Hierarchal Modeling of Creep Behavior of SnAg Solder Alloys

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Min Pei ◽  
Jianmin Qu
Keyword(s):  
Creep Test ◽  
Creep Behavior ◽  
Creep Model ◽  
Length Scale ◽  
Eutectic Region ◽  
Length Scales ◽  
Multiple Length Scales ◽  
Model Predictions ◽  
Snag Solder ◽  
Micrometer Size

In this paper, a microstructure-dependent creep model is developed that accounts for the hierarchal microstructure at multiple length scales. The model considers three distinguishable phases in the solder alloy at two different length scales: at the larger scale Sn dendrites of micrometer size are embedded in a homogeneous eutectic region; at a much smaller length scale the eutectic region consists of submicron size Ag3Sn particles embedded in a homogeneous Sn matrix. The model predictions agree well with creep test data of lanthanum doped SnAg solders.

A Multiscale Modeling Method for the Creep Behavior of SnAg Solder Alloys

2007 ◽  
Author(s):  
Min Pei ◽  
Jianmin Qu
Keyword(s):  
Multiscale Modeling ◽  
Creep Test ◽  
Eutectic Phase ◽  
Creep Model ◽  
Length Scale ◽  
Length Scales ◽  
Multiple Length Scales ◽  
Model Predictions ◽  
Snag Solder ◽  
Micrometer Size

In this paper, a microstructure-dependent creep model is developed that accounts for the hierarchal microstructure at multiple length scales. The model considers three distinguishable phases in the solder alloy at two different length scales: at the larger scale Sn dendrites of micrometer size are embedded in a homogeneous eutectic phase; at a much smaller length scale the eutectic phase consists of submicron size Ag3Sn particles embedded in a homogeneous Sn matrix. The model predictions agree well with creep test data of RE doped SnAg solders.

Modified Singh-Mitchell Creep Model for EPS Composite Soil

2011 ◽  
Vol 311-313 ◽  
pp. 339-343 ◽  
Author(s):  
Hong Mei Gao ◽  
Guo Xing Chen
Keyword(s):  
Creep Test ◽  
Creep Behavior ◽  
Engineering Properties ◽  
Creep Model ◽  
Deviator Stress ◽  
Fill Material ◽  
Confining Pressures ◽  
Lightweight Fill ◽  
Eps Composite Soil ◽  
Undrained Creep

EPS composite soil is a new kind of lightweight fill material. Its engineering properties have been widely studied. However, the creep behavior has not been well investigated. In this study, triaxial undrained creep test is conducted on EPS composite soil regarding various confining pressures. Based on the testing results, a modified Singh-Mitchell creep model is established for EPS composite soil considering the influence of the deviator stress on the parameter m. Compared with the original Singh-Mitchell model, the modified creep model can well describe the creep behavior of EPS composite soil. It can provide references for engineers to design the project using EPS composite soil.

Multiscale Characterization of Spatial Heterogeneity in Multiphase Composite Microstructures

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
M. A. Tschopp ◽  
G. B. Wilks ◽  
J. E. Spowart
Keyword(s):  
Spatial Heterogeneity ◽  
Reaction Yield ◽  
Length Scale ◽  
Length Scales ◽  
Phase Mixing ◽  
Multiple Length Scales ◽  
Three Phase ◽  
Reaction Stoichiometry ◽  
Multiphase Composite

A computational characterization technique is presented for assessing the spatial heterogeneity of two reactant phases in a three-phase chemically reactive composite. This technique estimates the reaction yield on multiple microstructure length scales based on the segregation of the two reactant phases and the expected reaction stoichiometry. The result of this technique is a metric, quantifying the effectiveness of phase mixing in a particular microstructure as a function of length scale. Assuming that the proportionate mixing of reactant phases on multiple length scales will enhance reaction kinetics and the overall level of reaction completion, this tool can subsequently be used as a figure-of-merit for optimizing microstructure via appropriate processing. To illustrate this point, an example is shown where a bimodal three-phase microstructure has a higher reaction yield at every length scale when compared with a monomodal three-phase microstructure with the same constituent loading.

