scholarly journals Laue-DIC: a new method for improved stress field measurements at the micrometer scale

2015 ◽  
Vol 22 (4) ◽  
pp. 980-994 ◽  
Author(s):  
J. Petit ◽  
O. Castelnau ◽  
M. Bornert ◽  
F. G. Zhang ◽  
F. Hofmann ◽  
...  
Keyword(s):  
Standard Technique ◽  
Field Measurements ◽  
European Synchrotron Radiation Facility ◽  
Image Correlation ◽  
New Method ◽  
Polycrystalline Materials ◽  
Element Analysis ◽  
Analytical Functions ◽  
Local Stresses ◽  
Micrometer Scale

A better understanding of the effective mechanical behavior of polycrystalline materials requires an accurate knowledge of the behavior at a scale smaller than the grain size. The X-ray Laue microdiffraction technique available at beamline BM32 at the European Synchrotron Radiation Facility is ideally suited for probing elastic strains (and associated stresses) in deformed polycrystalline materials with a spatial resolution smaller than a micrometer. However, the standard technique used to evaluate local stresses from the distortion of Laue patterns lacks accuracy for many micromechanical applications, mostly due to (i) the fitting of Laue spots by analytical functions, and (ii) the necessary comparison of the measured pattern with the theoretical one from an unstrained reference specimen. In the present paper, a new method for the analysis of Laue images is presented. A Digital Image Correlation (DIC) technique, which is essentially insensitive to the shape of Laue spots, is applied to measure the relative distortion of Laue patterns acquired at two different positions on the specimen. The new method is tested on anin situdeformed Si single-crystal, for which the prescribed stress distribution has been calculated by finite-element analysis. It is shown that the new Laue-DIC method allows determination of local stresses with a strain resolution of the order of 10−5.

scholarly journals A New Method Combining Finite Element Analysis and Digital Image Correlation to Assess Macroscopic Mechanical Properties of Dentin

Materials ◽  
2015 ◽  
Vol 8 (2) ◽  
pp. 535-550 ◽  
Author(s):  
Wenlong Wang ◽  
Nicolas Roubier ◽  
Guillaume Puel ◽  
Jean-Marc Allain ◽  
Ingrid Infante ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Image Correlation ◽  
New Method ◽  
Element Analysis

scholarly journals Determination of the Characteristic Parameters of Tension-Compression Asymmetry of Shape Memory Alloys Using Full-Field Measurements

2013 ◽  
Vol 738-739 ◽  
pp. 281-286 ◽  
Author(s):  
Yves Chemisky ◽  
Rachid Echchorfi ◽  
Fodil Meraghni ◽  
Nadine Bourgeois ◽  
Boris Piotrowski
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Field Measurements ◽  
Type Specimen ◽  
Image Correlation ◽  
Identification Algorithm ◽  
Characteristic Parameters ◽  
Element Analysis ◽  
Full Field ◽  
Tension Compression Asymmetry

In this work, a method for the identification of the transformation surface of Shape Memory Alloys based on full field measurements is presented. An inverse method coupled with a gradient-based algorithm has been developed to determine the characteristic parameters of the transformation surface. The constitutive equations of the chosen model that capture the macroscopic behavior of Shape Memory Alloys are first presented. The material parameters, to be identified, that are characteristic of the tension-compression asymmetry of the alloy are detailed. The identification algorithm, based on full field measurements obtained by Digital Image Correlation (DIC) and numerical simulation by Finite Element Analysis are introduced. The identification algorithm is validated using a numerically generated strain field on a Meuwissen-type specimen.

