Finite Element Computer Model Research Articles

Influence of Fatigue Damage on Criticality Cell Ultimate Load Capacity of Steel–Concrete Composite Section

In order to investigate the impact of fatigue damage on the ultimate load capacity of criticality cells in steel–concrete composite segments and to address the complex design challenges associated with bridge steel–concrete composite segments in practical engineering, this study designs two scaled criticality cell specimens with a scale ratio of 1:2 and performs ultimate load capacity tests after fatigue cyclic loading. By analyzing the stress distribution of each component and the force transmission ratio and combining the results from finite element model calculations, this study introduces the degree of structural fatigue damage and proposes a predictive model for the ultimate load capacity of steel–concrete composite segment criticality cells that is easy to apply. This model is compared with the finite element calculation results and experimental values, and the results are found to be in good agreement. Additionally, the number of shear connection members in the model is optimized based on the calculation results. The research findings indicate that the main failure mode of criticality cells is inclined compression failure. The strength of each part decreases in the following order: steel–concrete composite segment, steel structure segment, and concrete segment. Furthermore, fatigue damage has a significant impact on criticality cells. The optimized model exhibits similar stress performance and force transmission ratio to the original model and provides a reference for the design of practical engineering.

Temporally continuous thermofluidic–thermomechanical modeling framework for metal additive manufacturing

Additive manufacturing (AM) is known to generate large magnitudes of residual stresses (RS) within builds due to steep and localized thermal gradients. In the current state of commercial AM technology, manufacturers generally perform heat treatments in effort to reduce the generated RS and its detrimental effects on part distortion and in-service failure. Computational models that effectively simulate the deposition process can provide valuable insights to improve RS distributions. Accordingly, it is common to employ Computational fluid dynamics (CFD) models or finite element (FE) models. While CFD can predict geometric and thermal-fluid behavior, it cannot predict the structural response (e.g., stress–strain) behavior. On the other hand, an FE model can predict mechanical behavior, but it lacks the ability to predict geometric and fluid behavior. Thus, an effectively integrated thermofluidic–thermomechanical modeling framework that exploits the benefits of both techniques while avoiding their respective limitations can offer valuable predictive capability for AM processes. In contrast to previously published efforts, the work herein describes a one-way coupled CFD-FEA framework that abandons major simplifying assumptions, such as geometric steady-state conditions, the absence of material plasticity, and the lack of detailed RS evolution/accumulation during deposition, as well as insufficient validation of results. The presented framework is demonstrated for a directed energy deposition (DED) process, and experiments are performed to validate the predicted geometry and RS profile. Both single- and double-layer stainless steel 316L builds are considered. Geometric data is acquired via 3D optical surface scans and X-ray micro-computed tomography, and residual stress is measured using neutron diffraction (ND). Comparisons between the simulations and measurements reveal that the described CFD-FEA framework is effective in capturing the coupled thermomechanical and thermofluidic behaviors of the DED process. The methodology presented is extensible to other metal AM processes, including power bed fusion and wire-feed-based AM.

Computational finite element modeling of stress-state- and strain-rate-dependent failure behavior of ceramics with experimental validation

Computational finite element modeling of stress-state- and strain-rate-dependent failure behavior of ceramics with experimental validation

Numerical Investigation of Flow and Structural Characteristics of a Large High-Head Prototype Pump–Turbine during Turbine Start-Up

Transient processes that occur in pumped storage power plants can cause high-pressure conditions, which in turn can result in vibrations in the pump–turbine structure and even damage to structural components. It is therefore crucial to research the transient process of the large pump–turbine units and the flow-induced vibrations of the structural components. The three-dimensional flow field and structural field models of a high-head prototype pump–turbine were constructed to study its flow characteristics and structural characteristics under the turbine start-up. Calculations and analyses were performed on the pressure variation and the flow-induced stress concentrations of the pump–turbine during start-up in turbine mode. The simulated pressure distributions during the turbine start-up were mapped onto the finite element calculation model of the structures of the pump–turbine to calculate the flow-induced stress concentrations. This study provides a reference to improve the design and operation of high-head prototype pump–turbines based on the findings of the flow and structural characteristics.

