Lecture 7: Rheology and Milli-Microfluidic
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Accidental Discoveries
Accidental discoveries Part of the British Science Association’s British Science Week activity pack series. www.britishscienceweek.org British Science British British Science www.britishscienceweek.org 0 Accidental discoveries: Bakelite plastic Making silly putty More than one hundred years ago, electric wires were covered with ‘shellac’. It stopped people getting an electric shock if they touched the wire. It was very expensive because it was made from beetles that came from Asia. So, a man called Leo Baekeland decided to make a new type of covering. However, instead he discovered how to make the first plastic, called Bakelite. Plastics can be moulded into all kinds of shapes. They are used to make all sorts of things. You can have a go at making a bouncy plastic, called silly putty. You will need: 2 containers (such as plastic cups), a wooden stick (for This 1950s telephone is made from Bakelite stirring), some food colouring, PVA glue, borax solution (about 1 tablespoon of borax to a cup of water) What you do Put about one tablespoon of borax into one cup of water. Stir until it dissolves. Stir in two or three drops of food colouring. Put some PVA glue into the other container – just enough to cover the bottom. Pour some of the borax solution into the PVA glue. Stir the mixture until it makes a soft lump. By now the mixture should be joining together like putty. Take it out of the container and mould it into a ball in your hands. If it is still sticky, wash your hands with water and rinse the ball. -
On Nonlinear Strain Theory for a Viscoelastic Material Model and Its Implications for Calving of Ice Shelves
Journal of Glaciology (2019), 65(250) 212–224 doi: 10.1017/jog.2018.107 © The Author(s) 2019. This is an Open Access article, distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives licence (http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is unaltered and is properly cited. The written permission of Cambridge University Press must be obtained for commercial re- use or in order to create a derivative work. On nonlinear strain theory for a viscoelastic material model and its implications for calving of ice shelves JULIA CHRISTMANN,1,2 RALF MÜLLER,2 ANGELIKA HUMBERT1,3 1Division of Geosciences/Glaciology, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany 2Institute of Applied Mechanics, University of Kaiserslautern, Kaiserslautern, Germany 3Division of Geosciences, University of Bremen, Bremen, Germany Correspondence: Julia Christmann <[email protected]> ABSTRACT. In the current ice-sheet models calving of ice shelves is based on phenomenological approaches. To obtain physics-based calving criteria, a viscoelastic Maxwell model is required account- ing for short-term elastic and long-term viscous deformation. On timescales of months to years between calving events, as well as on long timescales with several subsequent iceberg break-offs, deformations are no longer small and linearized strain measures cannot be used. We present a finite deformation framework of viscoelasticity and extend this model by a nonlinear Glen-type viscosity. A finite element implementation is used to compute stress and strain states in the vicinity of the ice-shelf calving front. -
1 Fluid Flow Outline Fundamentals of Rheology
Fluid Flow Outline • Fundamentals and applications of rheology • Shear stress and shear rate • Viscosity and types of viscometers • Rheological classification of fluids • Apparent viscosity • Effect of temperature on viscosity • Reynolds number and types of flow • Flow in a pipe • Volumetric and mass flow rate • Friction factor (in straight pipe), friction coefficient (for fittings, expansion, contraction), pressure drop, energy loss • Pumping requirements (overcoming friction, potential energy, kinetic energy, pressure energy differences) 2 Fundamentals of Rheology • Rheology is the science of deformation and flow – The forces involved could be tensile, compressive, shear or bulk (uniform external pressure) • Food rheology is the material science of food – This can involve fluid or semi-solid foods • A rheometer is used to determine rheological