Reliability Study of High-Temperature-Resistant Mounting Structure Considering Shear Behavior of Joint Layer

2009 ◽  
Author(s):  
Masanori Yamagiwa ◽  
Masato Fujita ◽  
Qiang Yu ◽  
Hiromi Sugihara
Keyword(s):  
High Temperature ◽  
Thermal Cycle ◽  
Coefficient Of Thermal Expansion ◽  
Shear Behavior ◽  
Nano Particles ◽  
Image Correlation ◽  
New Method ◽  
Shear Direction ◽  
Element Analysis ◽  
Temperature Sinter

Wide band gap semiconductor devices such as Silicon Carbide (SiC) or Gallium Nitride (GaN) capable of operation at high temperature over 300 degrees offer the potential of higher performance with reduced size, weight and eventually cost in power electronics equipment. For these high-temperature-resistant devices, the authors have proposed a new chip mounting structure that the stress relaxation function rests with the circuit metal on the substrate rather than the joint layer. In this study, to evaluate thermal fatigue of the new structure precisely, material properties of the high-temperature-resistant joint layer were measured by a new method and this method enabled analysis using measured properties. The joint layer which became very thin was formed by a low temperature sinter technology using silver (Ag) nano particles. The shear test to obtain the nonlinear properties of the joint layer was carried out by a proposed new method using bimetal fixtures which are composed of two materials whose Coefficient of Thermal Expansion (CTE) is different. Displacement of shear direction on the joint layer formed between the fixtures can be generated by heating the fixtures. Micro displacement was measured by Digital Image Correlation Method (DICM) using optical microscope and minute load on the joint layer was detected by strain gauge attached at fixture. Using the properties of the joint layer obtained as the test results, shear behavior on the chip joint was evaluated by Finite Element Analysis (FEA). Furthermore, harsh Thermal Cycle Test between −50 and 300 degree Celsius was carried out in the samples as the same structure as FEA model. From these results, the fatigue mechanism became clear and an improvement of the thermal cycle life was discussed.

scholarly journals Design of a Unique Device for Residual Stresses Quantification by the Drilling Method Combining the PhotoStress and Digital Image Correlation

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 314
Author(s):  
Miroslav Pástor ◽  
Martin Hagara ◽  
Ivan Virgala ◽  
Adam Kaľavský ◽  
Alžbeta Sapietová ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Experimental Testing ◽  
Digital Processing ◽  
Image Correlation ◽  
Optical Systems ◽  
Hole Drilling ◽  
Element Analysis ◽  
Thin Specimen ◽  
Comparison Of The Results

This paper presents a uniquely designed device combining the hole-drilling technique with two optical systems based on the PhotoStress and digital image correlation (DIC) method, where the digital image correlation system moves with the cutting tool. The authors aimed to verify whether the accuracy of the drilled hole according to ASTM E837-13a standard and the positioning accuracy of the device were sufficient to achieve accurate results. The experimental testing was performed on a thin specimen made from strain sensitive coating PS-1D, which allowed comparison of the results obtained by both methods. Although application of the PhotoStress method allows analysis of the strains at the edge of the cut hole, it requires a lot of experimenter’s practical skills to assess the results correctly. On the other hand, the DIC method allows digital processing of the measured data. However, the problem is not only to determine the data at the edge of the hole, the results also significantly depend on the smoothing levels used. The quantitative comparison of the results obtained was performed using finite element analysis.

scholarly journals A new method of phase-shifting and displacement of unit motor to suppress the thrust fluctuation of linear motor

2021 ◽  
Vol 13 (4) ◽  
pp. 168781402110087
Author(s):  
Feng Zhou ◽  
Han Zhao ◽  
Xiaoke Liu ◽  
Fujia Wang
Keyword(s):  
Permanent Magnet ◽  
Linear Motor ◽  
Phase Shifting ◽  
New Method ◽  
Analysis Model ◽  
End Effects ◽  
Element Analysis ◽  
Suppression Effect ◽  
Permanent Magnet Linear Motor ◽  
Thrust Fluctuation

Permanent magnet linear motors can cause thrust fluctuation due to cogging and end effects, which will affect the operation stability of the linear motor. In order to solve this problem, a new method of eliminating alveolar force by using phase-shifting and displacement is proposed in this paper. Taking the cylindrical permanent magnet linear motor as an example, the traditional cylindrical permanent magnet linear motor is divided into two unit-motors, and established finite element analysis model of cylindrical permanent magnet linear motor. It is different from other traditional methods, the thrust fluctuation was reduced by both phase-shifting and displacement simultaneously in this paper, and through simulation analysis, it is determined that the thrust fluctuation suppression effect was the best when the cogging distance was shifted by half. Furthermore, a comparative simulation was made on whether the magnetic insulating material was used. The simulation results show that: The method proposed in this paper can effectively suppress the thrust fluctuation of the cylindrical permanent magnet linear motor. And it can be applied to other similar motor designs. Compared with the traditional method of suppressing thrust fluctuation, the mechanical structure and the technological process of suppressing thrust fluctuation used in this method are simpler.

