Simplified Finite Element Model Research Articles

Concept and numerical analysis of a double-stage coupling damper for multilevel seismic protection

A new double-stage coupling damper (DSCD), consisting of a friction component (FC) and a buckling restrained component (BRC) in series, is proposed for improving the seismic performance of structures under multilevel earthquakes. A robust numerical model for the DSCD is established based on experimental testing of conventional dampers. This numerical model explores the effects on the performance of the double-stage hysteresis behaviour of the ratio between the friction force of the FC and the yield force of the BRC, Rfy, as well as the length of slotted holes in the inner plate, Lsh and the number of FCs, Pfc. The results show that the energy dissipation capacity and the double-stage energy dissipation characteristics of the DSCD decrease with increasing Rfy and Lsh. The energy dissipation capacity of the DSCD with the single-sided FC is also higher than that of the two-sided FCs. Furthermore, a simple finite element model of the double-stage damper for general application in structural analysis is developed and validated against the detailed model. The simplified model is defined in OpenSees and applied to the nonlinear seismic analysis of single-degree-of-freedom structures. The results show that the DSCD reduces the displacements and accelerations of the structure more than the conventional BRB in most cases and for various seismic intensity levels.

Effects of humidity conditions on the physical, morphological and mechanical properties of bamboo fibers composites

This paper investigates effects of moisture (30RH%, 65RH%, 80RH% and 100RH%) on the morphological, physical and mechanical properties of unidirectional bamboo fibers reinforced composites at different fibers loadings (20, 30 and 40 wt%). Moisture adsorption kinetic, dimensional stability, adsorption-desorption and mechanical behaviour are determined. The obtained results showed that moisture adsorption and swelling monotonously increase with respect of the fibers content and relative humidity. Composites with 30 wt% fibers fraction show better tensile strength at 80RH% and 100RH%. However, all composites exhibit low tensile strength at small relative humidity, due to the shrinkage of fibers that increases interfacial voids. SEM and OM analyses allow to investigate the fracture surface of the specimens. A finite element model of the hygro-mechanical behaviour is performed and compared to analytical micromechanical predictions and experimental data. Interestingly, not only a simple finite element model but the coupling between hygroscopic and mechanical behaviours is used to analyze the internal stresses induced by swelling.

Topology optimization of single and double panels for improved sound insulation in specific frequency bands

Single and double panels are commonly employed in noise control, e.g., as partitioning elements between rooms and to enclose noisy machines. In presence of narrowband disturbances, related for example to rotating machines, further improvements in sound insulation can be obtained by properly distributing the material within the area of the panels. This allows maximizing the sound Transmission Loss (TL) in the frequency band of interest by controlling structural resonances and antiresonances. In order to achieve this goal, in this work, we apply numerical topology optimization to find the optimal material thickness distribution for single and double panels. In the iterative design process, single panels are schematized through a simple mechanical Finite Element (FE) model, while double panels are modelled considering the vibroacoustic coupling between the two mechanical plates and the internal acoustic air cavity. The sound insulation properties of the designed solution are evaluated by TL computations through hybrid Finite Element-Statistical Energy Analysis (FE-SEA) simulations. The method is applied targeting different frequency bands in the audible range and focusing on practically relevant design cases, such as single and double PMMA and glazing panels.

Temperature-dependent modal analysis of the InSight lander on Mars

The first high-performance seismometer on Mars, deployed by InSight, has been working for nearly two Martian years. However, the recorded seismic data are substantially affected by the natural frequencies of the lander. To analyze the effect of the natural frequencies of the lander on specific components of the seismic data, we have built a simplified finite-element model of the lander to conduct modal analyses. Three natural frequencies are modeled by comparing them with those identified from the observed data. These natural frequencies are nonconstant and temperature dependent, which can be explained as an elastic modulus reduction of the solar panels (35% at most) and/or the property changes of the ground media beneath the lander due to a daily air temperature variation of approximately 100 K on Mars. Compared with the previous studies based on the empirical models before the launch, our results can quantitatively evaluate natural modes and their temperature dependency. Thus, these analyses are helpful in avoiding the potential interference of natural frequencies and improving the reliability of seismic data applications.

