Prediction of the Linear Viscoelastic Shear Modulus of an Entangled Polybutadiene Melt from Simulation and Theory

2001 ◽  
Vol 34 (1) ◽  
pp. 134-139 ◽  
Author(s):  
Oleksiy Byutner ◽  
Grant D. Smith
Keyword(s):  
Shear Modulus ◽  
Linear Viscoelastic ◽  
Polybutadiene Melt

scholarly journals Relaxation time spectra of basaltic lavas between 500–1150 °C reveal patterns of Kramers–Kronig inconsistency of the complex viscoelastic shear modulus

2019 ◽  
Vol 49 (2) ◽  
pp. 109-132
Author(s):  
Martin Bednárik ◽  
Igor Kohút
Keyword(s):  
Relaxation Time ◽  
Shear Modulus ◽  
Field Experiments ◽  
Loss Modulus ◽  
Laboratory Data ◽  
Viscoelastic Model ◽  
Time Spectrum ◽  
Loss Angle ◽  
Linear Viscoelastic ◽  
Basaltic Lavas

Abstract An important, yet until now neglected, aspect of the viscoelastic behaviour of lavas is the Kramers–Kronig consistency of their complex viscoelastic shear modulus. The most general linear viscoelastic model – the generalized Maxwell body with continuous relaxation time spectrum – produces a consistent storage and loss modulus, as can be verified by Kramers–Kronig formulae. We reprocessed the original datasets of the high-precision laboratory data by James et al. (2004) supplied as pairs of magnitude of the complex viscoelastic shear modulus and the loss angle. We introduce the magnitude-borne and loss-angle-borne logarithmic relaxation time spectra and their ratio as a suitable indicator of the linear viscoelastic inconsistency. The basaltic lavas from Etna, Hawai’i and Vesuvius have shown a general convergence to the ideal consistency with increasing temperature, although each sample with an individual inconsistency pattern. The biggest surprise is the inconsistency ratio rising to ~20 in Etna 1992 top sample at 786 °C. Such a high inconsistency level still waits for an explanation and for the discoveries of its class-mates either in laboratory or field experiments.

Modeling of Tread Block Contact Mechanics Using Linear Viscoelastic Theory3

2008 ◽  
Vol 36 (3) ◽  
pp. 211-226 ◽  
Author(s):  
F. Liu ◽  
M. P. F. Sutcliffe ◽  
W. R. Graham
Keyword(s):  
High Speed ◽  
Slip Rate ◽  
Material Model ◽  
Contact Forces ◽  
Block Modeling ◽  
Rate Dependent ◽  
Linear Viscoelastic Material ◽  
Linear Viscoelastic ◽  
The Impact ◽  
Good Agreement

Abstract In an effort to understand the dynamic hub forces on road vehicles, an advanced free-rolling tire-model is being developed in which the tread blocks and tire belt are modeled separately. This paper presents the interim results for the tread block modeling. The finite element code ABAQUS/Explicit is used to predict the contact forces on the tread blocks based on a linear viscoelastic material model. Special attention is paid to investigating the forces on the tread blocks during the impact and release motions. A pressure and slip-rate-dependent frictional law is applied in the analysis. A simplified numerical model is also proposed where the tread blocks are discretized into linear viscoelastic spring elements. The results from both models are validated via experiments in a high-speed rolling test rig and found to be in good agreement.

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