scholarly journals Viscoelastic-Viscoplastic Modelling of the Scratch Response of PMMA

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
G. Kermouche ◽  
N. Aleksy ◽  
J. M. Bergheau
Keyword(s):  
Experimental Study ◽  
A Priori ◽  
Constitutive Models ◽  
Young Modulus ◽  
Element Model ◽  
Time Dependent ◽  
Viscoplastic Model ◽  
Solid Polymers ◽  
Dependent Behavior ◽  
In Series

This paper aims at understanding how to model the time-dependent behavior of PMMA during a scratch loading at a constant speed and at middle strain levels. A brief experimental study is first presented, consisting of the analysis of microscratches carried out at various scratching velocities and normal loads. The loading conditions have been chosen in such a way that neither (visco)elasticity nor (visco)plasticity of the PMMA may be neglected a priori. The main analyzed parameter is the tip penetration depth measured during the steady state. Then, a finite element model is used to investigate the potential of classical elastic-viscoplastic constitutive models to reproduce these experimental results. It is mainly shown that these models lead to unsatisfying results. More specifically, it is pointed out here that the time-independent Young modulus used in such models is not suitable. To take into account this feature, a viscoelastic-viscoplastic model based on the connection in series of a viscoelastic part with a viscoplastic part is proposed. It is shown that it leads to more acceptable results, which points out the importance of viscoelasticity in the scratch behavior of solid polymers.

Study on the Choice of Constitutive and Fatigue Models in Solder Joint Life Prediction

2002 ◽  
Author(s):  
Krishna Tunga ◽  
James Pyland ◽  
Raghuram V. Pucha ◽  
Suresh K. Sitaraman
Keyword(s):  
Experimental Data ◽  
Fatigue Life ◽  
Solder Joint ◽  
Predictive Models ◽  
Life Prediction ◽  
Constitutive Models ◽  
Ball Grid Array ◽  
Time Dependent ◽  
Dependent Behavior ◽  
Ball Grid Array Packages

Various constitutive and fatigue-life predictive models for lead-tin solders in SBGA (Super Ball Grid Array) packages are studied and compared with the results from experimental data. Two solder compositions, 62Sn/36Pb/2Ag and 63Sn/37Pb are studied in this work. The fatigue life of 62Sn/36Pb/2Ag solder is studied using different constitutive models that take into consideration both the time-independent and time-dependent behavior of the solder. The fatigue life of 62Sn/36Pb/2Ag solder is predicted using an energy-based predictive model and compared with the experimental data. The choice of various predictive models on the solder joint life is studied using 63Sn/37Pb solder. Various predictive models, available in the literature, for eutectic and near eutectic solder compositions are studied to predict the fatigue life. Guidelines are provided for selecting constitutive and predictive models with appropriate damage metrics.

Constitutive Modeling for Uniaxial Time-Dependent Ratcheting of SS304 Stainless Steel

2007 ◽  
Vol 340-341 ◽  
pp. 817-822 ◽  
Author(s):  
Guo Zheng Kang ◽  
Qian Hua Kan ◽  
Juan Zhang ◽  
Yu Jie Liu
Keyword(s):  
Stainless Steel ◽  
Room Temperature ◽  
Kinematic Hardening ◽  
Constitutive Models ◽  
Experimental Results ◽  
Time Dependent ◽  
Dominant Factor ◽  
Superposition Model ◽  
Viscoplastic Model ◽  
Reasonable Description

Based on the experimental results of uniaxial time-dependent ratcheting behavior of SS304 stainless steel at room temperature and 973K, three kinds of time-dependent constitutive models were employed to describe such time-dependent ratcheting by using the Ohno-Abdel-Karim kinematic hardening rule, i.e., a unified viscoplastic model, a creep-plasticity superposition model and a creep-viscoplasticity superposition model. The capabilities of such models to describe the time-dependent ratcheting were discussed by comparing with the corresponding experimental results. It is shown that the unified viscoplastic model cannot provide reasonable simulation to the time-dependent ratcheting, especially to those with certain peak/valley stress hold and at 973K; the proposed creep-plasticity superposition model is reasonable when the creep is a dominant factor of the deformation, however, it cannot provide a reasonable description when the creep is weak; the creep-viscoplastic superposition model is reasonable not only at room temperature but also at high temperature.

