Modelling of Shear Viscosity Behavior and Extrusion through Dies for Rubber Compounds

1987 ◽  
Vol 60 (2) ◽  
pp. 337-360 ◽  
Author(s):  
James L. White ◽  
Yeh Wang ◽  
Avraam I. Isayev ◽  
Nobuyuki Nakajima ◽  
Frederick C. Weissert ◽  
...  
Keyword(s):  
Cross Sections ◽  
Shear Viscosity ◽  
Flow Analysis ◽  
Elongational Flow ◽  
Extrudate Swell ◽  
Pressure Losses ◽  
Analysis And Design ◽  
Rubber Compounds ◽  
Viscosity Behavior ◽  
Active Research

Abstract This paper marks a first effort to develop a fundamental basis for die flow analysis and design for rubber compounds. We have accomplished a modelling of the shear viscosity function and its application to one- and two-dimensional shearing in die cross sections. There are major limitations in what we have done, much of which is apparent even in the early work of Mooney. In particular, we have not considered (i) slip phenomena on die walls, (ii) die entrance and exit pressure losses associated with converging and diverging dies, nor (iii) extrudate swell. We have an active research in our laboratories investigating these problems. In the future, we are seeking to generalize the procedures described in this paper to more complex die designs. Inclusion of entrance and exit effects and rigorous analysis of coathanger dies requires the handling of elongational flow contributions, a still unsolved problem.

Rheological Behavior and Extrudate Swell of Polypropylene/Silicon Carbide Composites

2013 ◽  
Vol 747 ◽  
pp. 595-598 ◽  
Author(s):  
Apaipan Rattanapan ◽  
Nuttaphong Sornsuwit ◽  
Rapeephun Dangtungee
Keyword(s):  
Silicon Carbide ◽  
Shear Stress ◽  
Shear Viscosity ◽  
Rheological Behavior ◽  
Sem Analysis ◽  
Elongation Rate ◽  
Capillary Rheometer ◽  
Extrudate Swell ◽  
Elongation Viscosity ◽  
Sic Composites

The rheological behavior and extrudate swell of polypropylene (PP)/silicon carbide (SiC) composites were investigated. Polypropylene-grafted-maleic anhydride (PP-g-MA) was introduced into blending system as a compatibilizer. The effect of silicon carbide loading and surface modification on the rheological behavior of PP/SiC composites were studied using a capillary rheometer and SEM analysis. The results showed that the composites exhibit pseudoplastic behavior as the shear stress and extrudate swell increased with increasing shear rate, while shear viscosity decreased. Moreover, an increasing elongation rate leads to reduce elongation viscosity. The addition of PP-g-MA in PP/SiC composites has significantly decreased the apparent shear stress, apparent shear viscosity and percentage of extrudate swell.

scholarly journals Simplified and Accurate Stiffness of a Prismatic Anisotropic Thin-Walled Box

2018 ◽  
Vol 12 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Giacomo Canale ◽  
Felice Rubino ◽  
Paul M. Weaver ◽  
Roberto Citarella ◽  
Angelo Maligno
Keyword(s):  
Cross Sections ◽  
Torsional Stiffness ◽  
Element Analysis ◽  
Cross Sectional ◽  
Analysis And Design ◽  
Proposed Model ◽  
Vertical Walls ◽  
Thin Walled ◽  
High Level ◽  
Realistic Geometries

Background:Beam models have been proven effective in the preliminary analysis and design of aerospace structures. Accurate cross sectional stiffness constants are however needed, especially when dealing with bending, torsion and bend-twist coupling deformations. Several models have been proposed in the literature, even recently, but a lack of precision may be found when dealing with a high level of anisotropy and different lay-ups.Objective:A simplified analytical model is proposed to evaluate bending and torsional stiffness of a prismatic, anisotropic, thin-walled box. The proposed model is an extension of the model proposed by Lemanski and Weaver for the evaluation of the bend-twist coupling constant.Methods:Bending and torsional stiffness are derived analytically by using physical reasoning and by applying bending and torsional stiffness mathematic definition. Unitary deformations have been applied when evaluation forces and moments arising on the cross section.Results:Good accuracy has been obtained for structures with different geometries and lay-ups. The model has been validated with respect to finite element analysis. Numerical results are commented upon and compared with other models presented in literature.Conclusion:For cross sections with a high level of anisotropy, the accuracy of the proposed formulation is within 2% for bending stiffness and 6% for torsional stiffness. The percentage of error is further reduced for more realistic geometries and lay-ups.The proposed formulation gives accurate results for different dimensions and length rations of horizontal and vertical walls.

