Multiple Loading-Unloading of an Elastic-Plastic Spherical Contact

2005 ◽  
Author(s):  
Yuri Kadin ◽  
Yuri Kligerman ◽  
Izhak Etsion
Keyword(s):  
Plastic Deformation ◽  
Elastic Limit ◽  
Loading Conditions ◽  
Spherical Contact ◽  
Elastic Plastic ◽  
Wide Range ◽  
Plastic Sphere ◽  
Multiple Loading

A model for multiple loading-unloading of an elastic-plastic sphere and a rigid flat is presented to cover a wide range of loading conditions far beyond the elastic limit. It is shown that although most of the plastic deformation occurs during the first loading, additional plastic deformation may evolve during the first unloading and a few subsequent loading-unloading cycles.

Cyclic Loading of an Elastic-Plastic Adhesive Contact

2008 ◽  
Author(s):  
Y. Kadin ◽  
Y. Kligerman ◽  
I. Etsion
Keyword(s):  
Numerical Simulation ◽  
Plastic Deformation ◽  
Cyclic Loading ◽  
Contact Interaction ◽  
Adhesive Contact ◽  
Cyclic Plasticity ◽  
Electric Contact ◽  
Elastic Plastic ◽  
Plastic Sphere ◽  
Mems Device

A numerical simulation is presented for several loading-unloading cycles of an adhesive contact between an elastic-plastic sphere and a rigid flat. The main goal of the simulation is to study the plastic deformation evolution in a contact bump material — the microscopic electrode found in a MEMS micro-switch for providing a good electric contact. This bump is subjected to a cyclic contact interaction with a harder substrate and cyclic plasticity of the bump material can lead to its wear and as result to a failure of the whole MEMS device.

The Evolution of Static Friction for Elastic-Plastic Spherical Contact in Pre-sliding

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
V. Zolotarevskiy ◽  
Y. Kligerman ◽  
I. Etsion
Keyword(s):  
Static Friction ◽  
Contact Condition ◽  
Spherical Contact ◽  
Elastic Plastic ◽  
Tangential Stiffness ◽  
Plastic Sphere ◽  
Dimensionless Equations

The evolution of static friction and tangential stiffness in presliding of an elastic-plastic sphere in contact with a rigid flat, under full stick contact condition, is analyzed. Empirical dimensionless equations are developed for these parameters.

Elastic-Plastic Finite Element Simulation and Fatigue Damage Analysis of Wrinklebends

2008 ◽  
Author(s):  
Xian-Kui Zhu ◽  
Brian N. Leis
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
Fatigue Damage ◽  
Pipeline Steel ◽  
Kinematic Hardening ◽  
Strain Curve ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Wide Range ◽  
Hardening Models

The elastic-plastic finite element analysis (FEA) is performed in this paper to simulate the complicated plastic deformation of wrinklbends during bending and operation. The effects of element types, mesh sensitivity, and material input data of a stress-strain curve on the FEA results are discussed in details. To characterize the work hardening and Bauschinger effect on cyclic plastic deformation, three plastic hardening models: isotropic, kinematic and combined isotropic/kinematic hardening models are used and compared in the FEA simulation. Based on these investigations, a reliable nonlinear FEA model is developed, and then detailed FEA calculations are conducted for a wide range of wrinkle sizes under the cyclic pressure of 72% to 10% of SMYS (specified minimum yield stress) of X42 pipeline steel. Using the numerical results and an energy-based fatigue damage parameter, fatigue damage is quantified and a criterion is formulated as an H/L-N curve for wrinklebends. In the criterion, the wrinkle aspect ratio H/L is a key parameter that is directly related to the fatigue life. The results show that the proposed criterion and the H/L-N curve are simple and can be effectively used to evaluate integrity and estimate service life for wrinklebends.

Transient Thermo-Mechanical Plowing Contact Between Rigid Sphere and Elastic-Plastic Sphere

2012 ◽  
Author(s):  
Wenping Song ◽  
Andrey Ovcharenko ◽  
Longqiu Li ◽  
Guangyu Zhang ◽  
Frank E. Talke
Keyword(s):  
Finite Element Analysis ◽  
Plastic Deformation ◽  
Finite Element ◽  
Contact Zone ◽  
Temperature Rise ◽  
Rigid Sphere ◽  
Mechanical Contact ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Plastic Sphere

Transient thermo-mechanical contact between a rigid sphere sliding over an elastic-plastic sphere with a larger radius is studied using finite element analysis. Plastic deformation and temperature rise in the contact zone between the two spheres are investigated.

On the nominal transverse shear strain to characterize the severity of creasing

TAPPI Journal ◽  
2018 ◽  
Vol 17 (04) ◽  
pp. 231-240
Author(s):  
Douglas Coffin ◽  
Joel Panek
Keyword(s):  
Shear Strain ◽  
Transverse Shear ◽  
Elastic Limit ◽  
Experimental Results ◽  
Transverse Shear Strain ◽  
Maximum Strain ◽  
Machine Direction ◽  
Engineering Approach ◽  
Wide Range ◽  
Analytic Expression

A transverse shear strain was utilized to characterize the severity of creasing for a wide range of tooling configurations. An analytic expression of transverse shear strain, which accounts for tooling geometry, correlated well with relative crease strength and springback as determined from 90° fold tests. The experimental results show a minimum strain (elastic limit) that needs to be exceeded for the relative crease strength to be reduced. The theory predicts a maximum achievable transverse shear strain, which is further limited if the tooling clearance is negative. The elastic limit and maximum strain thus describe the range of interest for effective creasing. In this range, cross direction (CD)-creased samples were more sensitive to creasing than machine direction (MD)-creased samples, but the differences were reduced as the shear strain approached the maximum. The presented development provides the foundation for a quantitative engineering approach to creasing and folding operations.

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