scholarly journals Comparison of Mechanical Impedance Methods for Vibration Simulation

1996 ◽  
Vol 3 (3) ◽  
pp. 223-232 ◽  
Author(s):  
Jeffrey A. Gatscher ◽  
Grzegorz Kawiecki
Keyword(s):  
Mechanical Impedance ◽  
Field Measurements ◽  
Cumulative Damage ◽  
Vibration Test ◽  
Element Analysis ◽  
Impedance Measurements ◽  
Testing Strategies ◽  
Impedance Testing ◽  
Vibration Simulation ◽  
Test Requirements

The work presented here explored the detrimental consequences that resulted when mechanical impedance effects were not considered in relating vibration test requirements with field measurements. The ways in which these effects can be considered were evaluated, and comparison of three impedance methods was accomplished based on a cumulative damage criterion. A test structure was used to simulate an equipment and support foundation system. Detailed finite element analysis was performed to aid in computation of cumulative damage totals. The results indicate that mechanical impedance methods can be effectively used to reproduce the field vibration environment in a laboratory test. The establishment of validated computer models, coupled with laboratory impedance measurements, can eliminate the overtesting problems inherent with constant motion, infinite impedance testing strategies.

A New Method of Field Measurements for Small-Aperture Magnets

1991 ◽  
Vol 30 (Part 1, No. 9A) ◽  
pp. 2082-2084
Author(s):  
Mitsuo Kikuchi ◽  
Hisayoshi Nakayama
Keyword(s):  
Field Measurements ◽  
New Method ◽  
Small Aperture

scholarly journals Finite element analysis of the grain size effect on diffusion in polycrystalline materials

2014 ◽  
Vol 95 ◽  
pp. 187-191 ◽  
Author(s):  
V. Lacaille ◽  
C. Morel ◽  
E. Feulvarch ◽  
G. Kermouche ◽  
J.-M. Bergheau
Keyword(s):  
Finite Element Analysis ◽  
Grain Size ◽  
Finite Element ◽  
Size Effect ◽  
Polycrystalline Materials ◽  
Grain Size Effect ◽  
Element Analysis

scholarly journals Validation of Welding Simulations Using Thermal Strains Measured with DIC

2011 ◽  
Vol 70 ◽  
pp. 129-134 ◽  
Author(s):  
Maarten De Strycker ◽  
Pascal Lava ◽  
Wim Van Paepegem ◽  
Luc Schueremans ◽  
Dimitri Debruyne
Keyword(s):  
Residual Stresses ◽  
Cross Section ◽  
Circular Cross Section ◽  
Welding Process ◽  
Weld Bead ◽  
Image Correlation ◽  
Steel Tubes ◽  
Element Analysis ◽  
Strain Evolution ◽  
The Cross

Residual stresses can affect the performance of steel tubes in many ways and as a result their magnitude and distribution is of particular interest to many applications. Residual stresses in cold-rolled steel tubes mainly originate from the rolling of a flat plate into a circular cross section (involving plastic deformations) and the weld bead that closes the cross section (involving non-uniform heating and cooling). Focus in this contribution is on the longitudinal weld bead that closes the cross section. To reveal the residual stresses in the tubes under consideration, a finite element analysis (FEA) of the welding step in the production process is made. The FEA of the welding process is validated with the temperature evolution of the thermal simulation and the strain evolution for the mechanical part of the analysis. Several methods for measuring the strain evolution are available and in this contribution it is investigated if the Digital Image Correlation (DIC) technique can record the strain evolution during welding. It is shown that the strain evolution obtained with DIC is in agreement with that found by electrical resistance strain gauges. The results of these experimental measuring methods are compared with numerical results from a FEA of the welding process.

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