Investigating the local deformation and transformation behavior of sintered X3CrMnNi16-7-6 TRIP steel using a calibrated crystal plasticity-based numerical simulation model

2020 ◽  
Vol 111 (5) ◽  
pp. 392-404
Author(s):  
Faisal Qayyum ◽  
Sergey Guk ◽  
Stefan Prüger ◽  
Matthias Schmidtchen ◽  
Ivan Saenko ◽  
...  
Keyword(s):  
Trip Steel ◽  
Material Model ◽  
Local Deformation ◽  
Physical Parameters ◽  
Dislocation Glide ◽  
Material Optimization ◽  
Compressive Loads ◽  
Static Tensile ◽  
Dislocation Pinning ◽  
Transformation Stress

Abstract In this study, DAMASK was used to model and elucidate the microstructural deformation behavior of sintered X3CrMnNi16-7-6 TRIP steel. The recently developed TRIP-TWIP material model was used within the DAMASK framework. Material optimization was performed using the least computationally expensive method, which yielded the desired results. The physical parameters of the material model were identified and tuned to fit the experimental observations. This tuned material model was used to run simulations utilizing 2D EBSD data. The local deformation, transformation, and twinning behaviors of the material under quasi-static tensile and compressive loads were analyzed. The results of this are in good agreement with previous experimental observations. The phenomena of dislocation glide, twinning, martensitic transformation, stress evolution, and dislocation pinning in different deformation stages are discussed.

scholarly journals Modeling the Local Deformation and Transformation Behavior of Cast X8CrMnNi16-6-6 TRIP Steel and 10% Mg-PSZ Composite Using a Continuum Mechanics-Based Crystal Plasticity Model

Crystals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 221 ◽  
Author(s):  
Faisal Qayyum ◽  
Sergey Guk ◽  
Matthias Schmidtchen ◽  
Rudolf Kawalla ◽  
Ulrich Prahl
Keyword(s):  
Acoustic Emission ◽  
Trip Steel ◽  
Electron Backscatter Diffraction ◽  
Tensile Load ◽  
Slight Modification ◽  
Material Model ◽  
Local Deformation ◽  
Steel Matrix ◽  
Emission Data ◽  
Dislocation Glide

A Transformation-Induced Plasticity (TRIP) steel matrix reinforced with magnesium-partially stabilized zirconia (Mg-PSZ) particles depicts a superior energy absorbing capacity during deformation. In this research, the TRIP/TWIP material model already developed in the framework of the Düsseldorf Advanced Material Simulation Kit (DAMASK) is tuned for X8CrMnNi16-6-6 TRIP steel and 10% Mg-PSZ composite. A new method is explained to more accurately tune this material model by comparing the stress/strain, transformation, twinning, and dislocation glide obtained from simulations with respective experimental acoustic emission measurements. The optimized model with slight modification is assigned to the steel matrix in 10% Mg-PSZ composite material. In the simulation model, zirconia particles are assigned elastic properties with a perfect ceramic/matrix interface. Local deformation, transformation, and the twinning behavior of the steel matrix due to quasi-static tensile load were analyzed. The comparison of the simulation results with acoustic emission data shows good correlation and helps correlate acoustic events with physical attributes. The tuned material models are used to run full phase simulations using 2D Electron Backscatter Diffraction (EBSD) data from steel and 10% Mg-PSZ zirconia composites. Form these simulations, dislocation glide, martensitic transformation, stress evolution, and dislocation pinning in different stages of deformation are qualitatively discussed for the steel matrix and ceramic inclusions.

Iceberg Shape Sensitivity in Ship Impact Assessment in View of Existing Material Models

2012 ◽  
Author(s):  
Martin Storheim ◽  
Ekaterina Kim ◽  
Jørgen Amdahl ◽  
Sören Ehlers
Keyword(s):  
Numerical Models ◽  
Significant Risk ◽  
Arctic Region ◽  
Material Model ◽  
High Energy ◽  
Structural Deformation ◽  
The Arctic ◽  
Physical Parameters ◽  
Material Models ◽  
The Arctic Region

