Biaxial Ratcheting and Cyclic Plasticity for Bree-Type Loading—Part II: Comparison Between Finite Element Analysis and Theory

1996 ◽  
Vol 118 (2) ◽  
pp. 161-167 ◽  
Author(s):  
C. Nadarajah ◽  
H. W. Ng
Keyword(s):  
Finite Element ◽  
Close Agreement ◽  
Design Procedure ◽  
Cyclic Stress ◽  
Analytical Models ◽  
Cyclic Plasticity ◽  
Finite Element Analyses ◽  
Element Analysis ◽  
Extensive Program ◽  
Walled Cylinder

In Part I of this two part paper (Ng and Nadarajah, 1996), the results of an extensive program of finite element analyses were described. The problem being considered is the phenomenon of ratcheting and cyclic stress-strain hysteresis loop behavior in a thin-walled cylinder subject to cyclic thermal stress and sustained internal pressure. The purpose of Part II is to compare the finite element results with two analytical solutions and review the applicability of the latter as a design procedure for assessment of these types of structures. The comparison shows that the ratcheting to shakedown boundaries based on F.E. and analytical models are in close agreement. The hoop ratcheting rates predicted by the uniaxial model enveloped the F.E. and biaxial models, while for the axial ratcheting rates, the F.E. results are upper bound.

Application of ASME Code Section XI Appendix L Using 3-D Finite Element Analyses

2020 ◽  
Author(s):  
Charles Fourcade ◽  
Minji Fong ◽  
James Axline ◽  
Do Jun Shim ◽  
Chris Lohse ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Crack Growth ◽  
Cyclic Stress ◽  
Finite Element Analyses ◽  
Element Analysis ◽  
Aspect Ratios ◽  
Flaw Tolerance ◽  
Asme Code ◽  
Stress Ratios

Abstract As part of a fatigue management program for subsequent license renewal, a flaw tolerance evaluation based on ASME Code, Section XI, Appendix L may be performed. The current ASME Code, Section XI, Appendix L flaw tolerance methodology requires determination of the flaw aspect ratio for initial flaw size calculation. The flaw aspect ratios listed in ASME Section XI, Appendix L, Table L-3210-2, for austenitic piping for example, are listed as a function of the membrane-to-gradient cyclic stress ratio. The Code does not explicitly describe how to determine the ratio, especially when utilizing complex finite element analyses (FEA), involving different loading conditions (i.e. thermal transients, piping loads, pressure, etc.). The intent of the paper is to describe the methods being employed to determine the membrane-to-gradient cyclic stress ratios, and the corresponding flaw aspect ratios (a/l) listed in Table L-3210-2, when using finite element analysis methodology. Included will be a sample Appendix L evaluation, using finite element analysis of a pressurized water reactor (PWR) pressurizer surge line, including crack growth calculations for circumferential flaws in stainless steel piping. Based on this example, it has been demonstrated that, unless correctly separated, the membrane-to-gradient cyclic stress ratios can result in extremely long initial flaw lengths, and correspondingly short crack growth durations.

Development of Steel Dual-Core Self-Centering Braces: Quasi-Static Cyclic Tests and Finite Element Analyses

2015 ◽  
Vol 31 (1) ◽  
pp. 247-272 ◽  
Author(s):  
Chung-Che Chou ◽  
Ying-Chuan Chen
Keyword(s):  
Finite Element ◽  
Low Cycle Fatigue ◽  
Design Procedure ◽  
Fatigue Tests ◽  
Finite Element Analyses ◽  
Axial Deformation ◽  
Cyclic Tests ◽  
Element Analysis ◽  
Core Self ◽  
Dual Core

This work presents mechanics, tests, and finite element analyses of a novel steel dual-core self-centering brace (SCB) with flag-shaped re-centering responses. The axial deformation capacity of the brace is doubled with respect to the SCED brace by serial deformations of two sets of parallel tensioning elements when both braces use the same tensioning elements. The mechanics of the brace is first explained; six tensioning elements and four dual-core SCBs are tested to evaluate their cyclic performance. The braces exhibit excellent performance up to a drift of 2% with a maximum axial force around 1,400 kN. The braces also survive 15 low-cycle fatigue tests at a drift of 1.5%. Tensioning elements fail when the braces are overloaded to 2.5–3% drift. Finite element analysis is conducted to further verify hysteretic responses of the dual-core SCB in cyclic tests. A design procedure for the proposed dual-core SCB is also included in the paper.

