A New Creep Constitutive Model for Eutectic Solder Alloy

2002 ◽  
Vol 124 (2) ◽  
pp. 85-90 ◽  
Author(s):  
X. Q. Shi ◽  
Z. P. Wang ◽  
W. Zhou ◽  
H. L. J. Pang ◽  
Q. J. Yang
Keyword(s):  
Constitutive Model ◽  
Testing Temperature ◽  
Creep Model ◽  
Temperature Dependent ◽  
Creep Tests ◽  
Creep Flow ◽  
Reliability Of Solder Joints ◽  
Power Law Creep ◽  
Creep Constitutive Model

In this study, a large number of creep tests were carried out to study the effect of stress level and testing temperature on the creep behavior of 63 Sn/37Pb solder in a systematic manner. Based on the dislocation controlled creep mechanism and Gibbs’ free-energy theory, a new creep constitutive model was proposed. The model was found to describe accurately the creep flow of the solder and to be capable of explaining the issues of stress and temperature dependent stress exponent and activation energy in the Arrhenius power-law creep model. Furthermore, the model was employed to predict accurately the long-term reliability of solder joints in a PBGA assembly.

scholarly journals Study on creep performance of launch canister under long-term storage

2019 ◽  
Vol 43 (2) ◽  
pp. 199-208 ◽  
Author(s):  
Cun-Gui Yu ◽  
Tong-Sheng Sun ◽  
Guang-Yuan Xiao
Keyword(s):  
Residual Deformation ◽  
Bottom Layer ◽  
Tensile Creep ◽  
Creep Model ◽  
Model Parameters ◽  
Creep Tests ◽  
Software Environment ◽  
Long Term Storage ◽  
Term Storage

In this paper, the creep performance of a multi-barrel rocket launch canister under long-term stacking storage is studied. Based on the Bailey–Norton model, a creep model for the frame material of a launch canister was established. Constant stress tensile creep tests under different stress levels at room temperature were carried out on the frame materials of the launch canister and the creep model parameters were obtained by test data fitting. The three-dimensional finite element model of the launch canister was established in the ABAQUS software environment and the creep deformation of the launch canister after long-term stacking storage was studied. The results indicated that the bottom layer of the launch canister frame presented an extended residual deformation when the stacking storage solution with the original support pad was used. Therefore, a position adjustment program of the support pad was put forward. The residual deformation of the launch canister frame after long-term storage could be significantly reduced, thus the performance requirements for the launch canister are guaranteed.

scholarly journals Nonlinear Viscoelastic-Plastic Creep Model of Rock Based on Fractional Calculus

2022 ◽  
Vol 2022 ◽  
pp. 1-7
Author(s):  
Erjian Wei ◽  
Bin Hu ◽  
Jing Li ◽  
Kai Cui ◽  
Zhen Zhang ◽  
...  
Keyword(s):  
Fractional Calculus ◽  
Fractional Order ◽  
Engineering Application ◽  
Creep Model ◽  
Nonlinear Viscoelastic ◽  
Rock Creep ◽  
Order Change ◽  
Creep Constitutive Model ◽  
Plastic Creep

A rock creep constitutive model is the core content of rock rheological mechanics theory and is of great significance for studying the long-term stability of engineering. Most of the creep models constructed in previous studies have complex types and many parameters. Based on fractional calculus theory, this paper explores the creep curve characteristics of the creep elements with the fractional order change, constructs a nonlinear viscoelastic-plastic creep model of rock based on fractional calculus, and deduces the creep constitutive equation. By using a user-defined function fitting tool of the Origin software and the Levenberg–Marquardt optimization algorithm, the creep test data are fitted and compared. The fitting curve is in good agreement with the experimental data, which shows the rationality and applicability of the proposed nonlinear viscoelastic-plastic creep model. Through sensitivity analysis of the fractional order β2 and viscoelastic coefficient ξ2, the influence of these creep parameters on rock creep is clarified. The research results show that the nonlinear viscoelastic-plastic creep model of rock based on fractional calculus constructed in this paper can well describe the creep characteristics of rock, and this model has certain theoretical significance and engineering application value for long-term engineering stability research.

scholarly journals In Situ Creep Model Testing for the Tunnel Anchor Foundation of Xingkang Suspension Bridge in Luding of China

2020 ◽  
Vol 2020 ◽  
pp. 1-19
Author(s):  
Lina Wen ◽  
Qiangong Cheng ◽  
Qiang Cheng ◽  
Xifeng Guo ◽  
Bin Zhang
Keyword(s):  
Suspension Bridge ◽  
Surrounding Rock ◽  
Creep Model ◽  
Left Bank ◽  
Creep Tests ◽  
The Real ◽  
Order Of Magnitude ◽  
Bridge Foundation

Due to the limitations of geography and geology, cast concrete tunnel anchors were used to provide counterforces for Xingkang Suspension Bridge foundation at the left bank of Daduhe River. In this study, the in situ creep tests were conducted on two model tunnel anchors at a scale of 1:10 near the real working anchor site. Thus, the long-term deformation of the real working tunnel anchors installed at the bridge foundation could be determined from the creep test of model tunnel anchors. The creep tests were conducted under three different loads and lasted for 102.2 h, 167.5 h, and 189.4 h, respectively. The model anchor, the surrounding rock, and their interface were all monitored and measured during the creep testing. In addition, the numerical calculation, in which the Burger creep constitution was used for describing the surrounding rock and the Mohr–Coulomb criterion for describing the concrete anchor, was performed to further evaluate the long-term stability of the real working tunnel anchors. The numerical calculations are in good agreement with the laboratory testing results, and the creep deformations of the anchor and the surrounding rock have the same order of magnitude. The results show that the tunnel anchor and surrounding rock of Xingkang Bridge are in a stable creep state under the three different loads.