Research on digital twin based temperature field monitoring system for LNG storage tanks

The temperature distribution is a critical indicator of the health condition of liquefied natural gas (LNG) storage tanks. Point measurements are the main method of traditional LNG tank temperature field monitoring. To obtain more abundant temperature data and realize the digital transformation of temperature field monitoring, an LNG tank temperature field monitoring system was constructed, which consists of a model layer, a data layer, and an application layer, by combining sensing data with digital twin (DT) technology. First, the temperature distribution of the LNG storage tank under working and leaking conditions was simulated, and the sensing monitoring network was constructed by combining Fiber Bragg Grating (FBG) sensor temperature-sensing experiments. Second, a finite element calculation model of the steady-state temperature field of an LNG storage tank was developed, and the twin model was generated by fusing the sensing data to realize the inversion from local sensing data to the whole temperature field. Finally, an LNG temperature field monitoring system based on the DT was constructed. Based on physical field leakage simulations performed with the Fluent software, the functions of visual interaction, construction splitting, temperature chart analysis, leakage diagnosis, and historical data management of the twin models were realized, which provided system building samples for digital monitoring of new LNG storage tanks.

Analysis of Fire Resistance of Prestressed Concrete T-Beam Based on ABAQUS Numerical Simulation

The analytical fire resistance calculations were carried out on 57 prestressed concrete T-beam models using the finite element software ABAQUS. The effects of different fire modes, different concrete strengths, different flange plate thicknesses, different ratios of the prestressing bar, and different concrete protection layer thicknesses were investigated in three cases with load ratios of n = 0.4, n = 0.6, and n = 0.8. The fire resistance of prestressed concrete T-beams shows a large variability under different fire modes. The fire mode significantly affects the fire resistance of the structure and should be given more consideration in the subsequent fire resistance design of the structure. The configuration of prestressing bars will significantly increase the fire resistance of concrete T-beams, while the thickness of the concrete protective layer and the concrete strength will significantly affect the fire resistance of prestressed concrete T-beams. Therefore, the fire resistance can be improved by adding prestressing bars, increasing the concrete strength, and increasing the thickness of the protective layer in the design. Finally, a fitting equation for fire resistance of the prestressed concrete T-beams based on the finite element model calculation data was created. The equation has good prediction accuracy and can provide a reference for the fire resistance design of prestressed concrete T-beams.

Evaluation study of pull-out capacity and deformation of bored pile foundation in a Jakarta building construction project

This study uses the finite element method to determine the value of deformation and Pullout Capacity on the Bored Pile. The results compared the calculation of the value of the deformation and Pullout Capacity on the Bored Pile with the finite element method with the pullout test results. The research method used finite element modeling and manual calculations. The results achieved in this study are that Soft Soil & Hard Soil modeling 6.47 mm for deformation and 267.495 tons for Pullout Capacity is closer to the actual value and MC Modelling is 9.08 mm for deformation and 268.497 tons for Pullout Capacity, which is the farthest modeling the actual value with a difference of approximately 50%. This is due to differences in correlation and actual soil type conditions between modeling and field conditions, because the finite element method modeling is assumed to be a perfect pile.

