Modelling of superplastic deformation for metallic alloys using a cavity based approach

2017 ◽  
Vol 2 (81) ◽  
pp. 61-69
Author(s):  
M. Hedayati Marzbali
Keyword(s):  
Superplastic Deformation ◽  
Hydrostatic Stress ◽  
Deformation Characteristic ◽  
Failure Criteria ◽  
Time Algorithm ◽  
Metallic Alloys ◽  
Finite Element Software ◽  
Pressure Time ◽  
Failure Predictions ◽  
Aluminum 5083

Purpose: In this study, modeling of superplastic deformation characteristic for metallic alloys was investigated using GTN failure criteria in viscoplastic framework. Design/methodology/approach: The proposed model studied the simultaneous effects of cavitation and deformation parameter and considered the effects of strain hardening, static and dynamic recoveries, and hydrostatic stress. This cavity based model was then implemented in a creep subroutine in ABAQUS 6.12 finite element software. Findings: Experimental results of Aluminum 5083 from different studies were used to verify the model and evaluate its reliability. Afterwards, numerical simulations for uniaxial tension were performed, and good agreement between experimental and modeling results was obtained. Research limitations/implications: This study showed that using a viscoplastic framework with a cavity criterion ensures more precise pressure-time algorithm, lower deformation time and better failure predictions. These capabilities provides forming more complex parts and different geometries. Accordingly, applying this model is recommended to predict the behaviour of other metallic superplastic alloys.

Transient Analysis of a Ceramic High Temperature Heat Exchanger and Chemical Decomposer

2007 ◽  
Author(s):  
Valery Ponyavin ◽  
Taha Mohamed ◽  
Mohamed Trabia ◽  
Yitung Chen ◽  
Anthony E. Hechanova
Keyword(s):  
Steady State ◽  
High Temperature ◽  
Heat Exchanger ◽  
Thermal Stresses ◽  
Three Dimensional ◽  
Failure Criteria ◽  
Operating Conditions ◽  
Finite Element Software ◽  
Micro Channels ◽  
Temperature Heat

Ceramics are suitable for use in high temperature applications as well as corrosive environment. These characteristics were the reason behind selection silicone carbide for a high temperature heat exchanger and chemical decomposer, which is a part of the Sulphur-Iodine (SI) thermo-chemical cycle. The heat exchanger is expected to operate in the range of 950°C. The proposed design is manufactured using fused ceramic layers that allow creation of micro-channels with dimensions below one millimeter. A proper design of the heat exchanges requires considering possibilities of failure due to stresses under both steady state and transient conditions. Temperature gradients within the heat exchanger ceramic components induce thermal stresses that dominate other stresses. A three-dimensional computational model is developed to investigate the fluid flow, heat transfer and stresses in the decomposer. Temperature distribution in the solid is imported to finite element software and used with pressure loads for stress analysis. The stress results are used to calculate probability of failure based on Weibull failure criteria. Earlier analysis showed that stress results at steady state operating conditions are satisfactory. The focus of this paper is to consider stresses that are induced during transient scenarios. In particular, the cases of startup and shutdown of the heat exchanger are considered. The paper presents an evaluation of the stresses in these two cases.

Finite Element Analysis of X-Cor Sandwich's Compressive Strength

2011 ◽  
Vol 306-307 ◽  
pp. 733-737
Author(s):  
Xu Dan Dang ◽  
Xin Li Wang ◽  
Hong Song Zhang ◽  
Jun Xiao
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Compressive Strength ◽  
Failure Modes ◽  
Failure Mechanisms ◽  
Element Model ◽  
Failure Criteria ◽  
Stiffness Degradation ◽  
Element Analysis ◽  
Finite Element Software

In this article the finite element software was used to analyse the values for compressive strength of X-cor sandwich. During the analysis, the failure criteria and materials stiffness degradation rules of failure mechanisms were proposed. The failure processes and failure modes were also clarified. In the finite element model we used the distributions of failure elements to simulate the failure processes. Meanwhile the failure mechanisms of X-cor sandwich were explained. The finite element analysis indicates that the resin regions of Z-pin tips fail firstly and the Z-pins fail secondly. The dominant failure mode is the Z-pin elastic buckling and the propagation paths of failure elements are dispersive. Through contrast the finite element values and test results are consistent well and the error range is -7.6%~9.5%. Therefore the failure criteria and stiffness degradation rules are reasonable and the model can be used to predict the compressive strength of X-cor sandwich.

