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Using the Chart Wizard to Create a
Custom Plot
A wide variety of plots are built into the
Weibull++ software,
as well as the ability to combine
separate data sets on a single plot using
the MultiPlot. However, sometimes a
desired plot is not available. For example,
suppose that you want to plot component reliabilities
and the system reliability obtained from a reliability block
diagram
on a single plot. In Weibull++, you can
obtain the plot of the component reliability versus time
in the Standard Folio, and the plot of system
reliability versus time using the Diagram. You can
then create a custom plot that combines these plots. This article will show the steps to create
such a custom plot in Weibull++.
Consider the case of a system that consists of two identical
components arranged reliability-wise in parallel. A
set of failure data is collected for 5 specimens
with the following times to failure in days: 29, 71, 74,
79 and 103. A Weibull distribution is fitted to
the data and the parameters β = 2.3325 and η = 81.3094
days are computed. In addition, a Diagram
representing the system is created and the system
reliability equation is found to be:
A table of component and system reliabilities is
created in a General Spreadsheet for times from 0 to 60
days, as shown in Figure 1.
Figure 1: Component and System Reliabilities for 0
to 60 Days
In order to use the Chart Wizard built in to
Weibull++ to create a scatter (XY) plot with N
series, each with M data points, the data must be rearranged into the format
shown in Table 1, where S represents a series, and X and
Y represent the x- and y-values of the data points.
Table 1: Data Format for Scatter
Plot
|
S1 Label |
|
S2 Label |
|
|
SN Label |
|
|
S1 X1 |
S1 Y1 |
S2 X1 |
S2 Y1 |
|
SN X1 |
SN Y1 |
|
S1 X2 |
S1 Y2 |
S2 X2 |
S2 Y2 |
|
SN X2 |
SN Y2 |
|
|
|
|
|
|
|
|
|
S1 XM |
S1 YM |
S2 XM |
S2 YM |
|
SN XM |
SN YM |
Another table is created in the General Spreadsheet
to rearrange the reliability data into this format, as
shown in Figure 2.
Figure 2: Component and System Reliabilities Ready
for Plot
The steps to create the plot are as follows:
- Select all the cells that contain the
series labels and the x- and y-values for the plot
(in this example, cells E1 through H32).
- Click the Chart Wizard icon.
- Click in the desired location for the top left corner of the
plot and drag to the desired location for the bottom right corner of
the plot.
- The Chart Wizard will appear. On the
Gallery page, select to use 2D charts and
select the XY (Scat) chart type, as shown in Figure 3,
then click Next.
Figure 3: Chart Type Options
- On the Style page, select the first chart style, as shown in Figure 4,
then click Next.
Figure 4: Chart
Style Options
- On the Layout page, enter the Chart Title, Chart Footnote and add a Chart
Legend, if desired, and then click Next. For this
example, a legend was placed at the bottom of the chart,
as shown in Figure 5.
Figure 5: Chart Layout Options
- On the Axes page, enter the appropriate axis titles, if desired, and then
click Finish. For this example, the Category (X)
label was set to "Time" and the Value (Y) label was set
to "Reliability," as shown in Figure 6.
Figure 6: Chart Axes Options
Figure 7 shows the resulting plot of the component and system
reliabilities as functions of time.
Figure 7: Component and System Reliabilities on a Single
Plot
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