Nonlinear creep response of oriented polypropylene tapes

2016 ◽  
Vol 232 (12) ◽  
pp. 987-992
Author(s):  
Nektaria M Barkoula ◽  
Ben Alcock ◽  
Tim B van Erp ◽  
Leon E Govaert ◽  
Ton Peijs
Keyword(s):  
Creep Compliance ◽  
Nonlinear Creep ◽  
Creep Response ◽  
Polypropylene Composites ◽  
Model Predictions ◽  
Oriented Polypropylene ◽  
Linear Viscoelastic ◽  
Polypropylene Tape ◽  
Oriented Polyethylene ◽  
Good Agreement

The creep response of a highly oriented polypropylene tape used for the manufacture of self-reinforced polypropylene or all-polypropylene composites was studied over a range of stresses and temperatures. Similar to oriented polyethylene, the creep compliance is linear viscoelastic at short loading times, whereas pronounced stress dependence is observed at longer loading times. A mathematical model is proposed, where the total deformation of the fibre is regarded as being composed of a stress-linear delayed elastic component and a nonlinear plastic flow contribution. Model predictions are in good agreement with the experimental data.

The Creep Behavior of a Floating Beam

1983 ◽  
Vol 27 (04) ◽  
pp. 271-280
Author(s):  
Paul C. Xirouchakis
Keyword(s):  
Cross Section ◽  
Creep Behavior ◽  
Failure Time ◽  
Failure Criteria ◽  
Secondary Creep ◽  
Nonlinear Creep ◽  
Double Membrane ◽  
Creep Response ◽  
Distributed Load ◽  
Linear Viscoelastic

The creep response is obtained for an inhomogeneous beam, with simple end supports, resting on a liquid foundation and subjected to a sinusoidally distributed load. The Norton-Bailey constitutive equations are used to describe secondary creep behavior and elastic effects are retained. The liquid foundation is taken as a continuous Winkler support. The beam cross section is replaced by a double-membrane model. The implications are discussed of using stress or deflection failure criteria in determining the magnitude of the instantaneous breakthrough load. The linear viscoelastic as well as nonlinear creep beam response is obtained explicitly. The influence of the beam geometric and material characteristics and of the presence of the liquid foundation on the growth of the deflections with time is discussed. The variation of the breakthrough load with failure time is also explored. Results obtained are compared with available sea ice laboratory test data.

Modelling of Nonlinear Creep and Recovery Behaviour of Cortical Bone

2011 ◽  
Vol 488-489 ◽  
pp. 186-189 ◽  
Author(s):  
Martina Lovrenić-Jugović ◽  
Zdenko Tonković ◽  
Ivica Skozrit
Keyword(s):  
Constitutive Model ◽  
Cortical Bone ◽  
Jacobian Matrix ◽  
Material Point ◽  
Creep Recovery ◽  
Nonlinear Creep ◽  
One Dimensional ◽  
Model Predictions ◽  
Point Level ◽  
Good Agreement

A new one-dimensional constitutive model for human cortical bone is proposed to simulate the viscoelastic–viscoplastic behaviour occurring during creep-recovery tests.The material parameters are determined by fitting experimental results of creep-recovery tests reported in the published literature. An efficient computational algorithm for the integration of the proposed constitutive model at the material point level is derived. The derived algorithm in conjunction with the Jacobian matrix is implemented in the finite element code ABAQUS. The model predictions are found to be in good agreement with the experimental data presented in literature.

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.

Rigid-Plastic Impact of Single Angular Particles

2021 ◽  
Author(s):  
Sandeep Dhar
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Orientation Dependence ◽  
Particle Orientation ◽  
Rigid Plastic ◽  
Plastic Model ◽  
Model Predictions ◽  
Good Agreement ◽  
Angular Particles

The trajectory of an angular particle as it cuts a ductile target is, in general, complicated because of its dependence not only on particle shape, but also on particle orientation at the initial instant of impact. This orientation dependence has also made experimental measurement of impact parameters of single angular particles very difficult, resulting in a relatively small amount of available experimental data in the literature. The current work is focused on obtaining measurements of particle kinematics for comparison to rigid plastic model developed by Papini and Spelt. Fundamental mechanisms of material removal are identified, and measurements of rebound parameters and corresponding crater dimensions of single hardened steel particles launched against flat aluminium alloy targets are presented. Also a 2-D finite element model is developed and a dynamic analysis is performed to predict the erosion mechanism. Overall, a good agreement was found among the experimental results, rigid-plastic model predictions and finite element model predictions.