Numerical study of reinforced concrete in post-tensioned anchorage zones

Prestressed structures have been put into practice in construction since the beginning of this century, but the prestressed structure is concerned with the bearing capacity of anchorage ends. Applying steel reinforcement in anchorage zones can significantly improve the structure behavior and bearing capacity of post-tensioned anchorage zones. Proper reinforcing can relieve congestion and poses difficulty in pouring concrete. Based on materials test data, the nonlinear Finite Element Model (FEM) under local compression was established as part of this study. The nonlinear analysis of the load process was completed based on ABAQUS software. In addition, the model's accuracy was verified by comparing the FEM calculation results with experimental results.Furthermore, the verified FEM was adapted for a parametric study to investigate the influence of various parameters on the bearing capacity, such as the spacing, shape, length of the bearing plate, and reinforcement spacing. The results demonstrate that enhancing steel reinforcement can withstand the forces and stresses and comprehensively improve the local bearing capacity of the specimens; with the decrease of reinforcement spacing, the bearing capacity of the specimen increases, indicating that the reinforcement can dissipate the high stresses among the member from the anchorage zone. The bearing capacity increases with the increase of the bearing plate length, meaning that the bearing plate has a significant influence on bearing the prestressing force in the anchorage zone. Meanwhile, the effect of the bearing plate shape was not obvious. The relationship between the local bearing capacity and the bearing plate length is linear, which indicates that the influence of the bearing plate length on the local pressure properties belongs to the structural layer.

Design of New Fan-Shaped Combined Wear-Resistant Plate for Super Tonnage Spherical Bearing

In order to improve the bearing and wear resistance of the sector composite wear plate, a new sector composite wear plate is designed based on the finite element method. By establishing the finite element calculation models of integral, segmented small circle inlaid and new fan-shaped combined anti-wear plate ball bearings, the pressure bearing and wear resistance of three types of wear plates are analyzed, calculated and compared. The results show that the three types of wear plates can meet the pressure bearing capacity. The pressure bearing capacity of the new fan-shaped composite wear-resistant plate is similar to that of the integral type, which is superior to that of the segmented small circle inlaid type. Because of the advantages in structure, processing and installation of the new fan-shaped composite wear-resistant plate, it is particularly worth popularizing and applying in the super spherical bearing.

Temperature patterns obtained in thermoelastic stress test at different frequencies, a FEM approach

PurposeThe goal of this work is to create a computational finite element model to perform thermoelastic stress analysis (TSA) with the usage of a non-ideal load frequency, containing the effects of the material thermal properties.Design/methodology/approachThroughout this document, the methodology of the model is presented first, followed by the procedure and results. The last part is reserved to results, discussion and conclusions.FindingsThis work had the main goal to create a model to perform TSA with the usage of non-ideal loading frequencies, considering the materials’ thermal properties. Loading frequencies out of the ideal range were applied and the model showed capable of good results. The created model reproduced acceptably the TSA, with the desired conditions.Originality/valueThis work creates a model to perform TSA with the usage of non-ideal loading frequencies, considering the materials’ thermal properties.

Effects of different test methods on the seismic dynamic response in inclined liquefiable soil

According to horizontal liquefiable free-field shaking table test carried out by the research group, a finite element numerical model of horizontal liquefiable free-field is established based on OpenSees finite element platform, and the influence of the model box on dynamic response of soil is considered in this numerical model, and the reliability of numerical model is verified by comparing with the shaking table test results. The inclined liquefiable free-field finite element calculation model is established based on the horizontal numerical model, and three different numerical models of inclined shear box model, inclined soil in shear box model and inclined soil in rigid box model are established to simulate the different test methods adopted in the shaking table test. Through comparison, the dynamic response results of free-field soil calculated by three numerical models under the action of 0.3g Wenchuan earthquake Wolong wave are analyzed, and the influences of three different test methods on the calculation results are discussed, and the results showed that the response of the lateral displacement of soil by two test methods of inclined shear box and inclined soil in shear box have great differences, and the maximum difference value can reach 45%; the response obtained by the two test methods of inclined soil in rigid box and in layer shear box have more obvious differences in pore water pressure lateral displacement and acceleration of soil.

