Modeling the temperature‐dependent viscoelastic behavior of glass fabric with binder in the compaction process

2021 ◽  
Author(s):  
Ming Mei ◽  
Yujia He ◽  
Kai Wei ◽  
Shuyong Duan ◽  
Maojun Li ◽  
...  
Keyword(s):  
Viscoelastic Behavior ◽  
Glass Fabric ◽  
Temperature Dependent ◽  
Compaction Process

Modeling of Underfilled PBGA Assemblies Using Both Viscoelastic and Elastic Material Properties

2019 ◽  
Author(s):  
Promod R. Chowdhury ◽  
Jeffrey C. Suhling ◽  
Pradeep Lall
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Solder Joint ◽  
Viscoelastic Properties ◽  
Computational Cost ◽  
Viscoelastic Behavior ◽  
Polymer Materials ◽  
Temperature Dependent ◽  
Solder Joint Fatigue ◽  
Underfill Material

Abstract In microelectronics packaging industry, polymer based materials are used extensively. These polymer materials show viscoelastic behavior when subject to time dependent loads or deformations. The viscoelastic behavior highly depends on both temperature and time. In many cases, these viscoelastic properties are often neglected due to saving computational cost or unavailability of full characterization of the viscoelastic properties. To make accurate predictions of packaging mechanical behavior and reliability, it is important to accurately characterize the viscoelastic behavior of mold compounds, underfill encapsulants, adhesives and other polymers used in electronic assemblies. After characterization, these parameters can be used as input material property data for finite element analysis (FEA) simulations. In this study, both frequency dependent dynamic mechanical analysis (DMA) measurements, and strain and temperature dependent stress relaxation experiments were performed on a typical underfill material in order to characterize its linear viscoelastic behavior. In both cases, a master curve was determined using the assumption of time-temperature equivalence, and Prony series expansions were utilized to model the underfill material relaxation behavior. After that, these viscoelastic underfill material parameters were used in finite element models of underfilled ball grid array packages (Ultra CSP) subjected to thermal cycling from −40 to 125 °C. Separate simulations were also performed using temperature dependent elastic properties for the underfill material. In both cases, the solder joint fatigue life was estimated, and the effects of using viscoelastic properties for the underfill in solder joint fatigue life simulation were investigated.

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.

scholarly journals Adhesive Behavior of Propolis on Different Substrates

2021 ◽  
Vol 7 ◽  
Author(s):  
Leonie Saccardi ◽  
Jonas Schiebl ◽  
Katharina Weber ◽  
Oliver Schwarz ◽  
Stanislav Gorb ◽  
...  
Keyword(s):  
Viscoelastic Behavior ◽  
Point Of View ◽  
Organic Substances ◽  
Compression Tests ◽  
Temperature Dependent ◽  
Scanning Calorimetry ◽  
Adhesive Properties ◽  
Wide Range ◽  
Medicinal Properties ◽  
Main Components

Propolis is a sticky substance used by bees to seal their hive and protect the colony against pathogens. Its main components are plant resins, beeswax, essential oils, pollen, and other organic substances. The chemical and medicinal properties of propolis have been extensively studied, but little is known about its physical and especially adhesive properties. To gain a better understanding of propolis and its potential for adhesive applications, we performed several experiments, including adhesion tests with propolis in different conditions and on various substrates, differential scanning calorimetry analysis, and compression tests. Propolis shows clear viscoelastic behavior and temperature-dependent mechanical properties. Our results demonstrate that propolis adheres well to a wide range of substrates from glass to PTFE, but also enables stronger adhesion at higher temperatures and longer contact times. Even underwater, in wet conditions, quite a substantial adhesion was measured. The data are interpreted from a biomechanical point of view, and the significance of the obtained results for bee biology is discussed.

A Frequency-Domain Model of Bitumen-Coated Armor Wires in Subsea Power Cables, Umbilicals, and Power Umbilicals

2016 ◽  
Author(s):  
Magnus Komperød
Keyword(s):  
Viscoelastic Behavior ◽  
Bending Moment ◽  
Bending Stiffness ◽  
Domain Model ◽  
The Novel ◽  
Power Cables ◽  
Simple Analytical Model ◽  
Temperature Dependent ◽  
Anticorrosion Protection ◽  
Novel Model

Bitumen is commonly used as anticorrosion protection for armor wires in subsea power cables, umbilicals, and power umbilicals. Bitumen’s viscoelastic behavior influences the cable’s mechanical properties. The present paper derives a simple, analytical model of bitumen-coated armor wires. The model calculates the axial stresses of the armor wires and the armor wires’ contribution to the cable’s bending stiffness. The model shows that there is a phase shift between the sinusoidal curvature oscillations and the corresponding armor wire stresses and cable bending moment. Two examples show that the armor wire stresses and the cable’s bending stiffness are strongly temperature-dependent. The purpose of the novel model is to calculate bending stiffness, fatigue stresses, and capacity (allowed combinations of axial cable tension and cable bending curvature) more accurately and to study these variables’ sensitivity to temperature and frequency. The model may also be included in calculations of bitumen’s influence on VIV damping.