Study on seismic behavior of oblique CFRP corrugated plate-steel plate light weight sandwich composite shear wall

To improve the seismic behavior of the thin steel plate shear wall (SPSW), carbon fiber reinforced polymer (CFRP) is introduced into the thin SPSW, and polyethylene terephthalate (PET) foam is filled between CFRP corrugated plates and steel plate. An oblique CFRP corrugated plate-steel plate lightweight sandwich composite shear wall specimen (hereinafter: sandwich composite plate specimen) is designed. Furthermore, this paper compares the failure mechanism and hysteresis performance of the sandwich composite plate specimen and traditional non-stiffened SPSW specimen under the quasi-static test, and explores the influence of sandwich composite plate on the performance of wallboard. Finally, a simplified finite element model is established and its accuracy is verified by experiments. The results show that compared with the non-stiffened SPSW structure, the initial stiffness of the sandwich composite plate structure is increased by 34.0%, the energy dissipation capacity is increased by 38.44% when loads to 2% drift, and the maximum out-of-plane deformation is reduced by 93.24%. The sandwich composite plate structure shows obvious four-stage stress characteristics, and has good cooperative working performance before the CFRP corrugated plates debond in a large area, also plays a great role in anti-buckling.

Mechanical performance of hybrid high-strength steel composite cellular beam under low cyclic loading

This study aimed to compensate for the impairments in structural load-carrying capacity and stiffness caused by conventional reduced web section beams, and to meet the strength design requirements for engineering. A new hybrid high-strength steel composite cellular beam (HHS-CCB) using high-strength steel in the beam flange and ordinary steel in the web was proposed. A composite cellular beam between the rigid joint and inflection point in the frame structure was selected as the research object, and low cyclic loading tests were conducted on one homogeneous ordinary steel composite cellular beam (HOS-CCB) and four HHS-CCB specimens. The effects of the hybrid use of high-strength steel and ordinary steel on the failure modes, load-carrying capacities, strength and stiffness degradation, ductility, and energy-dissipation capacities of the composite cellular beams were investigated. The test results show that with reasonable values for the diameter of the web opening and for the distance from the first opening at the beam end to the column surface (abbreviated as the hole edge distance), the HHS-CCB specimens exhibit local plastic damage at the first opening at the end of the beam but maintain a good ductility, stiffness degradation, strength degradation, and energy dissipation capacity, while significantly improving the structural load-carrying capacity loss owing to the web opening. Compared with HHS-CCB specimens using HHS in both the upper and lower flanges, the HHS-CCB specimens using HHS only in the lower flange show superior mechanical properties. Considering the poor plastic deformation capacity of HSS, the steel plate strength of the flange should not be much higher than that of the web to ensure the full development of plasticity in the cross-section, and Q460 steel or Q550 steel is generally recommended. A nonlinear finite element (FE) model was developed using ABAQUS software to predict the hysteresis behavior of specimens. Numerical simulation shows that the simplified FE model can be used to simulate the hysteresis performance of HOS-CCB and HHS-CCB.

Finite Element Model for Vibration Serviceability Evaluation of a Suspended Floor with and without Tuned Mass Dampers

This study aims to provide an accurate finite element (FE) modeling method for structural vibration serviceability evaluation of the suspended floor under human-induced excitation. The fundamental dynamic characteristics and human-induced vibration responses of a typical suspended floor were first measured via a series of field tests. Subsequently, the overall and local equivalent FE models of the suspended floor were respectively established, and their applicability was then verified by comparing the predicted dynamic characteristics and responses of the suspended floor with the corresponding field test results. Finally, passive tuned mass dampers (TMDs) were designed for vibration control of the suspended floor using the local equivalent FE model, and the applicability of the local FE model in assessing the vibration serviceability of the suspended floor with TMDs was further confirmed via pedestrian-induced vibration tests. Results demonstrate that the simplified local equivalent FE model proposed in this study can well replace the complicated overall FE model to evaluate the vibration serviceability of the suspended floor with and without TMDs.

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.

Investigating the post-yield behavior of mineralized bone fibril arrays using a 3D non-linear finite element unit-cell model