properties (how a material flows under different conditions) – Viscometers are a sub-set of rheometers 3 1 Applications of Rheology • Process engineering calculations – Pumping requirements, extrusion, mixing, heat transfer, homogenization, spray coating • Determination of ingredient functionality – Consistency, stickiness etc. • Quality control of ingredients or final product – By measurement of viscosity, compressive strength etc. • Determination of shelf life – By determining changes in texture • Correlations to sensory tests – Mouthfeel 4 Stress and Strain • Stress: Force per unit area (Units: N/m2 or Pa) • Strain: (Change in dimension)/(Original dimension) (Units: None) • Strain rate: Rate -
Understanding Silly Putty, Snail Slime and Other Funny Fluids
IMA Annual Program Year Tutorial An Introduction to Funny (Complex) Fluids: Rheology, Modeling and Theorems September 12-13, 2009 Understanding silly putty, snail slime and other funny fluids Chris Macosko Department of Chemical Engineering and Materials Science NSF- MRSEC (National Science Foundation sponsored Materials Research Science and Engineering Center) IPRIME (Industrial Partnership for Research in Interfacial and Materials Engineering) What is rheology? ρειν (Greek) = to flow τα παντα ρει = every thing flows rheology = study of flow?, i.e. fluid mechanics? honey and mayonnaise honey and mayo stress= viscosity = f/area stress/rate rate of deformation rate of deformation What is rheology? ρειν (Greek) = to flow τα παντα ρει = every thing flows rheology = study of flow?, i.e. fluid mechanics? honey and mayo rubber band and silly putty viscosity modulus = f/area rate of deformation time of deformation 4 key rheological phenomena rheology = study of deformation of complex materials fluid mechanician: simple fluids complex flows materials chemist: complex fluids complex flows rheologist: complex fluids simple flows rheologist fits data to constitutive equations which - can be solved by fluid mechanician for complex flows - have a microstructural basis from: Rheology: Principles, Measurement and Applications, VCH/Wiley (1994). ad majorem Dei gloriam Goal: Understand Principles of Rheology: (stress, strain, constitutive equations) stress = f (deformation, time) Simplest constitutive relations: Newton’s Law: Hooke’s Law: dγ τ = η = ηγ τ = Gγ dt Key Rheological Phenomena • shear thinning (thickening) h ( g ) • time dependent modulus G(t) • normal stresses in shear N1 η η • extensional > shear stress u > k k 1 ELASTIC SOLID 1 2 The power of any spring L´ is in the same proportion with the tension thereof. -
THE CHEMISTRY of SILLY PUTTY Silly Putty Is an Odd Substance – It Can Be Slowly Stretched Out, but Snaps If Pulled Apart with Greater Force
THE CHEMISTRY OF SILLY PUTTY Silly putty is an odd substance – it can be slowly stretched out, but snaps if pulled apart with greater force. It can be molded into shape, but bounces if rolled into a ball. What’s behind these strange properties? Here’s a quick look at the chemical composition and explanation. WHAT IS IT MADE OF? HOW DOES IT WORK? The most important compound in silly putty The presence of PDMS alone, and its is polydimethylsiloxane (PDMS). This is the viscoelasticity, doesn’t fully explain how silly simplest member of the polymer family known putty behaves. Another ingredient, boric acid, as the silicones. also makes a telling contribution. PDMS is viscoelastic. This means that it acts The boric acid helps to create ‘crosslinks’ like a viscous liquid and flows over long time between adjacent polymer chains. These help scales. However, over short time scales (for to give silly putty its putty-like nature, and also example, being rolled into a ball and thrown at help explain its strange behaviour. a hard surface), its behaviour is elastic, and it will bounce back. R Si O O Si R – EXAMPLE BORON-MEDIATED CROSSLINK B Si Si Si (R represents the rest of the PDMS polymer chain) O O R Si O O Si R n A POLYDIMETHYLSILOXANE The polydimethylsiloxanes in silly putty end in Si-OH groups. The boric (solid filled atoms represent carbon; smaller outlined atoms represent hydrogen) acid reversibly reacts with these to form short-lived crosslinks between polymer chains. Slow deformation gives these crosslinks time to break and reform, allowing viscous flow, but rapid, forceful deformation does At high molecular weights, the flexible polymer chains become loosely not, so elastic behaviour is instead seen. -
