scholarly journals Numerical Simulations of Ductile Fracture in Steel Angle Tension Members Connected with Bolts

2020 ◽  
Vol 30 (2) ◽  
pp. 32-54
Author(s):  
Edyta Bernatowska
Keyword(s):  
Ductile Fracture ◽  
Numerical Models ◽  
Fracture Initiation ◽  
Material Model ◽  
Experimental Investigations ◽  
Gusset Plates ◽  
Single Plate ◽  
Steel Angle ◽  
Parametric Studies ◽  
Tension Members

AbstractThe aim of the paper is to verify and present methodology for ultimate tensile resistance prediction in steel angle tension members connected to gusset plates with one row of bolts. After a description of the experimental investigations, the next step was to build numerical models. The subjects of the experiments consisted of single plate specimens with drilled holes and angles connected to gusset plates with 1, 2, 3, or 4 bolts. Close attention was given to choosing the appropriate material model, which takes into account the influence of microstructural damage and the process of ductile fracture initiation and propagation. The porous Gurson-Tvergaard-Needleman material model was analysed and the paper focuses on hierarchical validation of numerical models of steel angle bolted connections, which will then be used for parametric studies.

Numerical Analysis of the Influence of the Parameter of Ductility of Reinforcing Steel on the Behaviour of Narrow Three-Span Reinforced Concrete Slabs from the Point of View of Experimental Investigations

2015 ◽  
Vol 769 ◽  
pp. 133-138
Author(s):  
Mirosław Wieczorek
Keyword(s):  
Reinforced Concrete ◽  
Numerical Analysis ◽  
Laboratory Tests ◽  
Numerical Models ◽  
Material Model ◽  
Point Of View ◽  
Experimental Investigations ◽  
Concrete Slabs ◽  
Building Structures ◽  
Reinforced Concrete Slabs

In the time of exploitation of building structures frequently situations do occur, in which due to failures they are exposed to much higher loads than originally predicted. The subject matter of the performed investigations and a numerical analysis are models of four narrow reinforced concrete slabs with the dimensions 7140×500×190 mm. The paper presents the results of the numerical analysis, the aim of which was to reflect and to provide detailed information about phenomena occurring in the course of laboratory tests. Numerical models were constructed according to the system ANSYS, applying volumetric elements SOLID65 and bars LINK8. In order to determine the relation σ-ε of steel an isotropic model of strengthening in the system ANSYS was used, constructed by Misses. The behaviour of concrete was represented by the material model Concrete. The parameters applied in the material models had been obtained in laboratory tests of the material. The paper quotes the results of calculations compared with the results obtained in laboratory tests.

scholarly journals Behavior of Beam-to-Column Connections with Angles. Part 2-Numerical Analysis

2016 ◽  
Vol 6 (1) ◽  
pp. 35-40
Author(s):  
M. Ghindea ◽  
A. Cătărig ◽  
R. Ballok
Keyword(s):  
Numerical Simulations ◽  
Deformation Process ◽  
High Speed ◽  
Rotation Curve ◽  
Numerical Models ◽  
Experimental Tests ◽  
3D Models ◽  
Experimental Investigations ◽  
Software Packages ◽  
Parametric Studies

Abstract Based on the results of experimental tests, presented in the first part of this paper, Part 1-Experimental Investigations (Ghindea M., Catarig A., Ballok R.) advanced numerical simulations were performed using FEM based software Abaqus. The recently arise of high speed computers and advanced FEM software packages allow to create and solve extensively detailed 3D models. The aim of this second part of the paper is to develop accurate FEM models for better approach of the studied beam-to-column connections. The paper presents the designed numerical models and the results for four bolted beam-to-column connections using top-and-seat and/or web angle cleats, in different configurations. The objective of this paper is to achieve functional numerical models which, by faithfully running, reproduce the experimental results. Thus, calibrating the numerical results with the experimental ones it can be perform then parametric studies, achieving reliable results for similar configurations of joints. The results obtained after numerical simulations were compared with experimental data. The behavior moment-rotation curve and the deformation process of the experimental captured specimens were virtually reproduced with minimum deviation.