Large natural resources in the Arctic region will in the coming years require significant shipping activity within and through the Arctic region. When operating in Arctic open water, there is a significant risk of high-energy encounters with smaller ice masses like bergy bits and growlers. Consequently, there is a need to assess the structural response to high energy encounters in ice-infested waters. Experimental data of high energy ice impact are scarce, and numerical models could be used as a tool to provide insight into the possible physical processes and to their structural implications. This paper focuses on impact with small icebergs and bergy bits. In order to rely on the numerical results, it is necessary to have a good understanding of the physical parameters describing the iceberg interaction. Icebergs are in general inhomogeneous with properties dependent among other on temperature, grain size, strain rate, shape and imperfections. Ice crushing is a complicated process involving fracture, melting, high confinement and high pressures. This necessitates significant simplifications in the material modeling. For engineering purposes a representative load model is applied rather than a physically correct ice material model. The local shape dependency of iceberg interaction is investigated by existing representative load material models. For blunt objects and moderate deformations the models agree well, and show a similar range of energy vs. hull deformation. For sharper objects the material models disagree quite strongly. The material model from Liu et.al (2011) crush the ice easily, whereas the models from Gagnon (2007) and Gagnon (2011) both penetrate the hull. From a physical perspective, a sharp ice edge should crush initially until sufficient force is mobilized to deform the vessel hull. Which ice features that will crush or penetrate is important to know in order to efficiently design against iceberg impact. Further work is needed to assess the energy dissipation in ice during crushing, especially for sharp features. This will enable the material models to be calibrated towards an energy criterion, and yield more coherent results. At the moment it is difficult to conclude if any of the ice models behave in a physically acceptable manner based on the structural deformation. Consequently, it is premature to conclude in a design situation as to which local ice shapes are important to design against.

A thermomechanically coupled material model for TRIP-steel

2014 ◽  
Vol 55 ◽  
pp. 182-197 ◽  
Author(s):  
S. Prüger ◽  
A. Seupel ◽  
M. Kuna
Keyword(s):  
Trip Steel ◽  
Material Model

scholarly journals Universal poroelastic mechanism for hydraulic signals in biomimetic and natural branches

2017 ◽  
Vol 114 (42) ◽  
pp. 11034-11039 ◽  
Author(s):  
J.-F. Louf ◽  
G. Guéna ◽  
E. Badel ◽  
Y. Forterre
Keyword(s):  
Growth Response ◽  
Pressure Pulse ◽  
Vascular System ◽  
Water Pressure ◽  
Local Deformation ◽  
Physical Parameters ◽  
Hydromechanical Coupling ◽  
Long Distance ◽  
Whole Plant ◽  
Basic Features

Plants constantly undergo external mechanical loads such as wind or touch and respond to these stimuli by acclimating their growth processes. A fascinating feature of this mechanical-induced growth response is that it can occur rapidly and at long distance from the initial site of stimulation, suggesting the existence of a fast signal that propagates across the whole plant. The nature and origin of the signal is still not understood, but it has been recently suggested that it could be purely mechanical and originate from the coupling between the local deformation of the tissues (bending) and the water pressure in the plant vascular system. Here, we address the physical origin of this hydromechanical coupling using a biomimetic strategy. We designed soft artificial branches perforated with longitudinal liquid-filled channels that mimic the basic features of natural stems and branches. In response to bending, a strong overpressure is generated in the channels that varies quadratically with the bending curvature. A model based on a mechanism analogous to the ovalization of hollow tubes enables us to predict quantitatively this nonlinear poroelastic response and identify the key physical parameters that control the generation of the pressure pulse. Further experiments conducted on natural tree branches reveal the same phenomenology. Once rescaled by the model prediction, both the biomimetic and natural branches fall on the same master curve, enlightening the universality of our poroelastic mechanism for the generation of hydraulic signals in plants.

scholarly journals Две стадии формирования повреждения при ударном воздействии на поликристаллические соединения ZnS и ZnSe

2018 ◽  
Vol 60 (4) ◽  
pp. 760
Author(s):  
И.П. Щербаков ◽  
А.А. Дунаев ◽  
А.Е. Чмель
Keyword(s):  
Crack Nucleation ◽  
Synthesis Method ◽  
Barrier Properties ◽  
Interatomic Bond ◽  
Dislocation Motion ◽  
Local Deformation ◽  
Boundary Structure ◽  
Bond Rupture ◽  
Dislocation Glide ◽  
Excitation Mechanisms