Computational Rheology (4K430)
Computational Rheology (4K430) dr.ir. M.A. Hulsen [email protected] Website: http://www.mate.tue.nl/~hulsen under link ‘Computational Rheology’. – Section Polymer Technology (PT) / Materials Technology (MaTe) – Introduction Computational Rheology important for: B Polymer processing B Rheology & Material science B Turbulent flow (drag reduction phenomena) B Food processing B Biological flows B ... Introduction (Polymer Processing) Analysis of viscoelastic phenomena essential for predicting B Flow induced crystallization kinetics B Flow instabilities during processing B Free surface flows (e.g.extrudate swell) B Secondary flows B Dimensional stability of injection moulded products B Prediction of mechanical and optical properties Introduction (Surface Defects on Injection Molded Parts) Alternating dull bands perpendicular to flow direction with high surface roughness (M. Bulters & A. Schepens, DSM-Research). Introduction (Flow Marks, Two Color Polypropylene) Flow Mark Side view Top view Bottom view M. Bulters & A. Schepens, DSM-Research Introduction (Simulation flow front) 1 0.5 Steady Perturbed H 2y 0 ___ −0.5 −1 0 0.5 1 ___2x H Introduction (Rheology & Material Science) Simulation essential for understanding and predicting material properties: B Polymer blends (morphology, viscosity, normal stresses) B Particle filled viscoelastic fluids (suspensions) B Polymer architecture macroscopic properties (Brownian dynamics (BD), molecular dynamics (MD),⇒ Monte Carlo, . ) Multi-scale. ⇒ Introduction (Solid particles in a viscoelastic fluid) B Microstructure (polymer, particles) B Bulk rheology B Flow induced crystallization Introduction (Multiple particles in a viscoelastic fluid) Introduction (Flow induced crystallization) Introduction (Multi-phase flows) Goal and contents of the course Goal: Introduction of the basic numerical techniques used in Computational Rheology using the Finite Element Method (FEM). -
20. Rheology & Linear Elasticity
20. Rheology & Linear Elasticity I Main Topics A Rheology: Macroscopic deformation behavior B Linear elasticity for homogeneous isotropic materials 10/29/18 GG303 1 20. Rheology & Linear Elasticity Viscous (fluid) Behavior http://manoa.hawaii.edu/graduate/content/slide-lava 10/29/18 GG303 2 20. Rheology & Linear Elasticity Ductile (plastic) Behavior http://www.hilo.hawaii.edu/~csav/gallery/scientists/LavaHammerL.jpg http://hvo.wr.usgs.gov/kilauea/update/images.html 10/29/18 GG303 3 http://upload.wikimedia.org/wikipedia/commons/8/89/Ropy_pahoehoe.jpg 20. Rheology & Linear Elasticity Elastic Behavior https://thegeosphere.pbworks.com/w/page/24663884/Sumatra http://www.earth.ox.ac.uk/__Data/assets/image/0006/3021/seismic_hammer.jpg 10/29/18 GG303 4 20. Rheology & Linear Elasticity Brittle Behavior (fracture) 10/29/18 GG303 5 http://upload.wikimedia.org/wikipedia/commons/8/89/Ropy_pahoehoe.jpg 20. Rheology & Linear Elasticity II Rheology: Macroscopic deformation behavior A Elasticity 1 Deformation is reversible when load is removed 2 Stress (σ) is related to strain (ε) 3 Deformation is not time dependent if load is constant 4 Examples: Seismic (acoustic) waves, http://www.fordogtrainers.com rubber ball 10/29/18 GG303 6 20. Rheology & Linear Elasticity II Rheology: Macroscopic deformation behavior A Elasticity 1 Deformation is reversible when load is removed 2 Stress (σ) is related to strain (ε) 3 Deformation is not time dependent if load is constant 4 Examples: Seismic (acoustic) waves, rubber ball 10/29/18 GG303 7 20. Rheology & Linear Elasticity II Rheology: Macroscopic deformation behavior B Viscosity 1 Deformation is irreversible when load is removed 2 Stress (σ) is related to strain rate (ε ! ) 3 Deformation is time dependent if load is constant 4 Examples: Lava flows, corn syrup http://wholefoodrecipes.net 10/29/18 GG303 8 20. -
Fourteen K-12 Outreach Activities for Materials Scientists and Engineers