A progressive multi-scale fatigue model for life prediction of laminated composites

2017 ◽  
Vol 51 (20) ◽  
pp. 2949-2960 ◽  
Author(s):  
Seyed Ali Hosseini Kordkheili ◽  
H Toozandehjani ◽  
Z Soltani
Keyword(s):  
Fundamental Equation ◽  
Failure Criteria ◽  
Test Results ◽  
Multi Scale ◽  
Finite Element Software ◽  
Mechanical Fatigue ◽  
Proposed Model ◽  
Fatigue Model ◽  
Sinusoidal Load ◽  
Bridging Model

This article presents a multi-scale progressive micro-mechanical fatigue model. The model employs fundamental equation of the kinetic theory of fracture to calculate damage parameters of both fiber and matrix during cyclic loading. In order to adapt the equation, required material coefficients of the constituents can be achieved from fatigue test results of longitudinal and transverse unidirectional composites, only. Sharing stress capacities of fiber and matrix are determined using a modified progressive micro-mechanical bridging model in the presence of damage. The damage parameters in the constituents are calculated employing two different equivalent scalars. However, during sinusoidal load application, these damage parameters are also updated using a first kind Bessel function of amplitude stresses in the constituents as well as their material coefficients. The enhanced formulation is then implemented into the commercial finite element software of ABAQUS via a developed user material (UMAT) subroutine utilizing a suitable failure criteria and an own solution algorithm. Advantages of the proposed model are assessed and comparisons with available solutions are presented.

Ductile Failure Analyses for API X65 Pipes Based on Local Failure Criteria

2006 ◽  
Author(s):  
Chang-Kyun Oh ◽  
Yun-Jae Kim ◽  
Jong-Hyun Baek ◽  
Young-Pyo Kim ◽  
Woo-Sik Kim
Keyword(s):  
Experimental Data ◽  
Failure Criterion ◽  
Hydrostatic Stress ◽  
Stress Triaxiality ◽  
Ductile Failure ◽  
Failure Criteria ◽  
Local Failure ◽  
Defective Region ◽  
Api X65 Steel ◽  
X65 Steel

A local failure criterion for the API X65 steel is applied to predict ductile failure of full-scale API X65 pipes with simulated corrosion and gouge defects under internal pressure. The local failure criterion is the stress-modified fracture strain for the API X65 steel as a function of the stress triaxiality (defined by the ratio of the hydrostatic stress to the effective stress). Based on detailed FE analyses with the proposed local failure criteria, burst pressures of defective pipes are estimated and compared with experimental data. The Failure of corroded pipes is governed by local necking and plastic collapse in the defective region, rather than failure. For pipes with gouge defects, on the other hand, it is found that fracture is dominant. The predicted burst pressures are in good agreement with experimental data. Noting that an assessment equation against the gouge defect is not yet available, parametric study is performed, from which a simple equation is proposed to predict burst pressure for API X65 pipes with gouge defects.

