3 Modeling Workflow for FCM Simulation

Figure 3 ("Creating FBD workflow") depicts "WF04: Create FBD Model for FCM Simulations" — this is the same workflow diagram documented in the Bond & FCM Comparison Guide (bond-fcm-guide-when-to-use-and-conclusion.md). Reproduced here for completeness:

Pre-requisites

• A. MADE Project: a configured project.
• B. Bill of Materials (BOM): establishes the system configuration to build the functional block diagram (FBD) model.

Flowchart Steps

1. Create Model Item
2. Define Function(s)
3. Define Functional Flows
4. All Model Items Created? → No: loop back to step 1 / Yes: continue
5. Connect Functional Flows
6. Define Model Item Details (fed by: General Properties, Advanced Properties, Product Characteristics)
7. Define Flow Property General Details (fed by: Display Name, Unit, Initial Value, Internal Damping)
8. Define Functional Flow Causality Details (fed by: Polarity, Response Filter, Acausality, Causal Strength)
9. All Model Items Defined? → No: loop back to step 6 / Yes: continue
10. Review FCM Response Simulations
11. Responses Acceptable? → No: loop back to step 6 / Yes: continue
12. FBD Model For FCM Created → Propagation Table

Detailed Descriptions

1. Create model items with 'New Item' options under 'Modeling' in the main menu bar or via the context menu opened on the system model viewer canvas.
2. Define function(s) in the Functions Editor, accessed by 'Functions' via the right-click context menu opened on the model item. Click and drag the relevant function from the Function taxonomy and place on the canvas.
3. Click and drag the relevant functional flows from the Functional Flow taxonomy list onto the relevant in- or out-put. Connect Flow Properties clicking and dragging from In Flows to Out Flows.
4. Continue creating model items, defined with functions and functional flows.
5. Connect functional flows between model items by clicking and dragging from the output of one item, to the input of the other. Only same functional flows will connect.
6. Select a model item and define General details in the Properties viewer, which overlaps with Advanced details accessed by 'Advanced Properties' via the context menu opened on the model item. Also define Product Characteristics, if necessary.
7. Access Functions Editor and select a functional flow property to define General details in the Properties viewer.
8. Select a functional flow connection between flow properties to define causality details in the Properties viewer.
9. Select another model item, repeating previous steps until all are defined with the necessary details for FCM simulation.
10. Execute 'Propagate All' in the context menu opened on the system model viewer canvas, 'Select all' to view all functional flows and then 'Propagate', to review FCM response simulations.
11. Following review of FCM response simulations in the Propagation Table viewer, deem responses unacceptable, alter functional flows until acceptable, including creating model items.
12. FBD Model created for FCM simulations.

Outputs

• Propagation Table: tabulated results of failure propagations throughout system model for FCM response simulations, exportable as a .csv file.

---

The sections below describe each workflow step in further detail. This guide uses the Power Generation Subsystem under the Vehicle system from the Training Material as the basis for model construction and FCM simulation & analysis.

3.1 Create Logical Blocks (Step 2)

Each component in the Power Generation subsystem is recreated as logical blocks using the Add New Component or Add New Subsystem button.

The Power Generation subsystem consists of two Levels of Indenture (LOI), 10 components and 2 subsystems, as listed below:

• Power Generation Subsystem (1st LOI)
• Fuel Tank Component (2nd LOI)
• Control Unit (2nd LOI)
• Diesel Engine Subsystem (2nd LOI)
  • Air Filter Component (3rd LOI)
  • Coupling Component (3rd LOI)
  • Engine Component (3rd LOI)
  • Governor Component (3rd LOI)
  • Injector Pump Component (3rd LOI)
  • Lift Pump Component (3rd LOI)
  • Primary Fuel Filter Component (3rd LOI)
  • Secondary Fuel Filter Component (3rd LOI)

(Figure 4 shows these items as logical blocks in the "Power Generation" and "Diesel Engine" system model editors, with Mission Profile "New Group" and End Effect Item "Vehicle System", bracketed by IN/OUT ports.)

3.2 Assign Functions (Step 3)

For FCM parameters to be assigned, the user must first assign functions and flows. To do this:

• Open the Functions Editor
• Assign Functions from the Functions Taxonomy
• Save changes

These actions are repeated for both subsystems and components. (Figure 5 shows the Functions Editor with a "Supply" function being assigned to "Fuel Tank 1", and the Functions Taxonomy tree listing categories: Energy > Acoustic, Chemical, Electrical, Electromagnetic, Generic, Hydraulic, Magnetic, Mechanical - rotational, etc.)