Application of Computational Mechanics to Tire Design—Yesterday, Today, and Tomorrow

2011 ◽  
Vol 39 (4) ◽  
pp. 223-244 ◽  
Author(s):  
Y. Nakajima
Keyword(s):  
Finite Element ◽  
New Technologies ◽  
Computational Mechanics ◽  
Design Procedure ◽  
Side Wall ◽  
Rolling Resistance ◽  
Optimization Techniques ◽  
Stress Strain ◽  
Element Analysis ◽  
Crown Shape

Abstract The tire technology related with the computational mechanics is reviewed from the standpoint of yesterday, today, and tomorrow. Yesterday: A finite element method was developed in the 1950s as a tool of computational mechanics. In the tire manufacturers, finite element analysis (FEA) was started applying to a tire analysis in the beginning of 1970s and this was much earlier than the vehicle industry, electric industry, and others. The main reason was that construction and configurations of a tire were so complicated that analytical approach could not solve many problems related with tire mechanics. Since commercial software was not so popular in 1970s, in-house axisymmetric codes were developed for three kinds of application such as stress/strain, heat conduction, and modal analysis. Since FEA could make the stress/strain visible in a tire, the application area was mainly tire durability. Today: combining FEA with optimization techniques, the tire design procedure is drastically changed in side wall shape, tire crown shape, pitch variation, tire pattern, etc. So the computational mechanics becomes an indispensable tool for tire industry. Furthermore, an insight to improve tire performance is obtained from the optimized solution and the new technologies were created from the insight. Then, FEA is applied to various areas such as hydroplaning and snow traction based on the formulation of fluid–tire interaction. Since the computational mechanics enables us to see what we could not see, new tire patterns were developed by seeing the streamline in tire contact area and shear stress in snow in traction.Tomorrow: The computational mechanics will be applied in multidisciplinary areas and nano-scale areas to create new technologies. The environmental subjects will be more important such as rolling resistance, noise and wear.

Design and Analysis of Viscoelastic Seismic Dampers

2002 ◽  
Author(s):  
N. Shimizu ◽  
H. Nasuno ◽  
T. Yazaki ◽  
K. Sunakoda
Keyword(s):  
Finite Element ◽  
Constitutive Relation ◽  
Time Domain ◽  
Dynamic Properties ◽  
Design Procedure ◽  
Fe Analysis ◽  
Damping Capacity ◽  
Element Formulation ◽  
Element Analysis ◽  
Equivalent Viscous Damping

This paper describes a methodology of design and analysis of viscoelastic seismic dampers by means of the time domain finite element analysis. The viscoelastic constitutive relation of material incorporating with the fractional calculus has been derived and the finite element formulation based on the constitutive relation has been developed to analyze the dynamic property of seismic damper. A time domain computer program was developed by using the formulation. Dynamic properties of hysteresis loop, damping capacity, equivalent viscous damping coefficient, and equivalent spring constant are calculated and compared with the experimental results. Remarkable correlation between the FE analysis and the experiment is gained, and consequently the design procedure with the help of the FE analysis has been established.

Investigation on endurance evaluation of a portal crane: experimental, theoretical and finite element analysis

2020 ◽  
Vol 62 (4) ◽  
pp. 357-364
Author(s):  
Yusuf Aytaç Onur ◽  
Hakan Gelen
Keyword(s):  
Finite Element ◽  
Critical Points ◽  
Maximum Stress ◽  
Strain Gages ◽  
Finite Element Analyses ◽  
Element Analysis ◽  
Element Simulation ◽  
Main Girder ◽  
Stressed Component ◽  
Portal Crane

Abstract In this study, the stress on portal crane components at various payloads has been investigated theoretically, numerically and experimentally. The portal crane was computer-aided modeled and finite element analyses were performed so that the most stressed points at the each trolley position investigated on the main girder could be determined. In addition, the critical points were marked on the portal crane, and strain gages were attached to the those critical points so that stress values could be experimentally determined. The safety factor values at different payloads were determined by using finite element simulation. Results indicate that the most stressed component in the examined portal crane is the main girder. Experimental results indicate that the maximum stress value on the main girder is 3.05 times greater than the support legs and 8.99 times larger than the rail.

scholarly journals Simulating sauropod manus-only trackway formation using finite-element analysis

2010 ◽  
Vol 7 (1) ◽  
pp. 142-145 ◽  
Author(s):  
P. L. Falkingham ◽  
K. T. Bates ◽  
L. Margetts ◽  
P. L. Manning
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Surface Area ◽  
Fossil Record ◽  
Temporal Correlation ◽  
Finite Element Analyses ◽  
Centre Of Mass ◽  
Element Analysis ◽  
Mass Distributions ◽  
Track Formation

The occurrence of sauropod manus-only trackways in the fossil record is poorly understood, limiting their potential for understanding locomotor mechanics and behaviour. To elucidate possible causative mechanisms for these traces, finite-element analyses were conducted to model the indentation of substrate by the feet of Diplodocus and Brachiosaurus . Loading was accomplished by applying mass, centre of mass and foot surface area predictions to a range of substrates to model track formation. Experimental results show that when pressure differs between manus and pes, as determined by the distribution of weight and size of respective autopodia, there is a range of substrate shear strengths for which only the manus (or pes) produce enough pressure to deform the substrate, generating a track. If existing reconstructions of sauropod feet and mass distributions are correct, then different taxa will produce either manus- or pes-only trackways in specific substrates. As a result of this work, it is predicted that the occurrence of manus- or pes-only trackways may show geo-temporal correlation with the occurrence of body fossils of specific taxa.

