Investigation and prediction on the nonlinear viscoelastic behaviors of nylon1212 toughened with elastomer

2011 ◽  
Vol 123 (3) ◽  
pp. 1283-1292 ◽  
Author(s):  
Wanjie Wang ◽  
Zhanling Lu ◽  
Yanxia Cao ◽  
Jinzhou Chen ◽  
Jingwu Wang ◽  
...  
Keyword(s):  
Nonlinear Viscoelastic ◽  
Viscoelastic Behaviors

Constitutive Characterization of the Nonlinear Viscoelastic Response of Vocal Fold Tissues

2002 ◽  
Author(s):  
Roger W. Chan ◽  
Thomas Siegmund
Keyword(s):  
Time Dependence ◽  
Shear Deformation ◽  
Vocal Fold ◽  
Superposition Principle ◽  
Tensile Loading ◽  
Elastic Response ◽  
Viscoelastic Response ◽  
Strain Dependence ◽  
Nonlinear Viscoelastic ◽  
Viscoelastic Behaviors

Previous empirical studies have shown that vocal fold tissues exhibit nonlinear viscoelastic behaviors under different loading conditions. Hysteresis and strain rate-dependence of stress-strain curves have been observed for different layers of vocal fold tissues when subjected to cyclic tensile loading [1,2]. Nonlinear viscoelastic response has also been described for vocal fold tissues subjected to constant strain and constant stress tests under both tensile loading and large-strain shear deformation conditions [3,4]. These findings cannot be adequately described by many of the traditional constitutive formulations of linear and quasilinear viscoelasticity. For instance, models based on Y. C. Fung’s quasilinear viscoelastic theory typically apply two separate functions to describe the time dependence and the strain dependence of stress (e.g., the reduced relaxation function G(t) and the elastic response σe(ε), respectively), and combine the two functions by the Boltzmann superposition principle [5]. Such formulations assume that time dependence and strain dependence can be separated. However, recently obtained stress relaxation data of vocal fold tissues under various magnitudes of applied shear strain indicated that they are not separable, as relaxation became slower with increasing strain [4]. This paper attempts to characterize some nonlinear viscoelastic behaviors of vocal fold tissues under tensile and shear deformation conditions based on an implementation of the Bergstrom-Boyce model [6,7].

scholarly journals Viscoelastic Rheological Behaviors of Polypropylene and LMPP Blends

Polymers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 3485
Author(s):  
Feichao Zhu ◽  
Sohail Yasin ◽  
Munir Hussain
Keyword(s):  
Large Amplitude ◽  
Viscoelastic Behavior ◽  
Nonlinear Behavior ◽  
Oscillatory Shear ◽  
Large Amplitude Oscillatory Shear ◽  
Mechanical Responses ◽  
Nonlinear Viscoelastic ◽  
Linear Viscoelastic ◽  
Viscoelastic Behaviors ◽  
Linear And Nonlinear

Dynamic oscillatory shear testing is used to investigate polymeric viscoelastic behaviors. Small and large amplitude oscillatory shear tests are the canonical method for characterizing the linear and nonlinear viscoelastic behaviors of any polymeric material. With prominent and abundant work on linear viscoelastic studies, the nonlinear behavior is evasive in terms of generating infinite higher harmonics in the nonlinear regime. For this reason, intrinsic nonlinearities from large amplitude oscillatory shear (LAOS) studies have recently been used for insights on microstructural behaviors. This study is carried out for linear and nonlinear viscoelastic behavior with a main focus on LAOS of isostatic polypropylene (iPP) and relatively new low molecular weight and low modulus polypropylene-based polyolefin (LMPP) blends. The morphological results showed reduced spherulitic crystal nucleus size and increased distribution in blends with increasing LMPP. The blends showed subtle linear viscoelastic responses with strong nonlinear mechanical responses to variant strain and stress compared to pure iPP. The intracycle strain thickening and intracycle strain stiffening of high-content LMPP blends were comparatively dominant at medium strain amplitudes.

