal model

Expansive soils exhibit significant swelling-shrinkage characteristic under the cyclic moisture changes. The expansive soil slopes with high designing safety factor (gentle slope and low rainfall level) will also fail, which could not happen in an analysis ignoring expansive deformations. In this paper, the basic pore surface fractal model is derived and user-defined subroutines performing swelling-shrinkage deformation are developed to simulate the deformation features of expansive soil slopes under moisture variations. First, Fractal model is verified experimentally for accuracy in describing expansive soil issues. A hydro-mechanical coupling model based on the Fractal model in ABAQUS is then established to enable the numerical analysis of expansive soil slopes. In addition, the effects of swelling deformation, desiccation and slope ratio on deformation features are investigated. The results show that the consideration of swelling-shrinkage deformation causes the slope deformation features change, promotes larger additional displacements, and enhances water sensitivity. The simulated slopes can exhibit typical gentle sliding, shallow and progressive damage after several moisture cycling. This research provides a design reference for expansive soil slopes and expansive soil associated catastrophic issues.

Simulation of temperature and weld growth mechanism in ultrasonic welding of carbon fiber reinforced polyamide 66 composite: Employing the high frequency real-time horn vibration

Ultrasonic welding (UW) of carbon fiber reinforced polyamide 66 (CF/PA 66) composite is a very promising process for assembly of automobile component. Simulation of the temperature distribution and weld growth in UW process remains a difficulty issue. In this study, a high frequency sensor is equipped in the welder to collect the real-time horn vibration during UW. Then the real-time horn vibration is applied on tip of the horn and integrated into the finite element model in Abaqus. The simulation results are validated with experimental tests of temperature and weld evolution in UW of CF/PA 66. Results showed the ultrasonically welded CF/PA 66 joint made with a weld time of 2.7 s consisted of five distinct stages and the characteristics in stage 3 determined the quality of the weld. An index Q based on the amplitude and duration of T3 was proposed to evaluate the joint quality. The accuracy of Q was also verified through extensive experiments.

Study on vehicle-bridge coupling vibration response and impact factor of spatial Y-shaped tied arch bridge

The spatial Y-shaped steel arch bridge adopts a single and double arch rib composite structure, which has a complex spatial structure, and its structural dynamic characteristics are special, resulting in a more complex vehicle-bridge coupling vibration response law. To clarify the dynamic characteristics of the space Y-shaped steel arch bridge structure, this paper takes a space Y-shaped steel arch bridge under construction in China as the research object and uses ABAQUS to establish a vehicle-bridge coupling model. The correctness of the ABAQUS model is verified by the bridge model established by Midas Civil, and four grades of road roughness are established by using the ABAQUS kernel command. The influence of vehicle speed and road roughness on the spatial Y-shaped steel arch bridge is analyzed. The impact factor of the vehicle on the flat bridge deck at the design speed is calculated and compared with the current specification, which provides a reference for the design and maintenance of space Y-shaped steel arch bridge in the future.

A novel computer modeling and simulation technique for bronchi motion tracking in human lungs under respiration