Structural Stability Evaluation for Lifting Lug Design of Large Marine Engine by Finite Element Analysis

2007 ◽  
Vol 353-358 ◽  
pp. 2855-2859
Author(s):  
W.C. Lee ◽  
Chae Sil Kim ◽  
J.B. Na ◽  
D.H. Lee ◽  
S.Y. Cho ◽  
...  
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Design Procedure ◽  
Steel Structures ◽  
Stability Evaluation ◽  
Element Analysis ◽  
Marine Engines ◽  
Dimensional Finite Element ◽  
The Stability ◽  
Three Dimensional Finite Element

Since most marine engines are generally very huge and heavy, it is required to keep safety from accidents in dealing them. Several types of lifting lugs have been used to assemble hundred ton–large steel structures and carry the assembled engines. Recently a few crashes have been occurred in carrying engines due to breaking down the lugs. Although the stability evaluation of the lifting lug has therefore been very important for safety, systematic design procedure of the lugs, which includes the structural analysis considering stability, has few reported. This paper describes the three dimensional finite element structural modeling for a lifting lug, the studies for determining the reasonable loading and boundary conditions, and the stability evaluation with the results of structural analyses. It should be very helpful for designing the other types of lifting lugs with safety.

scholarly journals New Design Procedure of Transtibial ProsthesisBed Stump Using Topological Optimization Method

Symmetry ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 1837 ◽  
Author(s):  
Martin Sotola ◽  
David Stareczek ◽  
David Rybansky ◽  
Jiri Prokop ◽  
Pavel Marsalek
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Design Procedure ◽  
Optimization Method ◽  
Topological Optimization ◽  
Element Analysis ◽  
Current Application ◽  
Transtibial Prosthesis ◽  
Walking Biomechanics ◽  
The Impact

This paper presents a new design procedure for production of a transtibial prosthesis bed stump by three-dimensional (3D) printing with topological optimization. The suggested procedure combines the medical perspective with finite element analysis and facilitates regaining the symmetry in patients with transtibial prosthesis, which leads to life improvement. The particular focus of the study is the weight reduction of the lower part of the bed stump, while taking into account its stiffness and load-bearing capacity. The first part of the work deals with the analysis of the subject geometry of the bed stump, which is usually oversized in terms of the weight and stiffness that are necessary for the current application. In the second part, an analysis of walking biomechanics with a focus on the impact and rebound phases is presented. Based on the obtained information, a spatial model of the lower part of the bed stump is proposed in the third phase, in which the finite element method is described. In the fourth part, the topological optimization method is used for reducing the structure weight. In the last part, the results of the designed model are analyzed. Finally, the recommendations for the settings of the method are presented. The work is based on the practical industry requirements, and the obtained results will be reflected in the design of new types of transtibial prosthesis.

Study on the mechanism of preload decrease of bolted joints subjected to transversal vibration loading

2019 ◽  
Vol 233 (12) ◽  
pp. 2320-2329
Author(s):  
Hao Gong ◽  
Jianhua Liu ◽  
Xiaoyu Ding
Keyword(s):  
Finite Element ◽  
Comprehensive Evaluation ◽  
Evaluation Criteria ◽  
Bolted Joints ◽  
Cyclic Plasticity ◽  
Stress Release ◽  
Element Analysis ◽  
Transversal Vibration ◽  
Mechanical Products ◽  
As Stress

Sufficient preload in a bolted joint is key to ensuring the reliability of mechanical products; however, under vibration, preload decrease often occurs. The mechanism of preload decrease has not yet been fully clarified. In this study, finite element models of bolted joints with and without helix angles were constructed to study the mechanism of preload decrease under transversal vibration. Based on the finite element analysis results, a new cause of preload decrease, denoted as stress release and redistribution, was discovered and explained in detail. The mechanism of preload decrease caused by stress release and redistribution, cyclic plasticity deformation and rotation loosening is studied systematically, and the typical mode of preload decrease is proposed. Based on the preload decrease curve, more comprehensive evaluation criteria are established, quantified using three parameters to represent the locking behavior of bolted joints. Finally, experiments were conducted to verify the reliability of the preload decrease results.

Verification of Specimens for Low-Cycle Fatigue and Cyclic Plasticity Testing

1979 ◽  
Vol 101 (4) ◽  
pp. 321-327
Author(s):  
C. C. Schultz ◽  
H. M. Zien
Keyword(s):  
Finite Element ◽  
Low Cycle Fatigue ◽  
Cyclic Plasticity ◽  
Cycle Fatigue ◽  
Finite Element Analyses ◽  
Stress Strain ◽  
Inelastic Analysis ◽  
Analysis Methods ◽  
Strain Data

The results of inelastic finite element analyses of several uniaxial specimens used for low-cycle fatigue and cyclic plasticity testing are presented. The test specimens studied include both hourglass and uniform gage-type geometries. These results indicate that normally used hourglass specimens may significantly underestimate the strain for a given stress. Uniform gage specimens with commonly used length-to-diameter ratios are shown to provide adequate stress-strain data. Two extensively strain-gaged uniform gage specimens were tested to provide data to confirm the acceptability of the inelastic analysis methods.

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