Studies on Post-Yield Behavior of Cortical Bone

2012 ◽  
Vol 232 ◽  
pp. 157-161 ◽  
Author(s):  
N.K. Sharma ◽  
J. Nayak ◽  
D.K. Sehgal ◽  
R.K. Pandey
Keyword(s):  
Plastic Deformation ◽  
Cortical Bone ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Yield Behavior ◽  
Plastic Properties ◽  
Joint Replacements ◽  
Hierarchical Assembly ◽  
Plastic Modulus ◽  
Stiffness Loss

Complex hierarchical assembly and presence of large amount of organics and water content are responsible for enough amount of plasticity in bone material. Plastic properties are not only important to assess the various changes and fracture risk in bone but also for the development of better bone implants and joint replacements. The present study is focused on the post-yield behavior of cortical bone. The plastic properties of goat femoral and tibiae cortical bone were assessed and compared in terms of plastic modulus (H), tangent modulus (Et), plastic work (Wp) and plastic strain (εp) using uniaxial tensile test. Both femoral and tibiae cortical bone were found to be having similar post-yield behavior and significant stiffness loss was observed in both the bones during plastic deformation. The value of plastic modulus for femoral cortical bone was found to be 1.2 times higher as compared to the corresponding value for tibiae cortical bone. This shows higher hardening rate for femoral cortical bone. It was also observed that femoral bone requires higher energy during plastic deformation until fracture as compared to tibiae cortical bone.

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.

scholarly journals Investigation of the Dendritic Structure Influence on the Electrical and Mechanical Properties Diversification of the Continuously Casted Copper Strand

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5513
Author(s):  
Małgorzata Zasadzińska ◽  
Tadeusz Knych ◽  
Beata Smyrak ◽  
Paweł Strzępek
Keyword(s):  
Tensile Force ◽  
Dendritic Structure ◽  
Solidification Process ◽  
Total Elongation ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Sem Images ◽  
Plastic Properties ◽  
Tensile Direction ◽  
Continuous Casting Mould

The properties of copper in its solid state are strongly affected by the crystallization conditions of the liquid material. ETP grade copper (Electrolytic Tough Pitch Copper) contains oxygen, which causes Cu2O oxide to crystallize in the interdendritic spaces during solidification process which due to the shape of continuous casting mould and the feed of liquid copper during the crystallization process in strand casting might cause a high risk of macrosegregation of oxygen in the copper structure. In the current paper the implied interactions of the dendritic structure of the copper strand in terms of homogeneity at the cross-section of its electrical, mechanical and plastic properties determined based on the samples taken parallelly and perpendicularly to the surface of the dendritic boundaries were analysed. The obtained results were confronted with scanning electron microscopy (SEM) images of the fractures formed during uniaxial tensile test. It has been observed that when the crystallites were arranged perpendicularly to the tensile direction the yield strength (YS) was lower and the fractures were brittle. On the other hand, when the crystallites were arranged parallelly to the tensile direction the fractures were plastic and elongated necking was observed along with the higher YS and total elongation values. The differences in values vary in terms of the applied direction of the tensile force. A characteristic positioning of the Cu2O oxide particles inside the fracture depending on the crystallite alignment and the direction of the applied tensile force has been observed.

SMALL PUNCH TESTING: AN ALTERNATIVE TESTING TECHNIQUE TO EVALUATE TENSILE BEHAVIOR OF CORTICAL BONE

2017 ◽  
Vol 17 (06) ◽  
pp. 1750102
Author(s):  
JAGJIT SINGH ◽  
N. K. SHARMA ◽  
SATBIR S. SEHGAL
Keyword(s):  
Elastic Modulus ◽  
Tensile Test ◽  
Cortical Bone ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Testing Technique ◽  
Bone Material ◽  
Small Punch ◽  
Uniaxial Tensile Testing ◽  
Deformational Behavior

The tensile properties of cortical bone are usually determined with the help of uniaxial tensile test which requires enough amount of bone material. Further, it is very complicated to examine the heterogeneity and anisotropy associated with the deformational properties of cortical bone with the help of uniaxial tensile test. Through this study, small punch testing has been proposed as an alternate technique to evaluate the deformational behavior of cortical bone utilizing optimum amount of bone material. The comparison between elastic modulus values obtained from tensile test and stiffness values obtained through small punch testing was done for validation. The values of these properties were found to be having a significant positive correlation with each other. The effects of bone density and compositional parameters on these properties were also found to be having a similar trend. It is observed through this study that stiffness values from small punch technique are having a similarity with elastic modulus values from uniaxial tensile testing. It is proposed that small punch testing technique can be used as an alternate to examine the deformational behavior of cortical bone.

