Viscoelastic Characterization of an Epoxy-Based Molding Compound

1995 ◽  
Vol 390 ◽  
Author(s):  
V. H. Kenner ◽  
M. R. Julian ◽  
C. H. Popelar ◽  
M. K. Chengalva
Keyword(s):  
Stress Relaxation ◽  
Strain Rate ◽  
Constant Strain Rate ◽  
Viscoelastic Behavior ◽  
Tensile Tests ◽  
Prony Series ◽  
Master Curves ◽  
Molding Compound ◽  
Relaxation Curves

ABSTRACTThis paper describes the viscoelastic characterization of a highly filled epoxy molding compound commonly used in electronic packaging applications. Both stress relaxation tests and constant strain rate tensile tests were conducted. The material was found to be nonlinear in its viscoelastic behavior and to be amenable to horizontal shifting to form master curves. A representation of the master stress relaxation curves in terms of a Prony series is given, and the use of this representation illustrated in the context of both linear and nonlinear representations of the viscoelastic behavior to predict the results of the constant strain rate experiments.

Effect of Fiber Orientation and Strain Rate on the Nonlinear Uniaxial Tensile Material Properties of Tendon

2003 ◽  
Vol 125 (5) ◽  
pp. 726-731 ◽  
Author(s):  
Heather Anne Lynch ◽  
Wade Johannessen ◽  
Jeffrey P. Wu ◽  
Andrew Jawa ◽  
Dawn M. Elliott
Keyword(s):  
Stress Relaxation ◽  
Strain Rate ◽  
Material Properties ◽  
Poisson’S Ratio ◽  
Constant Strain Rate ◽  
Tensile Tests ◽  
Poisson's Ratio ◽  
Fiber Direction ◽  
Linear Region ◽  
Rate Dependent

Tendons are exposed to complex loading scenarios that can only be quantified by mathematical models, requiring a full knowledge of tendon mechanical properties. This study measured the anisotropic, nonlinear, elastic material properties of tendon. Previous studies have primarily used constant strain-rate tensile tests to determine elastic modulus in the fiber direction. Data for Poisson’s ratio aligned with the fiber direction and all material properties transverse to the fiber direction are sparse. Additionally, it is not known whether quasi-static constant strain-rate tests represent equilibrium elastic tissue behavior. Incremental stress-relaxation and constant strain-rate tensile tests were performed on sheep flexor tendon samples aligned with the tendon fiber direction or transverse to the fiber direction to determine the anisotropic properties of toe-region modulus E0, linear-region modulus (E), and Poisson’s ratio (ν). Among the modulus values calculated, only fiber-aligned linear-region modulus E1 was found to be strain-rate dependent. The E1 calculated from the constant strain-rate tests were significantly greater than the value calculated from incremental stress-relaxation testing. Fiber-aligned toe-region modulus E10=10.5±4.7 MPa and linear-region modulus E1=34.0±15.5 MPa were consistently 2 orders of magnitude greater than transverse moduli (E20=0.055±0.044 MPa,E2=0.157±0.154 MPa). Poisson’s ratio values were not found to be rate-dependent in either the fiber-aligned (ν12=2.98±2.59, n=24) or transverse (ν21=0.488±0.653, n=22) directions, and average Poisson’s ratio values in the fiber-aligned direction were six times greater than in the transverse direction. The lack of strain-rate dependence of transverse properties demonstrates that slow constant strain-rate tests represent elastic properties in the transverse direction. However, the strain-rate dependence demonstrated by the fiber-aligned linear-region modulus suggests that incremental stress-relaxation tests are necessary to determine the equilibrium elastic properties of tendon, and may be more appropriate for determining the properties to be used in elastic mathematical models.

