3.7 Generate FCM Simulations & Analyses (Step 10)

3.7.1 Failure Injection

Failure injection is used to inject a failure response into an item output flow, followed by propagating the responses of subsequent items throughout the system. The responses to the initial injected failure can be examined (stepped through) using the step table. The failure mode of a flow is the deviation of the functional outputs from its nominal state. These failure modes are propagated using FCM through the system model during automated failure analysis of the system.

Injecting a failure starts by introducing one (or multiple) failure responses to an item to investigate the propagation of the failure responses throughout the system. The steps below summarize the process required:

• Right-click an item in the system model
• Select Failure Injection → Flow Property the flow → Response (e.g. Up / Down)
• Select either an Up or a Down perturbation
• The injected failure will display at the top-left corner of the system model
• Select the Step Table Actions (Run to Equilibrium, Forward/Back One Step, Reset Step Table, Clear Step Table)

Figure 12 shows the right-click context menu on the Fuel Tank item in the Power Generation system model, with options: System Model, Failure Diagram, Functions, ABD Model, RBD Model, Back-Fit RCM, Maintenance Actions, Cut/Copy/Paste/Delete, Zoom In/Out, End Effect Item, Fault Tree, Response Paths, Monte Carlo (submenus), Propagate All..., Override Failure Diagram, Failure Injection → Liquid Static pressure → Up / Down (Down selected in the example), Response Simulation.

The figure shows a failure injection for static pressure in the Fuel Tank. The propagation of this failure response and its consequences on the other items are shown in the Propagation Table viewer (Figure 13):

• "Power Generation" system model: Functional Perturbation banner reads "Provide Liquid Static pressure (Fuel Tank) ↓". Fuel Tank shows ↓1, Diesel Engine shows ↓7 and ↓8 at its outputs, Control Unit shows a warning icon.
• "Diesel Engine" system model (same perturbation): Coupling 1 shows ↓7, Lift Pump ↓2, Primary Fuel Filter ↓3, Secondary Fuel Filter ↓4, Injector Pump ↓5, Engine shows ↓7 (angular velocity/torque outputs).

Figure 14 ("Failure Propagation Table showing the effects of a Failure Injection") is a Step Table for "Power Generation" listing, for each Component/Flow Property row, the perturbation value at each simulation step (columns 1–19+). Example rows and values (↓ = down perturbation, magnitude -1.0 unless noted):

Component	Flow Property	Notable step values
Air Filter	Gas Mass flow rate	0.0 (no perturbation)
Control Unit	Continuous Amplitude	0.0
Coupling / Coupling 1	Mechanical - rotational Torque	↓-1.0 from step 7 onward
Diesel Engine	Mechanical - rotational Angular ve...	↓-1.0 from step 7 onward
Differential	Mechanical - rotational Torque	↓-1.0 from step 12 onward
Driveline (x2)	Mechanical - rotational Torque / Angular ve...	↓-1.0 from step 14–15 onward
Driveshaft	Mechanical - rotational Torque	↓-1.0 from step 10 onward
Engine	Mechanical - rotational Torque	↓-1.0 from step 7 onward
Fuel Tank	Liquid Static pressure	↓-1.0 from step 1 onward (the injected failure)
Governor	Mechanical - linear Linear velocity	(blank / not perturbed in shown steps)
Half Shaft Front / Rear	Mechanical - rotational Torque	↓-1.0 from step 14–15 onward
Injector Pump	Liquid Dynamic pressure	↓-1.0 from step 5 onward
Lift Pump	Liquid Flow rate	↓-1.0 from step 2 onward
Planetary Gearbox / Gearbox	Mechanical - rotational Angular ve... / Torque	↓-1.0 from step 15–16 onward
Power Generation	Mechanical - rotational Torque	↓-1.0 from step 7 onward
Primary Fuel Filter	Liquid Flow rate	↓-1.0 from step 3 onward
Secondary Fuel Filter	Liquid Flow rate	↓-1.0 from step 4 onward
Transmission	Mechanical - rotational Angular ve...	↓-1.0 from step 8 onward
Vehicle	Mechanical - rotational Angular ve...	↓-1.0 from step 16 onward
Vehicle System	Liquid Flow rate / Mechanical - rotational Angular ve... / Gas Mass flow rate / Electrical Voltage	↓-1.0 from steps 16–18 onward, or 0.0 if unaffected
Wheel Front	Mechanical - rotational Angular ve...	↓-1.0 from step 18 onward
Wheel Resistance (Front/Rear)	Mechanical - rotational Angular ve...	↓-1.0 from step 17 onward

This table demonstrates how a single injected failure (Fuel Tank Liquid Static pressure, Down) propagates step-by-step outward through the fuel and drivetrain paths, with each downstream component's perturbation appearing at a later simulation step as the failure ripples through the causal connections, eventually settling at a steady-state magnitude of -1.0 for each affected flow property.

3.7.2 Response Simulation Graph

The user can determine the response of an item or flow based on the (functional/FCM) model configuration. This response is plotted as a graph in the Response Simulation viewer. To do this:

• Right-click on an item in the System Model
• Select Response Simulation from the right-click menu – this will expand an additional sub-menu
• Select the desired flow property to plot in the Response Simulation viewer

Figure 15 shows the "FCM Response Simulation - Vehicle System" viewer with the Lift Pump's "Liquid Flow rate" selected (tree: Vehicle System > Coupling, Driveline, Power Generation > Control Unit, Diesel Engine > Air Filter, Coupling 1, Engine, Governor, Injector Pump, Lift Pump [Liquid Flow rate checked], Primary Fuel Filter, Secondary Fuel Filter, Mechanical - rotational Torque; Fuel Tank; Vehicle; Mechanical - rotational Angular velocity ×2). The plotted graph starts at 0, drops sharply after the "FAILURE ACTIVATION" marker (around step 2–3), dips to about -0.8 by step 8, then partially recovers and stabilizes at approximately -0.775 by around step 10 onward.

4 Conclusion

This guide has outlined one of the approaches to creating and analyzing the functional model of complex systems in MADE. While this guide has not detailed all features associated with FCM modeling, it has given a broad idea of how FCM can be used to model the functional behavior of a complex system.

FCM is suitable for modeling signal and process-based systems and can be used to generate simulation response graphs and fault propagation tables to qualitatively analyze and troubleshoot the model of a system.

MADE's approach for modeling enables the user to have full control over modeling and simulation. However, this requires a comprehensive understanding of physical and mathematical relationships, knowledge of hardware, and familiarity with the modeling process. The graphical interface, flexibility in model representation, possibility of storing developed models for future use, and operation in real-time for hardware-in-loop simulation make MADE modeling very approachable.