Micro-asperity Contact Area considering Strain Hardening for Metallic Materials

2021 ◽  
pp. 1-31
Author(s):  
Jinli Xu ◽  
Jiwei Zhu ◽  
Wei Xia ◽  
Baolei Liu
Keyword(s):  
Strain Hardening ◽  
Contact Area ◽  
Work Hardening ◽  
Present Model ◽  
Strain Hardening Exponent ◽  
Asperity Contact ◽  
Metallic Materials ◽  
Area Index ◽  
Area Model ◽  
Plastic Regime

Abstract A novel micro-asperity contact area model, which considers influences of strain hardening, is proposed to describe contact area between a deformable sphere and a rigid flat for metallic materials. Firstly a generalized formula considering work-hardening behaviors (Pilling-up or Sinking-in) between contact area and interference is proposed for fully plastic regime based on the definition of plastic contact area index. Then a relationship to calculate the critical interference at the inception of fully plastic deformation is derived. In order to incorporate the transition from elastic regime to fully plastic regime, a quadratic rational form formula is proposed based volume conservation model for mixed elastoplastic regime. Therewith a modification is conducted to ensure continuity of contact area model at critical interference for fully plastic regime. Ultimately several representative models and experiment results are exhibited to analyze the availability of present model. It is noted considering work-hardening fully plastic contact area index is not a constant value of 2 for any metallic materials, which is a function of strain hardening exponent. Demonstration testifies that smoothness constraint is not necessary at the critical interferences. The prediction data of present model is consistent with experiment results contrasting that of other models. Current generalized contact area model considering influence of work-hardening results in a better understanding of the contact area between a deformable sphere and a rigid flat and indicates a probability to analyze contact characteristics of two mating rough surfaces accurately.

Anomaly of the Work Hardening of Zn-Cu Single Crystals Oriented for Slip in Secondary Systems

2011 ◽  
Vol 56 (4) ◽  
pp. 1021-1027
Author(s):  
K. Pieła
Keyword(s):  
Strain Hardening ◽  
Single Crystals ◽  
Yield Stress ◽  
Work Hardening ◽  
Temperature Anomaly ◽  
Strain Hardening Exponent ◽  
Plastic Behavior ◽  
Thermal Dependence ◽  
Copper Addition ◽  
Secondary Systems

Anomaly of the Work Hardening of Zn-Cu Single Crystals Oriented for Slip in Secondary SystemsThe copper alloyed (up to 1.5%) zinc single crystals oriented for slip in non-basal systems (orientation close to < 1120 >) were subjected to compression test within a range of temperatures of 77-293K. It has been stated, that Zn-Cu crystals exhibit characteristic anomalies of the thermal dependence of yield stress and of the strain hardening exponent. Both of them are related to the change in type and sequence of active non-basal slip systems: pyramidal of the 1storder {1011} < 1123 > (Py-1) and pyramidal of the 2ndorder {1122} < 1123 > (Py-2). The temperature anomaly of the yield stress results from the change of the slip from Py-2 systems to simultaneous slip in the Py-2 and Py-1 (Py-2 + Py-1) systems, occurring in the preyielding stage. On the other hand, sequential activation of pyramidal systems taking place in advanced plastic stage (i.e. the first Py-2 and next Py-2 + Py-1 systems) is responsible for temperature anomaly of strain hardening exponent. Increase in copper addition favors the activity of Py-2 systems at the expense of Py-1 slip, what leads to a drastic differences in plastic behavior of zinc single crystals.

scholarly journals THE ABILITY TO CLINCHING AS A FUNCTION OF MATERIAL HARDENING BEHAVIOR

2018 ◽  
Vol 24 (1) ◽  
pp. 58
Author(s):  
Tadeusz Balawender
Keyword(s):  
Strain Hardening ◽  
Strength Properties ◽  
Strain Hardening Exponent ◽  
Special Importance ◽  
Metallic Materials ◽  
Forming Process ◽  
Plastic Properties ◽  
Plastic Materials ◽  
Mechanical Clinching ◽  
Induced Defects

<p><span lang="EN-GB">Mechanical clinching can be used to joining different metallic materials. The only restriction are their plastic properties. However some plastic materials, with good ductility, do not conform strong clinch joint, e.g. materials, featured by high strain hardening phenomena are difficult to clinching and do not create durable clinch joint. In case of others materials with limited ductility clinch forming generates the process-induced defects such as cracks. So, there are material’s features which are very important for the clinch forming process and among them the strain hardening properties seem to be in special importance.</span></p><p><span lang="EN-GB"><span>                </span>The clinch joints of different materials with diversified plastic and strength properties<span>  </span>were tested. A single overlap clinch joints with one clinch bulge were realized in the tests. The joints were tested in the pull test. The obtained results showed the relation of the clinch joinability to the materials’ strain hardening exponent. The good quality and good strength joints, were obtained for materials with low value of strain hardening<span>  </span>exponent below n = 0,22.</span></p>

