Session 6.5: Modeling for PHM and Additional Features

Session 6.5 Outline

• 6.5.1: Create Diagnostic Groups in the Model
• 6.5.2: Add Symptoms to Failure Diagrams
• 6.5.3: Use Diagnostic Groups and Symptoms in Diagnostic Analyses

Discussion 6.5.1: Create Diagnostic Groups in the Model

• Diagnostic Groups in MADE are groupings of failures that do not require complete diagnostic coverage, rather the failures may acceptably be ambiguous with one another.
• Failures would be grouped due to several circumstances:
  • Items are in an LRU (entire group is replaced at one time so further specific diagnosis is not required)
  • Items are physically close to one another so any maintenance that is directed by the diagnostic suite will allow access to further testing by maintenance personnel
  • Sensor numbers are limited and grouping failures gives greater control over where the inevitable ambiguities end up as a result

Exercise 6.5.1: Create Diagnostic Groups in the Model

To turn on the preference for Diagnostic Groups to be included in analysis:

1. Select Preferences > Application Preferences from the main menu
2. Go to the Propagation Table section and within select the preference set Use Diagnostic Groups in PHM Analysis to Yes (this option may have already been selected)
3. Select OK to apply the changes and close the dialog

Exercise 6.5.1 (continued): Create Diagnostic Groups in the Model

To create Diagnostic Groups in the model:

1. Open the Driveline system model
2. Select the Transmission component
3. From the Properties viewer, select the General tab
4. Select the Diagnostic Groups option from the Maintainability section
5. In the Diagnostic Groups dialog, select New Group >

Exercise 6.5.1 (continued): Create Diagnostic Groups in the Model

Select the checkboxes followed by Create for the following items:

• Transmission
• Driveshaft
• Differential

Repeat so that the following groupings are created:

• Diagnostic Group 1: Transmission, Driveshaft, Differential
• Diagnostic Group 2: Wheel Rear, Wheel Resistance Rear
• Diagnostic Group 3: Planetary Gearbox Front, Planetary Gearbox Rear

Discussion 6.5.2: Create Symptoms and Symptom Groups in the Model

• Symptoms are physical events that occur due to a failure and may be used to provide or aid in the diagnosis of failures.
• Symptoms are added into the model via the Failure Diagram and will then appear in the PHM Propagation Table and Analysis given certain conditions are met:
  1. Does the symptom provide observability of all paths that lead to each failure mode it (the symptom) interacts with?
     • If yes: include the symptom in the propagation table as a column (used for coverage and syndrome POD calculations)
     • If no: go to test 2
  2. Does the symptom have ambiguity between multiple failure modes? (i.e. the associated faults are connected to multiple failure modes)
     • If no: include in path POD (then used in overall POD calculation)
     • If yes: invalid symptom (not used in coverage or POD)

Discussion 6.5.2 (continued): Create Symptoms and Symptom Groups in the Model

• Symptom Groups are when two or more symptoms are grouped for the purpose of failure detection and diagnosis.
• This is to represent the circumstance where multiple failures manifest the same physical symptom and that the symptom may potentially be sensed using the one sensor (or location).
• An example of this may be two similar components with common failure modes in the system resulting in the same vibration.
• This vibration could potentially be sensed at either location and may indicate that either of the similar components have failed.

Exercise 6.5.2: Create Symptoms and Symptom Groups in the Model

Create a Symptom Group in the model:

1. In Project Explorer, right-click the Planetary Gearbox Front component and select the Failure Diagram
2. Select the add icon in the Failure Concepts window
3. Select Vibration and place it onto the Failure Diagram canvas
4. Connect the Functional Failure Mode to the Vibration concept
5. Repeat for the Planetary Gearbox Rear component

Exercise 6.5.2 (continued): Create Symptoms and Symptom Groups in the Model

1. Select one of the Vibration concepts
2. In the Properties viewer go to the Symptom Groups tab and select the add icon
3. From the dialogue, select New Group
4. In the Symptom field drop down menu, select Vibration
5. Within the Items section select the two Vibration symptom check boxes
6. Select Create and then select OK

Exercise 6.5.3: Run a Diagnostic Analysis with the Updated Model

To run a Diagnostic Analysis:

1. Select Analyses > Diagnostic Analyses from the main menu
2. Select the create/add icon
3. In the dialogue, select the following:
   • Indenture Selection: Driveline
   • Type of Diagnostic Analysis: Automated
4. Select Next
5. Enter the following details for the Analysis:
   • Name: Driveline PHM Analysis
   • Propagation Type: Bond
   • Check the Include symptom information check box
6. Select Next

Exercise 6.5.3 (continued): Run a Diagnostic Analysis with the Updated Model

1. Select the Optimize LRU Coverage check box
2. Under Analysis Options set Number of Sets to 10
3. Select generate/create

Note: If there are errors in the bond model, a warning message will appear.

Session 6.5 Summary

• 6.5.1: Create Diagnostic Groups in the Model
• 6.5.2: Add Symptoms to Failure Diagrams
• 6.5.3: Use Diagnostic Groups and Symptoms in Diagnostic Analyses

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Session 6 Overall Summary

(from the Session 6 closing "PHM Analyses" summary slide)

• 6.1: Sensor Library
• 6.2: Test Points
• 6.3: Automated Diagnostic Analysis
• 6.4: User-defined Diagnostic Analysis
• 6.5: Modeling for PHM and Additional Features