A Local-to-Global Dimensional Error Calculation Framework for the Riveted Assembly Using Finite-Element Analysis

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Jun Ni ◽  
Wencheng Tang ◽  
Yan Xing ◽  
Kecun Ben ◽  
Ming Li
Keyword(s):  
Finite Element ◽  
Large Scale ◽  
Fe Analysis ◽  
Main Process ◽  
Fe Model ◽  
Parameter Uncertainties ◽  
Element Analysis ◽  
Dimensional Error ◽  
Error Calculation ◽  
Inherent Strain

Mechanical structures of large-scale antennas are sheet metals connected by thousands of rivets. The antenna dimensional error after riveting often violates the limit allowed. The prediction of the global dimensional error induced by many rivet connections requires a rapid and accurate assembly deformation calculation method. Main process parameters of these local rivet connections are the local connection dimension, material property, local clamp position, rivet upsetting direction, and the hammer time-to-displacement impact, except for the riveting sequence. We neglect the process parameter uncertainties and consider that the main riveting parameters equate to a dynamic finite-element (FE) model of single rivet connection. The dynamic FE analysis result yields an inherent strain database for the riveted local parts. Then, we propose an iterative loop of static FE analyses for the global structure taking the inherent strain database and possible former static FE analysis result as the boundary conditions. The loop forms a local-to-global framework. Two examples are involved through the framework representation and realistic application. Framework advantages include: (1) a good balance between the cost and precision of dimensional error calculation; (2) the sequence simulation of all the riveting operations; and (3) supporting the further assembly process optimization to reduce the global dimensional error of the assembly with thousands of rivets.

Experimental and Numerical Study on Crashworthiness Parameters of Mild Steel Square Tube under Quasi-Static Axial Compression

2020 ◽  
Vol 12 (2) ◽  
Author(s):  
Shinde Rushikesh ◽  
Mali Kiran ◽  
M. Kathiresan ◽  
Kulkarni Dhananjay
Keyword(s):  
Finite Element ◽  
Numerical Study ◽  
Experimental Testing ◽  
Testing Machine ◽  
Fe Analysis ◽  
Fe Model ◽  
Element Analysis ◽  
Static Test ◽  
Collapse Mode ◽  
Crash Behaviour

In the present research, an experimental and numerical study on the crush response of square tube is presented. The explicit Finite Element Analysis (FEA) in LS-DYNA software is carried out to simulate crash behaviour under the quasi-static test conditions. Compression load is applied quasi-statically in an experimental study on the square tube specimens using Universal Testing Machine (UTM). In quasi-static test the bottom platen speed used is 1 mm/min. From experimental testing symmetric collapse mode is observed in all deformed specimens. The development of the symmetric collapse mode in a Finite Element (FE) model is also observed. Thus fold formation and crush response predicted by FE analysis are observed to be in very good correlation with the results obtained from experimental testing. Furthermore, the effect of the thickness of tube on crashworthiness parameters is investigated. From the FE analysis, it is found that the thickness of the square tube influences significantly the crashworthiness parameters.

Overpressure Fragility Evaluation of a Mark I Drywell Using Thermal-Mechanical Finite Element Analysis

2014 ◽  
Author(s):  
Mohamed M. Talaat ◽  
David K. Nakaki ◽  
Kyle S. Douglas ◽  
Philip S. Hashimoto ◽  
Yahya Y. Bayraktarli
Keyword(s):  
Finite Element ◽  
Stress Analysis ◽  
Fe Analysis ◽  
Heat Transfer Analysis ◽  
Fe Model ◽  
Head Region ◽  
Element Analysis ◽  
Differential Movement ◽  
Steady State Heat ◽  
Steady State Heat Transfer

