Experimental results of high damping rubber under combined compression and cyclic shear

2013 ◽  
pp. 467-472
Keyword(s):  
Experimental Results ◽  
Cyclic Shear ◽  
High Damping Rubber

A Damage Mechanics-Based Fatigue Life Prediction Model for Solder Joints

2003 ◽  
Vol 125 (1) ◽  
pp. 120-125 ◽  
Author(s):  
Hong Tang ◽  
Cemal Basaran
Keyword(s):  
Fatigue Life ◽  
Prediction Model ◽  
Life Prediction ◽  
Damage Mechanics ◽  
Solder Joints ◽  
Experimental Results ◽  
Fatigue Life Prediction ◽  
Isotropic Hardening ◽  
Cyclic Shear ◽  
Life Prediction Model

A thermomechanical fatigue life prediction model based on the theory of damage mechanics is presented. The damage evolution, corresponding to the material degradation under cyclic thermomechanical loading, is quantified thermodynamic framework. The damage, as an internal state variable, is coupled with unified viscoplastic constitutive model to characterize the response of solder alloys. The damage-coupled viscoplastic model with kinematic and isotropic hardening is implemented in ABAQUS finite element package to simulate the cyclic softening behavior of solder joints. Several computational simulations of uniaxial monotonic tensile and cyclic shear tests are conducted to validate the model with experimental results. The behavior of an actual ball grid array (BGA) package under thermal fatigue loading is also simulated and compared with experimental results.

Experimental Study on High Damping Rubber Under Combined Action of Compression and Shear

2015 ◽  
Vol 137 (1) ◽  
Author(s):  
Tinard Violaine ◽  
Nguyen Quang Tam ◽  
Fond Christophe
Keyword(s):  
Static Load ◽  
Mullins Effect ◽  
Compression Tests ◽  
Static Compression ◽  
Cyclic Shear ◽  
Combined Action ◽  
Loading Tests ◽  
High Damping Rubber ◽  
Quasi Static Compression ◽  
Time Dependance

High damping rubber (HDR) is used in HDR bearings (HDRBs) which are dissipating devices in structural systems. These devices actually have to support permanent static load in compression and potential cyclic shear when earthquakes occur. Mastering the behavior of bearings implies an accurate understanding of HDR response in such configuration. The behavior of HDR is, however, complex due to the nonlinearity and time dependance of stress–strain response and especially Mullins effect. To the authors' knowledge, tests on HDR under combined quasi-static compression and cyclic shear (QC-CS) have not been performed with regard to Mullins effect yet. The purpose of this study is thus to assess experimentally Mullins effect in HDR, especially under QC-CS. In order to achieve this aim, cyclic tensile and compression tests were first carried out to confirm the occurrence of Mullins effect in the considered HDR. Then, an original biaxial setup allowing testing HDR specimen under QC-CS was developed. This setup enables us to identify Mullins effect of the considered HDR under this kind of loading. Tests carried out with this setup were thus widened to the study of the influence of compression stress on shear response under this loading, especially in terms of shear modulus and density of energy dissipation.

Implementation of a Thermodynamic Framework for Damage Mechanics of Solder Interconnects in Microelectronic Packaging

2002 ◽  
Author(s):  
Cemal Basaran ◽  
Hong Tang
Keyword(s):  
Damage Mechanics ◽  
Internal State ◽  
Fatigue Loading ◽  
Cyclic Softening ◽  
Experimental Results ◽  
Isotropic Hardening ◽  
Cyclic Shear ◽  
Softening Behavior ◽  
Thermodynamic Framework ◽  
Bga Package

A thermo mechanical fatigue life prediction model based on the theory of damage mechanics is presented. The damage evolution, corresponding to the material degradation under cyclic thermo mechanical loading, is quantified thermodynamic framework. The damage, as an internal state variable, is coupled with unified viscoplastic constitutive model to characterize the response of solder alloys. The damage-coupled viscoplastic model with kinematic and isotropic hardening is implemented in ABAQUS finite element package to simulate the cyclic softening behavior of solder joints. Several computational simulations of uniaxial monotonic tensile and cyclic shear tests are conducted to validate the model with experimental results. The behavior of an actual Ball Grid Array (BGA) package under thermal fatigue loading is also simulated and compared with experimental results.

