Elasto-Plastic Analysis of a Miniature Circular Disk Bending Specimen

2006 ◽  
Author(s):  
Vishnu Verma ◽  
A. K. Ghosh ◽  
G. Behera ◽  
Kamal Sharma ◽  
R. K. Singh
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
Yield Stress ◽  
Material Properties ◽  
Stable Solution ◽  
Bending Test ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Plastic Behavior ◽  
Element Analysis

Miniature disk bending test is used to evaluate the mechanical behavior of irradiated materials and its properties — mainly ductility loss due to irradiation in steel. In Miniature Disk Bending Machine the specimen is firmly held between the two horizontal jaws of punch, and an indentor with spherical ball travels vertically. Researchers have observed reasonable correlations between values of the yield stress, strain hardening and ultimate tensile strength estimated from this test and mechanical properties determined from the uniaxial tensile test. Some methods for the analysis of miniature disk bending, proposed by various authors have been discussed in the paper. It is difficult to distinguish between the regimes of elastic and plastic deformation since local plastic deformation occurs for very small values of load when the magnitude of spatially averaged stress will be well below the yield stress. Also, the analytical solution for large amplitude, plastic deformation becomes rather unwieldy. Hence a finite element analysis has been carried out. The finite element model, considers contact between the indentor and test specimen, friction between various pairs of surfaces and elastic plastic behavior. The load is increased in steps and converged solution has been obtained and analysis terminated at a load beyond which a stable solution cannot be obtained. A sensitivity study has been carried out by varying the various parameters defining the material properties by ±10% around the base values. This study has been carried out to generate a data base for the load-deflection characteristics of similar materials from which the material properties can be evaluated by an inverse calculation. It is seen that the deflection obtained by analytical elastic bending theory is significantly lower than that obtained by the elasto-plastic finite element solution at relatively small values of load. The FE solution and experimental results are in reasonably good agreement.

Elastoplastic Analysis of a Miniature Circular Disk Bending Specimen

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Vishnu Verma ◽  
A. K. Ghosh ◽  
G. Behera ◽  
Kamal Sharma ◽  
R. K. Singh
Keyword(s):  
Finite Element ◽  
Analytical Solutions ◽  
Material Properties ◽  
Finite Element Solution ◽  
Bending Test ◽  
Experimental Result ◽  
Strain Hardening Exponent ◽  
Plastic Behavior ◽  
Element Solution ◽  
Element Analysis

The miniature disk bending test is used to evaluate the mechanical behavior of irradiated materials and their properties (e.g., yield stress and strain hardening exponent) to determine mainly ductility loss in steel due to irradiation from the load-deflection behavior of the disk specimen. In the miniature disk bending machine the specimen is firmly held between the two horizontal jaws of punch, and an indentor with a spherical ball travels vertically. Analytical solutions for large amplitude plastic deformation become rather unwieldy. Hence, a finite element analysis has been carried out. The finite element model considers contact between the indentor and test specimen, friction between various pairs of surfaces, and elastic plastic behavior. This paper presents the load versus deflection results of a parametric study where the values of various parameters defining the material properties have been varied by ±10% around the base values. Some well-known analytical solutions to this problem have also been considered. It is seen that the deflection obtained by analytical elastic bending theory is significantly lower than that obtained by the elastoplastic finite element solution at relatively small values of load. The finite element solution has been compared with one experimental result and values are in reasonably good agreement. With these results it will be possible to determine the material properties from the experimentally obtained values of load and deflection.