The Effects of Physical Ageing and of Prior Immersion on the Esc Behaviour of Polycarbonate in Ethanol

1993 ◽  
Vol 305 ◽  
Author(s):  
J. C. Arnold ◽  
A. R. Eccott
Keyword(s):  
Strain Rate ◽  
Immersion Time ◽  
Constant Strain Rate ◽  
Tensile Tests ◽  
Strain Rates ◽  
Physical Ageing ◽  
Diffusion Effects ◽  
Craze Initiation ◽  
Comparison Of Tests

AbstractThe effects of physical ageing and prior immersion time on the ESC behaviour of polycarbonate in ethanol were studied. Constant strain rate tensile tests were performed at a range of strain rates for samples with ageing times varying from 100 hours to 3000 hours and for prior immersion times of between 1 hour and 500 hours. Comparison of tests performed in ethanol and in air gave a good indication of the point of craze initiation. The results showed that there was a reduction in strain to crazing as the strain rate decreased, apart from with the lowest strain rate used. A longer prior immersion time also promoted craze formation. Both of these results are attributable to diffusion effects. Physical ageing had little effect on the ESC behaviour, due to the large amounts of deformation encountered in this system.

Tensile Stress-Strain Curves Modeling of Four Kinds of Solders with Temperature and Rate Dependence

2005 ◽  
Vol 297-300 ◽  
pp. 905-911 ◽  
Author(s):  
Xu Chen ◽  
Li Zhang ◽  
Masao Sakane ◽  
Haruo Nose
Keyword(s):  
Tensile Stress ◽  
Constitutive Model ◽  
Strain Rate ◽  
Constant Strain Rate ◽  
Tensile Tests ◽  
Strain Rate Range ◽  
Rate Dependence ◽  
Strain Rates ◽  
Stress Strain ◽  
Rate Range

A series of tensile tests at constant strain rate were conducted on tin-lead based solders with different Sn content under wide ranges of temperatures and strain rates. It was shown that the stress-strain relationships had strong temperature- and strain rate- dependence. The parameters of Anand model for four solders were determined. The four solders were 60Sn-40Pb, 40Sn-60Pb, 10Sn-90Pb and 5Sn-95Pb. Anand constitutive model was employed to simulate the stress-strain behaviors of the solders for the temperature range from 313K to 398K and the strain rate range from 0.001%sP -1 P to 2%sP -1 P. The results showed that Anand model can adequately predict the rate- and temperature- related constitutive behaviors at all test temperatures and strain rates.

scholarly journals Recyclable Organocatalyzed Poly(Thiourethane) Covalent Adaptable Networks

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2913
Author(s):  
Francesco Gamardella ◽  
Sara Muñoz ◽  
Silvia De la Flor ◽  
Xavier Ramis ◽  
Angels Serra
Keyword(s):  
Stress Relaxation ◽  
Mechanical Characterization ◽  
Tensile Tests ◽  
Thermomechanical Analysis ◽  
Hexamethylene Diisocyanate ◽  
Relaxation Rates ◽  
Ftir Studies ◽  
New Type ◽  
And Performance

A new type of tetraphenylborate salts derived from highly basic and nucleophilic amines, namely 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU) and triazabicyclodecene (TBD), was applied to the preparation of networked poly(thiourethane)s (PTUs), which showed a vitrimer-like behavior, with higher stress-relaxation rates than PTUs prepared by using dibutyl thin dilaurate (DBTDL) as the catalyst. The use of these salts, which release the amines when heated, instead of the pure amines, allows the formulation to be easily manipulated to prepare any type of samples. The materials prepared from stoichiometric mixtures of hexamethylene diisocyanate (HDI), trithiol (S3) and with a 10% of molar excess of isocyanate or thiol were characterized by FTIR, thermomechanical analysis, thermogravimetry, stress-relaxation tests and tensile tests, thus obtaining a complete thermal and mechanical characterization of the materials. The recycled materials obtained by grinding the original PTUs and hot-pressing the small pieces in the optimized time and temperature conditions were fully characterized by mechanical, thermomechanical and FTIR studies. This allowed us to confirm their recyclability, without appreciable changes in the network structure and performance. From several observations, the dissociative interchange trans-thiocarbamoylation mechanism was evidenced as the main responsible of the topological rearrangements at high temperature, resulting in a vitrimeric-like behavior.