Modular incorporation of deformable spine and 3D neck musculature into a simplified human body finite element model

Spinal injuries are a concern for automotive applications, requiring large parametric studies to understand spinal injury mechanisms under complex loading conditions. Finite element computational human body models (e.g. Global Human Body Models Consortium (GHBMC) models) can be used to identify spinal injury mechanisms. However, the existing GHBMC detailed models (with high computational time) or GHBMC simplified models (lacking vertebral fracture prediction capabilities) are not ideal for studying spinal injury mechanisms in large parametric studies. To overcome these limitations, a modular 50th percentile male simplified occupant model combining advantages of both the simplified and detailed models, M50-OS + DeformSpine, was developed by incorporating the deformable spine and 3D neck musculature from the detailed GHBMC model M50-O (v6.0) into the simplified GHBMC model M50-OS (v2.3). This new modular model was validated against post-mortem human subject test data in four rigid hub impactor tests and two frontal impact sled tests. The M50-OS + DeformSpine model showed good agreement with experimental test data with an average CORrelation and Analysis (CORA) score of 0.82 for the hub impact tests and 0.75 for the sled impact tests. CORA scores were statistically similar overall between the M50-OS + DeformSpine (0.79 ± 0.11), M50-OS (0.79 ± 0.11), and M50-O (0.82 ± 0.11) models (p > 0.05). This new model is computationally 6 times faster than the detailed M50-O model, with added spinal injury prediction capabilities over the simplified M50-OS model.

Discussions on liquid bismuth target use as an alternative for astatine-211 production

Astatine-211 is an alpha emitter that has been identified as a good candidate for targeted alpha therapy. There is an increasing demand on this radionuclide. Very intense beam from linac being put in operation nowadays could be used to meet this demand. This document presents the design exploration of concepts of liquid bismuth targets dedicated to astatine-211 production. Three concepts are presented and analyzed: a capsule, a fluid loop and a windowless fluid loop. Structural and thermal sizing were performed using mechanical Finite Element models (ANSYS Workbench) and Computational Fluid Dynamic models (FLUENT). Production rates were assessed accordingly. Feasibility and expected performances are discussed in conclusion.

Моделирование процессов сверления заготовок из полимерных композиционных материалов путем использования цифровых двойников

Polycrystalline composite materials made of carbon fiber reinforced plastics have more and more widespread application in mechanical engineering and become the main material for the production of modern types of high-speed transport. Thus, their share has already reached 35–45 % in the structural design of passenger aircrafts. However, the technology of machining surfaces of parts made of these materials, in particular, holes, is characterized by insufficient knowledge, the absence of regulatory standards for cutting modes and is most often based on the production experience of enterprises. When changing the processing conditions and the material, the pre-production engineering duration causes a significant increase in the cost of manufacturing parts due to the need for experimental selection of the cutting mode rational elements. To exclude the empirical selection of rational elements of the machining equipment cutting mode, the authors considered the possibility of using digital twins for studying the processes of drilling holes in the blanks made of composite materials, including those with the ultrasonic field energy introduction into the new surface shaping zone (to improve the processing quality and productivity). When modeling, the LS-DYNA program was used. The authors prepared the models and processed the results using the LS-PrePost 4.8 program. During the study, an explicit modeling method was used with preliminary validation and calibration of the results of tests of composites. The authors carried out calibration on test operations of tension, three-point bending, and interlaminar shear of the ВКУ-39 polymer composite material based on carbon fibers (carbon fiber reinforced plastic) widely used in domestic engineering. The developed finite element computer models allow simulating drilling procedures without carrying out rather complicated and expensive field tests. As a result of modeling, a simulation file was obtained, which reflects the process of drilling holes in a polymer composite material blank, as close as possible to the real-life situation with chip removal.