Method of Evaluation of the Properties of Thin Steel Sheets by Springback Test

2018 ◽  
Vol 919 ◽  
pp. 370-378
Author(s):  
Emil Spišák ◽  
Janka Majerníková ◽  
Ľuboš Kaščák
Keyword(s):  
Tensile Test ◽  
Strength Properties ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Double Reduction ◽  
Plastic Properties ◽  
Steel Sheets ◽  
Thin Steel ◽  
The Individual ◽  
Method Of Evaluation

Production of thin packaging sheets has gone through significant changes in recent years. Thickness of thin packaging sheets has decreased from 0.24mm down to 0.14 – 0.18mm due to the material saving, and the thickness of tin coating layer has decreased as well. Thin packaging sheets with the thickness lower than 0.18mm are produced with so called double reduction. Materials produced with this method possess higher strength properties and lower plastic properties. There exist several tests for examination of strength and plastic properties. Requirements of the processors of these sheets are that these tests are simple, without a complicated production of specimens, and easily repeatable. Exactly because of these reasons, the springback test is used for evaluation of double reduced packaging sheets by many processors from various countries. This contribution compares properties of double reduced thin packaging sheets obtained with the springback test, uniaxial tensile test and biaxial tensile test. Goal of this comparison is to objectify mechanical and plastic properties of packaging sheets obtained with the individual tests.

Anisotropic Damage Evolution for Perforated Sheet under Tensile Deformation

2016 ◽  
Vol 725 ◽  
pp. 489-494
Author(s):  
Shigeru Nagaki ◽  
Daigo Saboi ◽  
Kenta Muroi ◽  
Makoto Iizuka ◽  
Kenichi Oshita
Keyword(s):  
Plastic Deformation ◽  
Void Growth ◽  
Damage Evolution ◽  
Tensile Deformation ◽  
Yield Function ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Thermodynamic Consideration ◽  
Perforated Sheets ◽  
Growth Of Voids

It is important to formulate a constitutive equation which represents the growth of voids during plastic deformation in order to predict ductile fracture of metallic materials. For this purpose, we proposed an anisotropic Gurson’s yield function with the damage tensor, which represents the anisotropy due to the void distribution and the damage evolution was assumed isotropic for simplicity. Then we also proposed an anisotropic void growth law derived from the anisotropic Gurson’s yield function based on thermodynamic consideration. In this study we carried out the uniaxial tensile test of perforated sheets of stainless steel and aluminum alloy as the ideal two dimensional model of the damaged material and investigate the damage growth during plastic deformation. As a result, we obtained a good agreement between the experimental and the calculated void growth for both materials and it is also found that material parameters for damage evolutions are almost the same for both materials and are hardly affected by the work-hardening exponent.

Surface Roughening and Formability in Sheet Metal Forming of Polycrystalline Metal

2013 ◽  
Vol 535-536 ◽  
pp. 231-234 ◽  
Author(s):  
Takeji Abe
Keyword(s):  
Plastic Deformation ◽  
Sheet Metal ◽  
Uniaxial Tensile ◽  
Surface Irregularity ◽  
Surface Roughening ◽  
Uniaxial Tensile Test ◽  
Polycrystalline Metal ◽  
Biaxial Stretching ◽  
R Value ◽  
The Difference

The r–value is defined as the ratio of the width strain to the thickness strain under the uniaxial tensile test of the sheet metal. Based on r-value of grains, a model of plastic deformation of polycrystalline metal and surface roughening after plastic deformation was proposed in the previous paper. Meanwhile, Marciniak and Kuczynski proposed the so-called M-K model which give the analytical estimation of the formability of sheet metal under biaxial stretching considering a certain irregularity of the thickness of the sheet metal. Yamaguchi et al showed that the experimentally measured surface roughness may correspond to the surface irregularity suggested in the M-K model. In the present paper, the formability of sheet metal under biaxial stretching is analyzed based on the previous analysis of surface roughening caused by the difference of the r-value in the sheet metal.

scholarly journals Calculated Shoulder to Gauge Ratio of Fatigue Specimens in PWR Environment