AbstractMechanoluminescence (ML) in ductile solids is caused by the motion of charged dislocations in the deformable material. Interatomic bond ruptures followed by electronic structure reconfiguration are the main source of ML in brittle bodies. We studied ML in ceramics composed of mixed ionic/covalent ZnS and ZnSe compounds, which are generated during impact loading higher than the limit deformation. Depending on synthesis method and thermal treatment, the resulting ceramics had different size and geometry of grains and intergrain boundary structure, which presumably may have a significant effect on the dislocation glide. In both materials, the time sweeps of ML pulses have two well-resolved peaks. The position of the peaks along the time axis is substantially dependent on the size of ceramic-forming grains and, to a smaller extent, on the barrier properties of intergrain boundaries. The first peak is associated with plastic deformation preceding disintegration of the crystal structure. The second peak emerges upon crack nucleation as interatomic bonds are ruptured and the material is undergoing local deformation in tips of propagating cracks. The distributions of ML pulse amplitudes (the dependences between the number of pulses and their amplitude) calculated for both peaks individually follow the power law, which demonstrates that the electronic processes having different excitation mechanisms (dislocation motion vs bond rupture) are correlated.

Ultimate and Crushing Strength of Plated Structures

1995 ◽  
Vol 39 (03) ◽  
pp. 250-261 ◽  
Author(s):  
Jeom Kee Paik ◽  
P. Terndrup Pedersen
Keyword(s):  
Rate Sensitivity ◽  
Material Model ◽  
Dynamic Loads ◽  
Elastic Model ◽  
Dynamic Effects ◽  
Rigid Plastic ◽  
Compressive Loads ◽  
Collapse Behavior ◽  
Theoretical Results ◽  
Mathematical Process

An efficient theoretical approach is developed which calculates in the same mathematical process the pre-and post-collapse behavior in addition to the deep-collapse response of plated structures under static/ dynamic compressive loads. In the analysis of complex plated structures, each plate element composing the structure is modeled as one plate unit. Two principal models, one elastic model for analysis of the ultimate strength and the other rigid-plastic model for analysis of the crushing load, for the plate unit subjected to static/dynamic loads are derived theoretically. The models are basically formulated as a quasi-static loading condition, but dynamic effects are included by taking into account the influence of strain rate sensitivity in the material model. The procedure is verified by a comparison of experimental and other theoretical results.

Simulation of an Armoured Vehicle for Blast Loading

2017 ◽  
Vol 67 (4) ◽  
pp. 449 ◽  
Author(s):  
Sanjit Mahajan ◽  
R. Muralidharan
Keyword(s):  
Finite Element ◽  
Numerical Methods ◽  
Time History ◽  
Material Model ◽  
Element Model ◽  
Local Deformation ◽  
Comparison Results ◽  
History Of ◽  
Areas Of Interest ◽  
Improvised Explosive

Occupant safety in an armoured vehicle is of paramount importance. Most serious threat to armoured vehicles comes in the form of explosion of buried charge or an improvised explosive device. The use of numerical methods in the validation process of light armoured vehicles reduces the number of prototypes required and decreases the design time. This paper elucidates the process by which one such validation using numerical methods was done. The process of finite element method used for simulation of blast is a prominent method of numerical method of simulation. The finite element model (FEM) process starts with discretisation. By discretisation or meshing, Shell (Quad/Tria) and solid (Tetra/Hexa) elements are generated. The FEM thus created is provided with relevant material model / properties and loading and boundary conditions. The loading conditions are adopted from STANAG 4569 Level II standards. Local deformation, global displacement, stresses and time history of displacement of particular areas of interest are obtained as results. Comparison results include the effect of with and without thermal softening under blast. Based on the results and comparison, suggestions regarding re-engineering the vehicle are presented.

scholarly journals Self-repairing of polymer-cement concrete

2013 ◽  
Vol 61 (1) ◽  
pp. 195-200 ◽  
Author(s):  
P. Łukowski ◽  
G. Adamczewski
Keyword(s):  
Epoxy Resin ◽  
Building Materials ◽  
Cement Composite ◽  
Material Model ◽  
The Self ◽  
Cement Composites ◽  
Cement Concrete ◽  
Material Optimization ◽  
The Subject ◽  
Self Repair

