scholarly journals SIMULAÇÃO COMPUTACIONAL DE PILARES DE AÇO SUBMETIDOS À COMPRESSÃO AXIAL

2020 ◽  
Vol 15 (2) ◽  
pp. 203-2016
Author(s):  
Leonardo Carvalho Mesquita ◽  
Arthur Filipe Freire Gomes ◽  
Filipe Silveira Leão
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Computational Models ◽  
Structural Behavior ◽  
Future Research ◽  
Elastic Buckling ◽  
Geometric Imperfections ◽  
Steel Columns ◽  
Plastic Analysis ◽  
Two Stages

RESUMO: Este trabalho teve como objetivo simular computacionalmente o comportamento estrutural de pilares de aço submetidos à compressão axial e avaliar a influência das imperfeições geométricas e de materiais (tensões residuais) sobre a capacidade resistente destes elementos. Para isso, desenvolveu-se, com auxílio do software Abaqus, modelos computacionais de elementos finitos que foram analisados em duas etapas, a primeira correspondente a uma análise de flambagem elástica (Buckle) e a segunda a uma análise não-linear plástica (Static Ricks). Os resultados obtidos pelos modelos desenvolvidos foram comparados com os resultados apresentados pela equação de flambagem elástica proposta por Euler e pela curva de flambagem prescrita pela ABNT NBR 8800:2008. De forma geral, os resultados computacionais se aproximaram dos valores de referência, o que indica que os modelos computacionais conseguiram simular o comportamento estrutural de um pilar real e que a metodologia proposta é válida. Ao analisar a influência das imperfeições geométricas observou-se que os modelos com imperfeições de L/1000 e L/1500 foram os que mais se aproximaram dos valores de referência. No caso das imperfeições de materiais, os modelos com 10% e 15% de tensões residuais foram os que mais se aproximaram. Desta forma, as estratégias adotadas podem contribuir para futuras pesquisas relacionadas à flambagem de pilares de aço submetidos à compressão axial. ABSTRACT: This research aimed to simulate the structural behavior of steel columns subjected to axial compression and to evaluate the influence of geometric and material imperfections (residual stresses) on the strength of these elements. In order to achieve this aim, finite element computational models were developed using Abaqus, which were analyzed in two stages: an elastic buckling analysis (Buckle) and a nonlinear plastic analysis (Static Ricks). The results obtained were compared with the results presented by the elastic buckling equation proposed by Euler and the buckling curve prescribed by ABNT NBR 8800: 2008. In general, the results obtained were very close if compared to the reference values. It indicates that the computational models were able to simulate the structural behavior of a real pillar and that the proposed methodology is valid. When analyzing the influence of the geometric imperfections, it was observed that the models with imperfections of L/1000 and L/1500 were the ones that most approached the expected results. In the case of material imperfections, the models with 10% and 15% of residual stresses were the ones that presented the best results. In this way, the adopted strategies may contribute to future research related to the structural behavior of columns and buckling.

scholarly journals ANÁLISE NUMÉRICA DE PERFIS DE AÇO FORMADOS A FRIO EM SEÇÃO “I” CONSTITUÍDA POR DUPLO “U” SUBMETIDOS À COMPRESSÃO

2020 ◽  
Vol 12 (1) ◽  
pp. 95-110
Author(s):  
Gabriel Cintra Macedo ◽  
Wanderson Fernando Maia
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Plate Thickness ◽  
Experimental Studies ◽  
Structural Behavior ◽  
The Finite Element Method ◽  
Geometric Imperfections ◽  
Initial Geometric Imperfections ◽  
Normal Strength ◽  
Double Channel

Although the section “I”, in double channel, is widely used, there are few studies on its behavior. Therefore, this work aims to contribute to a greater mastery over the structural behavior of this built-up sections. A nonlinear numerical analysis was performed using the Finite Element Method in the Ansys program, using existing experimental studies as a comparative database. The effect of length, number of connections, plate thickness and the presence of geometric and material imperfections on the normal strength of the columns. For this analysis, it was essential to consider the initial geometric imperfections, because there was a considerable reduction in the normal strength of the columns, thus getting closer to the values obtained experimentally. With regard to normative procedures, values against security were found in most cases, showing the need to conduct further studies in the area for the development of more appropriate formulations.