In this work, we proposed a novel computer modeling and simulation technique for motion tracking of lung bronchi (or tumors) under respiration using 9 cases of computed tomography (CT)-based patient-specific finite element (FE) models and Ogden’s hyperelastic model. In the fabrication of patient-specific FE models for the respiratory system, various organs such as the mediastinum, diaphragm, and thorax that could affect the lung motions during breathing were considered. To describe the nonlinear material behavior of lung parenchyma, the comparative simulation for biaxial tension-compression of lung parenchyma was carried out using several hyperelastic models in ABAQUS, and then, Ogden’s model was adopted as an optimal model. Based on the aforementioned FE models and Ogden’s material model, the 9 cases of respiration simulation were carried out from exhalation to inhalation, and the motion of lung bronchi (or tumors) was tracked. In addition, the changes in lung volume, lung cross-sectional area on the axial plane during breathing were calculated. Finally, the simulation results were quantitatively compared to the inhalation/exhalation CT images of 9 subjects to validate the proposed technique. Through the simulation, it was confirmed that the average relative errors of simulation to clinical data regarding to the displacement of 258 landmarks in the lung bronchi branches of total subjects were 1.10%~2.67%. In addition, the average relative errors of those with respect to the lung cross-sectional area changes and the volume changes in the superior-inferior direction were 0.20%~5.00% and 1.29 ~ 9.23%, respectively. Hence, it was considered that the simulation results were coincided well with the clinical data. The novelty of the present study is as follows: (1) The framework from fabrication of the human respiratory system to validation of the bronchi motion tracking is provided step by step. (2) The comparative simulation study for nonlinear material behavior of lung parenchyma was carried out to describe the realistic lung motion. (3) Various organs surrounding the lung parenchyma and restricting its motion were considered in respiration simulation. (4) The simulation results such as landmark displacement, lung cross-sectional area/volume changes were quantitatively compared to the clinical data of 9 subjects.

Prediction of FLD using Abaqus and Gurson Model for Simple Flat Spacemen

In the past century, in many industries, such as, metal forming industry, it has been important to predict ductile damage and fracture of metals under complex loadings. Regarding damage mechanics, one of the most classical models is the GTN, which was originated from Gurson and later enhanced by Tvergaard and Needleman. The inprovement was achieved by introducing an equivalent void volume fraction f and two more parameters called q1 and q2 into the yield function of Gurson’s model.

Structural behavior of UHPC epoxy composite plate subjected to velocity impact loading

This article aims to investigate the structural behavior of Ultra High Performance Epoxy Composite Plate subjected to velocity impact loading. Two types of material were utilized for the composite plate: epoxy, and UHPC. UHPC plate plays as a front layer to strengthen the energy absorption and protect the epoxy layer. The material model used to simulate the epoxy plate was verified by experimental results to prove its accuracy and efficiency. Impact loading was implemented in the Abaqus model by an impactor nose which has 25mm diameter. The projectile was assumed at the velocity of 120 m/s. The damage propagated due to the increment of the impact energy was estimated by the Johnson-Holmsquist concrete (JHC) material model in Abaqus. Maximum deflection, the kinetic energy versus internal energy were also investigated in the current article. Based on the obtained result, the Epoxy material combined with UHPC material was proved to be a potential application in impact resistance design.

Predictive Modeling of Spring-Back Behavior in V-Bending of SS400 Steel Sheets under Elevated Temperatures Using Combined Hardening Laws

This research presents an innovative methodology for accurately predicting spring-back tendencies in V-bending of SS400 steel sheets under elevated temperatures. The study leverages extensive tensile test data to determine parameters for pure isotropic and kinematic hardening laws at varying temperatures, crucial inputs for Finite Element Method (FEM) simulations. While using pure isotropic or kinematic hardening laws alone has limitations, especially at elevated temperatures, a hybrid approach is recommended for robust predictive models in ABAQUS 6.13 software. To address this challenge, a novel method is introduced, utilizing flow stress curve ratios between elevated and room temperatures as a function of equivalent strain to derive combined hardening law parameters. Rigorous comparison of simulation and experimental results confirms the model’s effectiveness in predicting spring-back in the V-bending of SS400 steel sheets, particularly under elevated temperatures. This innovative approach enhances understanding of material behavior at high temperatures and improves predictive capabilities for designing and optimizing complex V-bending processes.

Investigating Ice Loads on Subsea Pipelines with Cohesive Zone Model in Abaqus

Subsea pipelines and cables placed in ice-prone regions may be at risk of iceberg damage. In particular, pipes that are not buried may come in direct contact with iceberg keels. Knowing the range of interaction forces helps to assess the types and magnitudes of potential damage. Experimental studies provide the most valuable data about the interaction forces, while numerical modeling may give insight into configurations that are difficult to study experimentally. This work applies the cohesive zone model to investigate the fracture behavior of ice samples. Simulations are performed in 2D with Abaqus explicit solver. Modeled interaction forces from multiple simulations are recorded and compared to understand how the geometry of the samples affects the fracture. Repeat interactions with different grain configurations are conducted to investigate associated variance in fracture patterns and loads. t-tests show that the force application angle and the indenter’s position significantly affect the fracture force.

