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Rheology describes the molecular and supermolecular dynamics of complex materials. It is one of the most sensitive indicators of changes in a material while it also determines the processing and end-use of many materials. While rheological knowledge has advanced significantly over the last decade, it remained difficult to access and has rarely been applied to its full potential. In response to this problem, Winter and Mours (2006) created a software platform for the world’s leading rheologists to share their work with a wider community of materials researchers and practitioners.
Figure 1: Global sharing of rheology software through Rheo-Hub (picture from Amherst Rheology Course, June 2005). The user (student, researcher, practitioner, etc.) enters a virtual environment that instantly activates a research scenario in which he/she can explore authentic research questions, follow up on thought experiments, ask what-if questions and visualize results before continuing to further analysis and exploration. Software codes and documentation from each of the rheology expert groups are represented by one or more software “engines” which are connected to a domain platform on the users’ laptops.
What is Rheo-Hub? Rheo-Hub is a highly structured software platform with modeling/ simulation codes (“engines”) attached. Its main purpose is to integrate experimental results with theoretical predictions for the rheology of complex materials. It serves as rheological tool kit for researchers, students, and practitioners who want to explore rheological ideas and develop new materials or new formulations. It has also proven useful for classroom teaching, see figure 1. The main technical attributes of the IRIS technology are described below.
Ease of Use Rheo-Hub is easy-to-use. Because of its structure, the platform program is easy to browse and intuitive to navigate
Rapid Data Analysis and Modeling Rheo-Hub is purposely designed to produce results in a short time (within minutes, normally). This allows an efficient use of time. It is important to notice that, quite often, rheology projects do not get pursued in depth because of lack of time (tedious access to data or difficult calculation). This slowness of rheological work is in discrepancy with nearly instantaneous access to information in other areas and with our desire to make decisions without delay. The short response time of the Rheo-Hub addresses that problem.
High Data Throughput Materials researchers are faced with insurmountable data volumes. This also applies to rheology. Rheo-Hub, because of its quick response time, is well suited for accommodating a high volume of rheological data.
Universal Data Standard, Tracability, and Data Repository In 1992 we introduced a universal data standard for developing Rheo-Hub. Data from heterogeneous sources (different rheometer types, different analysis programs, various data repositories, etc.) can be traced, shared, analyzed, and compared. The data standard is a prerequisite for establishing communication between laboratories worldwide. For generating a data repository, Rheo-Hub merges standardized data into metafiles.
Modeling with Cutting-Edge Theories The dynamics of polymeric materials can be explored through calculations with cutting-edge theories (including multiscale models and simulation) of globally distributed expert groups of nine countries (Australia, Belgium, Germany, Israel, Italy, Japan, Switzerland, UK, USA). Winter and Mours’ (2006) method of merging expert codes onto a computer platform is generic and can be extended to further topics and other material groups.
Code-Code Coupling and Code-Data Coupling An efficient workflow requires the integration of data and computer modeling (and simulation) as provided by Rheo-Hub. Data from one code can be entered into the next code or can be directly compared to experimental data. Major advances can be expected from integrating experimental data with predictive modeling and simulation tools. An experimentalist in a rheometry laboratory will not be limited to produce data but will also be able to understand the data’s significance and ask “what-if” questions. Vice versa, a theoretician can explore the underlying principles that govern his/her theory and directly compare predictions to experiments. A deeper understanding will be gained when generating such interactive modeling/data environment. The meaningful use of such advanced Rheo-Hub will require training of a user base (see further below).
Rheology Anywhere & Anytime The interactive tools of Rheo-Hub on a laptop are ready to produce information promptly whenever and wherever needed. They support seamless communication within a community of (Rheo-Hub)-literate users anywhere in the world. Communication will become ever more efficient from integration into grid technology and other middleware tools.
Inter-Discipline and Multi-Scale Rheology combines mathematics, physics, chemistry, and engineering in complicated ways that make it difficult to utilize rheological knowledge. To bridge between disciplines, Rheo-Hub is designed to perform calculations that integrate science and engineering. The scale of modeling ranges from molecular size to machine size.
Functions of Current Rheo-Hub Temperature shift, second shift, steady shear analysis (time-temperature shift, viscosity fit functions, yield stress), spectrum calculation (relaxation, retardation), creep, extensional viscosity, linear viscoelastic theory (classical linear viscoelasticity theories, empirical models), material functions (relaxation modulus, creep compliance, Cox-Merz, Booij-Palmen, Cole-Cole, and more), non-linear viscoelastic theory (classical non-linear viscoelasticity theories, empirical models), time-resolved mechanical spectroscopy (gelation), tube dilation theory (McLeish-Milner theory), hierarchical model (Larson theory), independent alignment theory of Doi/Edwards, Phan-Tien-Tanner model, molecular stress function theory (MH Wagner theory), molecular weight distribution (Nobile/Cocchini), NAPLES simulation code (Masubuchi/Ianniruberto), plotting, data editing and repository.
Security of Proprietary Data Data are typically secured on a server with restricted access. Rheo-Hub can read data only if access is given to the server.
Hardware and Software Requirements The Rheo-Hub is a platform program that runs on any PC with MS Windows operating system.
Literature Reference Winter HH, Mours M (2006) The Cyber Infrastructure Initiative for Rheology. Rheol Acta 45:331-338.
Licensing Rheo-Hub can be licensed from Interactive Rheology Information Systems (IRIS) Development LLC
Short Courses The ease-of-use of the Rheo-Hub can best be appreciated after having performed a few tutorials on your own PC. The further learning of the underlying science will require participation in a short course. For this purpose, the Amherst Rheology Course (see http://rheology.tripod.com/ARC.htm) has been taught annually since 2004 and will continue to be taught on a regular basis.
e-mail contact: IRISrheo@yahoo.com
Figure 2: |
Waveform of dynamic mechanical experiment
Figure 3: |
Predicted dynamic moduli of polymer solution with 100%, 80%, 60%, 40%, and 20% polymer (tube dilation theory of McLeish and coworkers). Polymer: linear, flexible chains of uniform size.