An Inverse Approach for Extracting Elastic–plastic Properties of Thin Films from Small Scale Sharp Indentation

2012 ◽  
Vol 28 (7) ◽  
pp. 626-635 ◽  
Author(s):  
Z.S. Ma ◽  
Y.C. Zhou ◽  
S.G. Long ◽  
C.S. Lu
Keyword(s):  
Thin Films ◽  
Small Scale ◽  
Plastic Properties ◽  
Elastic Plastic ◽  
Inverse Approach ◽  
Sharp Indentation

Reliability Analysis of Solderless Press-Fit Interconnections

2007 ◽  
Author(s):  
Hironori Tohmyoh ◽  
Kiichiro Yamanobe ◽  
Masumi Saka ◽  
Jiro Utsunomiya ◽  
Takeshi Nakamura ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Printed Circuit Boards ◽  
Circuit Board ◽  
Small Scale ◽  
Plastic Properties ◽  
Printed Circuit ◽  
Elastic Plastic ◽  
Press Fit ◽  
The Press ◽  
Plated Through Hole

This paper treats typical mechanical problems met in a solderless press-fit assembly. First, the elastic-plastic properties of a pin and the friction coefficient of the pin in thin plated through hole (TH) are determined by the experiments and the three-dimensional finite element (FE) analysis. The elastic-plastic properties of the press-fit pin are determined by the small scale three-point bending. The friction coefficient of the pin in the TH is successfully determined from the load-displacement relationship of the pin during press-fit assembly. The validity of the determined parameters is to be clarified by conducting the press-fit assemblies into the holes with different diameters. By comparing the damaged area of the printed circuit boards after assembly and the stress distributions obtained numerically, the failure stress of the board is determined. Finally, both the retention force of the pin and the damage of the printed circuit board after assembly become possible to be predicted by the numerical analysis.

New sharp indentation method of measuring the elastic–plastic properties of compliant and soft materials using the substrate effect

2006 ◽  
Vol 21 (12) ◽  
pp. 3134-3151 ◽  
Author(s):  
Manhong Zhao ◽  
Xi Chen ◽  
Nagahisa Ogasawara ◽  
Anghel Constantin Razvan ◽  
Norimasa Chiba ◽  
...  
Keyword(s):  
Finite Thickness ◽  
Indentation Test ◽  
Soft Materials ◽  
Substrate Effect ◽  
Plastic Properties ◽  
Application Range ◽  
Elastic Plastic ◽  
Elastoplastic Properties ◽  
Uniqueness Of The Solution ◽  
Sharp Indentation

We propose a new theory with the potential for measuring the elastoplastic properties of compliant and soft materials using one sharp indentation test. The method makes use of the substrate effect, which is usually intended to be avoided during indentation tests. For indentation on a compliant and soft specimen of finite thickness bonded to a stiff and hard testing platform (or a compliant/soft thin film deposited on a stiff/hard substrate), the presence of the substrate significantly enhances the loading curvature which, theoretically, enables the determination of the material power-law elastic-plastic properties by using just one conical indentation test. Extensive finite element simulations are carried out to correlate the indentation characteristics with material properties. Based on these relationships, an effective reverse analysis algorithm is established to extract the material elastoplastic properties. By utilizing the substrate effect, the new technique has the potential to identify plastic materials with indistinguishable indentation behaviors in bulk forms. The error sensitivity and uniqueness of the solution are carefully investigated. Validity and application range of the proposed theory are discussed. In the limit where the substrate is taken to be rigid, the fundamental research is one of the first steps toward understanding the substrate effect during indentation on thin films deposited on deformable substrates.

Analysis of Solderless Press-Fit Interconnections During the Assembly Process

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Hironori Tohmyoh ◽  
Kiichiro Yamanobe ◽  
Masumi Saka ◽  
Jiro Utsunomiya ◽  
Takeshi Nakamura ◽  
...  
Keyword(s):  
Printed Circuit Boards ◽  
Small Scale ◽  
Assembly Process ◽  
Circuit Boards ◽  
Element Analysis ◽  
Plastic Properties ◽  
Printed Circuit ◽  
Elastic Plastic ◽  
Press Fit ◽  
The Press