Development of a static plate test finite element calculation model

In the last few years as the budget for the road sector has been decreasing in Latvia, the number of road pavement structure reinforcement projects has been increasing. In order to ensure the long-term viability of the road it is necessary to assess the load-bearing capacity of the existing road structure and the subgrade. During the geotechnical research, the load-bearing capacity of the existing base layers is assessed using static plate test. However, the accuracy of the results is strongly influenced by the thickness of the existing asphalt layer and the size of the dismantled asphalt area. In order to determine the load-bearing capacity of the existing road base in the deeper layers, the engineer performs a subjective experience-based interpretation that is not based on mathematical calculations. With the development of geotechnical survey equipment and engineers’ understanding of the bearing capacity of the subgrade, it is also possible to use other field research methods, such as probing and interpretation of their data. Various software’s for soil calculations have been developed worldwide. With the help of software’s, it is possible to evaluate the properties of soil layers, predict deformations and develop reinforcement solutions, however, the obtained results do not reflect the basic bearing capacity, which is expressed in MPa units. It is planned to develop a Finite Element Method simulation of static plate test based on the values of the soil layer parameters obtained from the interpretations of the probe data and to compare the results with the static plate test performed on site. The aim of the study is to determine whether the load-bearing capacity of the existing base can be accurately determined by finite element calculations - a simulation of a static plate test based on the physical-mechanical properties of the soil determined during the geotechnical survey.

Study on Key Technology of Assembling Installation of Long-Span Composite Girder Cable-Stayed Bridge

PDF HTML XML Export Cite reminder Study on Key Technology of Assembling Installation of Long-Span Composite Girder Cable-Stayed Bridge DOI: 10.59238/j.pt.2023.01.007 Author: Affiliation: (Sichuan Highway Planning, Survey, Design and Research Institute Ltd. , Chengdu 610041, China) Clc Number: Fund Project: Article | Figures | Metrics | Reference | Related | Cited by | Materials | Comments Abstract:The Nanxi (Xianyuan) Yangtze River Bridge in Yibin is a composite beam cable-stayed bridge with twin towers and double cable planes and a main span of 572 m. The superstructure is erected by the assembly method. In order to ensure the precise installation and control of internal forces for steel girders and bridge deck slabs of composite beams while also considering the construction efficiency of composite beams, a control method for the installation and erection of the superstructure has been proposed. This method is based on optimizing the internal force and geometric states of segments throughout the entire process, achieved by establishing finite element calculation models for both the full bridge and segmented sections and combining these with comparative studies of on-site monitoring data. With the installation stress and precision of composite beams properly controlled, construction efficiency has been enhanced through the optimization of the pouring process for wet joints between steel girders and concrete bridge deck slabs, as well as the tensioning process for stay cables. The equivalent tension method is applied to the tension process of the stay cable, thus ensuring the uniformity of the cable force of the steel strand. The relevant conclusions are applicable to the same type of composite girder cable-stayed bridge erection construction. Reference Related Cited by

Numerical analysis of axial compressed multifaceted concrete-filled tube elements

The object of study is multifaceted steel concrete- filled poles. The subject of research is the bearing capacity and parameters of the stress-strain state of multifaceted steel concrete- filled poles. The purpose of the research is to numerically study the features of the operation of multifaceted concrete-filled structures under axial compression. Are discussed the features of creating a computational finite element model of such structures in ANSYS APDL. Analytical methods are described for determining the parameters of the nonlinearity of the materials used, as well as the physical and mechanical characteristics of concrete operating under compression conditions. On specific examples the change in the bearing capacity for the object of study under various conditions of materials adhesion (friction coefficient μ varied within 0.1...0.6 with step 0.1). Is analyzed the "unified" analytical method for determining the bearing capacity of steel multifaceted concrete-filled structures, indicating the degree of variability of ultimate compressive load depending on the variation in the number of faces and thickness of the metal wall of the multifaceted model. The considered features of creating a computational model in the ANSYS APDL finite element analysis system, using various laws of deformation of steel and concrete, made it possible to determine the qualitative and quantitative levels of variability of their bearing capacity, which in combination will allow designers of such structures to reach a qualitatively new level when creating structures based on pipe concrete elements.