scholarly journals Buckling of laminated glass plates using the effective thickness concept

2020 ◽  
pp. 109963622092700 ◽  
Author(s):  
Manuel Aenlle-López ◽  
Fernandez Pelayo ◽  
Miguel M Calvente ◽  
Maria J Lamela-Rey
Keyword(s):  
Material Properties ◽  
Viscoelastic Behavior ◽  
Thin Plates ◽  
Laminated Glass ◽  
The Finite Element Method ◽  
Temperature Dependent ◽  
Plane Shear ◽  
Linear Elastic ◽  
Glass Panels ◽  
Glass Plates

The critical buckling loads of laminated glass panels are time and temperature dependent because the mechanical behavior of these elements is governed by the material properties of the interlayers, which exhibit a viscoelastic behavior. Although structural stability is one of the design requirements in laminated glass panels, the literature about buckling of these elements is sparse. The finite element method can be used to calculate the response of laminated glass plates, but the classical eigenvalue buckling analysis implemented in these programs does not consider the time and temperature dependency of the interlayers. In this paper, a simplified analytical method to calculate the buckling critical load of rectangular laminated glass plates is presented, where the equations corresponding to linear-elastic monolithic thin plates are modified with an effective stiffness [Formula: see text] dependent on the geometry, material properties, and boundary conditions of the plate. The analytical equations are validated by numerical simulations on simply-supported laminated glass plates subject to uniaxial, biaxial, and in-plane shear, the maximum discrepancies being less than 10% for all the cases studied in the paper.

Dynamic Infrared Linear Dichroism Study of the Temperature-Dependent, Viscoelastic Behavior of a Poly(Ester Urethane)

2005 ◽  
Vol 59 (3) ◽  
pp. 305-315 ◽  
Author(s):  
Yanqia Wang ◽  
Steven R. Aubuchon ◽  
Mark E. Smith ◽  
Jon R. Schoonover ◽  
Richard A. Palmer
Keyword(s):  
Molecular Level ◽  
Viscoelastic Behavior ◽  
Linear Dichroism ◽  
Mechanical Analysis ◽  
Multivariate Curve Resolution ◽  
Temperature Dependent ◽  
Curve Resolution ◽  
Spectral Changes ◽  
Storage And Loss Moduli ◽  
Insight Into

In the study reported here, of the poly(ester urethane), Estane® 5703, simultaneous dynamic mechanical analysis (DMA) and dynamic infrared linear dichroism (DIRLD) measurements have been carried out at continuously variable temperatures from −50 to +30 °C. Multivariate curve resolution–alternating least squares (MCR-ALS) analysis of the spectral data has been correlated with the thermo-mechanical properties. Spectral changes, analyzed as a function of temperature, are compared with the storage and loss moduli to provide insight into viscoelastic behavior at the molecular level. In addition, the data for pure Estane have been compared to those for plasticized Estane samples, which contain 10 and 30% plasticizer by weight. These comparisons show a strong and consistent correlation between the macroscopic rheological properties and the microscopic (molecular, inter-molecular, and sub-molecular) responses of this block co-polymer.

The Temperature-Dependent Viscoelastic Behavior of Dielectric Elastomers

2015 ◽  
Vol 82 (9) ◽  
Author(s):  
Jingkai Guo ◽  
Rui Xiao ◽  
Harold S. Park ◽  
Thao D. Nguyen
Keyword(s):  
Stress Relaxation ◽  
Master Curve ◽  
Viscoelastic Model ◽  
Viscoelastic Behavior ◽  
Thermomechanical Analysis ◽  
Quantitative Agreement ◽  
Dielectric Elastomers ◽  
Time To Failure ◽  
Temperature Dependent ◽  
Viscoelastic Creep

In this paper, we investigated the temperature-dependent viscoelastic behavior of dielectric elastomers (DEs) and the effects of viscoelasticity on the electro-actuation behavior. We performed dynamic thermomechanical analysis to measure the master curve of the stress relaxation function and the temperature dependence of the relaxation time of VHB 4905, a commonly used DE. The master curve was applied to calculate the viscoelastic spectrum for a discrete multiprocess finite deformation viscoelastic model. In addition, we performed uniaxial creep and stress relaxation experiments and electrical actuation experiments under different prestretch conditions. The measured spectrum was applied to predict the experimental results. Generally, the model produced good quantitative agreement with both the viscoelastic and electro-actuation experiments, which shows the necessity of using a multiprocess relaxation model to accurately capture the viscoelastic response for VHB. However, the model underpredicted the electro-actuated creep strain for high voltages near the pull-in instability. We attributed the discrepancies to the complex boundary conditions that were not taken into account in the simulation. We also investigated the failure of VHB membrane caused by viscoelastic creep when prestretched and subjected to constant voltage loading. The experimental time to failure for the specimens decreased exponentially with voltage, which agreed well with the predictions of the model.

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