Viscoelastic relaxation in liquid mixtures

1969 ◽  
Vol 309 (1499) ◽  
pp. 473-496 ◽  
Keyword(s):  
Molecular Weight ◽  
Binary Mixtures ◽  
Mole Fraction ◽  
Supercooled Liquids ◽  
Experimental Results ◽  
Viscoelastic Relaxation ◽  
Cyclic Shear ◽  
Additional Constant ◽  
Family Of Curves ◽  
Complex Compliance

The authors have previously described a model from which the viscoelastic relaxation of supercooled liquids in alternating shear can be predicted. According to this model, the complex compliance of the liquid is represented by the equation J * = 1/ G ∞ [1+1/j ωr +2/(j ωr ) 4 ], where G ∞ is the limiting high frequency shear modulus and r is the Maxwell relaxation time ( = η/G ∞ ). Measurements have now been made of the viscoelastic properties of binary mixtures of pure liquids which separately conform to the description of the above model and results obtained on seven such mixtures are reported in this paper. In all cases, it is found that viscoelastic relaxation in these systems can be accounted for by the introduction of a single additional constant, K , into the equation for the complex compliance such that J * = 1/ G ∞ [1 + 1/j ωr + 2 K /(j ωr ) 1/2 ]. The value of the constant K is found by comparing experimental results over the region of viscoelastic relaxation with a family of curves computed for different values of K . For binary mixtures in which the two components have either closely similar molecular weights or are isomers, the original model ( K = 1) applies for all concentrations investigated. However, if the components of the mixture differ appreciably in molecular weight, a systematic variation of K with mole fraction is found. A single curve of K against mole fraction of the lower molecular weight components represents the results obtained on four such mixtures of liquids which differ significantly in molecular composition. The maximum value of K is 1·8 at 0·8 mole fraction and the minimum value is 0·25 at 0·2 mole fraction. For all mixtures K is equal to unity at 0·5 mole fraction. Results are given for a number of other liquids including white oil ( K = 1) and castor oil, for which K is equal to 2·90. Without exception, all non-polymeric liquids on which measurements have been made show a viscoelastic behaviour in cyclic shear which can be fitted by the present model with an appropriate choice for the value of the constant K . Agreement between the calculated curves and experimental results is within experimental error over the ranges of frequency and temperature employed in this work. In accordance with previous work, K is equal to unity for pure supercooled liquids.

Experimental Assessment of High Damping Rubber Under Combined Compression and Shear

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Virginio Quaglini ◽  
Paolo Dubini ◽  
Giacomo Vazzana
Keyword(s):  
Seismic Isolation ◽  
Compression Stress ◽  
Vertical Load ◽  
Experimental Assessment ◽  
Elastomeric Bearings ◽  
Experimental Procedure ◽  
Cyclic Shear ◽  
High Damping Rubber ◽  
Rubber Bearings ◽  
Correct Understanding

High damping rubber (HDR) is used in the manufacturing of elastomeric bearings for seismic isolation of building and structures. In practical situations, rubber bearings are subjected to a permanent vertical load which may change at the occurrence of the earthquake, and concurrent shear deformation, due to either service movements of the structure or earthquake-induced ground motion. The study presents an experimental procedure for the assessment of HDR specimens under combined compression and shear, reproducing the same typical load regimes which rubber isolators experience in service. Five commercial HDRs were tested according to the procedure. The results point to the importance of considering the influence of the compression stress for a correct understanding of the behavior of HDRs under cyclic shear.

Diagnostics of Gold Laser Plasmas

1988 ◽  
Vol 102 ◽  
pp. 357-360
Author(s):  
J.C. Gauthier ◽  
J.P. Geindre ◽  
P. Monier ◽  
C. Chenais-Popovics ◽  
N. Tragin ◽  
...  
Keyword(s):  
Experimental Results ◽  
Pure Gold ◽  
Electronic Temperature ◽  
X Ray ◽  
Laser Plasmas ◽  
Collisional Radiative Model ◽  
Radiative Model

AbstractIn order to achieve a nickel-like X ray laser scheme we need a tool to determine the parameters which characterise the high-Z plasma. The aim of this work is to study gold laser plasmas and to compare experimental results to a collisional-radiative model which describes nickel-like ions. The electronic temperature and density are measured by the emission of an aluminium tracer. They are compared to the predictions of the nickel-like model for pure gold. The results show that the density and temperature can be estimated in a pure gold plasma.