Prediction of Residual Stresses in Butt Welded Plates Using Inherent Strains

1993 ◽  
Vol 115 (4) ◽  
pp. 417-423 ◽  
Author(s):  
Y. Ueda ◽  
M. G. Yuan
Keyword(s):  
Finite Element Method ◽  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
The Finite Element Method ◽  
Butt Weld ◽  
Butt Welds ◽  
Plastic Analysis ◽  
Inherent Strain ◽  
Element Method

The source of residual stresses in the vicinity of a weld may be expressed in terms of inherent strains. The characteristics of the inherent strain distributions in butt welds are investigated. It is found that the patterns vary little with changes in the welding conditions and sizes of the welded plates. With some assumptions, simple formulas are derived for the distribution and magnitude of inherent strain in a butt weld. A method of predicting the residual stress in a butt-welded plate using the characteristics of inherent strain distributions is presented. The validity of the method is confirmed by thermal elasto-plastic analysis using the finite element method (FEM).

Obtaining Residual Stresses in Metal Forming After Neglecting Elasticity on Loading

1989 ◽  
Vol 56 (2) ◽  
pp. 318-327 ◽  
Author(s):  
Yong-Shin Lee ◽  
Paul R. Dawson
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Residual Stresses ◽  
Metal Forming ◽  
Quantitative Assessment ◽  
Finite Element Formulation ◽  
Elastic Response ◽  
Element Formulation ◽  
Plastic Analysis ◽  
Loading And Unloading

A methodology for computing residual stresses in forming operations is examined in which the elasticity is neglected during the loading phase of the operation. The elastic response is recovered on unloading through the analysis of an initially-stressed body. Two examples are presented which provide a quantitative assessment of the accuracy of the approach. The first is the axisymmetric expansion of a thick-walled tube. In this case the residual stresses are compared to those computed with an elastic-plastic analysis for both the loading and unloading phases. The second example is a ring upsetting application that has been analyzed using a finite element formulation and for which there are experimental data available for comparison.

Verification, Validation, and Uncertainty Quantification of Spinal Rod Computational Models Under Three-Point Bending

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Srinidhi Nagaraja ◽  
Galyna Loughran ◽  
Anup Gandhi ◽  
Jason Inzana ◽  
Andrew P. Baumann ◽  
...  
Keyword(s):  
Finite Element ◽  
Best Practices ◽  
Uncertainty Quantification ◽  
Medical Devices ◽  
Computational Models ◽  
Experimental Testing ◽  
Future Research ◽  
Element Analysis ◽  
Bend Testing ◽  
Point Bend

Abstract Verification, validation, and uncertainty quantification (VVUQ) can increase confidence in computational models by providing evidence that a model accurately represents the intended reality of interest. However, there are currently few examples demonstrating the application of VVUQ best practices for medical devices. Therefore, the objectives of this study were to understand the reproducibility and repeatability of experimental testing and finite element analysis (FEA), perform VVUQ activities that guide the development and refinement of a finite element model, and document best practices for future research. This study focused on experiments and simulations of three-point bend testing, which is a fundamental element of a hierarchical validation study of medical devices (e.g., spinal rod-screw systems). Experimental three-point bend testing was performed at two laboratories using medical-grade titanium (Ti-6Al-4V) spinal rods. FEA replicating the experimental test was performed by four independent institutions. Validation activities included comparing differences in mechanical properties between FEA and experimental results, where less than 10% difference was observed for all quantities of interest. Computational model uncertainties due to modeling assumptions and model input parameters were estimated using the sensitivity coefficient method. An importance factor analysis showed that rod diameter was the parameter driving uncertainty in the initial elastic region, while the material model is the primary contributor beyond this point. These results provide a proof of concept in the use of VVUQ for the use of FEA for medical device applications.