A method for the prediction of ductile fracture by central bursts in axisymmetric extrusion

2005 ◽  
Vol 219 (3) ◽  
pp. 237-250 ◽  
Author(s):  
P McAllen ◽  
P Phelan
Keyword(s):  
Ductile Fracture ◽  
Defect Formation ◽  
Ductile Failure ◽  
Failure Criteria ◽  
Wire Drawing ◽  
Damage Development ◽  
Die Geometry ◽  
Finite Element Software ◽  
Reduction In Area ◽  
Further Development

A new approach for the prediction of central burst defects in extrusion and wire drawing is proposed. Central burst defects are troublesome in industry as it is impossible to detect these defects by simple visual examination alone. It is therefore important to identify the combination of process parameters that will reduce the probability of these defects occurring. The proposed approach is capable of accurately predicting when and where a central burst is likely to occur. The influence of die geometry on damage development and subsequent central burst formation is examined using the modelling capabilities of Abaqus finite element software. The ductile fracture criteria of Cockcroft and Latham, Oyane and Chaouadi were employed using a Fortran subroutine, and their ability to predict the onset and evolution of the central burst defect was examined. For relatively lower area reductions and die angles the considered criteria are capable of accurately predicting the morphology of the defect. Under these conditions, the proposed approach shows good agreement with experimental results, confirming its effectiveness and suitability for industrial application. The failure criteria are inadequate in predicting central burst defect formation during conditions of large reduction in area and large semi-die angles. Further development of ductile failure criteria is necessary to accurately simulate defect evolution for all die angles and area reductions.

ORTHOTROPIC DAMAGE MODEL USING TSAI-WU FAILURE CRITERIA

2021 ◽  
Author(s):  
M. R. T. ARRUDA ◽  
L. ALMEIDA-FERNANDES, ◽  
L. CASTRO ◽  
J. R. CORREIA
Keyword(s):  
Failure Modes ◽  
Numerical Models ◽  
Equivalent Stress ◽  
Damage Model ◽  
Failure Criteria ◽  
Simple Method ◽  
Finite Element Software ◽  
User Subroutine ◽  
Novel Approach ◽  
The Moment

This paper presents a novel approach concerning the development of an orthotropic damage model, based on the original plane Tsai-Wu failure criteria. In its original formulation, the Tsai-Wu is a mode independent criterion only capable of acknowledging the existence of damage in a certain point of the material. It is not capable of identifying if the damage is located in the fiber, matrix or intralaminar zone. This work plans to fill this gap in knowledge by providing a simple method, based on equivalent stress and strains, that identifies the failure modes when the Tsai-Wu failure criteria is near the on-set of damage. Using this novel method, it is possible to implement classical damage evolutions constitutive laws based on the MTL formulation. At the moment the proposed damage formulation is based on plane stress space and Mode I fracture, but it is expected in the future to evolve in to a full 3D damage model. The damage model is implemented in the commercial finite element software ABAQUS using user-subroutine UMAT, and all numerical models are compared with the experimental results.

3D Numerical Simulation and Optimization of Processing Parameters in Fine Blanking of Back Plate of Brake

2011 ◽  
Vol 291-294 ◽  
pp. 440-443 ◽  
Author(s):  
Chun Dong Zhu ◽  
Fu Tao Li ◽  
Zhi Qiang Gu
Keyword(s):  
Numerical Simulation ◽  
Hydrostatic Stress ◽  
Equivalent Stress ◽  
Processing Parameters ◽  
Fine Blanking ◽  
Simulation And Optimization ◽  
Finite Element Software ◽  
2D Simulation ◽  
Back Plate ◽  
Blanking Process

Due to the limitation of 2D simulation in fine blanking, finite element software DEFORM-3D was used to simulate the 3D model of Back Plate. In this article the Normalized Cockroft&Latham fracture criterion was chosen to simulate the blanking process. The distribution and developing trend of the hydrostatic stress, equivalent stress in the fine blanking process are predicted. When the die radii are between 0.4mm and 0.6mm, burnished surface improves. It shows that the ideal blanking clearance value is 0.6% of the material thickness. The results indicate that FE numerical simulation could effectively optimize fine blanking process and offer basis for quality improvement.