Observation of Phase Contrast Images in STEM and CTEM Modes by Using 100 kV Field Emission Electron Gun

1974 ◽  
Vol 32 ◽  
pp. 390-391
Author(s):  
Y. Harada ◽  
T. Goto ◽  
H. Koike ◽  
T. Someya
Keyword(s):  
Field Emission ◽  
Phase Contrast ◽  
Image Formation ◽  
Fresnel Diffraction ◽  
Experimental Results ◽  
Electron Gun ◽  
Scanning Microscopy ◽  
Emission Electron ◽  
Lattice Images

Since phase contrasts of STEM images, that is, Fresnel diffraction fringes or lattice images, manifest themselves in field emission scanning microscopy, the mechanism for image formation in the STEM mode has been investigated and compared with that in CTEM mode, resulting in the theory of reciprocity. It reveals that contrast in STEM images exhibits the same properties as contrast in CTEM images. However, it appears that the validity of the reciprocity theory, especially on the details of phase contrast, has not yet been fully proven by the experiments. In this work, we shall investigate the phase contrast images obtained in both the STEM and CTEM modes of a field emission microscope (100kV), and evaluate the validity of the reciprocity theory by comparing the experimental results.

A new dissociation mode for dislocations in silicon

1978 ◽  
Vol 36 (1) ◽  
pp. 346-347
Author(s):  
A. Ourmazd ◽  
G.R. Booker ◽  
C.J. Humphreys
Keyword(s):  
Detailed Examination ◽  
Experimental Results ◽  
Dislocation Network ◽  
Weak Beam ◽  
Phosphorus Doped

A (111) phosphorus-doped Si specimen, thinned to give a TEM foil of thickness ∼ 150nm, contained a dislocation network lying on the (111) plane. The dislocation lines were along the three <211> directions and their total Burgers vectors,ḇt, were of the type , each dislocation being of edge character. TEM examination under proper weak-beam conditions seemed initially to show the standard contrast behaviour for such dislocations, indicating some dislocation segments were undissociated (contrast A), while other segments were dissociated to give two Shockley partials separated by approximately 6nm (contrast B) . A more detailed examination, however, revealed that some segments exhibited a third and anomalous contrast behaviour (contrast C), interpreted here as being due to a new dissociation not previously reported. Experimental results obtained for a dislocation along [211] with for the six <220> type reflections using (g,5g) weak-beam conditions are summarised in the table below, together with the relevant values.

Multislice calculations of RHEED patterns from vicinal Si (001)

1993 ◽  
Vol 51 ◽  
pp. 1000-1001
Author(s):  
Scott Lordi
Keyword(s):  
Misorientation Angle ◽  
Incident Angle ◽  
Incident Beam ◽  
Experimental Results ◽  
Bragg Condition ◽  
Vicinal Surfaces ◽  
Kinematic Theory ◽  
Step Edges

Vicinal Si (001) surfaces are interesting because they are good substrates for the growth of III-V semiconductors. Spots in RHEED patterns from vicinal surfaces are split due to scattering from ordered step arrays and this splitting can be used to determine the misorientation angle, using kinematic arguments. Kinematic theory is generally regarded to be inadequate for the calculation of RHEED intensities; however, only a few dynamical RHEED simulations have been attempted for vicinal surfaces. The multislice formulation of Cowley and Moodie with a recently developed edge patching method was used to calculate RHEED patterns from vicinal Si (001) surfaces. The calculated patterns are qualitatively similar to published experimental results and the positions of the split spots quantitatively agree with kinematic calculations.RHEED patterns were calculated for unreconstructed (bulk terminated) Si (001) surfaces misoriented towards [110] ,with an energy of 15 keV, at an incident angle of 36.63 mrad ([004] bragg condition), and a beam azimuth of [110] (perpendicular to the step edges) and the incident beam pointed down the step staircase.

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