This paper deals with typical mechanical problems that are encountered in a solderless press-fit assembly process. First, the elastic-plastic properties of two types of press-fit pins and the friction coefficients of the pins in thin plated through holes are determined both experimentally and by three-dimensional finite element analysis. The elastic-plastic properties of the press-fit pins are determined by small-scale testing under three-point bending. The coefficients of friction of the pins in the through holes are successfully determined from the load-displacement relationships of the pins during press-fit assembly processes. The validity of the parameters that are determined is clarified by inserting the press-fit pins into holes of different diameters. By comparing the damaged areas of the printed circuit boards after assembly and the numerically obtained stress distributions, the failure stress of the boards is determined. Finally, both the retention force of the pins and the degree of damage to the printed circuit boards after assembly are predicted by numerical analysis.

scholarly journals Finite Pure Plane Strain Bending of Inhomogeneous Anisotropic Sheets

Symmetry ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 145
Author(s):  
Sergei Alexandrov ◽  
Elena Lyamina ◽  
Yeong-Maw Hwang
Keyword(s):  
Plane Strain ◽  
Yield Criterion ◽  
Large Strains ◽  
Rigid Plastic ◽  
Plastic Properties ◽  
Elastic Plastic ◽  
Starting Point ◽  
The Difference ◽  
Inside Radius ◽  
Elastic Unloading

The present paper concerns the general solution for finite plane strain pure bending of incompressible, orthotropic sheets. In contrast to available solutions, the new solution is valid for inhomogeneous distributions of plastic properties. The solution is semi-analytic. A numerical treatment is only necessary for solving transcendent equations and evaluating ordinary integrals. The solution’s starting point is a transformation between Eulerian and Lagrangian coordinates that is valid for a wide class of constitutive equations. The symmetric distribution relative to the center line of the sheet is separately treated where it is advantageous. It is shown that this type of symmetry simplifies the solution. Hill’s quadratic yield criterion is adopted. Both elastic/plastic and rigid/plastic solutions are derived. Elastic unloading is also considered, and it is shown that reverse plastic yielding occurs at a relatively large inside radius. An illustrative example uses real experimental data. The distribution of plastic properties is symmetric in this example. It is shown that the difference between the elastic/plastic and rigid/plastic solutions is negligible, except at the very beginning of the process. However, the rigid/plastic solution is much simpler and, therefore, can be recommended for practical use at large strains, including calculating the residual stresses.

Determining Elastic-Plastic Properties of Al6061-T6 from Micro-Indentation Technique

2013 ◽  
Vol 592-593 ◽  
pp. 610-613
Author(s):  
Sina Amiri ◽  
Nora Lecis ◽  
Andrea Manes ◽  
Davide Mombelli ◽  
Marco Giglio
Keyword(s):  
Manufacturing Process ◽  
Optimization Procedure ◽  
Test System ◽  
Standard Test ◽  
Material Behavior ◽  
Plastic Properties ◽  
Representative Strain ◽  
Elastic Plastic ◽  
Dimensionless Analysis ◽  
Micro Indentation

Different approaches have been proposed in order to determine the material behavior of ductile materials. Since, the mechanical properties of a mechanical component are modified during manufacturing process due to plastic deformation, heat treatment and etc, a non-destructive indentation experimental procedure addressed to predict the elastic-plastic properties of material after manufacturing process is of interest. This is especially true for small size components where it is complex to extract specimens to test on standard test system. Based on dimensionless analysis and the concept of a representative strain, different approaches have been proposed to determine the material properties of power law materials by using indentation process. In this work, the Johnson-Cook (JC) constitutive model of the aluminum alloy Al6061-T6 is characterized by means of a well-defined optimization procedure based on micro-indentation testing and high fidelity finite element models and an optimization procedure but without the concept of dimensionless analysis and a representative strain. This methodology allows determining a set of JC constants for Al6061-T6. The obtained results have good agreement with parameters calibrated by means of universal standard tests and reverse engineering approach.

Evaluation of elastic, elastic-plastic properties of thin Pt wire by mechanical bending test

2010 ◽  
Vol 103 (2) ◽  
pp. 493-496 ◽  
Author(s):  
S. K. Deb Nath ◽  
Hironori Tohmyoh ◽  
M. A. Salam Akanda
Keyword(s):  
Bending Test ◽  
Plastic Properties ◽  
Elastic Plastic ◽  
Mechanical Bending
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