In this study, we propose a 3D non-linear finite element (FE) unit-cell model to investigate the post-yield behavior of mineralized collagen fibril arrays (FAY). We then compare the predictions of the model with recent micro-tensile and micropillar compression tests in both axial and transverse directions. The unit cell consists of mineralized collagen fibrils (MCFs) embedded in an extrafibrillar matrix (EFM), and the FE mesh is equipped with cohesive interactions and a custom plasticity model. The simulation results confirm that MCF plays a dominant role in load bearing prior to yielding under axial tensile loading. Damage was initiated via debonding in shear and progressive sliding at the MCF/EFM interface, and resulted in MCF pull-out until brittle failure. In transverse tensile loading, EFM carried most of the load in pre-yield deformation, and then mixed normal/shear debonding between MCF and EFM began to form, which eventually produced brittle delamination of the two phases. The loading/unloading FE analysis in compression along both axial and transverse directions demonstrated perfect plasticity without any reduction in elastic modulus, i.e., damage due to the interfaces as seen in micropillar compression. Beyond the brittle and ductile nature of the stress–strain curves, in tensile and compressive loading, the simulated post-yield behavior and failure mechanism are in good quantitative agreement with the experimental observations. Our rather simple but efficient unit-cell FE model can reproduce qualitatively and quantitatively the mechanical behavior of bone ECM under tensile and compressive loading along the two main orientations. The model's integration into higher length scales may be useful in describing the macroscopic post-yield and failure behavior of trabecular and cortical bone in greater detail.

Analysis of axial and rotational restrained concrete-filled steel tube columns at elevated temperature

This paper has two aims, first, to develop a simplified finite element (FE) model to simulate and study the behaviour of restrained concrete-filled steel tube (CFST) columns subjected to axial force and fire, and second, to propose simplified design equations. FE model has been developed using the ABAQUS program and verified against published data. Furthermore, a parametric study has been conducted using the verified FE model to study different parameters that might affect the behaviour of restrained concrete-filled steel tube columns subjected to axial force under elevated temperatures. These parameters are load level, section type (circular and square), axial and/or rotational restraint ratio, type of steel tube (carbon and stainless steel), type of concrete (carbonate and siliceous concrete aggregate), steel yielding strength, concrete compressive strength, column dimension, width to thickness ratio and reinforcement ratio. Finally, simplified design equations are proposed to determine the buckling time, critical time and maximum load capacity of axial and rotational restrained CFST columns under fire.

Bionic artificial penile Tunica albuginea

Bionic artificial penile Tunica albuginea

Structural Design and Mechanical Properties of a Plate-Shell Structure Bridge

PDF HTML XML Export Cite reminder Structural Design and Mechanical Properties of a Plate-Shell Structure Bridge DOI: 10.59238/j.pt.2023.01.006 Author: Affiliation: (1.Department of Bridge Engineering, Tongji University, Shanghai 200092, China;2.Tongji Architectural Design (Group) Co., Ltd., Shanghai 200092, China) Clc Number: Fund Project: Article | Figures | Metrics | Reference | Related | Cited by | Materials | Comments Abstract:The main bridge of Quzhou Academy Bridge is a V-shaped rigid frame bridge with a hanging hole, the span arrangement is 75 m+150 m+75 m=300 m, the middle span hanging hole was provided with a 60 m steel box girder, and the V-leg structure and the main beam are all prestressed concrete box girders with variable height. Due to the need for bridge landscapes and pedestrian viewing platforms, the large extension arc V-leg structure extends 6 m to each side of the bridge deck, and the total width is 41 m. It was necessary to consider the stress effect of the shell in the longitudinal and transverse directions. The stress and deformation of the shell in two directions are analyzed by using the finite element method solid model, and the difference between the solid model and the frame model is compared in detail. Finally, the overall structure was analyzed and checked in the modified simplified frame finite element model. Reference Related Cited by

On Identifying Natural Frequencies in the JAST80 Telescope and Validation With a Simplified 3-D Model

The instrumentation of professional telescopes is very sensitive to vibrations. These vibrations, caused by wind, terrain, or its actuators, affect the quality of the images taken. If vibrations present frequency components coinciding with the natural frequencies associated with the proper modes of the telescope mount, the vibratory response is amplified and cause a decrease in image quality below the required standards. The goal of our study is to identify the natural frequencies of the german-equatorial mount of the JAST80 telescope of the Observatorio Astrofísico de Javalambre (OAJ) and to validate a simplified Finite Element Model (FEM). In addition, the interaction of the vibrations produced by the actuators in a right ascension (RA) movement with the natural frequencies obtained by means of a Finite Element Analysis (FEA) is analyzed. To excite the structure of the telescope, the response of it in free vibration after an unexpected emergency stop of an RA movement was used. A setup of three accelerometers allowed us to compare the excitation frequencies of the structure with those obtained with the FEA. Natural frequency values obtained through the FEM showed deviations below 12% with respect to the experimental values, thus validating the simplified 3D numerical model of the telescope mount for further analysis of its dynamic behavior. On the other hand, the analysis of the measured vibratory indicated that the natural frequencies of the mount for a RA movement in normal operation were not excited by the actions produced by the actuator and therefore the quality of the images taken is not compromised. Finally, the possibility of using the measurement of the vibrational response of the mount in emergency stop conditions to monitor its structural integrity is pointed out.