Implementation of ABAQUS User Subroutines for Viscoplasticity of 316 Stainless Steel and Zircaloy-4

This paper describes the formulations for the viscoplasticity of metals based on the Chaboche and Delobelle model. The implementations of the viscoplastic models were detailed herein and then implemented via user subroutines for material models (UMAT) in ABAQUS. Two typical metals, i.e., 316 Stainless Steel and Zircaloy-4, were chosen as examples and their viscoplastic behaviors were captured. Numerical simulations are compared to reported experiments in order to validate the models and the UMAT codes. The typical viscoplastic behaviors of both metals, such as stress relaxation and creep, were captured well through the available experiments. We have publicized all the data and codes.

Fatigue strength assessment of riveted shear splices

AbstractOld‐steel riveted bridges are part of the heritage asset in many countries. Assessing the remaining life and fatigue strength of their structural riveted details is crucial in managing these structures. According to JRC‐ECCS document Assessment of Existing Steel Structures: Recommendations for Estimation of Remaining Fatigue Life, fatigue class 71 is recommended to estimate the fatigue strength of riveted details. However, the predicted fatigue behaviour can lead to excessively conservative estimates. Hence the research community is still focusing on the suitability of current recommendations. This work performs a numerical study to evaluate the fatigue strength of riveted double‐shear splices. Experimental fatigue test results are collected from the literature, and some are used to develop a finite element model in ABAQUS and Fe‐Safe. The adopted modelling fatigue approach is applied to investigate the fatigue behaviour of double‐shear riveted connections with different geometrical properties. The numerical results are compared with all collected data, showing the procedure's effectiveness in predicting the fatigue strength of double‐shear riveted splices. Finally, the numerical and experimental results are compared with the recommended S‐N curves.

Finite Element Analyses of Demountable Shear Connection in Cold‐Formed Steel‐Concrete Composite Beam Based on Experimental Data

AbstractThere is a surging demand for innovations that would increase the value of construction elements and materials in their life cycle. Therefore, the subject of this research is the shear connection in the floor composite system of cold‐formed steel and concrete slab. Composite systems can be further improved by a demountable type of shear connection, which shows good performance compared to traditional solutions but also allow for system demountability, fulfilling some sustainability policy aspects. Here, two configurations of CFS‐concrete composite systems with bolted shear connections were considered. The first configuration considers two directly connected back‐to‐back CFS profiles, while the second considers two back‐to‐back CFS profiles spaced apart simulating the presence of a corrugated web in between. Based on the experimental results of the second configuration, the numerical model in ABAQUS was developed and calibrated. A detailed comparison of the two configurations has been carried out. Additionally, the behaviour of considered configurations was also analysed regarding the number of bolts within the rib of the concrete slab. The obtained results show that close spacing of the shear connectors can prevent the development of their full bearing capacity.

Experimental and numerical study of a damage‐free self‐centring link for seismic resilient EBFs

AbstractSignificant progress has been made in recent years for the definition of seismic‐resilient structures, chasing the urgent need for structures able to return to undamaged, fully functional conditions in a short time after an extreme event. Seismic‐resilient steel structures have been widely investigated, mainly considering solutions based on moment‐resisting and concentrically braced frames. However, while the first category may be characterised by low stiffness, the second is often characterised by low ductility. Eccentrically Braced Frames (EBFs) allow overcoming these drawbacks and well‐balance stiffness, strength and ductility. This paper presents the numerical and experimental study of a damage‐free self‐centring link for EBFs. The proposed device uses post‐tensioned bars to control the self‐centring behaviour and friction devices to provide dissipation capacity. Experimental cyclic tests have been carried out to evaluate the response of the device. A 3D ABAQUS model has been developed to investigate the local response. Finally, a six‐storey EBF has been numerically investigated in OpenSees to evaluate the global response. Incremental Dynamic Analyses were performed demonstrating the increased seismic performance of the proposed solution.