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 376
Author(s):  
Igor Simonovski ◽  
Alec Mclennan ◽  
Kevin Mottershead ◽  
Peter Gill ◽  
Norman Platts ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Water Environment ◽  
Hysteresis Loops ◽  
Constitutive Law ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Material Behaviour ◽  
Pressurized Water ◽  
Elastic Plastic ◽  
Gauge Section

A ratio of shoulder to gauge displacements (S2G) is calculated for three different fatigue specimens in a pressurized water environment. This ratio needs to be known beforehand to determine the applied shoulder displacements during the experiment that would result in the desired strain amplitude in the gauge section. Significant impact of both the applied constitutive law and specimen geometry on the S2G is observed. The calculation using the fully elastic constitutive law results in the highest S2G values and compares very well with the analytical values. However, this approach disregards the plastic deformation within the specimens that mostly develops in the gauge section. Using the constitutive laws derived from actual fatigue curves captures the material behaviour under cyclic loading better and results in lower S2G values compared to the ones obtained with the fully elastic constitutive law. Calculating S2G values using elastic–plastic constitutive law based on the monotonic uniaxial tensile test should be avoided as they are significantly lower compared to the ones computed with elastic–plastic laws derived from hysteresis loops at half-life.

Model for the variation of the residual stress state during plastic deformation under uniaxial tension

1998 ◽  
Vol 33 (5) ◽  
pp. 367-372 ◽  
Author(s):  
T Gurova ◽  
J R Teodósio ◽  
J M A Rebello ◽  
V Monin
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Surface Layer ◽  
Theoretical Model ◽  
Bulk Material ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Surface Residual Stress ◽  
Residual Stress State ◽  
The Difference

A theoretical model has been developed to explain the variation of surface residual stress introduced by shot-peening with external plastic deformation, during a uniaxial tensile test. The model is based on the difference of yield stress values of the shot-peened surface layer and the remaining bulk material. It has been shown that the model fits well with experimental results obtained for the base metal and heat-affected zone of a 5.0Cr-0.5Mo steel.

Numerical Study of Mechanical Behaviour of Heterogeneous Materials

2012 ◽  
Vol 730-732 ◽  
pp. 549-554
Author(s):  
Rui M. Branco ◽  
Pedro Prates ◽  
Marta C. Oliveira ◽  
Nataliya A. Sakharova ◽  
J. Valdemar Fernandes
Keyword(s):  
Mechanical Behaviour ◽  
Numerical Study ◽  
Local Stress ◽  
Image Correlation ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Correlation Technique ◽  
Element Analysis ◽  
Plastic Properties ◽  
The Difference

The mechanical behaviour of heterogeneous specimens under uniaxial tensile test is studied using finite element analysis. The difference between mechanical properties of adjacent regions in the heterogeneous specimen creates constraints which alter the strain path relatively to pure tension. A methodology for determining the local stress-strain curves is proposed and successfully tested numerically on the heterogeneous specimen composed by two materials with dissimilar plastic properties. This methodology has recourse to the same type of variables which are usually obtained experimentally with the digital image correlation technique.

scholarly journals Biomechanical-Structural Correlation of Chordae tendineae in Animal Models: A Pilot Study

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1678
Author(s):  
Justyn Gach ◽  
Izabela Janus ◽  
Agnieszka Mackiewicz ◽  
Tomasz Klekiel ◽  
Agnieszka Noszczyk-Nowak
Keyword(s):  
Mitral Valve ◽  
Complex Structure ◽  
Future Research ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Histopathological Analysis ◽  
Papillary Muscles ◽  
Chordae Tendineae ◽  
Structural Correlation ◽  
Ring Valve

The mitral valve apparatus is a complex structure consisting of the mitral ring, valve leaflets, papillary muscles and chordae tendineae (CT). The latter are mainly responsible for the mechanical functions of the valve. Our study included investigations of the biomechanical and structural properties of CT collected from canine and porcine hearts, as there are no studies about these properties of canine CT. We performed a static uniaxial tensile test on CT samples and a histopathological analysis in order to examine their microstructure. The results were analyzed to clarify whether the changes in mechanical persistence of chordae tendineae are combined with the alterations in their structure. This study offers clinical insight for future research, allowing for an understanding of the process of chordae tendineae rupture that happens during degenerative mitral valve disease—the most common heart disease in dogs.

Sign in / Sign up

Export Citation Format

Share Document