Viscosity Models Based on Network Theory for Polymer Melts

2010 ◽  
Vol 129-131 ◽  
pp. 1244-1247
Author(s):  
Hai Hang Xu ◽  
Lei Zhong
Keyword(s):  
Experimental Data ◽  
Kinetic Equation ◽  
Constitutive Equation ◽  
Polymer Composites ◽  
Network Theory ◽  
Polymer Melts ◽  
Structure Parameter ◽  
Viscosity Models ◽  
Model Predictions ◽  
Good Agreement

New shear and extensional viscosity models based on Fredrickson kinetic equation coupled with Dewitt constitutive equation were established to predict viscosities of polymer melts. The experimental data of 125°C LDPE and LDPE filled with 35% glass beads reported from references were compared with the model predictions. The predictions showed good agreement with the measurements. The models are simple and easy to use. Because they contain no structure parameter, they are capable to describe the viscosities of pure polymer and polymer composites.

Obtaining shear relaxation modulus and creep compliance of linear viscoelastic materials from instrumented indentation using axisymmetric indenters of power-law profiles

2009 ◽  
Vol 24 (10) ◽  
pp. 3013-3017 ◽  
Author(s):  
Yang-Tse Cheng ◽  
Fuqian Yang
Keyword(s):  
Inverse Problem ◽  
Laplace Transform ◽  
Power Law ◽  
Creep Compliance ◽  
Relaxation Modulus ◽  
Instrumented Indentation ◽  
Loading Paths ◽  
Linear Viscoelastic ◽  
Shear Relaxation ◽  
Analytical Expressions

Using Laplace transform, we solve the inverse problem of obtaining the shear relaxation modulus and creep compliance of linear viscoelastic solids from indentation by axisymmetric indenters of power-law profiles. We identify several simple, though nontrivial, loading paths for carrying out indentation measurements such that the inverse problem has analytical solutions. We show that the shear relaxation modulus and creep compliance may be readily obtained using the newly derived analytical expressions together with proposed indentation loading paths.

Modeling the Effect of Water Activity, pH, and Temperature on the Probability of Enterotoxin A Production by Staphylococcus aureus

2016 ◽  
Vol 79 (1) ◽  
pp. 148-152 ◽  
Author(s):  
TIAN DING ◽  
YAN-YAN YU ◽  
CHENG-AN HWANG ◽  
QING-LI DONG ◽  
SHI-GUO CHEN ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Water Activity ◽  
Storage Temperature ◽  
Probability Model ◽  
Toxin Production ◽  
Factors Affecting ◽  
Model Predictions ◽  
And Storage ◽  
Storage Temperatures ◽  
Good Agreement

ABSTRACT The objectives of this study were to develop a probability model of Staphylococcus aureus enterotoxin A (SEA) production as affected by water activity (aw), pH, and temperature in broth and assess its applicability for milk. The probability of SEA production was assessed in tryptic soy broth using 24 combinations of aw (0.86 to 0.99), pH (5.0 to 7.0), and storage temperature (10 to 30°C). The observed probabilities were fitted with a logistic regression to develop a probability model. The model had a concordant value of 97.5% and concordant index of 0.98, indicating that the model satisfactorily describes the probability of SEA production. The model showed that aw, pH, and temperature were significant factors affecting the probability of toxin production. The model predictions were in good agreement with the observed values obtained from milk. The model may help manufacturers in selecting product pH and aw and storage temperatures to prevent SEA production.

A Study of Abrasive Jet Micro-Grooving of Quartz Crystals

2010 ◽  
Vol 443 ◽  
pp. 645-651 ◽  
Author(s):  
Alireza Moridi ◽  
Jun Wang ◽  
Yasser M. Ali ◽  
Philip Mathew ◽  
Xiao Ping Li
Keyword(s):  
Predictive Models ◽  
Deep Understanding ◽  
Machining Process ◽  
Micro Machining ◽  
Machining Performance ◽  
Quartz Crystals ◽  
Abrasive Jet Machining ◽  
Model Predictions ◽  
Micro Grooving ◽  
Good Agreement

Owing to its various distinct advantages over the other machining technologies, abrasive jet machining has become a promising machining technology for brittle and hard-to-machine materials. An experimental study is presented on the micro-grooving of quartz crystals using an abrasive airjet. The effect of the various process parameters on the major machining performance measures are analysed to provide a deep understanding of this micro-machining process. Predictive models are then developed for quantitatively estimating the machining performance. The models are finally verified by an experiment. It shows that the model predictions are in good agreement with the experimental results under the corresponding conditions.

A Control Strategy and Upper Bound Solution for Non-Flat Tool Open Die Forging Automation

1999 ◽  
Author(s):  
T. J. Nye
Keyword(s):  
Control Strategy ◽  
Upper Bound ◽  
Sequence Generation ◽  
Bound Solution ◽  
Upper Bound Solution ◽  
Die Forging ◽  
Strategy Model ◽  
Model Predictions ◽  
Open Die Forging ◽  
Good Agreement

Abstract The open die forging process can provide a number of benefits if its costs can be made competitive through automation. This paper describes a control strategy for automated open die forging forming sequence generation. An upper bound solution for forging with radiused tools is developed, along with a method for using this solution to estimate forming results, a necessary component of the control strategy. Model predictions are compared to physical experimental data using plasticine, and show good agreement.

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