Abstract Self-repairing means ability to the total or partial recovering of the properties which were worsened as a consequence of damage of the material. The subject of the paper is evaluation of ability to self-repair of a cement composite modified with epoxy resin without a hardener. The methodology of investigation of self-repairing building materials, developed by the authors, has been described, with controllable enforcing of the limited weakening of the material. Also, the self-repair degree has been defined as the measure of self-repairing ability of the building composites. The material model of the epoxy-cement composite has been developed on the basis of the tests results. The material optimization of the composite towards the maximum self-repairing ability has also been carried out. The results of investigation have confirmed the possibility of self-repairing of the cement composite modified with the epoxy resin without hardener. The conclusion and further research needs in the range of the self-repairing epoxy-cement composites have been pointed out

scholarly journals A population-specific material model for sagittal craniosynostosis to predict surgical shape outcomes

2019 ◽  
Vol 19 (4) ◽  
pp. 1319-1329 ◽  
Author(s):  
Alessandro Borghi ◽  
Naiara Rodriguez Florez ◽  
Federica Ruggiero ◽  
Greg James ◽  
Justine O’Hara ◽  
...  
Keyword(s):  
Relaxation Modulus ◽  
Population Data ◽  
Material Model ◽  
Sagittal Craniosynostosis ◽  
Material Optimization ◽  
Model Predictions ◽  
Specific Material ◽  
3D Scans ◽  
Tomography Data

Abstract Sagittal craniosynostosis consists of premature fusion (ossification) of the sagittal suture during infancy, resulting in head deformity and brain growth restriction. Spring-assisted cranioplasty (SAC) entails skull incisions to free the fused suture and insertion of two springs (metallic distractors) to promote cranial reshaping. Although safe and effective, SAC outcomes remain uncertain. We aimed hereby to obtain and validate a skull material model for SAC outcome prediction. Computed tomography data relative to 18 patients were processed to simulate surgical cuts and spring location. A rescaling model for age matching was created using retrospective data and validated. Design of experiments was used to assess the effect of different material property parameters on the model output. Subsequent material optimization—using retrospective clinical spring measurements—was performed for nine patients. A population-derived material model was obtained and applied to the whole population. Results showed that bone Young’s modulus and relaxation modulus had the largest effect on the model predictions: the use of the population-derived material model had a negligible effect on improving the prediction of on-table opening while significantly improved the prediction of spring kinematics at follow-up. The model was validated using on-table 3D scans for nine patients: the predicted head shape approximated within 2 mm the 3D scan model in 80% of the surface points, in 8 out of 9 patients. The accuracy and reliability of the developed computational model of SAC were increased using population data: this tool is now ready for prospective clinical application.

The Analysis of Stress States in Steel Rods Surfaced by Welding

2013 ◽  
Vol 58 (4) ◽  
pp. 1243-1252 ◽  
Author(s):  
J. Winczek
Keyword(s):  
Phase Transformations ◽  
Experimental Tests ◽  
Material Model ◽  
Welding Parameters ◽  
Stress Equilibrium ◽  
Thermal Fields ◽  
Austenitic Transformation ◽  
Heating And Cooling ◽  
Stress States ◽  
Transformation Stress

Abstract In work is presented a method of calculating elasto-plastic states in thermally loaded rods, which takes into account phase transformations that occur during surfacing by welding. Kinetics of phase transformations during heating and cooling is limited by temperature values at the beginning and at the end of austenitic transformation, while the progress of phase transformations during cooling is determined on the basis of TTT-welding diagram, basing on Johnson-Mehl-Avrami-Kolomogorov law for diffusional transformations and Koistinen-Marburger for martensitic transformation. Stress state of a bar subjected to thermo-mechanical loads is described assuming the planar cross section hypothesis and using integral equations of stress equilibrium of a bar as well as simple Hook’s law. Dependence of stresses from strains is assumed on the basis of tensile curves of particular structures, taking into account the influence of temperature. Computations of strains and stresses are investigated in a rod made of S235 steel, loaded by thermal fields generated by a point welding heat source of different intensities. The analysis of origination and development of plastic strains is carried out. In order to verify correctness of the model, experimental tests are carried out on a rod made of S235 steel surfaced with GMA method with geometry and welding parameters assumed in numerical simulations. Residual stresses, calculated taking into account phase transformations and for homogenous material model, are compared with experimental results.

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