Version  0.9.9998 - April 21, 2009

The current version of RHEA™ Software is updated to 0.9.9998

It was noted that the modified CA fit to G* data alone was not always working whereas a fit was always provided for G' G" data.  This version was updated to correct that a results in the program giving a CA fit in all known cases for the G* alone.  The type of fit is the CAS version of the CA equation - which is a three parameter fit with a variable glassy modulus.

Version 0.9.9997 - September 30, 2008

Mechanistic-Empirical Pavement Design Guide
In preparation for the introduction of the MEPDG work has been conducted to represent the output of mixture data in this format. Two windows provide this data - first using the polynomial shifting the shift is represented in the standard logistic sigmoid used in the MEPDG. Frequency is converted to time using the approximate relationship and E* is the expressed as a function of loading time.

A second expression of the results is provided under the listing of the output. The model used in the MEPDG is called the "standard logistic." In addition to the fitting parameters a measure of the fit is provided via the root mean square analysis. The expression given in this equation is in terms of frequency which is the rheologically correct manner of expressing E* data.

Alternate Sigmoid
In addition to the sigmoid in the MEPDG format an alternate format is provide as the Richards curve. In some cases this is expressed as a limiting Gompertz curve. These sigmoid allow for non-symmetrical sigmoid formats more typical of asphalt materials. In addition, Abatech has found that this type of expression more correctly accounts for the behavior of polymer blends and those with significant filler volume.

Solid vs. Liquid Analysis
Additional functionality has been provided allowing the user for force either a visco-elastic solid or liquid analysis (partly dependent upon data) along with the calculation of discrete relaxation and retardation spectra.

Oberst Analysis
The Oberst test is used in industries concerned with damping properties. The Oberst results can be calculated from a frequency sweep analysis/master curve thus allowing prediction of this test data at different frequencies and temperatures.



File Formats
We have been working with the integration of Signal data from both IPC and Interlaken data sets to produce analysis of material master curves.

IPC data - RHEA will handle IPC data - sum files in the file reader.
TA data - If TA data is exported from TA software in a prescribed manner then RHEA will handle this in the file reader to make a ttd file.

Various other updates have been made

• WLF is allowed with grater or equal three isotherms
• Pairwise shifting graphs are provided
• G* or E* can be used alone to produce shifted curve - with a calculated phase angle from the discrete spectra fit

Planned Updates for 2009

• Additional work will be conducted on the V-E solid master curve fitting.
• Further evaluation of Kaelble shift factor