A complete elastic-plastic spherical asperity contact model with the effect of isotropic strain hardening

2020 ◽  
pp. 135065012092989 ◽  
Author(s):  
A Megalingam ◽  
KS Hanumanth Ramji
Keyword(s):  
Strain Hardening ◽  
Rough Surface ◽  
Contact Area ◽  
Poisson’S Ratio ◽  
Combined Effect ◽  
Contact Model ◽  
Poisson's Ratio ◽  
Contact Load ◽  
Asperity Contact ◽  
Strain Hardening Rate

Understanding the deformation behavior of rough surface contacts is essential to minimise the tribological consequences of contacts. Mostly, statistical, deterministic and fractal approaches are adopted to explore the contact of rough surfaces. In statistical approach, a single asperity contact model is developed and extended to the whole surface. In the present work, a deformable spherical asperity contact with a rigid flat is modeled and analysed by accounting the combined effect of Young’s modulus, Poisson’s ratio, yield strength and isotropic strain hardening rate using finite element method. The results reveal that the elastic, elastoplastic and plastic contact states are highly influenced by E/Y ratio and strain hardening rate followed by Poisson’s ratio. The dimensionless contact radius is an inadequate parameter to explore the combined effect of material properties. For all E/Y ratio and Poisson’s ratio, as the strain hardening rate increases, the dimensionless contact area decreases for the same dimensionless contact load at elastoplastic and fully plastic contact states. As the strain hardening rate increases, the fully plastic contact state is reached at low dimensionless interference compared to elastic perfectly plastic materials for all E/Y ratio and Poisson’s ratio. For a common elastic-plastic material, empirical relations are developed to calculate the contact load and contact area appropriately with E/Y ratio, Poisson’s ratio and interference ratio as input variables. It can be utilised to study the interaction of rough surface contacts for most of the practical materials.

Strain hardening exponents and strength coefficients for aeroengine isotropic metallic materials – a reverse engineering approach

2014 ◽  
Vol 23 (3-4) ◽  
pp. 101-106 ◽  
Author(s):  
R. Rajendran ◽  
M. Venkateshwarlu ◽  
Vijay Petley ◽  
Shweta Verma
Keyword(s):  
Strain Hardening ◽  
Direct Method ◽  
Ultimate Tensile Stress ◽  
Strain Hardening Exponent ◽  
Published Data ◽  
Flow Rule ◽  
Metallic Materials ◽  
Accurate Design ◽  
Laboratory Test Results ◽  
Aeroengine Components

AbstractThe strain hardening exponent and strength coefficient of the Ramberg-Osgood flow rule are required for the accurate design analysis of the materials of aeroengine components. A direct method of deriving these parameters involves the processing of the complete raw data of tensile testing as per ASTM E-646. More often, a first design effort of aeroengine components is made using catalogue data, as the evaluation of material tensile properties is a time-consuming process that takes place concurrently. Catalogue-supplied data on the monotonic loading typically contains elastic modulus, 0.2% proof stress, and ultimate tensile stress along with other data for various temperatures. A methodology was evolved in this work to construct the Ramberg-Osgood flow rule with these three parameters and was validated with laboratory test results and published data through a comparison with ASTM E-646. The strain hardening exponents and strength coefficients were established for a family of aeroengine metallic materials for various temperatures, which can serve as a first design effort input.

Method for Determining the Plastic Properties of Metallic Materials by Instrumented Indentation with Dual Pyramidal Indenters

2014 ◽  
Vol 941-944 ◽  
pp. 1445-1452
Author(s):  
Wei Chen ◽  
De Jun Ma ◽  
Jia Liang Wang ◽  
Yong Huang
Keyword(s):  
Finite Element ◽  
Yield Strength ◽  
Strain Hardening ◽  
Engineering Application ◽  
Strain Hardening Exponent ◽  
Metallic Materials ◽  
Instrumented Indentation ◽  
Plastic Properties ◽  
Functional Relationships ◽  
Element Simulation

Method for determining the plastic properties of metallic materials was proposed based on the functional relationships between representative stress, representative strain and nominal hardness which were established with the aid of dimensional analysis and finite element simulation. The errors of 0.2% yield strength and strain hardening exponent of five engineering metals were from-17.1% to 15.4% and from -0.125 to 0.11, respectively,which satisfied the need of engineering application and verified the effectiveness of the method.

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