Analysis and Design of Smart Electromagnetic Structures

2008 ◽  
Author(s):  
Prashanth Ramesh ◽  
Gregory Washington
Keyword(s):  
Dielectric Permittivity ◽  
Electric Field ◽  
Ambient Temperature ◽  
Ferroelectric Properties ◽  
Mechanical Strain ◽  
Ferroelectric Materials ◽  
Analysis And Design ◽  
Antenna Performance ◽  
Active Research ◽  
The Relationship

Use of ferroelectric materials to improve antenna performance is an area of active research. Applying an electric field across a ferroelectric used as the dielectric in an antenna enables tuning the antenna performance. Ferroelectrics also have coupled electromechanical behavior due to which it is sensitive to mechanical strains and fluctuations in ambient temperature. Use of ferroelectrics in antenna structures, especially those subject to mechanical and thermal loads, requires knowledge of the phenomenological relationship between the ferroelectric properties of interest (especially dielectric permittivity) and the external physical variables, viz. electric field(s), mechanical strains and temperature. To this end, a phenomenological model of ferroelectric materials based on the Devonshire thermodynamic theory is presented. This model is then used to obtain a relationship expressing the dependence of the dielectric permittivity on the mechanical strain, applied electric field and ambient temperature. The relationship is compared with published experimental data and other models in literature. Subsequently, a relationship expressing the dependence of antenna performance on those physical quantities is described.

scholarly journals Recoverable Extensional Flow of Polymer Melts and Its Relevance for Processing

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1512
Author(s):  
Helmut Münstedt
Keyword(s):  
Polymer Melts ◽  
Extensional Flow ◽  
Elongational Flow ◽  
Fused Deposition Modelling ◽  
Extrudate Swell ◽  
Fused Deposition ◽  
Rigid Particles ◽  
Experimental Parameters ◽  
Slit Die

While the uniaxial elongational viscosity is widely investigated, and its relevance for processing is described in the literature, much less has been published on the recoverable extensional flow of polymer melts. This paper presents a short overview of the dependencies of the recoverable elongation on the molecular structure of a polymer, and on some experimental parameters. Its main focus lies on the discussion of processing operations and applications that are largely affected by the elastic components of elongational flow. The recoverable portions of stretched films are considered, and the exploitation of the shrinkage of films, due to the recovery of frozen recoverable deformations, and its role for applications are addressed. The analysis of measurements of velocity fields in the entry region of a slit die and results on the determination of the recoverable elongation from uniaxial experiments, according to the literature, lead to the conclusion of dominant elastic extensions. Considering these facts, the assumptions for Cogswell’s widely used method of determining elongational viscosities under processing conditions from entrance flow are not realistic. As examples of a direct application of extrudate swell from short dies for processing, pelletizing and fused deposition modelling within additive manufacturing are addressed. The special features of extrudate swell from short dies, and uniaxial recoverable elongation for a polymer filled with rigid particles in comparison to an immiscible polymer blend, are presented and discussed.

Analysis and Design of a Lightweight High Specific Power Two-Stroke Polygon Engine

2013 ◽  
Vol 136 (4) ◽  
Author(s):  
K. R. Anderson ◽  
A. Clark ◽  
D. Forgette ◽  
M. Devost ◽  
R. Okerson ◽  
...  
Keyword(s):  
Compression Ratio ◽  
Air Flow ◽  
Flow Analysis ◽  
Weight Ratio ◽  
System Level ◽  
Specific Power ◽  
Kinematic Modeling ◽  
Analysis And Design ◽  
Piston Speed ◽  
Piston Displacement

Current trends in engine design have pushed the state of the art regarding high power-to-weight ratio gasoline engines. Newly developed engine systems have a power-to-weight ratio near 1 hp per pound. The engine configuration presented herein makes it possible to package a large number of power producing pistons in a small volume, resulting in a power-to-weight ratio near 2 hp per pound, which has never before been realized in a production engine. The analysis and design of a lightweight two-stroke 6-sided in-plane polygon engine having a geometric compression ratio of 15.0, an actual compression ratio of 8.8, and a piston speed of 3500 ft/min are presented in this investigation. Typical results show that for a hexagonal engine with 2 in. diameter pistons and 1.25 in. stroke, a single piston displacement is 7.85 cubic in., while the total engine displacement is 47. 1 cubic in. Full power at 12,960 rpm at an air flow rate of 353 cubic feet per minute affords 0.444 cubic ft/min/hp for specific power. For an efficiency of 21%, the blower power is 168 hp. Our air-flow analysis shows that the power of the engine does not depend on the number of pistons, but rather on the volume of the gas-air mixture which passes through the engine. System level engineering of power output, kinematic modeling, air-flow modeling, efficiency, scavenging predictions, crankshaft sizing, and weight estimates are presented.

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