3.3 Assign Flow Properties & Flows (Step 4 – 5)

The user determines whether modeling and simulating power transmission is the main consideration for creating the model. If this is not the case, the user proceeds in assigning flows from energy, material and signal categories.

Figure 6 shows the "Supply" function on "Fuel Tank 1" with a full Liquid flow-property taxonomy list available for both IN FLOWS and OUT FLOWS: Bulk modulus, Contamination, Density, Dynamic pressure, Dynamic viscosity, Flow direction, Flow rate, Flow velocity, Kinematic viscosity, Reynolds number, Static pressure, Temperature, Timing, Volume.

3.4 Connect Flow Properties & Flows (Step 6)

The user connects the selected input flow properties to the output flow properties to establish a causal connection. The causal connection is represented as a line through. Once this is completed for all items, the user can connect flows in the system model.

Figure 7 shows a causal connection drawn from IN FLOWS "Flow rate" (checked) to OUT FLOWS "Static pressure" (checked) on the Fuel Tank 1 "Supply" function.

Figure 8 shows the resulting connected system model: IN → Fuel Tank → Diesel Engine → OUT, with Control Unit also feeding into Diesel Engine — flow lines colored green (material/liquid) and red/blue for other categories, and a warning icon on Control Unit indicating an incomplete definition.

3.5 Enter Model Item Details (Step 7)

The user adds additional information to the item listed in the advanced properties. Figure 9 ("Fields and Options available to FBD items") is a large reference matrix of which fields apply to which FBD block type (System, Subsystem, Component, Part, Part-Pair), organized into three tab groups:

General tab Parameters (Properties Viewer): Item Name, Item Number, Physical Description, Functional Narrative, Instance Count, Is Critical?, LRU/SRU — each available at different combinations of System/Subsystem/Component/Part/Part-Pair (e.g. Item Name applies to all 5; Instance Count and Is Critical? only apply to Part; LRU/SRU applies to System/Subsystem/Component/Part-Pair but not Part).

Overview tab Parameters (Advanced Properties): Vendor Name, Vendor Number, Synonyms, Documents, Drawing Reference Number, Reference Drawing, Digital Image, Icon — generally available for System/Subsystem/Component/Part (not Part-Pair).

Maintenance Actions tab Parameters (Advanced Properties): MTTR, Action ID, Action Name, Description, Location of Maintenance, Maintenance Type, Maintenance Sub-Type, Continuous Monitoring, Maintenance Interval, Inspection Interval, Task ID, Personnel ID, Task Description, Personnel Description, Downtime, Duration, Rate, Personnel, Item ID, Item Name, Cost, Quantity — all available for System/Subsystem/Component/Part (not Part-Pair).

Product Characteristics tab Parameters (Advanced Properties): Design Description & Rationale, Failure History, Operational Use, Effects on Subsystem, Redundancy Screen (Subsystem), Pass/Fail (Subsystem), Acceptance, Qualification, Effects on Interface, Redundancy Screen (Interface), Receiving, Assembly/Installation, Testing, Contamination Control, Effects on Mission, Redundancy Screen (Mission), Pass/Fail (Mission), Effects on Human/System, Redundancy Screen (Human/System), Pass/Fail (Human/System) — all available for System/Subsystem/Component/Part (not Part-Pair).

3.6 Set Item Parameters

Item Parameters are options available in the Properties Viewer when selecting causal connections or output flow properties in the Functions editor. The main options are:

• Initial Value: A range between -10.0 and 10.0, which impacts the initial flow response and consequent FCM calculations.
• Internal Damping: A coefficient subtracted from the output flow property for each step in the FCM simulation (used to model damping/consumption behavior of a flow).
• Polarity: Used to indicate positive (directly proportional) or negative (inversely proportional) polarity for a causal connection.
• Response Filter: Options to block specific types of incoming flow responses.
• Acausal: Limits the causal connection to the initial flow and prevents its application to subsequent feedback loops.
• Causal Strength: The degree to which the target functional output flow will be perturbed up or down by the input flow.

Figure 10 shows the Properties viewer for the output flow property "Static pressure" on Fuel Tank 1's Supply function: Name = Static pressure, Flow Property = Static pressure, Function = Supply - Liquid (OUT), Unit = psi, Initial Value slider = 0.0 (range -10 to 10), Internal Damping slider = 0.0 (range 0 to 10).

Figure 11 shows the Properties viewer for the causal connection "Flow rate -> Static pressure": Source = Supply Liquid Flow rate (Fuel Tank 1), Target = Supply Liquid Static pressure (Fuel Tank 1), Function = Supply, Polarity = Positive (selected) / Negative, Response Filter = No Filter, Acausal checkbox (unchecked), Causal Strength slider = 10.00 (range 1–10).