scholarly journals A Fractional Creep Constitutive Model for Frozen Soil in Consideration of the Strengthening and Weakening Effects

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Feng Hou ◽  
Quanming Li ◽  
Enlong Liu ◽  
Cheng Zhou ◽  
Mengke Liao ◽  
...  
Keyword(s):  
Shear Stress ◽  
Constitutive Model ◽  
Test Specimen ◽  
Confining Pressure ◽  
Frozen Soil ◽  
Strengthening Effect ◽  
Term Strength ◽  
Test Results ◽  
Creep Constitutive Model

The triaxial creep tests of frozen silty clay mixed with sands were performed under different pressures, and the test results demonstrated that, under the low confining pressure, when the shear stress is lower than the long-term strength, the test specimen exhibits an attenuation creep because the strengthening effect is greater than the weakening effect. When the shear stress is higher than the long-term strength, the test specimen exhibits a nonattenuation creep due to the level of the strengthening and weakening effects change in different stages. As the confining pressure increases, the test specimens only exhibit an attenuation creep because of the enhancing strengthening effect. Both the hardening parameter and the damage variable were introduced to describe the strengthening and weakening effects, respectively, and a new creep constitutive model for frozen soil considering these effects was put forward based on the theory of elastoviscoplastic and the fractional derivative. Finally, the model parameters were analyzed and their determination method was also provided to reveal the trend of parameters according to the triaxial test results. The calculated results of the constitutive model show that the proposed model can describe the whole creep process of frozen soil well.

scholarly journals Study of the Long-Term Deformation Characteristics of Municipal Sludge Solidified Soil under the Coupling Action of Dry-Wet Cycles and Initial Static Deviatoric Stress

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Aiwu Yang ◽  
Shaokun Yang ◽  
Guofang Xu ◽  
Wei Zhang
Keyword(s):  
Small Deformation ◽  
Deviatoric Stress ◽  
Creep Model ◽  
Hyperbolic Function ◽  
Deformation Characteristics ◽  
Municipal Sludge ◽  
Creep Tests ◽  
Short Period ◽  
Deviatoric Stresses

A self-developed curing agent is used to solidify the municipal sludge taken from Tianjin. Then, the long-term deformation characteristics of the sludge solidified soil are investigated by means of unconsolidated undrained creep tests with different dry-wet cycles for considering the influence of climate. The experimental results show that the attenuation rate of the shear peak strength of municipal sludge solidified soil decreases gradually with the increase of the number of dry-wet cycles, and the strength remains unchanged when the number of dry-wet cycles is greater than 10. The variation laws under different initial static deviatoric stresses are basically identical. When the applied stress is less than the yield stress of the sludge solidified soil, the duration curves of creep show only attenuated stage, i.e., with very small deformation, and the deformation reaches a constant in a short period of time. When the deviatoric stress reaches the long-term strength of the soil, the instantaneous deformation of the sludge solidified soil becomes large and damage occurs quickly. Under the same deviatoric stress, the creep deformation increases with the increase of the number of dry-wet cycles. When the load applied in each step is of the same magnitude, the higher the initial static deviatoric stress is, the larger the deformation of sludge solidified soil will be. It is found that the stress-strain relationship and the relationship between creep strain and time can be well described by an exponential function and a hyperbolic function, respectively. On this basis, a creep model is proposed for the long-term deformation considering the effect of dry-wet cycle times and initial static deviatoric stress. The model is further validated by comparing the predictions with the test results under different deviatoric stresses; the good agreement between which shows the potential application of the model to relevant practical engineering.

scholarly journals Study on the Creep Constitutive Model of a Sandstone Rock under the Water-Rock Interaction

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Zuosen Luo ◽  
Zuoxiang Zhu ◽  
Jianlin Li ◽  
Lehua Wang ◽  
Qiao Jiang ◽  
...  
Keyword(s):  
Rock Mass ◽  
Constitutive Model ◽  
Nonlinear Creep ◽  
Rock Interaction ◽  
Long Term Stability ◽  
Sandstone Rock ◽  
Influence Of Water ◽  
Creep Constitutive Model ◽  
Water Rock Interaction

With the continuous construction of large-scale geotechnical engineering, more and more attention has been paid to the long-term stability of rock mass engineering, especially the problem of rock creep under the influence of water. Combined with the author’s previous research on the triaxial creep characteristics of sandstone under water-rock interaction, a nonlinear creep constitutive model was established to capture the degradation behavior of a sandstone rock due to cyclic wetting and drying of the reservoir water. Due to the limitations of the visco-elastoplastic model, a thorough modification was done to account the effect of the water-rock interaction on the mechanical degradation of the sandstone rock. Finally, the predicted results were proved to be in a good agreement with the experimental results. Moreover, the strong correlations between the predicted results and the experimental results show the effectiveness of the modified model to scrutinize the nonlinear creep behavior of sandstone rock. Relevant research results have important theoretical significance for the accurate prediction and effective control of the long-term stability of rock mass engineering under the influence of water-rock interaction.

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