Experimental and numerical study of T-shaped irregularly concrete-filled steel tube columns under combined axial loads and moments

T-shaped irregularly concrete-filled steel tube column (T-ICFSTC) is formed by I-shaped steel, U-shaped steel and infilled concrete. The I-shaped steel and U-shaped steel are welded together to form a multi-cell CFST column. The T-ICFSTCs can be used in the corner of T-shaped intersection location of two walls in the buildings, which can avoid the exposure of the columns and increase the available area of the indoor space. The overall flexural stability performance of the T-ICFSTCs under axial loads and moments may still be an important problem in engineering design. This paper studies the overall flexural stability performance of the T-ICFSTCs under combined axial loads and moments. Firstly, the experiments of two T-ICFSTC specimens under eccentric loading with eccentric distance of 100 mm and opposite eccentric directions were carried out. Subsequently, the refined finite element (FE) models and the simplified finite element (FE) models are established and verified by the experimental results. The simplified FE models use beam elements (B31) and have higher calculation efficiency than the refined FE models, and are adopted for the numerical investigation of the T-ICFSTCs. Finally, based on the simplified FE model verified by the experimental results, the parametric analysis of the overall flexural stability capacity of the T-ICFSTCs under axial loads and unidirectional moments is carried out. The parameters studied include the height of the T-ICFSTCs, several geometric parameters of the cross section and the strength of material. Based on the results of numerical investigations, a preliminary design formula of the overall flexural stability capacity of the T-ICFSTCs under axial loads and unidirectional moments is proposed. This paper provides reference for engineering design of the T-ICFSTCs and the foundation to establish a complete design formula of the T-ICFSTCs under axial loads and unidirectional moments.

An efficient micromechanics-based finite element model for failure analysis of laminated composites

Accurately predicting ultimate strength of composite laminate is still a great challenge, especially only based on the constituent properties. In this paper, the micromechanics Bridging Model and systematic failure criteria for the constituent materials with emphasis on matrix failures subjected to three dimensional (3D) loads are compiled into a UMAT subroutine for ABAQUS to analyze failures of a laminated composite structure. The main purpose of this research is to greatly reduce calculation costs for loading conditions of in-plane tension or compression by introducing a simplified 3D finite element model based on the Pipes-Pagano theory. In all calculation cases, only the constituent properties together with the transverse tensile strength of unidirectional composite are needed as input data. Later in this paper, sufficient illustrations of 81 different composite laminates composed of 14 material systems are analyzed to confirm the practicability of this model.

Interference screws 3D printed with polymer-based biocomposites (HA/PLA/PCL)

ABSTRACT Anterior cruciate ligament (ACL) reconstruction frequently employs the bioabsorbable interference screw, which is 3D printed with biocomposite filaments. The purpose of this research was to construct interference screws using 3D printing filaments (HA, PLA, and PCL) at different nozzle temperatures. In this experiment, nozzle temperatures of 190, 195, 200, and 205°C were used. Density tests, torsion tests, fracture analysis, and biodegradable tests were also used to characterize interference screws. A simple finite element model (FEM) of tibial screw fixation in hamstring ACL reconstruction was also presented. The interference screw was also compared to a commercial one. Within the maximum and minimum values of cortical bone density, the density of the interference screw prepared in this study is the best fit for implants. The current model can predict stress in tunnel wall regions caused by screw fixation. However, the clamping quality of the commercial screw in the clamping failure area for torque efficiency was better than that of the interference screw produced in this study. Commercial interference screws deteriorated the most quickly. The method has shown the ability to manufacture interference screw components with improved biodegradability.