PROLONGED TRUNK FLEXION CAN INCREASE SPINE LOADS DURING A SUBSEQUENT LIFTING TASK: AN INVESTIGATION OF THE EFFECTS OF TRUNK FLEXION DURATION AND ANGLE USING A SAGITTALLY SYMMETRIC, VISCOELASTIC SPINE MODEL

2013 ◽  
Vol 16 (04) ◽  
pp. 1350022 ◽  
Author(s):  
N. Toosizadeh ◽  
M. A. Nussbaum
Keyword(s):  
Injury Risk ◽  
Muscle Activation ◽  
Initial Step ◽  
Axial Stiffness ◽  
Trunk Flexion ◽  
Nonlinear Viscoelastic ◽  
Solid Models ◽  
Spine Model ◽  
Viscoelastic Behaviors ◽  
Load Peak

Load-relaxation of the human trunk following prolonged flexion has been observed earlier, yet the adverse effects of such viscoelastic behaviors on performing demanding tasks (e.g. lifting) remain poorly understood. Theoretically, trunk stiffness reduces following flexion exposures and requires a compensatory increase in paraspinal muscle activation and spine loads. Here, a multi-segment model with nonlinear viscoelastic properties was developed. After evaluating the model, it was used to predict changes, due to a range of trunk flexion exposures, in several outcome measures (i.e. peak spine load, peak axial stiffness and absorbed energy) at L5/S1 during simulated lifting. All three measures increased during lifting following flexion exposures, including a ~ 9% (~ 284 N) increase in spine loads, and these changes were magnified by increasing flexion duration and angle. These results support prior epidemiological evidence that occupational low back injury risk is elevated when prolonged trunk flexion along with lifting are required. Further, the dependency of spine loads on loading conditions was determined in response to several flexion angles and loading durations. The current modeling approach is considered as an initial step toward implementing Kelvin-solid models in future viscoelastic spine models.

MODELING NONLINEAR VISCOELASTIC BEHAVIOR UNDER LARGE DEFORMATIONS

2015 ◽  
Vol 88 (1) ◽  
pp. 28-39 ◽  
Author(s):  
Bing Jiang
Keyword(s):  
Large Deformations ◽  
Viscoelastic Behavior ◽  
Mathematical Structure ◽  
Material Parameters ◽  
Nonlinear Viscoelastic ◽  
Wide Range ◽  
Linear Spring ◽  
Nonlinear Viscoelastic Behavior ◽  
Viscoelastic Behaviors ◽  
Voigt Model

ABSTRACT A simple model was developed to describe the nonlinear viscoelastic behavior of rubberlike materials under large deformation in which the linear spring in the classical Kelvin-Voigt model is replaced by the Langevin-chain spring. This model has a simple mathematical structure and has only three material parameters. The model can capture the main features of the viscoelastic behaviors of polymers in wide range, from linear to nonlinear.

scholarly journals A Fictive Stress Model and Nonlinear Viscoelastic Behaviors in Metallic Glasses

2001 ◽  
Vol 42 (4) ◽  
pp. 597-605 ◽  
Author(s):  
H. S. Chen ◽  
Hidemi Kato ◽  
Akihisa Inoue
Keyword(s):  
Metallic Glasses ◽  
Stress Model ◽  
Nonlinear Viscoelastic ◽  
Viscoelastic Behaviors

Rheological characterization of tack and viscoelasticity of compositions of crepe coating used in the Yankee dryer

TAPPI Journal ◽  
2019 ◽  
Vol 18 (11) ◽  
pp. 641-649
Author(s):  
JOSHUA OMAMBALA ◽  
CARL MCINTYRE
Keyword(s):  
Normal Force ◽  
Weight Ratio ◽  
Good Combination ◽  
Rheological Characterization ◽  
Nonlinear Viscoelastic ◽  
Coating Composition ◽  
Linear And Nonlinear ◽  
Work Done ◽  
Tissue Production

The vast majority of tissue production uses creping to achieve the required set of properties on the base sheet. The Yankee coating helps to develop the desired crepe that in turn determines properties such as bulk and softness. The adhesion of the sheet to the Yankee surface is a very important characteristic to consider in achieving the desired crepe. The coating mix usually consists of the adhesive, modifier, and release. A good combination of these components is essential to achieving the desired properties of the tissue or towel, which often are determined by trials on the machine that can be time consuming and lead to costly rejects. In this paper, five compositions of an industrial Yankee coating adhesive, modifier, and release were examined rheologically. The weight ratio of the adhesive was kept constant at 30% in all five compositions and the modifier and release ratios were varied. The normal force and work done by the different compositions have been shown at various temperatures simulating that of the Yankee surface, and the oscillatory test was carried out to explain the linear and nonlinear viscoelastic characteristic of the optimal coating composition.

Sign in / Sign up

Export Citation Format

Share Document