Finite Element Analysis on Nitinol Medical Applications

2002 ◽  
Author(s):  
Xiao-Yan Gong ◽  
Alan R. Pelton
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Material Behavior ◽  
Nonlinear Material ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Element Analysis ◽  
Highly Nonlinear ◽  
Device Applications ◽  
Specific Material

Nitinol, an alloy of about 50% Ni and 50% Ti, is a very unique material. At constant temperature above its Austenite finish (Af) temperature, under uniaxial tensile test, the material is highly nonlinear and capable of large deformation to the ultimate strain on the order of 15%. This material behavior, known as superelasticity, along with its excellent biocompatibility and corrosion resistance, makes Nitinol a perfect material candidate for many medical device applications. However, the nonlinear material response also requires a specific material description to perform the stress analysis. The user developed material subroutine from HKS/West makes the simulation of the Nitinol devices possible. This article presents two case studies of the nonlinear finite element analysis using ABAQUS/Standard and the Nitinol UMAT.

scholarly journals Extracting elastic constitutive parameters using the VFM within peridynamics

2019 ◽  
Author(s):  
Rolland Delorme ◽  
Patrick Diehl ◽  
Ilyass Tabiai ◽  
Louis Laberge Lebel ◽  
Martin Levesque
Keyword(s):  
Finite Element ◽  
Displacement Field ◽  
Material Properties ◽  
Noise Analysis ◽  
Image Correlation ◽  
Bending Test ◽  
Virtual Fields Method ◽  
Element Analysis ◽  
Constitutive Parameters

This paper implements the Virtual Fields Method within the ordinary state based peridynamic framework to identify material properties. The key equations derived in this approach are based on the principle of virtual works written under the ordinary state based peridynamic formalism for two-dimensional isotropic linear elasticity. In-house codes including a minimization process have also been developed to implement the method. A three-point bending test and two independent virtual fields arbitrarily chosen are used as a case study throughout the paper. The numerical validation of the virtual fields method has been performed on the case study by simulating the displacement field by finite element analysis. This field has been used to extract the elastic material properties and compared them to those used as input in the finite element model, showing the robustness of the approach. Noise analysis and the effect of the missing displacement fields on the specimen’s edges to simulate digital image correlation limitations have also been studied in the numerical part. This work focuses on pre-damage properties to demonstrate the feasibility of the method and provides a new tool for using full-field measurements within peridynamics with a reduced calculation time as there is no need to compute the displacement field. Future works will deal with damage properties which is the main strength of peridynamics.

Analysis on Oil Extraction Progressing Cavity Pump Three-Dimensional Finite Element Model

2014 ◽  
Vol 644-650 ◽  
pp. 670-673
Author(s):  
Guo You Han ◽  
Ming Qi Wang ◽  
Yu Hou ◽  
Qiang Li
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Finite Element Model ◽  
Fluid Pressure ◽  
Three Dimensional ◽  
Element Model ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Analysis Model ◽  
Element Analysis

The finite element analysis of PCP involves three nonlinear of geometry, material and contact, and the load of PCP is diversity, leading to it difficult to establish the finite element model and calculate by finite method. This article takes GLB120-27 as an example, to establish 3D solid model of PCP by using SolidWorks; to determine M-R model constant of stator rubber by using the data of uniaxial tensile test: to separate the seal band from the stator chamber by using Boolean operation and set up contact pairs, to achieve the correct simulation of stator chamber fluid pressure; to correctly simulate the interference fit between stator and rotor through setting correlation parameters; to establish 3D finite element analysis model and verify the correctness by using the experiment data of hydraulic characteristics of PCP.

An Artificial Neural Network Model to Predict Material Characteristics From the Results of Miniature Circular Disk Bending Tests

2006 ◽  
Author(s):  
A. K. Ghosh ◽  
G. Behera ◽  
V. Verma
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Plastic Deformation ◽  
Yield Stress ◽  
Material Properties ◽  
Bending Test ◽  
Second Phase ◽  
Spatial Average ◽  
Artificial Neural ◽  
Load Displacement