FOURTEEN K-12 OUTREACH ACTIVITIES FOR MATERIALS SCIENTISTS AND ENGINEERS Foreward The activities described in this document were performed by volunteers from ASM International chapters as part of our volunteer leader training in 2007. The event took place in an elegant room with carpet, drapes, and wallpaper so heat treating was done in advance. A similar approach could be used to make the “heat treating” activities safe for younger students. Please take the utmost care to consider safety aspects as you plan your outreach event. Safety glasses that fit over corrective lenses are needed for many of these activities, and you may have trouble finding them small enough to fit young students. Many of the activities were gleaned from the ASM Materials Education Foundation’s “Teachers Camp” curriculum and have been proven in classrooms. I’m particularly grateful to Debbie Goodwin (Master Teacher) and Matt Perricone for their contributions to this compilation, and to Dr. Kathy Hayrynen of the Detroit Chapter of ASM International for her ongoing contributions to ASM’s outreach projects at many levels. All of the experimental descriptions in this compilation are either free of copyright protection, or have been used in accordance with the use restrictions of the original source. Original sources for each activity have been noted in the appendices. Commercial sources for some supplies have been mentioned as a convenience, and are not an endorsement of the particular company by ASM International, The ASM Foundation, or me. I hope you’ll have as much fun sharing our profession with students and teachers as I do. -
Guide to Rheological Nomenclature: Measurements in Ceramic Particulate Systems
NfST Nisr National institute of Standards and Technology Technology Administration, U.S. Department of Commerce NIST Special Publication 946 Guide to Rheological Nomenclature: Measurements in Ceramic Particulate Systems Vincent A. Hackley and Chiara F. Ferraris rhe National Institute of Standards and Technology was established in 1988 by Congress to "assist industry in the development of technology . needed to improve product quality, to modernize manufacturing processes, to ensure product reliability . and to facilitate rapid commercialization ... of products based on new scientific discoveries." NIST, originally founded as the National Bureau of Standards in 1901, works to strengthen U.S. industry's competitiveness; advance science and engineering; and improve public health, safety, and the environment. One of the agency's basic functions is to develop, maintain, and retain custody of the national standards of measurement, and provide the means and methods for comparing standards used in science, engineering, manufacturing, commerce, industry, and education with the standards adopted or recognized by the Federal Government. As an agency of the U.S. Commerce Department's Technology Administration, NIST conducts basic and applied research in the physical sciences and engineering, and develops measurement techniques, test methods, standards, and related services. The Institute does generic and precompetitive work on new and advanced technologies. NIST's research facilities are located at Gaithersburg, MD 20899, and at Boulder, CO 80303. -
Chapter 3 Newtonian Fluids
CM4650 Chapter 3 Newtonian Fluid 1/23/2020 Mechanics Chapter 3: Newtonian Fluids CM4650 Polymer Rheology Michigan Tech Navier-Stokes Equation v vv p 2 v g t 1 © Faith A. Morrison, Michigan Tech U. Chapter 3: Newtonian Fluid Mechanics TWO GOALS •Derive governing equations (mass and momentum balances •Solve governing equations for velocity and stress fields QUICK START V W x First, before we get deep into 2 v (x ) H derivation, let’s do a Navier-Stokes 1 2 x1 problem to get you started in the x3 mechanics of this type of problem solving. 