Numerical Analysis of the Influence of the Parameter of Ductility of Reinforcing Steel on the Behaviour of Single-Span Reinforced Concrete Beams from the Viewpoint of Experimental Investigations

2015 ◽  
Vol 769 ◽  
pp. 139-144
Author(s):  
Mirosław Wieczorek
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Numerical Models ◽  
Material Model ◽  
Reinforced Concrete Beams ◽  
Experimental Investigations ◽  
Isotropic Model ◽  
Material Models ◽  
Laboratory Investigations ◽  
Brittle Destruction

One of the fundamental elements applied in reinforced concrete structures are beams. Depending on the proportion of the dimensions and the way of imposing the load, two fundamental mechanisms of destruction are to be distinguished (brittle destruction caused by shearing the supporting zones or flexural destruction in the zone of the span). The present paper provides the results of the analysis of four reinforced concrete beams with the dimensions 4000×400×200 mm, reinforced with steel of varying ductility. The aim of this analysis was to reflect and to provide more detailed information about the phenomena observed in the course of laboratory investigations. The numerical models were constructed in compliance with the system ANSYS, applying volumetric elements Solid 65 and bars Link 8. In order to determine the relation σ-ε of the steel an isotropic model of strengthening according to Misses was implemented in the system ANSYS. The behaviour of concrete was represented making use of the material model Concrete. The parameters applied in the material models were obtained basing on laboratory tests of materials. The results of calculations have been quoted in the paper, as well as their comparison with the results of investigations carried out in the laboratory.

scholarly journals Net section fracture assessment of steel bolted joints with shear lag effect

2019 ◽  
Vol 262 ◽  
pp. 09002
Author(s):  
Edyta Bernatowska ◽  
Lucjan Ślęczka
Keyword(s):  
Cross Section ◽  
Computational Models ◽  
Load Capacity ◽  
Steel Structures ◽  
Bolted Joints ◽  
Experimental Investigations ◽  
Fastener Hole ◽  
Steel Angle ◽  
Fracture Assessment ◽  
Tension Members

Bolted connections are willingly used in steel structures because of their easiness of fabrication and assembly, but often they are the weakest component in the construction. In case of tensile lap connections, fracture of net cross section usually determines a joint capacity. Additionally, possible eccentricities can affect the distribution of stresses in the cross section and hence its load capacity. Analysis of fracture is a completely different issue compared to well-known and established problems of stability or plastic resistance. Paper relates to steel angle tension members connected by one bolt. It starts from the description of experimental investigations which results were used for hierarchical validation of computational models. Choice between two types of material models (elastic-plastic and Gurson–Tvergaard–Needleman) and building of FE models, representing different degrees of complexity, were described. Paper ends with parametric study taking into account influence of the edge distance from the centre of a fastener hole to the adjacent edge of angle. The paper’s aim is to verify and present the methodology for fracture prediction in steel angle tension members, which can be next extended for bolted joints with larger number of bolts and different geometrical configurations.

scholarly journals An Efficient Approach for Identifying Constitutive Parameters of the Modified Oyane Ductile Fracture Criterion at High Temperature

2013 ◽  
Vol 2013 ◽  
pp. 1-4 ◽  
Author(s):  
Sergei Alexandrov ◽  
Yusof Mustafa ◽  
Mohd Yazid Yahya
Keyword(s):  
High Temperature ◽  
Ductile Fracture ◽  
Computational Models ◽  
Fracture Criterion ◽  
Fracture Initiation ◽  
Material Model ◽  
Material Behavior ◽  
Ductile Fracture Criterion ◽  
Path Dependent ◽  
Constitutive Parameters