Estimation of the displacement time history of high-rise building structures using limited measurement data and structural information

A method is proposed to estimate the seismic displacement time history of a high-rise building structure. The structure is simplified to a flexural-shear mass-spring model, and the optimal parameter values of the model are determined using particle swarm optimization. Limited measured acceleration and roof residual displacement data are used to calculate the model error in the optimization process. In this method, only the number of stories and the heights of each story are needed as known structural information. The displacement time history calculated for the optimal model is treated as the estimation of the actual response of the original structure. The responses of a 13-story reinforced-concrete frame-shear wall structure obtained from numerical simulation of the ABAQUS model are used to verify the performance of the method. The results show that the average estimation error of the maximum story displacement is 5.2% and that of the maximum inter-story drift ratio is 5.3%. Having the acceleration responses of 1/3–1/4 stories is sufficient to accurately estimate the story displacement and inter-story drift ratio if the root mean square noise-to-signal ratio of the acceleration is less than 30%. The shaking table test data of a 15-story reinforced-concrete shear structure are used to verify the method’s effectiveness; the average estimation error of the maximum story displacements of the 7th, 8th, and 15th stories is found to be 4.8%.

Thermo-mechanical behavior of composite beams with corrugated steel webs exposed to localized fire

In this study, a one-way coupling methodology combining fire simulation based computational fluid dynamics (CFD) with finite element (FE) analysis is proposed to investigate the thermo-mechanical behaviors of composite beams with corrugated steel webs (CSWs) under localized fire exposure. Fire Dynamics Simulator (FDS) is used to simulate the local fire environment, and the adiabatic surface temperature (AST) data obtained in FDS are imported into the FE models in ABAQUS by the fds2ascii coupling tool. The validations of FDS models and the CFD-FE coupling method are verified by a localized fire test on a steel beam conducted by the National Institute of Standards and Technology (NIST). Then, the CFD-FE coupling method is applied to analyze the thermo-mechanical behaviors of composite beams with concrete flanges and CSWs exposed to localized fire. As the fire exposure time increases, the composite beam appears significant variation of the temperature gradient at elevated temperature, and induce the dynamic, uneven temperature field in the structural members. Due to the influences of the temperature gradient field, the traditional design assumptions for composite beams with CSWs are not valid when the structures suffered a localized fire. It found that the shear stress on the CSWs is no longer evenly distributed along the depth at elevated temperatures, and the concrete flange resists a considerable part of the sectional shear force, particularly of the fire-affect zone. This study hopes to provide a basis for the fire resistance design of composite girder bridges with CSWs.

Influence of surface cracking, anchor head profile, and anchor head size on cast-in headed anchors in geopolymer concrete

In this study, the concrete cone capacity, concrete cone angle, and load–displacement response of cast-in headed anchors in geopolymer concrete are explored using numerical analyses. The concrete damaged plasticity (CDP) model in ABAQUS is used to simulate the behavior of concrete substrates. The tensile behavior of anchors in geopolymer concrete is compared with that in normal concrete as well as that predicted by the linear fracture mechanics (LFM) and concrete capacity design (CCD) models. The results show that the capacity of the anchors in geopolymer concrete is 30%–40% lower than that in normal concrete. The results also indicate that the CCD model overestimates the capacity of the anchors in geopolymer concrete, whereas the LFM model provides a much more conservative prediction. The extent of the difference between the predictions by the numerical analysis and those of the above prediction models depends on the effective embedment depth of the anchor and the anchor head size. The influence of concrete surface cracking on the capacity of the anchor is shown to depend on the location of the crack and the effective embedment depth. The influence of the anchor head profile on the tensile capacity of the anchors is found to be insignificant.