Multi length scale porosity as a playground for organic thermoelectric applications

2021 ◽  
Author(s):  
Quentin Weinbach ◽  
Christian Nielsen ◽  
Laure Biniek
Keyword(s):  
Organic Materials ◽  
Length Scale ◽  
Length Scales ◽  
Materials Properties ◽  
Multiple Length Scales ◽  
Covalent Structure

Porous organic materials have interesting materials properties governed not only by their covalent structure but also by their intrinsic porosity which when controlled over multiple length scales gives rise to...

scholarly journals A Phenomenological Primary–Secondary–Tertiary Creep Model for Polymer-Bonded Composite Materials

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2353
Author(s):  
Xiaochang Duan ◽  
Hongwei Yuan ◽  
Wei Tang ◽  
Jingjing He ◽  
Xuefei Guan
Keyword(s):  
Composite Materials ◽  
Creep Behavior ◽  
Reference Model ◽  
Creep Model ◽  
Creep Process ◽  
Validation Dataset ◽  
Testing Conditions ◽  
Proposed Model ◽  
Testing Data ◽  
Bonded Composite

This study develops a unified phenomenological creep model for polymer-bonded composite materials, allowing for predicting the creep behavior in the three creep stages, namely the primary, the secondary, and the tertiary stages under sustained compressive stresses. Creep testing is performed using material specimens under several conditions with a temperature range of 20 °C–50 °C and a compressive stress range of 15 MPa–25 MPa. The testing data reveal that the strain rate–time response exhibits the transient, steady, and unstable stages under each of the testing conditions. A rational function-based creep rate equation is proposed to describe the full creep behavior under each of the testing conditions. By further correlating the resulting model parameters with temperature and stress and developing a Larson–Miller parameter-based rupture time prediction model, a unified phenomenological model is established. An independent validation dataset and third-party testing data are used to verify the effectiveness and accuracy of the proposed model. The performance of the proposed model is compared with that of an existing reference model. The verification and comparison results show that the model can describe all the three stages of the creep process, and the proposed model outperforms the reference model by yielding 28.5% smaller root mean squared errors on average.

scholarly journals Subject-specific multiscale modeling of aortic valve biomechanics

2021 ◽  
Author(s):  
G. Rossini ◽  
A. Caimi ◽  
A. Redaelli ◽  
E. Votta
Keyword(s):  
Aortic Valve ◽  
Boundary Conditions ◽  
Narrow Range ◽  
Radial Strain ◽  
Length Scale ◽  
Length Scales ◽  
Anatomical Features ◽  
Wide Range ◽  
Subject Specific ◽  
Cell Strains

AbstractA Finite Element workflow for the multiscale analysis of the aortic valve biomechanics was developed and applied to three physiological anatomies with the aim of describing the aortic valve interstitial cells biomechanical milieu in physiological conditions, capturing the effect of subject-specific and leaflet-specific anatomical features from the organ down to the cell scale. A mixed approach was used to transfer organ-scale information down to the cell-scale. Displacement data from the organ model were used to impose kinematic boundary conditions to the tissue model, while stress data from the latter were used to impose loading boundary conditions to the cell level. Peak of radial leaflet strains was correlated with leaflet extent variability at the organ scale, while circumferential leaflet strains varied over a narrow range of values regardless of leaflet extent. The dependency of leaflet biomechanics on the leaflet-specific anatomy observed at the organ length-scale is reflected, and to some extent emphasized, into the results obtained at the lower length-scales. At the tissue length-scale, the peak diastolic circumferential and radial stresses computed in the fibrosa correlated with the leaflet surface area. At the cell length-scale, the difference between the strains in two main directions, and between the respective relationships with the specific leaflet anatomy, was even more evident; cell strains in the radial direction varied over a relatively wide range ($$0.36-0.87$$ 0.36 - 0.87 ) with a strong correlation with the organ length-scale radial strain ($$R^{2}= 0.95$$ R 2 = 0.95 ); conversely, circumferential cell strains spanned a very narrow range ($$0.75-0.88$$ 0.75 - 0.88 ) showing no correlation with the circumferential strain at the organ level ($$R^{2}= 0.02$$ R 2 = 0.02 ). Within the proposed simulation framework, being able to account for the actual anatomical features of the aortic valve leaflets allowed to gain insight into their effect on the structural mechanics of the leaflets at all length-scales, down to the cell scale.