Miniature disk bending test was developed to evaluate the mechanical behavior of irradiated materials - mainly to identify the ductility loss in steels. The analytical solution for large amplitude, elasto-plastic deformation with contact and friction becomes rather unwieldy. It is difficult to distinguish between the regimes of elastic and plastic deformation since local plastic deformation occurs for very small values of load when the magnitude of spatial average stress is well below the yield stress. Thus the inverse problem of evaluating properties from the experimentally observed values of the deflection of the specimen is rather difficult to solve analytically. The paper discusses some of the published work in this area and the difficulties associated with them. The approach in this work is to first generate a large database - by a finite element (FE) solution - of load-displacement (P-w) records for varying material properties viz. elastic modulus (E), yield stress (σy) and the constants (A0, m) appearing in the plastic stress-strain relation. An artificial neural network (ANN) is trained with the specified material properties and the corresponding load-displacement records. In the second phase, this network is tested with known data and then used with the experimentally observed (P-w) records to predict the abovementioned material properties. The paper presents the details of modeling (FE and ANN), a summary of the results obtained by the FE analysis (database) and the results obtained by the ANNs in the training and the testing phases. The errors in the various values of the parameters during testing were found to be within 5%.

Finite Element Analysis of Elastic and Plastic Deformation during Growth of Si1−xGex/Si Heterostructures

2004 ◽  
Vol 824 ◽  
Author(s):  
F. Sahtout Karoui ◽  
A. Karoui ◽  
G. Rozgonyi
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
Stress Distribution ◽  
Von Mises Stress ◽  
Plastic Behavior ◽  
Element Analysis ◽  
Strained Si ◽  
Von Mises ◽  
Elastic And Plastic Deformation ◽  
Plastic Stress

AbstractThe elastic and plastic stress distribution in strained Si1−xGex heterostructure (x=0.2 and x=0.5), was investigated during the growth process using a nonlinear transient finite element modeling. The material plastic behavior is described by the von Mises yield criteria coupled with isotropic work hardening conditions. The calculated stress distribution during growth of the SiGe cap layer shows that the von Mises stress fluctuates strongly within the layers and at the interfaces. The surface of constant composition Si1−xGex layer is found under compressive stress in both cases. Within that layer the normal stress in the growth direction remains compressive for x=0.2, while it changes from compressive to tensile for x=0.5. In the graded layer the stress goes from tensile to compressive for x=0.5 and in the opposite way for x=0.2. High plastic deformation is observed in the layers, with the maximum von Mises plastic stress being higher for x=0.5 and localized in the SiGe graded region. The plastic strain vanishes monotonically up to 8 μ deep into the Si bulk substrate, in agreement with TEM images that revealed dislocation loops penetrating into the substrate. The time dependent analysis shows that elastic and plastic deformation appear almost instantaneously in the sublayers, while in the Si substrate it is delayed up to 300 s.

Effect of Defect on Elastic/Plastic and Creep Behavior of Bone: A Finite Element Study

2007 ◽  
Author(s):  
A. Ajdari ◽  
P. K. Canavan ◽  
H. Nayeb-Hashemi ◽  
G. Warner
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Trabecular Bone ◽  
Fatigue Loading ◽  
Dimensional Structure ◽  
Plastic Behavior ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Local Bone ◽  
Osteoporotic Vertebral Fractures

Three-dimensional structure of trabecular bone can be modeled by 2D or 3D Voronoi structure. The effect of missing cell walls on the mechanical properties of 2D honeycombs is a first step towards understanding the effect of local bone resorption due to osteoporosis. In patients with osteoporosis, bone mass is lost first by thinning and then by resorption of the trabeculae [1]. Furthermore, creep response is important to analyze in cellular solids when the temperature is high relative to the melting temperature. For trabecular bone, as body temperature (38 °C) is close to the denaturation temperature of collagen (52 °C), trabecular bone creeps [1]. Over the half of the osteoporotic vertebral fractures that occur in the elderly, are the result of the creep and fatigue loading associated with the activities of daily living [2]. The objective of this work is to understand the effect of missing walls and filled cells on elastic-plastic behavior of both regular hexagonal and non-periodic Voronoi structures using finite element analysis. The results show that the missing walls have a significant effect on overall elastic properties of the cellular structure. For both regular hexagonal and Voronoi materials, the yield strength of the structure decreased by more than 60% by introducing 10% missing walls. In contrast, the results indicate that filled cells have much less effect on the mechanical properties of both regular hexagonal and Voronoi materials.

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