Structural Stability of Tailwater Penstock in Xiamen Pumped Storage Power Station

To study the external water pressure that can be borne by the steel lining of the tailwater penstock of a pumped storage power station, the optimization of the steel lining shape provides the basis for ensuring its normal operation. In this paper, based on the finite element method and finite element analysis software ABAQUS, the calculation and analysis model of different stiffening ring schemes for tailrace penstock is established, structural stability is calculated and the influence of different stiffening schemes is compared and analyzed. The results show that the structural stability can meet the requirements of the code by setting the T-shaped stiffening ring and longitudinal stiffening rib. With the addition of longitudinal stiffeners, the steel lining tends to the stress characteristics of the two-way slab, and the overall stress deformation tends to be balanced, which can improve the external pressure resistance of the steel lining in the gradual change section to a certain extent.

Propagation of multiple hydraulic fractures in a transversely isotropic shale formation

Shale anisotropy can lead to deviated patterns of hydraulic fractures in multi-stage hydraulic fracturing (MSHF) operations, significantly hindering hydrocarbon production. Such deviation usually occurs in formations where the induced fractures interfere with natural bedding planes or where the stress shadow is created. In this work, the elastic behavior of a transversely isotropic shale rock during MSHF is investigated using the extended finite element method (XFEM) in conjunction with the cohesive zone model (CZM) in ABAQUS. In comparison to the linear elastic fracture mechanics approach, the CZM considers the plasticity and softening effects at the fracture tip, and therefore, leads to a more accurate prediction of fracture geometry. The XFEM model is capable of simulating fractures with an arbitrary path without requiring re-meshing. The 2D numerical model is first verified against the Kristianovich-Geertsma-de Klerk (KGD) analytical solutions. Five injection clusters in a single fracturing stage are simulated to analyze the effects of the material isotropy, the dip angle of shale bedding, and the fracture spacing on the geometry of multiple hydraulic fractures. The transversely isotropic poroelasticity model predicts narrower and longer hydraulic fractures than the isotropic poroelasticity model. The bedding dip angle plays a crucial role in the deviation and the shape of multiple hydraulic fractures. Increasing the dip angle from zero to 90° results in an increase in the average fracture width and an increase-peak-decrease trend in the fracture length. A strong correlation is observed between the fracture spacing and the fracture geometry, and a spacing of 75 m is considered optimal because it results in no discernible stress shadow at all dip angle cases.

Sliding U-shaped steel damper for multi-directional displacement

A U-shaped steel damper may undergo multi-directional displacements. However, U-shaped energy-dissipation plates with large width-to-thickness ratio may experience unexpected torsional deformation during an out-of-plane displacement and provide an unstable restoring force and energy dissipation. Discussed here is a sliding U-shaped steel damper that uses connecting structures to obtain force-free sliding in out-of-plane directions. Cyclic performances under multi-directional displacements were verified experimentally, and out-of-plane force-free sliding was observed. The energy-dissipation plates only exhibited in-plane plastic deformation and provided a stable restoring force as well as energy dissipation. Equations for the yield and ultimate restoring forces were developed by considering the loading angle, and a finite element model in ABAQUS reproduced physical tests. Connection structures were thus improved for higher stiffness, and lateral sliding that considered the peak vertical force was also proposed. Finally, an analytical hysteretic model for the sliding U-shaped steel damper was abstracted based on the test and simulation results, which shows acceptable agreement with the test results.

Numerical and experimental investigation on AZ91 friction stir welding joints: mechanics, properties

The present endeavour is to evaluate numerically and experimentally the influence of friction stir welding (FSW) parameters on peak temperatures, microstructures and mechanical properties of AZ91 magnesium alloy joints. A full 3D finite element ABAQUS model was developed to simulate the temperature distribution along the joint line. Therefrom, a total of nine different parametric combinations were derived for experimentations. Important insights relating to the material flow patterns and grain morphologies observed while altering the processing parameters have been elaborated. The parametric influence on the peak temperatures, grain morphologies, intermittent phases, tensile strength, and hardness are discussed through several mechanisms. Remarkably, the specimens prepared with the highest tool rotation speeds exhibited superior properties owing to several strengthening mechanisms.