The overpressure fragility of a Mark I boiling water reactor drywell was performed by detailed finite element (FE) analysis. The drywell overpressure capacity is controlled by the onset of leakage in the bolted head flange connection once separation exceeds the capacity of the silicone rubber O-ring seals. The FE analysis was conducted at 6 discrete accident temperatures, ranging from 150 to 425°C. The overpressure evaluation used an axisymmetric model of the drywell head region for computational efficiency, and verified it by comparing to results from one FE model which used 3D solid elements. The mechanical properties of the steel materials were defined as temperature-dependent linear-elastic. The median overpressure capacity at each temperature was determined using a 2-step thermal-stress analysis procedure. First, a steady-state heat transfer analysis was conducted to map out the temperature distribution in the drywell wall, which is exposed to the accident temperature on the inside and ambient temperature on the outside. Second, a quasi-static multi-step stress analysis was performed. The vertical differential movement between the flange surfaces was monitored and compared to the O-ring rebound capacity to define the pressure at the onset of leakage. After leakage occurred, the relationship between leakage area and increased pressure was recorded. The evaluation predicted the median overpressure capacity and the lognormal standard deviation for uncertainty in O-ring rebound capacities, bolt preload, and model sophistication, in addition to the median pressure-leak area relationship.

The biomechanical study of cervical spine: A Finite Element Analysis

2021 ◽  
pp. 039139882199549
Author(s):  
Pechimuthu Susai Manickam ◽  
Sandipan Roy
Keyword(s):  
Finite Element ◽  
Cervical Spine ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Biomechanical Study ◽  
Fe Analysis ◽  
Von Mises Stress ◽  
Fe Model ◽  
Element Analysis ◽  
End Plate

The biomechanical study helps us to understand the mechanics of the human cervical spine. A three dimensional Finite Element (FE) model for C3 to C6 level was developed using computed tomography (CT) scan data to study the mechanical behaviour of the cervical spine. A moment of 1 Nm was applied at the top of C3 vertebral end plate and all degrees of freedom of bottom end plate of C6 were constrained. The physiological motion of the cervical spine was validated using published experimental and FE analysis results. The von Mises stress distribution across the intervertebral disc was calculated along with range of motion. It was observed that the predicted results of functional spine units using FE analysis replicate the real behaviour of the cervical spine.

Visco-Anisotropic Hyperelastic Finite Element Analysis of Knee Joint Considering Deformation Induced Anisotropy Evolution of Meniscus

2017 ◽  
Author(s):  
Tsuyoshi Eguchi ◽  
Yoshihiro Tomita ◽  
Koji Yamamoto ◽  
Yusuke Morita ◽  
Eiji Nakamachi
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Knee Joint ◽  
Constitutive Equations ◽  
Collagen Fiber ◽  
Collagen Fibers ◽  
Fe Analysis ◽  
Fe Model ◽  
Element Analysis ◽  
Human Knee Joint

Recently, the observation technology of micro structure has made great progress, and then collagen fiber orientation of meniscus can be measured accurately. This makes it possible to evaluate the stress in knee joint by considering the collagen fiber orientations at the micro scale. In this study, we developed visco-isotropic/anisotropic hyperelastic constitutive equations (Iso-VHE/Aniso-VHE) for menisci, which can reflect the initial collagen fiber orientations and their deformation induced rotations. Subsequently, we constructed a finite element (FE) model of normal human knee joint by using the magnetic resonance (MR) tomography images. The FE analysis with the proposed constitutive equations and FE model clarifies the reinforcement effect of collagen fibers on mechanical characteristics of knee joint. Our computational prediction clarified that the stress concentration occurred on the contact parts of articular cartilages of femur and tibia, which met the tendency of the experimental results. Furthermore, the maximum compressive stresses evaluated by Aniso-VHE always showed a lower value as compared with Iso-VHE. This suggested that the anisotropy of meniscal collagen fibers relieved the stress concentration and lowered the maximum value. Therefore, our proposed FE analysis was proved to have a potential to reveal the functions of meniscus and knee joint.