The paper presents the theoretical part of a method for identifying constitutive parameters involved in the modified Oyane ductile fracture criterion at high temperature. Quite a general rigid viscoplastic model is adopted to describe material behavior. The ductile fracture criterion is in general path-dependent and involves stresses. Therefore, the identification of constitutive parameters of this criterion is a difficult task which usually includes experimental research and numerical simulation. The latter requires a precisely specified material model and boundary conditions. It is shown in the present paper that for a wide class of material models usually used to describe the behavior of materials at high temperatures, the criterion is significantly simplified when the site of fracture initiation is located on traction free surfaces. In particular, this reduced criterion does not involve stresses. Since there are well established experimental procedures to determine the input data for the reduced criterion, the result obtained can be considered as a theoretical basis for the efficient method for identifying constitutive parameters of the modified Oyane ductile fracture criterion at high temperature. The final expression can also be used in computational models to increase the accuracy of predictions.

scholarly journals A Computational Approach to Solve a System of Transcendental Equations with Multi-Functions and Multi-Variables

Mathematics ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 920
Author(s):  
Chukwuma Ogbonnaya ◽  
Chamil Abeykoon ◽  
Adel Nasser ◽  
Ali Turan
Keyword(s):  
Numerical Models ◽  
Problem Formulation ◽  
Science And Engineering ◽  
Physical Systems ◽  
Engineering Problems ◽  
Parametric Studies ◽  
Independent Variable ◽  
Transcendental Equations ◽  
The Waves ◽  
Modelling Approach

A system of transcendental equations (SoTE) is a set of simultaneous equations containing at least a transcendental function. Solutions involving transcendental equations are often problematic, particularly in the form of a system of equations. This challenge has limited the number of equations, with inter-related multi-functions and multi-variables, often included in the mathematical modelling of physical systems during problem formulation. Here, we presented detailed steps for using a code-based modelling approach for solving SoTEs that may be encountered in science and engineering problems. A SoTE comprising six functions, including Sine-Gordon wave functions, was used to illustrate the steps. Parametric studies were performed to visualize how a change in the variables affected the superposition of the waves as the independent variable varies from x1 = 1:0.0005:100 to x1 = 1:5:100. The application of the proposed approach in modelling and simulation of photovoltaic and thermophotovoltaic systems were also highlighted. Overall, solutions to SoTEs present new opportunities for including more functions and variables in numerical models of systems, which will ultimately lead to a more robust representation of physical systems.

scholarly journals Prediction of Ductile Fracture in Metal Blanking

1999 ◽  
Vol 122 (3) ◽  
pp. 476-483 ◽  
Author(s):  
A. M. Goijaerts ◽  
L. E. Govaert ◽  
F. P. T. Baaijens
Keyword(s):  
Finite Element ◽  
Tensile Test ◽  
Ductile Fracture ◽  
Experimental Error ◽  
Fracture Initiation ◽  
Fracture Model ◽  
Ductile Fracture Model ◽  
Blanking Process ◽  
Ductile Fracture Initiation

This study is focused on the description of ductile fracture initiation, which is needed to predict product shapes in the blanking process. Two approaches are elaborated using a local ductile fracture model. According to literature, characterization of such a model should take place under loading conditions, comparable to the application. Therefore, the first approach incorporates the characterization of a ductile fracture model in a blanking experiment. The second approach is more favorable for industry. In this approach a tensile test is used to characterize the fracture model, instead of a complex and elaborate blanking experiment. Finite element simulations and blanking experiments are performed for five different clearances to validate both approaches. In conclusion it can be stated that for the investigated material, the first approach gives very good results within the experimental error. The second approach, the more favorable one for industry, yields results within 6 percent of the experiments over a wide, industrial range of clearances, when a newly proposed criterion is used. [S1087-1357(00)02202-4]

scholarly journals Considering multiple process observables to determine material model parameters for FE-cutting simulations

2021 ◽  
Author(s):  
Marvin Hardt ◽  
Thomas Bergs
Keyword(s):  
Chip Thickness ◽  
Material Model ◽  
Experimental Investigations ◽  
Model Parameters ◽  
Inverse Approach ◽  
Local Material ◽  
Novel Approach ◽  
Validation Parameters ◽  
Multiple Process ◽  
Cutting Simulations