An Experimental Study of Grease in Elastohydrodynamic Lubrication

1972 ◽  
Vol 94 (1) ◽  
pp. 27-34 ◽  
Author(s):  
S. Y. Poon
Keyword(s):  
Experimental Study ◽  
High Temperature ◽  
Low Temperature ◽  
Elastohydrodynamic Lubrication ◽  
Time Dependent ◽  
Base Oil ◽  
Mineral Oils ◽  
Lubricating Film ◽  
Dependent Behavior ◽  
Inlet Zone

The formation of a lubricating film by grease in conditions pertinent to elastohydrodynamic lubrication is studied in a disk machine, and the thickness measured by means of a magnetic reluctance technique. The greases examined are three lithium hydroxystearate greases, of different soap structures and soap contents, a low temperature sodium-based grease, and a high temperature clay-based grease, all in mineral oils. The film thickness of greases in EHL differs from that of pure mineral oils in one important aspect: with one charge of the lubricant the thickness decreases continuously with time. The time-dependent behavior of greases is examined in relation to the thickener structure, viscosity of the base oil, and the conditions of the inlet zone.

Time-Dependent Behavior of the Tunnels in Squeezing Ground: An Experimental Study

2021 ◽  
Vol 54 (4) ◽  
pp. 1755-1777
Author(s):  
Ketan Arora ◽  
Marte Gutierrez ◽  
Ahmadreza Hedayat ◽  
Erick Christian Cruz
Keyword(s):  
Experimental Study ◽  
Time Dependent ◽  
Squeezing Ground ◽  
Dependent Behavior

Experimental Study on Time-Dependent Behavior of Cracked UHP-FRCC Under Sustained Loads

2016 ◽  
pp. 101-109 ◽  
Author(s):  
Tomoya Nishiwaki ◽  
Sukmin Kwon ◽  
Hiroto Otaki ◽  
Go Igarashi ◽  
Faiz U.A. Shaikh ◽  
...  
Keyword(s):  
Experimental Study ◽  
Time Dependent ◽  
Dependent Behavior ◽  
Sustained Loads

Creep and Dilatancy Behavior of Rock Salt around Underground Caverns

2012 ◽  
Vol 629 ◽  
pp. 418-422
Author(s):  
S. Nazary Moghadam ◽  
H. Mirzabozorg ◽  
A. Noorzad ◽  
K. Nazokkar
Keyword(s):  
Finite Element ◽  
Rock Salt ◽  
Time Dependent ◽  
Finite Element Analyses ◽  
Volume Changes ◽  
Viscoplastic Model ◽  
Dependent Behavior ◽  
Underground Caverns ◽  
Finite Element Procedure ◽  
Stress And Deformation

In the present paper, the time-dependent behavior of a salt cavern was analyzed using finite element method. A viscoplastic model considering inelastic volume changes was utilized to describe the time-dependent mechanical behavior of rock salt. The model was then implemented in a finite element procedure to analyze the stress and deformation of rock salt around an underground cavern using an axisymmetric representation. Finally, finite element analyses results were compared with those obtained by a viscoplastic model neglecting inelastic volume changes.

scholarly journals Long-term behavior of connections for glubam-concrete composite beams

2019 ◽  
Vol 275 ◽  
pp. 01001
Author(s):  
Xin Ye ◽  
Bo Shan ◽  
Qian Yue ◽  
Zhenyu Wang
Keyword(s):  
Concrete Slab ◽  
Constitutive Models ◽  
Time Dependent ◽  
Construction Technique ◽  
Relative Slip ◽  
Laminated Bamboo ◽  
Dependent Behavior ◽  
Bcc Structure ◽  
Long Term Behavior

Glubam-concrete composite (BCC) structure is a construction technique where glue-laminated bamboo beam is connected to an upper concrete slab using different types of connectors. The long-term behavior and creep mechanism of BCC system are very complex due to different time-dependent behavior of three components. This paper performed a series long-term push-out tests on four types of connections under static load. The tests lasted for a period of seven months in uncontrolled sheltered indoor condition. Important results such as the relative slip-time curves are presented in order to characterize time-dependent behavior of connectors. Furthermore creep coefficient constitutive models are provided for predicting the long-term behavior of connections.

Time-Dependent Cyclic Deformation and Failure Behavior and Its Damage Coupled Simulation for Solder Alloy 63Sn-37Pb

2005 ◽  
Vol 297-300 ◽  
pp. 881-886 ◽  
Author(s):  
Xianjie Yang ◽  
Qing Gao
Keyword(s):  
Solder Alloy ◽  
Failure Criterion ◽  
Cyclic Deformation ◽  
Cyclic Strain ◽  
Cyclic Stress ◽  
Time Dependent ◽  
Failure Behavior ◽  
Deformation And Failure ◽  
Viscoplastic Model ◽  
Dependent Behavior

The tests of 63Sn-37Pb under cyclic strain and stress were conducted to investigate the material’s time-dependent behavior. A damage-coupled viscoplastic model and its failure criterion are proposed. The prediction of the proposed viscoplastic model implies that the model can describe the cyclic strain and cyclic stress ratcheting behavior, and the fatigue lives very well.

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