The Thermo-Viscoelastic, Viscoplastic Characterization of Vetrotex 324∕Derakane 510A-40 Through Tg

2006 ◽  
Vol 128 (4) ◽  
pp. 586-594 ◽  
Author(s):  
Steven E. Boyd ◽  
John J. Lesko ◽  
Scott W. Case
Keyword(s):  
Viscoelastic Behavior ◽  
Creep Data ◽  
Master Curves ◽  
Reinforced Plastics ◽  
Accumulated Damage ◽  
Nonlinear Viscoelastic ◽  
Nonlinear Viscoelastic Behavior ◽  
Fiber Reinforced Plastics ◽  
Fire Loading

The increased use of fiber reinforced plastics (FRPs) in ship topside structures necessitates the need to understand how such structures respond to fire exposure. For this reason we have characterized the nonlinear, thermo-viscoelastic behavior of Vetrotex 324∕Derakane 510A-40 using tensile loading of [±45]2S laminates. Nonlinearity is observed at elevated stress and temperatures above Tg. The data reduction sufficiently modeled the experimental master-curves over the whole temperature range, but suffered from inconsistencies in the creep data and recovery data, perhaps due to accumulated damage during the creep cycle. Our results indicate that the nonlinear viscoelastic behavior significantly contributes to structural behavior under fire loading conditions.

Packaging Induced Die Stresses—Effect of Chip Anisotropy and Time-Dependent Behavior of a Molding Compound

2003 ◽  
Vol 125 (4) ◽  
pp. 520-526 ◽  
Author(s):  
W. D. van Driel ◽  
J. H. J. Janssen ◽  
G. Q. Zhang ◽  
D. G. Yang ◽  
L. J. Ernst
Keyword(s):  
Creep Compliance ◽  
Viscoelastic Behavior ◽  
Master Curves ◽  
Temperature Dependent ◽  
Molding Compound ◽  
Dependent Behavior ◽  
Quad Flat Package ◽  
Different Temperatures ◽  
Induced Stresses

This paper investigates the effect of the anisotropic behavior of the die and the time- and temperature-dependent behavior of epoxy molding compound on the packaging induced stresses for a quad flat package. Finite element (FE) simulations using isotropic and anisotropic properties of the die are carried out, respectively, and the results are compared. Creep experiments were performed at different temperatures ranging from −65°C to 230°C to obtain the long-term master curves and the related shift factors for the creep compliance of the molding compound. FE models which incorporate the viscoelastic constitutive relation of the material are constructed to simulate the thermo-mechanical stresses caused by the packaging processes. The influences of both the chip anisotropy and the viscoelastic behavior of the molding compound on the packaging induced stresses are discussed.

Characterization of Hot Deformation Behavior of Ti-Al-Nb-Zr-Mo-Cr Alloy

2021 ◽  
Vol 1035 ◽  
pp. 328-333
Author(s):  
Li Wei Zhu ◽  
Zhi Shou Zhu ◽  
Xin Nan Wang
Keyword(s):  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Constant Strain Rate ◽  
Test Machine ◽  
Peak Efficiency ◽  
Hot Deformation Behavior ◽  
Dynamic Materials ◽  
Significant Difference

The hot deformation behavior of Ti-Al-Nb-Zr-Mo-Cr titanium alloy has been investigated using a Gleeble-1500D thermal simulation test machine in the temperature range of 855°C~1015°C,at constant strain rate from 0.01 s-1 to 10s-1 and with height reduction of 45%. The flow curves characteristic under different deformation parameters show significant difference. According to the stress-strain curves of the alloy and its stress characteristics, the Arrhenius constitutive equation was obtained. The average activation energy is about 541 kJ/mol in the α+β field, and about 243 kJ/mol in the β field, respectively. Based on the dynamic materials model, the processing map is generated, which shows that the peak efficiency domain appears at the temperature of 874°C~900°C and the strain rate of 0.001 s-1~0.06s-1 with a peak efficiency of 0.58 at about 887°C/0.001s-1.

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