MADE Training > Session 2 > Session 2.4: Failure Analysis

Session 2.4: Failure Analysis

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SESSION 2.4 OUTLINE

2.4.1: Functional Failures 2.4.2: Component Failure Diagrams 2.4.3: Failure Diagram Failure Conditions 2.4.4: Part-level Failure Diagrams 2.4.5: System & Subsystem Failure Diagrams 2.4.6: Response Paths 2.4.7: Propagation Table

Session 2.4: Failure Analysis

DISCUSSION 2.4 FAILURE ANALYSIS

This session will cover all aspects of how failures are generated in MADE We will cover the difference between functional and physical failures We will use failure diagrams to define more detail of a failure We will generate response paths to look at all of the generated failures by the software We will look at the propagation table for responses generated by the software

Session 2.4: Failure Analysis

DISCUSSION 2.4.1 FUNCTIONAL FAILURES

Failures are automatically derived from functions and flows Deviations from the nominal state are considered failures in MADE

   We consider these Functional Failures

Flow typically have two failure responses: High or Low deviation Different domains (flows) have different linguistic terms:

   Flow rate & Contamination use Increase or Decrease
   Flow direction uses Misdirected +/-
   Timing uses Advanced +/Delayed �
   Contamination only has High as a failure response
   Also see: Alignment, Position, Shape, Timing

These failure responses can be managed from the Properties viewer

Session 2.4: Failure Analysis

EXERCISE 2.4.1 FUNCTIONAL FAILURE

To edit a functional failure:

   Open the system model of the `Diesel Engine'
   Select the `Primary Fuel Filter'
   Navigate to the Properties Viewer and select Functional Failures tab
   Tick the Override failure diagram check box
   Disable the High Fuel Flow rate
   This overrides the failure analysis failure paths with the selected functional failure: Low Flow Rate

Session 2.4: Failure Analysis

DISCUSSION 2.4.2 FAILURE DIAGRAMS

Failure diagrams look at the causes & progression of failure

Failure diagrams are focussed on physical aspect of failures

Failure diagrams use a peer-reviewed taxonomy to assist in definition

Taxonomy for failure concepts are shown below

Failure Concept Symbol Definition Cause The abnormal state of input, loading or environment that leads to the degradation of an item.

Mechanism The chemical, electrical, mechanical or software processes which causes physical degradation of a system element and Fault results in a fault. Symptom The physically degraded state of a system element or a change in its behaviour which will result in a failure mode or the inability to carry out its function.

                The response of a failed system element or a loss generated by a failure process that can be used to detect a failure mode.

Failure Conditions A Failure Condition describes the behaviour of a failure mode and its potential effects.

Failure Mode The observable manner in which a system or system element fails to fulfil its function, expressed in terms of the deviation of its output flow from the specified or nominal limits.

Session 2.4: Failure Analysis

EXERCISE 2.4.2 COMPONENT FAILURE DIAGRAMS

To construct a component failure diagram:

Open the system model for the Power Generation' subsystem Right-click the Control Unit' component Select Failure Diagram from right-click menu Select Mechanisms in the Failure Concepts viewer Under Electrical category, click-and-drag Burnout & Dielectric Breakdown mechanisms onto the failure diagram editor

Session 2.4: Failure Analysis

EXERCISE 2.4.2 COMPONENT FAILURE DIAGRAMS (CONTINUED)

You will find that there is a repeat of Over-current and Over-Voltage Causes and Open circuit fault We can simplify the failure diagram by deleting duplicates

  Delete repeated failure concepts: Over-voltage, Over-current and Open circuit

Connect all faults to the Functional failure mode

Note: To select multiple mechanisms, hold Ctrl and select. When multiple mechanisms are selected and placed onto the failure diagram canvas, it will be automatically simplified.

Session 2.4: Failure Analysis

EXERCISE 2.4.2 COMPONENT FAILURE DIAGRAMS (CONTINUED)

Failure diagrams have an underlying taxonomy, however, users may choose to edit the display name to better represent or provide additional information to the failure.

To change the display name of the Transient electrical loads:

Select the Transient electrical loads cause Using the Properties viewer, edit the Name field to: Transient electrical loads due to varying power source

Session 2.4: Failure Analysis

DISCUSSION 2.4.3 FAILURE DIAGRAM FAILURE CONDITIONS

Failure condition describes the behaviour of the failure and is connected to the fault. It can be direct or consequential to the failure causing adverse operational conditions.

Session 2.4: Failure Analysis

EXERCISE 2.4.3 FAILURE DIAGRAM FAILURE CONDITIONS

To add a failure condition to the Control Unit failure diagram:

Select the failure condition icon in Failure concepts Select and drag the Intermittent Operation failure concept to the failure diagram Delete the connection between Dielectric strength decreased and the Functional failure mode Connect the Dielectric strength decreased fault to the failure condition Connect the failure condition to the failure mode

Session 2.4: Failure Analysis

DISCUSSION 2.4.4 PART-LEVEL FAILURE DIAGRAMS

Part-level failure diagrams capture a more accurate location of failures

Part-failure failure diagrams contain the most amount of detail on a failure

Part-failure diagrams allow for better understanding of failures

   Better informed root cause analysis & diagnosis of failures
   Maintenance actions e.g. repair can be conducted more

     quickly and successfully as the root cause is identified

Part failure diagrams describe how physical failures result in a component's loss of function/s

Session 2.4: Failure Analysis

EXERCISE 2.4.4 PART-LEVEL FAILURE DIAGRAMS

To construct part-level failure diagrams:

Open the system model for the Fuel Tank' Right-click the Inlet' part and select Failure Diagram From the Failure Concepts viewer select the Corrosive attack mechanism and add to the canvas

Session 2.4: Failure Analysis