A Finite-Element Model for Residual Stresses and Deflections in Girth-Butt Welded Pipes

1978 ◽  
Vol 100 (3) ◽  
pp. 256-262 ◽  
Author(s):  
E. F. Rybicki ◽  
D. W. Schmueser ◽  
R. W. Stonesifer ◽  
J. J. Groom ◽  
H. W. Mishler
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Computational Models ◽  
Strain Range ◽  
Element Model ◽  
304 Stainless Steel ◽  
Transient Temperature ◽  
Stress Strain ◽  
Nonlinear Stress ◽  
Welded Pipe

Computational models for predicting transient temperature distributions, residual stresses, and residual deflections for girth-butt welds are described. Comparisons of predicted and measured temperatures for a two-pass welded pipe show agreement to within 9 percent and 17 percent of the measured values for passes one and two, respectively, the model for predicting residual stresses and residual deflections is based on a finite-element representation recognizing individual passes, temperature dependent elastic-plastic constitutive behavior, elastic unloading for material in the nonlinear stress-strain range, and changes in geometry due to the deformation of each weld pass. Load incrementation and incremental stress-strain relations are also used. Results for a two-pass girth-butt welded pipe show good correlation between residual stresses and residual deflections obtained from the computational model and data obtained from a welded 304 stainless steel pipe.

scholarly journals Effect of residual stresses and cold-straightening on the compressive resistance of solid round steel columns

2021 ◽  
Author(s):  
Jin Xu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Residual Stresses ◽  
Diffraction Method ◽  
X Ray Diffraction ◽  
Element Analysis ◽  
Steel Columns ◽  
Thermal Residual Stresses ◽  
Different Diameters ◽  
Compressive Resistance

The objective of this research is to study the effects of residual stresses and cold-straightening on the compressive resistance of solid round steel columns. Thermal residual stresses in selected solid round sizes were determined from experimental study, finite element analysis, and previous research. In the experimental investigation, classical boring-out method using water-jet technology was applied on four samples with different diameters. Finite element models were constructed for the determination of thermal reidual stresses for columns with 12 different diameters. The results were then compared with results obtained from a recent study on the predictionof symmetrical residual stresses in solid rounds using X-ray diffraction method. For the non-symmetrical residual stresses arising from cold-straightening, the equation developed by Nitta and Thurlimann was adopted in the finite element modeling to study the effect of non-symmetrical residual stresses on the compressive resistance of solid round steel columns. The Finite Element Analysis has been conducted on different bar diameter (1.5 inch to 12 inch diameter) and length, as well as initial out-of-straightness.

scholarly journals Effect of residual stresses and cold-straightening on the compressive resistance of solid round steel columns

2021 ◽  
Author(s):  
Jin Xu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Residual Stresses ◽  
Diffraction Method ◽  
X Ray Diffraction ◽  
Element Analysis ◽  
Steel Columns ◽  
Thermal Residual Stresses ◽  
Different Diameters ◽  
Compressive Resistance

The objective of this research is to study the effects of residual stresses and cold-straightening on the compressive resistance of solid round steel columns. Thermal residual stresses in selected solid round sizes were determined from experimental study, finite element analysis, and previous research. In the experimental investigation, classical boring-out method using water-jet technology was applied on four samples with different diameters. Finite element models were constructed for the determination of thermal reidual stresses for columns with 12 different diameters. The results were then compared with results obtained from a recent study on the predictionof symmetrical residual stresses in solid rounds using X-ray diffraction method. For the non-symmetrical residual stresses arising from cold-straightening, the equation developed by Nitta and Thurlimann was adopted in the finite element modeling to study the effect of non-symmetrical residual stresses on the compressive resistance of solid round steel columns. The Finite Element Analysis has been conducted on different bar diameter (1.5 inch to 12 inch diameter) and length, as well as initial out-of-straightness.

