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.

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.

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.

Assessing Flanged Joint Leakage and Tube-to-Tubesheet Joint Failure due to Fluid Temperature Differentials in a Floating Head Heat Exchanger Using Finite Element Analysis

2013 ◽  
Author(s):  
Phillip E. Prueter ◽  
Brian Macejko ◽  
David J. Dewees ◽  
Robert G. Brown
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Heat Exchanger ◽  
Tube Bundle ◽  
Three Dimensional ◽  
Heat Transfer Analysis ◽  
Fluid Temperature ◽  
Element Analysis ◽  
Process Fluid ◽  
Steady State Heat Transfer

This paper uses three dimensional (3D) finite element analysis (FEA) to investigate the likelihood of leakage at the head-to-tubesheet joint and the possibility of failure at the tube-to-tubesheet joints due to temperature differentials between the shell-side and tube-side process fluid in a four-pass, floating head heat exchanger. The gasket at the floating head-to-tubesheet joint is explicitly modeled and the flange bolts are included with the appropriate amount of preload. Steady-state heat transfer analysis is performed on the 3D model to obtain realistic temperature gradients that are used to evaluate the system behavior in the ensuing structural analyses. Furthermore, different methods of approximating the stiffness of the tube bundle and the corresponding gasket stresses and tubesheet deflections are investigated in detail and compared. These comparisons indicate that simplified methods of modeling the tube bundle permit efficient thermal-mechanical evaluation of complex, multi-pass heat exchangers while achieving reasonable tubesheet and flanged joint behavior.

A Study on Jumping Characteristics in Synchronous Belt Drives: Experimental Results and FE Analysis at Driven Pulley Jumping

2003 ◽  
Author(s):  
Tomio Koyama ◽  
Weiming Zhang ◽  
Masanori Kagotani ◽  
Hiroyuki Ueda
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Analysis ◽  
Load Distribution ◽  
Fe Analysis ◽  
Experimental Results ◽  
Experimental Result ◽  
Element Analysis ◽  
Belt Drives ◽  
The Finite Element Analysis

The jumping characteristics at the driven pulley of L type synchronous belt drives are experimentally and analytically discussed. The number of the driving and the driven pulley teeth is the same and the wrapping angle of the belt on both pulleys is π radian. In this paper, the meshing state of belts on both of the driving and driven pulleys just before jumping is analyzed using the Finite Element analysis. Standardized L type synchronous belts and pulleys are used for analysis and experiments of the meshing states between belt and pulley, load distribution stress analysis and jumping torque. A 337L075 trapezoidal tooth profile synchronous belt and a 36L075 synchronous pulley are used in the analysis and the experiments. The wrapping angle of belt on both the driving and the driven pulley is equal to π radian. “ABAQUS/Standard” is used for the simulation and analysis of the belt. The simulation of the FE analysis of the wrapping angle of the belt on the driven pulley is almost the same with the experimental result. FE analysis of the load distribution just before jumping on the driven pulley agrees well with the experimental results.

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.

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.

Stress Analysis of Pipe Support Attachments: A Comparison of Analytical Methods and Finite Element Analysis for Circular and Non-Circular Attachments

2013 ◽  
Author(s):  
Anindya Bhattacharya
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Analysis ◽  
Analytical Methods ◽  
Theoretical Background ◽  
Fe Analysis ◽  
Design Parameters ◽  
Post Processing ◽  
Element Analysis ◽  
Custom Made

Despite the availability of special purpose FE codes with post processing facilities as per rules of ASME SEC VIII Division 2, use of simple analytical methods like ring loading around a circumference or more complex methods like Welding Research council bulletins 107 and 297, will continue to be used in the industry for a significant period of time for stress analysis of pipe support attachments. The reasons are few: not all engineering companies have such custom made FE codes, lack of trained personnel to work with general purpose FE codes, ease of implementation of the available methods and their successful design history, cost and time issues with FE analysis etc. In this paper these available methods will be reviewed based on their theoretical background, their range of applicability w.r.t the typical design parameters and their comparison with FE analysis. More recent analytical methods based on mathematically accurate space curves of intersections for circular attachments will also be discussed. This study will include both circular as well as non-circular attachments. This paper will highlight the strengths and weaknesses of the conventionally used methods especially with respect to their mathematical limitations to make an analyst aware of the potential over conservatism and under conservatism of these analytical methods. Finite element analysis models will be discussed in detail specifically in relation to elements used, element parameters, boundary conditions and post processing.

Experimentally Validated Finite Element Analysis of Railroad Bearing Adapter Operating Temperatures

2012 ◽  
Author(s):  
Andoni Zagouris ◽  
Arturo A. Fuentes ◽  
Constantine M. Tarawneh ◽  
Javier A. Kypuros ◽  
Andrea Arguelles
Keyword(s):  
Finite Element ◽  
Temperature Distribution ◽  
Operating Conditions ◽  
Finite Element Analyses ◽  
Element Analysis ◽  
Distribution Maps ◽  
Temperature Tracking ◽  
Steady State Heat ◽  
Railroad Bearing ◽  
Steady State Heat Transfer

Currently, railroad bearing temperatures are monitored using wayside infrared devices known as hot-box detectors (HBDs). HBDs take a snapshot of the bearing temperature at designated wayside detection sites which, depending on the track, may be spaced as far apart as 65 km (∼40 mi). Even though these devices have significantly reduced the number of derailments since their implementation, their discrete nature and limited accuracy prevents them from being utilized as a bearing health monitoring system. Future technologies are focusing on continuous temperature tracking of bearings. Since placing sensors directly on the bearing cup is not feasible due to cup indexing during service, the next logical location for such sensors is the bearing adapter. Understanding the thermal behavior of bearing adapters during operation is essential for sensor selection and placement within the adapter (e.g., typical temperature sensors have operating ranges of up to 125°C). To this end, this paper quantifies the steady-state heat transfer to the bearing adapter through a series of experiments and finite element analyses. The commercial software package ALGOR 20.3™ is used to conduct the thermal finite element analyses. Different heating scenarios are simulated with the purpose of obtaining the bearing adapter temperature distribution during normal and abnormal operating conditions. This paper presents an experimentally validated finite element thermal model which can be used to attain temperature distribution maps of bearing adapters in service conditions. These maps are useful for identifying ideal locations for sensor placement.

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.

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