AbstractAnalyzing the chip formation process by means of the finite element method (FEM) is an established procedure to understand the cutting process. For a realistic simulation, different input models are required, among which the material model is crucial. To determine the underlying material model parameters, inverse methods have found an increasing acceptance within the last decade. The calculated model parameters exhibit good validity within the domain of investigation, but suffer from their non-uniqueness. To overcome the drawback of the non-uniqueness, the literature suggests either to enlarge the domain of experimental investigations or to use more process observables as validation parameters. This paper presents a novel approach merging both suggestions: a fully automatized procedure in conjunction with the use of multiple process observables is utilized to investigate the non-uniqueness of material model parameters for the domain of cutting simulations. The underlying approach is two-fold: Firstly, the accuracy of the evaluated process observables from FE simulations is enhanced by establishing an automatized routine. Secondly, the number of process observables that are considered in the inverse approach is increased. For this purpose, the cutting force, cutting normal force, chip temperature, chip thickness, and chip radius are taken into account. It was shown that multiple parameter sets of the material model can result in almost identical simulation results in terms of the simulated process observables and the local material loads.

Leakage Flow Investigations on a Through-Wall Crack Related to Thermal Fatigue of Nuclear Power Plant Piping

2017 ◽  
Author(s):  
Stefan Schmid ◽  
Rudi Kulenovic ◽  
Eckart Laurien
Keyword(s):  
Experimental Data ◽  
Nuclear Power ◽  
Numerical Models ◽  
Measurement Techniques ◽  
Experimental Investigations ◽  
Leakage Flow ◽  
Test Rig ◽  
Reduced Pressure ◽  
Flow Rates ◽  
Set Up

For the validation of empirical models to calculate leakage flow rates in through-wall cracks of piping, reliable experimental data are essential. In this context, the Leakage Flow (LF) test rig was built up at the IKE for measurements of leakage flow rates with reduced pressure (maximum 1 MPA) and temperature (maximum 170 °C) compared to real plant conditions. The design of the test rig enables experimental investigations of through-wall cracks with different geometries and orientations by means of circular blank sheets with integrated cracks which are installed in the tubular test section of the test rig. In the paper, the experimental LF set-up and used measurement techniques are explained in detail. Furthermore, first leakage flow measurement results for one through-wall crack geometry and different imposed fluid pressures at ambient temperature conditions are presented and discussed. As an additional aspect the experimental data are used for the determination of the flow resistance of the investigated leak channel. Finally, the experimental results are compared with numerical results of WinLeck calculations to prove specifically in WinLeck implemented numerical models.

Influence of Phase Transformations on Residual Stresses in Welded Structures

2013 ◽  
Author(s):  
R. J. Dennis ◽  
R. Kulka ◽  
O. Muransky ◽  
M. C. Smith
Keyword(s):  
Phase Transformation ◽  
Residual Stresses ◽  
Phase Transformations ◽  
Numerical Models ◽  
Material Model ◽  
Transformation Model ◽  
Austenitic Steels ◽  
Beam Specimen ◽  
Welded Structures ◽  
The Impact

A key aspect of any numerical simulation to predict welding induced residual stresses is the development and application of an appropriate material model. Often significant effort is expended characterising the thermal, physical and hardening properties including complex phenomena such as high temperature annealing. Consideration of these aspects is sufficient to produce a realistic prediction for austenitic steels, however ferritic steels are susceptible to solid state phase transformations when heated to high temperatures. On cooling a reverse transformation occurs, with an associated volume change at the isothermal transformation temperature. Although numerical models exist (e.g. Leblond) to predict the evolution of the metallurgical phases, accounting for volumetric changes, it remains a matter of debate as to the magnitude of the impact of phase transformations on residual stresses. Often phase transformations are neglected entirely. In this work a simple phase transformation model is applied to a range of welded structures with the specific aim of assessing the impact, or otherwise, of phase transformations on the magnitude and distribution of predicted residual stresses. The welded structures considered account for a range of geometries from a simple ferritic beam specimen to a thick section multi-pass weld. The outcome of this work is an improved understanding of the role of phase transformation on residual stresses and an appreciation of the circumstances in which it should be considered.

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