The study of the elastic deformation of a flexible wheel by a cam wave generator

2020 ◽  
Vol 65 (1) ◽  
pp. 51-58
Author(s):  
Sava Ianici
Keyword(s):  
Numerical Simulation ◽  
Finite Element Method ◽  
Finite Element ◽  
Elastic Deformation ◽  
Theoretical Study ◽  
Elastic Field ◽  
The Finite Element Method ◽  
Elastic Deformations ◽  
Wave Generator ◽  
Two Stages

The paper presents the results of research on the study of the elastic deformation of a flexible wheel from a double harmonic transmission, under the action of a cam wave generator. Knowing exactly how the flexible wheel is deformed is important in correctly establishing the geometric parameters of the wheels teeth, allowing a better understanding and appreciation of the specific conditions of harmonic gearings in the two stages of the transmission. The veracity of the results of this theoretical study on the calculation of elastic deformations and displacements of points located on the average fiber of the flexible wheel was subsequently verified and confirmed by numerical simulation of the flexible wheel, in the elastic field, using the finite element method from SolidWorks Simulation.

PENGEMBANGAN SKALA LOCUS OF CONTROL

2017 ◽  
Vol 2 (3) ◽  
pp. 417-424
Author(s):  
Hendryadi Hendryadi
Keyword(s):  
Locus Of Control ◽  
Internal Consistency ◽  
Convergent Validity ◽  
Discriminant Validity ◽  
Short Form ◽  
Employee Selection ◽  
Future Research ◽  
Validity And Reliability ◽  
Control Scale ◽  
Two Stages

This article aims to develop a short form of the locus of control scale. The study was conducted in two stages: a study of 66 respondents as pilot testing which aims to test content validity, structure validity, and internal consistency. Study 2 was conducted on 328 respondents used to test the validity and reliability of the scale evaluated by the PLS-SEM method (such as internal consistency, convergent validity, and discriminant validity). The analysis concludes that the 8-item locus of control scales tested have adequate validity and reliability. A short form locus of control scale was developed and validated in this study, so it can be used in future research and evaluation for HR management practitioners in employee selection Keywords: locus of control, EFA, CFA, scale construction

Recent Advances on the Semi-Supervised Learning for Long Non-Coding RNA-Protein Interactions Prediction: A Review

2020 ◽  
Vol 27 (5) ◽  
pp. 385-391
Author(s):  
Lin Zhong ◽  
Zhong Ming ◽  
Guobo Xie ◽  
Chunlong Fan ◽  
Xue Piao
Keyword(s):  
Supervised Learning ◽  
Protein Interactions ◽  
Computational Models ◽  
Prediction Models ◽  
Chromatin Modification ◽  
Computational Prediction ◽  
Human Diseases ◽  
Future Research ◽  
Non Coding Rna ◽  
Long Non Coding Rna

: In recent years, more and more evidence indicates that long non-coding RNA (lncRNA) plays a significant role in the development of complex biological processes, especially in RNA progressing, chromatin modification, and cell differentiation, as well as many other processes. Surprisingly, lncRNA has an inseparable relationship with human diseases such as cancer. Therefore, only by knowing more about the function of lncRNA can we better solve the problems of human diseases. However, lncRNAs need to bind to proteins to perform their biomedical functions. So we can reveal the lncRNA function by studying the relationship between lncRNA and protein. But due to the limitations of traditional experiments, researchers often use computational prediction models to predict lncRNA protein interactions. In this review, we summarize several computational models of the lncRNA protein interactions prediction base on semi-supervised learning during the past two years, and introduce their advantages and shortcomings briefly. Finally, the future research directions of lncRNA protein interaction prediction are pointed out.

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