Finite Element Analysis on Load-Bearing Behavior of Concrete Filled Steel Tubular Composite Frames

2011 ◽  
Vol 71-78 ◽  
pp. 1683-1686
Author(s):  
Yuan Huang ◽  
Wei Jian Yi ◽  
Jian Guo Nie
Keyword(s):  
Finite Element ◽  
Seismic Behavior ◽  
Fe Analysis ◽  
Constitutive Law ◽  
Plastic Behavior ◽  
Fe Model ◽  
Element Analysis ◽  
Composite Frames ◽  
Composite Frame ◽  
Analysis Models

This paper presents a nonlinear finite element (FE) analysis on the mechanic behavior of concrete filled steel tubular (CFST) composite frames. The main purpose of the FE analysis was to investigate the seismic behavior of composite frames. Three kinds of nonlinearity, namely material nonlinearity, contact nonlinearity and geometry nonlinearity, were taken into account in the FE model using MSC.Marc. The element type, connection between element, material constitutive law and boundary condition was described in detail. The elasto-plastic behavior, as well as fracture and post-fracture behavior, of the FE analysis models fitted well with those of the test specimens. The beam and panel zone deformation of the analysis models is also in good agreement with that of the test specimen. It is concluded that FE model of CFST composite frame is reliable and could be regarded as a helpful tool to expand the information on seismic behavior of CFST composite frame.

TO STUDY THE EFFECTS OF INTRASTROMAL CORNEAL RING GEOMETRY AND SURGICAL CONDITIONS ON THE POSTSURGICAL OUTCOMES THROUGH FINITE ELEMENT ANALYSIS

2016 ◽  
Vol 16 (07) ◽  
pp. 1650101 ◽  
Author(s):  
SALMAN N. KHAN ◽  
PANOS S. SHIAKOLAS
Keyword(s):  
Finite Element ◽  
Linear Regression Analysis ◽  
Fe Analysis ◽  
Fe Model ◽  
Control Parameters ◽  
Element Analysis ◽  
Intrastromal Corneal Ring ◽  
Implantation Depth ◽  
Depth Analysis ◽  
Surgical Conditions

Intrastromal corneal ring (ICR) is a transparent circular implant inserted in the cornea to provide structural support in an attempt to alleviate preexisting refractive errors. This is a surgical procedure whose success depends on control parameters such as, ICR geometry which includes ICR thickness and diameter, and surgical conditions which includes ICR implantation depth and diameter of corneal pocket. This research utilizes finite element (FE) analysis techniques to develop a high fidelity and computationally efficient three-dimensional axisymmetric cornea model to study the relative effects of ICR implant geometry and surgical conditions on the postsurgical shape of the cornea utilizing corneal apical displacement results. The FE analysis results indicate that ICR implantation reduces myopia, and the amount of myopic rectification is dependent on the control parameters which include ICR geometry and surgical conditions. The results show that an increase in ICR thickness leads to an increase in myopic rectification, whereas an increase in ICR radius leads to a decrease in myopic rectification. ICR implantation depth analysis results suggest that corneal depth of 40–75% provides steady myopic rectification. Corneal pocket diameter analysis revealed that smaller corneal pockets lead to increase in myopic rectification. Overall, the FE model results are in qualitative agreement with published clinical studies. Finally, the combined impact of the control parameters on myopic rectification was studied by conducting a sensitivity analysis and an equation relating myopic rectification with control parameters was developed utilizing simple linear regression analysis.

Finite Element Analysis of the Distributed Vibration Absorbers for Structural Noise Control

2005 ◽  
Author(s):  
Ashwini Gautam ◽  
Chris Fuller ◽  
James Carneal
Keyword(s):  
Finite Element ◽  
Numerical Model ◽  
Base Plate ◽  
Element Model ◽  
Fe Model ◽  
Vibration Absorbers ◽  
Element Analysis ◽  
Poroelastic Media ◽  
Hexahedral Elements ◽  
Component Models

This work presents an extensive analysis of the properties of distributed vibration absorbers (DVAs) and their effectiveness in controlling the sound radiation from the base structure. The DVA acts as a distributed mass absorber consisting of a thin metal sheet covering a layer of acoustic foam (porous media) that behaves like a distributed spring-mass-damper system. To assess the effectiveness of these DVAs in controlling the vibration of the base structures (plate) a detailed finite elements model has been developed for the DVA and base plate structure. The foam was modeled as a poroelastic media using 8 node hexahedral elements. The structural (plate) domain was modeled using 16 degree of freedom plate elements. Each of the finite element models have been validated by comparing the numerical results with the available analytical and experimental results. These component models were combined to model the DVA. Preliminary experiments conducted on the DVAs have shown an excellent agreement between the results obtained from the numerical model of the DVA and from the experiments. The component models and the DVA model were then combined into a larger FE model comprised of a base plate with the DVA treatment on its surface. The results from the simulation of this numerical model have shown that there has been a significant reduction in the vibration levels of the base plate due to DVA treatment on it. It has been shown from this work that the inclusion of the DVAs on the base plate reduces their vibration response and therefore the radiated noise. Moreover, the detailed development of the finite element model for the foam has provided us with the capability to analyze the physics behind the behavior of the distributed vibration absorbers (DVAs) and to develop more optimized designs for the same.