Research of Shock Wave Damage Evaluation Method Based on LY-12 Effect Plate

2014 ◽  
Vol 532 ◽  
pp. 88-95
Author(s):  
Li Ping Li ◽  
De Ren Kong ◽  
Chuan Rong Zhao ◽  
Yu Hang ◽  
Fan Yang ◽  
...  
Keyword(s):  
Shock Wave ◽  
Finite Element ◽  
Evaluation Method ◽  
Structural Characteristics ◽  
Specific Impulse ◽  
Aluminum Plate ◽  
Positive Pressure ◽  
Plate Deformation ◽  
Finite Element Software ◽  
Pressure Time

This paper discusses the problems in electrometric method of measuring shock wave pressure, including frequency characteristic and installation method of the sensor, parasitic effect in damage conditions, as well as the unduplication of measuring environment and so on. These problems will lead to serious distortion. In this paper, on the structural characteristics of damage target, shock wave equivalent target method is proposed. The article discusses the use of methods and principles of equivalent target, uses the finite element software to do modal analysis with 1.5mm thickness aluminum plate and analyses the effects of shock wave to simulation results with different rise time, positive pressure time and specific impulse. Through sequentially loading gradient in 0.005Mpa~10MPa range to LY-12 aluminum plate in size of, target plate deformation damage can be observed. By using finite element numerical simulation, shock wave power of different equivalent explosion field can be reflected qualitatively.

A particular criterion for progressive failure analysis of carbon/phenolic tape-wounded conic shells

2021 ◽  
pp. 105678952199591
Author(s):  
SA Hosseini Kordkheili ◽  
M Karimian ◽  
HR Jafari
Keyword(s):  
Failure Analysis ◽  
Composite Structures ◽  
Progressive Failure ◽  
Failure Criteria ◽  
Solution Algorithm ◽  
Shell Structures ◽  
Finite Element Software ◽  
Progressive Failure Analysis ◽  
Conic Shell ◽  
Margin Of Safety

Conic shell structures are widely used in aerospace industries. In the literature various models have been proposed to failure analysis of composite materials. Clearly, each model has a favorable range of applications. In this paper tensile, compressive, shear and thermal expansion properties of tape-wounded Carbon/Phenolic composites are firstly measured at various temperatures in range 23–200°C. The captured properties are then taken into account to progressive failure analysis of a conic Carbon/Phenolic structure under internal pressure and thermal loadings. For this end, a particular failure criterion is proposed to predict failure in the composite structures with a reasonable margin of safety. The enhanced model is then implemented into the commercial finite element software of ABAQUS via a developed user material (UMAT) subroutine utilizing a suitable solution algorithm. Advantages of the model are assessed and comparisons with other failure criteria as well as experiment are presented.

scholarly journals COMPARING THE HOEK-BROWN AND MOHR-COULOMB FAILURE CRITERIA IN FEM ANALYSIS

2021 ◽  
Vol 30 ◽  
pp. 69-75
Author(s):  
Tereza Poklopová ◽  
Veronika Pavelcová ◽  
Michal Šejnoha
Keyword(s):  
Fem Analysis ◽  
Failure Criteria ◽  
Correct Choice ◽  
Failure Model ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Finite Element Software ◽  
Coulomb Failure ◽  
Coulomb Model ◽  
The Stability

This paper revisits the issue of a potential substitutions of the Hoek-Brown failure model by the standard Mohr-Coulomb model in the stability analysis of rock masses. The derivation of equivalent shear strength parameters of the Mohr-Coulomb proposed by Hoek et al. [1] is addressed with emphases on the suitable range of stresses for which the equivalence of the two failure criteria applies. To that end, a simple numerical analysis of the oedometric test is carried out. It is seen that a correct choice of the upper limit of the minimum compressive principal stress is crucial for the Mohr-Coulomb model to provide predictions comparable to the Hoek-Brown model. This issue is addressed next in the light of the solution of slope stability problem. All the presented results were derived with the help of the GEO5 FEM finite element software [2].

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