A Novel Simplified FE Rail Vehicle Model in Longitudinal and Lateral Collisions

It is a challenge to efficiently and accurately predict train dynamic responses during complex collisions. In this paper, a novel numerical simplification method for high-speed rail vehicles during complex impact configurations is proposed. The central section of high-speed rail vehicles is a sandwich corrugated hollow double-shell structure. Starting with a baseline detailed finite element (FE) model of a high-speed train, the central section was first simplified as a solid single-shell structure. A parametric study with various simplification thickness ratios of the simplified FE rail vehicle model in different longitudinal rigid-wall collisions and lateral rigid-cylinder impacts was then performed using LS-DYNA. Furthermore, a correlation and analysis (CORA) objective rating method was used to evaluate the related responses between the simplified and detailed baseline FE rail vehicle models. The results demonstrate that the simplified FE model could effectively predict the rail vehicle impact responses. The displacement and impact force time histories of the simplified vehicle model with a thickness ratio of 0.38 matched closely with the results of the baseline detailed FE model under both longitudinal and lateral impacts (total combined CORA rating score: 93%). The rail vehicle impact deformations of the simplified vehicle model were similar to those of the baseline detailed model. The application of the simplified vehicle FE model substantially reduced the computational time (approximately 55% reduction). This work provides a solid basis for efficiently exploring train impact responses in complex collisions, and will be especially useful for train occupant injury assessment.

Design and Manufacture of Similar Model of Folding Wings and Study on Dynamic Characteristics

The research on full-size folding wings is limited by many factors, and the similar model has an irreplaceable role in its development and manufacturing process. In this study, a folding wing with core board and dimensional structure is designed and manufactured based on the principle of functional similarity and structural similarity, and the similar model can accomplish continuous folding from 0° to 90°. Based on the designed model, the finite element model simulation calculation and ground knocking modal test are completed, and the correction of the finite element model (FEM) is completed by comparing the test and simulation data. Finally, the full-component finite element model with small vibration frequency error and high matching of vibration MAC value is obtained and compared with the manufactured model. Since the gradient analysis of the full-component finite element model is extremely inefficient, a fast method of building the finite element model is proposed based on the simplified finite element model as a case study, which not only improves the efficiency of the FEM modeling and simulation analysis without changing the model structure and function, but also provides a good agreement of the vibration mode compared with the test data. In addition, the influence of the geometric parameters of the spring plate on the vibration mode of the finite element model is explored based on the simplified model to meet the demand for modal control of the similar model.

Experimental study and numerical simulation of the interfacial bonding performance of ordinary concrete reinforced with reactive powder concrete

To solve the problems of poor durability and low bearing capacity of existing concrete reinforcement technology, a bisurface shear test between reactive powder concrete (RPC) and ordinary concrete (OC) was conducted based on the technique for strengthening concrete structures with reactive powder concrete and steel mesh (RPCSM). The shear strength, failure mode and load-slip curves of each specimen were analysed. The influence of roughness, rebar planting rate, and steel mesh specifications on the shear performance of the interface of the RPCSM-OC was discussed. The results show that the RPCSM-OC interface has better bonding performance, and that the increase in shear strength and ductility is significant after reinforcement. Within a certain range, the shear strength of the bonded interface increases as the roughness increases; the shear strength and ductility increase with increasing the rebar planting rate; and the steel mesh specifications have a significant influence on the interface ductility. Second, a three-dimensional finite element model (FEM) of 27 specimens was established using ABAQUS software, and a simple FEM considering bonding effects was proposed. From the damage modes of the specimens and the stress distribution of RPC, OC and steel bars, the simulation results are shown to be in good agreement with the experimental results. On this basis, a calculation model of the shear strength of the RPCSM-OC bonded interface was established, and a formula for comprehensively calculating the shear strength of the RPCSM-OC interface was proposed. The calculation results were in good agreement with the test results, and the experimental shear strength values were within 10% error of the simulated values, which provides a theoretical basis for the engineering application of RPCSM-OC reinforcement technology.

Lateral displacement mode of column-supported modular steel structures with semi-rigid connections

The lateral displacement of a column-supported modular steel structure with semi-rigid connections (CSMSS-SRC) owing to lateral loading was investigated to determine the corresponding lateral displacement mode and establish a foundation for a direct displacement-based seismic design method. Theoretical equations for the lateral displacement caused by the bending deformation of beams and columns, axial deformation of columns, and shear deformation of the vertical inter-module connections were theoretically derived using slope–deflection equations, unit-load method, and shear deformation definition, respectively. Two simplified single frame finite element models were then established to verify the theoretical equations and study the effects of the rotational and horizontal shear stiffnesses of the vertical inter-module connections on the lateral displacement of the CSMSS-SRC. The results showed that the proposed lateral displacement equations are highly accurate. Furthermore, although the rotational stiffness of the vertical inter-module connection did not exert an appreciable effect on the lateral displacement of the CSMSS-SRC, its horizontal shear stiffness did. These results are expected to provide a reference for the engineering design of CSMSS-SRC.