An Experimental Study on the Effect of Prior Plastic Straining on Creep Behavior of 304 Stainless Steel

1993 ◽  
Vol 115 (2) ◽  
pp. 200-203 ◽  
Author(s):  
Z. Xia ◽  
F. Ellyin
Keyword(s):  
Stainless Steel ◽  
Plastic Strain ◽  
Strain Rate ◽  
Creep Behavior ◽  
Test Procedure ◽  
Constant Strain Rate ◽  
304 Stainless Steel ◽  
Creep Model ◽  
Plastic Strain Rate ◽  
Creep Tests

Constant strain-rate plastic straining followed by creep tests were conducted to investigate the effect of prior plastic straining on the subsequent creep behavior of 304 stainless steel at room temperature. The effects of plastic strain and plastic strain-rate were delineated by a specially designed test procedure, and it is found that both factors have a strong influence on the subsequent creep deformation. A creep model combining the two factors is then developed. The predictions of the model are in good agreement with the test results.

Fracture resistance of human cortical bone across multiple length-scales at physiological strain rates

Biomaterials ◽  
2014 ◽  
Vol 35 (21) ◽  
pp. 5472-5481 ◽  
Author(s):  
Elizabeth A. Zimmermann ◽  
Bernd Gludovatz ◽  
Eric Schaible ◽  
Björn Busse ◽  
Robert O. Ritchie
Keyword(s):  
Cortical Bone ◽  
Fracture Resistance ◽  
Strain Rates ◽  
Physiological Strain ◽  
Length Scales ◽  
Human Cortical Bone ◽  
Multiple Length Scales

Analysis of Thick-Walled Pipeline Elements Operating in Creep Conditions

2015 ◽  
Vol 712 ◽  
pp. 63-68
Author(s):  
Przemysław Osocha ◽  
Bohdan Węglowski
Keyword(s):  
Finite Element ◽  
Test Data ◽  
Creep Test ◽  
Power Plants ◽  
Steam Pressure ◽  
Creep Model ◽  
Creep Process ◽  
Fe Model ◽  
Element Analysis ◽  
Wide Range

In some coal-fired power plants, pipeline elements have worked for over 200 000 hours and increased number of failures is observed. The paper discuses thermal wear processes that take place in those elements and lead to rupture. Mathematical model based on creep test data, and describing creep processes for analyzed material, has been developed. Model has been verified for pipeline operating temperature, lower than tests temperature, basing on Larson-Miller relation. Prepared model has been used for thermal-strength calculations based on a finite element method. Processes taking place inside of element and leading to its failure has been described. Than, basing on prepared mathematical creep model and FE model introduced to Ansys program further researches are made. Analysis of dimensions and shape of pipe junction and its influence on operational element lifetime is presented. In the end multi variable dependence of temperature, steam pressure and element geometry is shown, allowing optimization of process parameters in function of required operational time or maximization of steam parameters. The article presents wide range of methods. The creep test data were recalculated for operational temperature using Larson-Miller parameter. The creep strain were modelled, used equations and their parameters are presented. Analysis of errors were conducted. Geometry of failing pipe junction was introduced to the Ansys program and the finite element analysis of creep process were conducted.

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