Analysis of the mechanical behavior and prediction of the plastic zone of a large-diameter buried gas pipeline under ground overload

Plastic failure of pipelines caused by ground overload is increasing. The one-dimensional model based on mechanical nodal parameters cannot predict the plastic failure characteristics of the three-dimensional structure of the pipeline. In order to predict the evolution of the plastic failure of the pipeline with the yield strength as the evaluation criterion, a multidimensional model is needed to consider the changes in the external loads and the changes in the mechanical properties of the pipeline along the circumferential and axial directions. In this study, a finite element calculation model for a large-diameter gas pipeline underground overload was established to investigate the law of stress change in the plastic zone. The nonlinear surface fitting method was used to establish the angle fitting model of the plastic zone and the depth fitting model of the plastic zone. The variation of the area of the plastic zone was described, and the reliability of the results was verified. In addition, the accuracy of the fitting model and the cost of the finite element calculation were evaluated. The results showed that the pipeline entered plasticity at a ground load of P = 25 MPa, and the plastic zone developed continuously in the axial and circumferential directions as the ground load increased. The angle and depth increased to 36° and 1.8 m, respectively, at P = 50 MPa. The average absolute errors for the plastic zone depth fitting model and the plastic zone angle fitting model were 6.42% and 6.64%, respectively, both of which can provide an accurate description of the plastic zone. The calculation results of the plastic zone angle fitting model could meet requirements of data processing and analysis. The plastic zone depth fitting model could be used to obtain solutions with higher accuracy, but it increases the cost of finite element simulation.

Theoretical analysis and simulation calculation of hydrodynamic pressure pulsation effect and flow induced vibration response of radial gate structure

This work aims to explore the characteristics of stochastic fluctuant water pressure acted on the surface of large radial gate, and to investigate the flow-induced vibration response of the whole radial gate structure. The finite element calculation model structure of the radial gate is established by taking a large-scale radial gate as prototype to discuss the hydrodynamic pressure acting on the gate leaf with different opening, analyze the dynamic pressure time curves, and achieve the flow-induced vibration response by deeming hydrodynamic pressure as dynamic load. When taking 10% opening of the radial gate, the results indicate that the hydrodynamic pressure distributed on the arc surface of the radial gate changes with the flow conditions, with the maximum pressure occurred at the center of the lower edge of the gate leaf. One point in the time history curve of fluctuating water pressure can be taken as the dynamic load for the flow-induced vibration analysis. The flow-induced vibration responses at the monitoring point of the radial gate structure show periodic changes in the X, Y, and Z directions. The finite element simulation results agree well with the theoretical calculation results, so reference can be provided for the hydrodynamic pressure testing and the flow-induced vibration response calculations.

3D‐Printed Soft and Hard Meta‐Structures with Supreme Energy Absorption and Dissipation Capacities in Cyclic Loading Conditions

The main objective of this article is to introduce novel 3D bio‐inspired auxetic meta‐structures printed with soft/hard polymers for energy absorption/dissipation applications under single and cyclic loading–unloading. Meta‐structures are developed based on understanding the hyper‐elastic feature of thermoplastic polyurethane (TPU) polymers, elastoplastic behavior of polyamide 12 (PA 12), and snowflake inspired design, derived from theory and experiments. The 3D meta‐structures are fabricated by multi‐jet fusion 3D printing technology. The feasibility and mechanical performance of different meta‐structures are assessed experimentally and numerically. Computational finite element models (FEMs) for the meta‐structures are developed and verified by the experiments. Mechanical compression tests on TPU auxetics show unique features like large recoverable deformations, stress softening, mechanical hysteresis characterized by non‐coincident compressive loading–unloading curve, Mullins effect, cyclic stress softening, and high energy absorption/dissipation capacity. Mechanical testing on PA 12 meta‐structures also reveals their elastoplastic behavior with residual strains and high energy absorption/dissipation performance. It is shown that the developed FEMs can replicate the main features observed in the experiments with a high accuracy. The material‐structural model, conceptual design, and results are expected to be instrumental in 3D printing tunable soft and hard meta‐devices with high energy absorption/dissipation features for applications like lightweight drones and unmanned aerial vehicles (UAVs).