MAIN MENU

Analyzing failure modes using RBDs in Weibull++

ReliaSoft Weibull++ provides the ability to use a reliability block diagram (RBD) to model series, parallel and k-out-of-n configurations. In this article, we will give an example of how to use an RBD to conduct failure modes analysis.
Software engineers analyzing data on computer screen

ReliaSoft Weibull++

An electronic device can fail due to six independent primary failure modes: A, B, C, D, E and F. The component fails if mode A, mode B or mode F occurs. If mode C, mode D or mode E occurs alone, the component does not fail; however, the component will fail if any two (or more) of these modes occur (i.e., C and D; D and E; E and C; or C, D and E). The objective is to analyze each data set using the 2-parameter Weibull distribution with MLE and to determine the lower 1-sided 90% confidence interval on the reliability of this component at 100 hours.

Experiment and data

The following tables present the time-to-failure data for these modes (in hours).



Mode A Mode B Mode C
NumberStateTime NumberStateTime NumberStateTime
in Groupin Groupin Group
1F1144 1F2221 1F19
1F1719 1F2257 1F140
1F2129 1F2569 1F292
1F2803 1F3029 1F432
1F3020 1F3805 1F528
1F3082 10S5000 1F552
1F3589      1 F605
1F3973      1 F734
1F4337      1 F779
1F5011      1 F874
1F5029        
18S5500        


 		 



         
Mode D Mode E Mode F
NumberStateTime NumberStateTime NumberStateTime
in Groupin Groupin Group
1F1063 1F1290 1F605
1F1085 1F2261 1F760
1F1399 1F2355 1F773
1F1445 1F3209 1F854
1F1550 1F3284 1F890
1F2056 1F3394 1F1165
1F4384 1F3596 1F1220
1F4863 1F4203 1F1320
8S5000 1F4254 1F1967
    1F4294 1F2606
    1F4420 1F2834
    10S5000 15S3000

Analysis

Step 1: Using Weibull++, the first step is to create a new data sheet for grouped times-to-failure data with suspensions.

Step 2: Rename the folio to "Component" and the data sheet to "Mode A." Enter the data given for Mode A and use the 2-parameter Weibull distribution with MLE to calculate the parameters, as shown next.

Step 3: Insert another data sheet of the same type named "Mode B," enter the data given for Mode B and calculate the parameters. Repeat for the remaining failure modes.

Step 4: Choose Home > Insert > Diagram.

Step 5: Build the RBD that describes the reliability-wise configuration of the failure modes, as shown next.

Note that the node in the diagram requires 2 of the 3 paths to succeed.

 

Step 6: Click Calculate to analyze the diagram.

Calculate Icon

 

Then use the Quick Calculation Pad (QCP) to calculate the reliability at 100 hours with the lower 1-sided 90% confidence bound, as shown next.

The lower bound is estimated to be 96.71%.

Support Content