scholarly journals Stator Non-Uniform Radial Ventilation Design Methodology for a 15 MW Turbo-Synchronous Generator Based on Single Ventilation Duct Subsystem

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2760
Author(s):  
Ruiye Li ◽  
Peng Cheng ◽  
Hai Lan ◽  
Weili Li ◽  
David Gerada ◽  
...  
Keyword(s):  
Finite Element ◽  
Temperature Distribution ◽  
Design Methodology ◽  
Large Scale ◽  
Synchronous Generator ◽  
Axial Direction ◽  
Scale Model ◽  
Element Analysis ◽  
Axial Temperature ◽  
Ventilation Duct

Within large turboalternators, the excessive local temperatures and spatially distributed temperature differences can accelerate the deterioration of electrical insulation as well as lead to deformation of components, which may cause major machine malfunctions. In order to homogenise the stator axial temperature distribution whilst reducing the maximum stator temperature, this paper presents a novel non-uniform radial ventilation ducts design methodology. To reduce the huge computational costs resulting from the large-scale model, the stator is decomposed into several single ventilation duct subsystems (SVDSs) along the axial direction, with each SVDS connected in series with the medium of the air gap flow rate. The calculation of electromagnetic and thermal performances within SVDS are completed by finite element method (FEM) and computational fluid dynamics (CFD), respectively. To improve the optimization efficiency, the radial basis function neural network (RBFNN) model is employed to approximate the finite element analysis, while the novel isometric sampling method (ISM) is designed to trade off the cost and accuracy of the process. It is found that the proposed methodology can provide optimal design schemes of SVDS with uniform axial temperature distribution, and the needed computation cost is markedly reduced. Finally, results based on a 15 MW turboalternator show that the peak temperature can be reduced by 7.3 ∘C (6.4%). The proposed methodology can be applied for the design and optimisation of electromagnetic-thermal coupling of other electrical machines with long axial dimensions.

scholarly journals Design and analysis of concrete-filled tubular flange girders under combined loading

2021 ◽  
pp. 136943322110015
Author(s):  
Rana Al-Dujele ◽  
Katherine Ann Cashell
Keyword(s):  
Finite Element ◽  
Axial Force ◽  
Failure Modes ◽  
Numerical Study ◽  
Combined Loading ◽  
Torsional Stiffness ◽  
Fe Model ◽  
Combined Effects ◽  
Element Analysis ◽  
Hollow Section

This paper is concerned with the behaviour of concrete-filled tubular flange girders (CFTFGs) under the combination of bending and tensile axial force. CFTFG is a relatively new structural solution comprising a steel beam in which the compression flange plate is replaced with a concrete-filled hollow section to create an efficient and effective load-carrying solution. These members have very high torsional stiffness and lateral torsional buckling strength in comparison with conventional steel I-girders of similar depth, width and steel weight and are there-fore capable of carrying very heavy loads over long spans. Current design codes do not explicitly include guidance for the design of these members, which are asymmetric in nature under the combined effects of tension and bending. The current paper presents a numerical study into the behaviour of CFTFGs under the combined effects of positive bending and axial tension. The study includes different loading combinations and the associated failure modes are identified and discussed. To facilitate this study, a finite element (FE) model is developed using the ABAQUS software which is capable of capturing both the geometric and material nonlinearities of the behaviour. Based on the results of finite element analysis, the moment–axial force interaction relationship is presented and a simplified equation is proposed for the design of CFTFGs under combined bending and tensile axial force.

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