CORA and ISO-18571

CORA: The Correlation Analysis (CORA) calculates the correlation metric between CAE and Test Data signals in the form of time history. Includes both corridor and cross correlation, which are calculated independently and then combined to give a comprehensive error. The error calculation can be biased toward either the measured time history (Test) or the computed (CAE) time history, with the former being the most common.
CORA(CORRIDOR): The Corridor method (CR) calculates the correlation between two signals by corridor fitting. The error calculation can be biased toward either the measured time history (Test) or the computed (CAE) time history, with the former being the most common.
CORA(CROSS CORRELATION): The cross correlation method (CRCR) calculates the correlation between two signals by calculating phase shift, size, and progression. The weighted sum of these three values gives the total cross correlation rating.
ISO-18571: The ISO metric combines different types of algorithms to a get reliable and robust assessment between CAE and Test Data signals in the form of time history. Includes corridor, phase, magnitude, and slope, which are calculated independently and then combined to give an overall ISO rating. The error calculation can be biased toward either the measured time history (Test) or the computed (CAE) time history, with the former being the most common.

Open the Curve Correlation Dialog

From the File menu, click File > Open > Plot to open the Create Curves by File dialog.
From the Open File dialog, navigate to your working directory and select a file to open and plot some curves.
From the Plot Browser, select a reference curve, right-mouse click, and select Curve Correlation.
From the Correlation Type drop-down menu, select a correlation method.

Figure 1.
Select Cora to display the following options.

Figure 2.
Retain the default settings or change the defaults per your requirements and click Plot.
Notes are displayed with the correlation metrics in the plot window.

Reference Curve

Select reference curves through the Plot Browser or enter a list of ID’s. For example, 1-4.

Correlation Curve IDs

An individual ID or list of IDs. For example, 5-7.

Correlation Type

Supported methods include:

Evaluation Interval Parameters: Description
A_THRES: Threshold to set the start of the interval of evaluation. Varies between 0 and 1.
B_THRES: Threshold to set the end of the interval of evaluation. Varies between 0 and 1.
A_EVAL: Automatically calculated interval of evaluation. Varies between 0 and 1.
B_DELTA_END: Shortens the end of the interval of evaluation if it is calculated automatically. Varies between 0 and 1.
Tmin/Tmax: Defines the start and the end time of the evaluation interval.

Corridor Parameters: Description
K: Exponent factor (progression) for the calculation of the corridor rating.
G-1: Weighting factor of the corridor rating.
a0: Width of the inner and outer corridor.
b0: Width of the inner and outer corridor.
a_sigma: Factors of the standard deviation to widen the inner corridor.
b_sigma: Factors of the standard deviation to widen the outer corridor.

Cross Correlation Parameters: Description
D_MIN: Calculates the interval of evaluation. Varies between 0 and 1.
D_MAX: Calculates the interval of evaluation. Varies between 0 and 1.
INT_MIN: Minimum overlap of the interval. Varies between 0 and 1.
K_V: Exponent factor (progression) of the calculation of the progression rating, V.
K_G: Exponent factor (progression) of the calculation of the size rating, G.
K_P: Exponent factor (progression) of the calculation of the phase shift rating, P.
G_V: Weighting factors of the progression rating.
G_G: Weighting factors of the size rating.
G_P: Weighting factors of the phase shift rating.
G_2: Weighting factors of the cross-correlation method.

Signal Parameters: Description
MIN_NORM: The limit to start the special treatment of the secondary axis. Varies between 0 and 1.
Y_NORM: Calculation type of Y_NORM; options include extremum or value.
WF_NORM: Normalization of the weighting factors; options include YES or NO.

Select ISO-18571 to display the following options:

Evaluation Interval Parameters
A_THRES: Threshold to set the start of the interval of evaluation. Varies between 0 and 1.
B_THRES: Threshold to set the end of the interval of evaluation. Varies between 0 and 1.
A_EVAL: Automatically calculated interval of evaluation. Varies between 0 and 1.
B_DELTA_END: Shortens the end of the interval of evaluation if it is calculated automatically. Varies between 0 and 1.
Tmin/Tmax: Keyword that defines the start and end time of the interval of evaluation.

Corridor Parameters
K: Exponent factor (progression) for the calculation of the corridor rating.
W_Z: Weighting factor of the corridor rating.
a0: Width of the inner and outer corridor.
b0: Width of the inner and outer corridor.
a_sigma: Factors of the standard deviation to widen the inner corridor.
b_sigma: Factors of the standard deviation to widen the outer corridor.

Signal Parameters
MIN_NORM: The limit to start special treatment of a secondary axis. Varies between 0 and 1.
Y_NORM: Calculation type of Y_NORM; options include extremum or value.
WF_NORM: Normalization of the weighting factors; options include YES or NO.

Phase(P): Display the phase value.
Progression(V): Display the progression value.
Size(G): Display the size value.
Total Correlation Rating(C2): Display the total correlation rating value.
Total Cross Correlation Rating(C1): Display the total cross correlation rating value.
Corridor Rating: Display the corridor rating value.
Reference Curve Label: Display the reference curve label.
Correlation Curve Label: Display the correlation curve label.