2 © Faith A. Morrison, Michigan Tech U. 1 CM4650 Chapter 3 Newtonian Fluid 1/23/2020 Mechanics EXAMPLE: Drag flow between infinite parallel plates •Newtonian •steady state •incompressible fluid •very wide, long V •uniform pressure W x2 v1(x2) H x1 x3 3 EXAMPLE: Poiseuille flow between infinite parallel plates •Newtonian •steady state •Incompressible fluid •infinitely wide, long W x2 2H x1 x3 v (x ) x1=0 1 2 x1=L p=Po p=PL 4 2 CM4650 Chapter 3 Newtonian Fluid 1/23/2020 Mechanics Engineering Quantities of In more complex flows, we can use Interest general expressions that work in all cases. (any flow) volumetric ⋅ flow rate ∬ ⋅ | average 〈 〉 velocity ∬ Using the general formulas will Here, is the outwardly pointing unit normal help prevent errors. of ; it points in the direction “through” 5 © Faith A. Morrison, Michigan Tech U. The stress tensor was Total stress tensor, Π: invented to make the calculation of fluid stress easier. Π ≡ b (any flow, small surface) dS nˆ Force on the S ⋅ Π surface V (using the stress convention of Understanding Rheology) Here, is the outwardly pointing unit normal of ; it points in the direction “through” 6 © Faith A. -
The Abbott Guide to Rheology Prof Steven Abbott
The Abbott Guide to Rheology Prof Steven Abbott Steven Abbott TCNF Ltd, Ipswich, UK and Visiting Professor, University of Leeds, UK [email protected] www.stevenabbott.co.uk Version history: First words written 7 November 2018 First draft issued 25 November 2018 Version 1.0.0 8 December 2018 Version 1.0.1 9 December 2018 Version 1.0.2 16 October 2019 Copyright © 2018/9 Steven Abbott This book is distributed under the Creative Commons BY-ND, Attribution and No-Derivatives license. Contents Preface 4 1 Setting the scene 6 1.1 Never measure a viscosity 8 2 Shear-rate dependent viscosity 10 2.1.1 Shear thinning and your process 12 2.1.2 What causes shear thinning? 13 2.1 Thixotropy 17 2.1.1 What to do with the relaxation times 19 2.1.2 What to do with thixotropy measurements 21 3 Yield Stress 22 3.1 Yield Strain 25 3.2 Using yield stress or strain values 26 4 Semi-Solids 27 4.1 G', G'' and tanδ 28 4.1.1 Storage and Loss 30 4.2 TTE/TTS/WLF 30 4.3 How do we use G':G'' and WLF information? 32 4.3.1 Your own G':G'', WLF insights 34 4.4 Are G':G'' all we need? 35 5 Interconversions 36 5.1 Relaxation and creep 37 5.2 The power of interconversions 40 5.3 Entanglement 43 5.4 Mc from Likhtman-McLeish theory 45 5.5 Impossible interconversions? 47 5.6 What can we do with interconversions? 48 6 Beyond linearity 49 6.1 LAOS 49 7 Particle rheology 50 7.1 Low Shear and Yield Stress 50 7.1.1 Yield stress 52 7.1.2 Microrheology 53 7.2 High Shear 54 7.2.1 Increasing φm 55 7.3 Particle Size Distributions 56 7.4 Hydrodynamic and Brownian modes 58 7.4.1 The Péclet number 59 7.5 Shear thickening 60 7.6 Can we apply particle rheology to the real world? 61 8 Summary 63 Preface "Maybe we should check out the rheology of this system" is the sort of sentence that can create panic and alarm in many people. -
Ductile Deformation - Concepts of Finite Strain
327 Ductile deformation - Concepts of finite strain Deformation includes any process that results in a change in shape, size or location of a body. A solid body subjected to external forces tends to move or change its displacement. These displacements can involve four distinct component patterns: - 1) A body is forced to change its position; it undergoes translation. - 2) A body is forced to change its orientation; it undergoes rotation. - 3) A body is forced to change size; it undergoes dilation. - 4) A body is forced to change shape; it undergoes distortion. These movement components are often described in terms of slip or flow. The distinction is scale- dependent, slip describing movement on a discrete plane, whereas flow is a penetrative movement that involves the whole of the rock. The four basic movements may be combined. - During rigid body deformation, rocks are translated and/or rotated but the original size and shape are preserved. - If instead of moving, the body absorbs some or all the forces, it becomes stressed. The forces then cause particle displacement within the body so that the body changes its shape and/or size; it becomes deformed. Deformation describes the complete transformation from the initial to the final geometry and location of a body. Deformation produces discontinuities in brittle rocks. In ductile rocks, deformation is macroscopically continuous, distributed within the mass of the rock. Instead, brittle deformation essentially involves relative movements between undeformed (but displaced) blocks. Finite strain jpb, 2019 328 Strain describes the non-rigid body deformation, i.e. the amount of movement caused by stresses between parts of a body.