Data Analysis

Specialists in Mechanical Testing and Reliability of Optical Fibers

Data Analysis and Graphing Software

Purpose

We supply specialized software for producing a variety of graphs in publication quality. The software comprises plug-ins for SigmaPlot (Systat Software, www.systat.com). The customer must own a registered version of SigmaPlot.

Weibull Plots

This Weibull Analysis plug-in for SigmaPlot graphs up to ten sets of data on a Weibull probability plot. Data can be supplied in a variety of units (MPa, GPa, strain, failure load, etc.) and are automatically converted to consistent units. Two example graphs are shown below. The plug-in calculates the Weibull parameters using standard linear regression techniques. In addition, the parameters and their confidence intervals are calculated using an unbiased maximum likelihood estimator (MLE) technique. Linear regression is not an appropriate technique for determining distribution parameters because the underlying assumptions are not valid for this application. In particular, linear regression greatly underestimates the confidence in the parameters. The MLE technique is designed specifically for determining distribution parameters and the parameter confidence intervals are correctly estimated.

Calculations are also made using techniques specified in standard test procedures, such as FOTP-28, ITM-13, IEC 60793-1-33, ASTM C1239, etc..


This example shows a simple Weibull plot with four sets of data used for a dynamic fatigue plot.	This image shows a portion of the worksheet for the graph to the left. It shows the parameters calculated for each set of data for to the various standards.	This example shows how the graph can be customized to separately graph the high and low strength modes of a bimodal distribution.
(click on an image for a full sized version - zoom the resulting image to 100% for best quality)

Dynamic Fatigue Plots

The Dynamic Fatigue plug-in for SigmaPlot graphs up to six sets of data on a standard fatigue plot (log strength versus log rate). Data can be supplied in a variety of units (MPa, GPa, strain, etc.) and are automatically converted to consistent units. Two example graphs are shown below. The plug-in calculates the fatigue parameter, n, using techniques specified in standard test procedures such as FOTP-28, ITM-13, IEC 60793-1-33, etc.. Several customizations are implemented, such as ignoring the weakest at each rate as specified in FOTP28.


This example shows fatigue plots for four sets of data.	This graph shows an example of how the graph can be customized. In this case, a "bad" outlier point is graphed but is omitted from the fatigue analysis.
(click on an image for a full sized version - zoom the resulting image to 100% for best quality)

Static Fatigue Plots

The Static Fatigue plug-in for SigmaPlot graphs up to six sets of data on a standard static fatigue plot (log time to failure versus log applied stress). Data can be supplied in a variety of units (seconds, minutes, hours etc.) and are automatically converted to consistent units. Two example graphs are shown below. The plug-in calculates the fatigue parameter, n, using techniques specified in standard test procedures such as IEC 60793-1-33 etc..


This example shows how the data before and after the "fatigue knee" can be analyzed separately.	This graph shows a more complex example of how the graph can be customized. In this case, the data analysis can be to all data or to just some of the data.
(click on an image for a full sized version - zoom the resulting image to 100% for best quality)

Ordering Information

Description	Part #
SigmaPlot plug-in for Weibull plots	SP-WEIB
SigmaPlot plug-in for static fatigue plots	SP-STAT
SigmaPlot plug-in for dynamic fatigue plots	SP-DYN
SigmaPlot version 12.0	SIGMAPLOT