Session 1.8: System Modeling (Functions)

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Session 1.8: System Modeling (Functions)

SESSION 1.8 OUTLINE

1.8.1: Functional Modeling 1.8.2: System & Subsystem Functions and Flows 1.8.3: Component Functions and Flows 1.8.4: Pair Functions and Flows 1.8.5: Connecting Model Items

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Session 1.8: System Modeling (Functions)

DISCUSSION 1.8.1 FUNCTIONAL MODELING

Objective: Defining the functions and flows for a system and its items

MADE has a defined functions taxonomy to assist modeling and increase model repeatability

Functions: A description of an operation to be performed by a device, artifact or item, expressed as a verb A list of MADE function categories found is listed below:

Category Definition Branch To cause a material or energy to no longer be joined or mixed. Channel To cause a material or energy to move from one location to another location. Connect To bring two or more energies or materials together. Control To alter or govern the size or amplitude of material, signal or energy. Convert To change from one form of energy or material to another. Provide To accumulate or provide material or energy. Signal To provide information. Stop To cease, or prevent, the transfer of a material, signal or energy. Support To firmly fix a material into a defined location, or secure an energy into a specific course.

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Session 1.8: System Modeling (Functions)

DISCUSSION 1.8.1 FUNCTIONAL MODELING (CONTINUED)

MADE has a defined flows taxonomy to assist modeling and increase model repeatability Flow: A change in material, energy or signal with respect to time, expressed as the object of a function Flows represent the interfaces throughout the system A list of MADE flow categories is listed below:

Category Definition Energy Any flow that is characterized by the exchange of energy. Material Any flow that is characterized by the exchange and/or interaction of material. Signal Any flow that is characterized by the exchange of information.

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Session 1.8: System Modeling (Functions)

EXERCISE 1.8.2 SYSTEM & SUBSYSTEM FUNCTIONS AND FLOWS

To assign functions and flows:

Right-click on the `Vehicle System' in the Project Explorer and select Functions This action will open the Functions window where the following are defined:

  System Function
  Flow Property (In Flows and Out Flows)

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Session 1.8: System Modeling (Functions)

EXERCISE 1.8.2 SYSTEM & SUBSYSTEM FUNCTIONS AND FLOWS (CONTINUED)

Locate the Convert function Click-and-drag to grey area to assign function

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Session 1.8: System Modeling (Functions)

EXERCISE 1.8.2 SYSTEM & SUBSYSTEM FUNCTIONS AND FLOWS (CONTINUED)

Locate and select the Flows tab (this will be automatic selected after adding the first function) Click-and-drag into the In Flows:

  Liquid (Material)
  Gas (Material)
  Electrical (Energy)

Click-and-drag into the Out Flows:

  Mechanical � rotational (Energy) (x2)

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Session 1.8: System Modeling (Functions)

EXERCISE 1.8.2 SYSTEM & SUBSYSTEM FUNCTIONS AND FLOWS (CONTINUED)

The completed functions editor should look like the image on the left System Model shows IN/OUT mux bars with a function and input & output flows

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Session 1.8: System Modeling (Functions)

EXERCISE 1.8.2 SYSTEM & SUBSYSTEM FUNCTIONS AND FLOWS (CONTINUED)

Repeat function editor steps for the Power Generation' & Driveline' subsystem using the table below

   Subsystem   Functions             Input Flows             Output Flows

Power Generation Convert Liquid Mechanical � rotational Gas Driveline Branch Electrical Mechanical � rotational Branch Mechanical � rotational Mechanical � rotational

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Session 1.8: System Modeling (Functions)

EXERCISE 1.8.2 SYSTEM & SUBSYSTEM FUNCTIONS AND FLOWS (CONTINUED)

Completed functions editors for Power Generation' & Driveline' subsystems are shown below

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Session 1.8: System Modeling (Functions)

DISCUSSION 1.8.3 COMPONENT FUNCTIONS AND FLOWS

Functional modeling is a top-down process however connecting flows are a bottom-up process

E.g. Define System Functions, then Subsystem, then Components etc.
E.g. Flows between components are connected, then subsystem flows, then flows to the system

Component functions should relate to subsystem functions

E.g. If a subsystem function is to `provide torque', then a component function could be to `convert torque'

Flow properties represent the measurable attributes of a flow Causality is defined in components based on the relationship between input and output flows Once connected together a subsystem will inherit flow paths from its children items

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Session 1.8: System Modeling (Functions)

EXERCISE 1.8.3 COMPONENT FUNCTIONS AND FLOWS

Open the system model for the Power Generation' subsystem Right-click the Fuel Tank' and select Functions Assign the Provide Function Assign the Material - Liquid flow into the In Flows Assign the Material - Liquid flow into the Out Flows Left-click and drag the Flow rate property in the In Flows to the Static pressure property in the Out Flows

Note: The functional description will read as Provide Liquid Static pressure

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Session 1.8: System Modeling (Functions)

EXERCISE 1.8.3 COMPONENT FUNCTIONS AND FLOWS (CONTINUED)

Right-click the `Control Unit' from the Project Explorer and select Functions Assign the flows as indicated in the table:

Subsystem Functions In Flows Out Flows Control Unit Process Energy - Electrical Signal - Continuous

Note: The Process function is located within the Signal folder. Alternatively, use the Search bar to search for Process Connect the Electrical � Voltage input flow to the Continuous � Amplitude output flow

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Session 1.8: System Modeling (Functions)

EXERCISE 1.8.3 COMPONENT FUNCTIONS AND FLOWS (CONTINUED)

Right-click the `Transmission' from the Project Explorer and select Functions Assign the Distribute function (Under Branch folder) Assign Energy � Mechanical - rotational flow into the In Flows Assign Energy � Mechanical - rotational flow into the Out Flows Connect the Torque In Flow property to Angular Velocity Out Flow property

Note: This will read as Distribute � Mechanical � rotational Angular velocity

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Session 1.8: System Modeling (Functions)

EXERCISE 1.8.3 COMPONENT FUNCTIONS AND FLOWS (CONTINUED)

To model the `Driveline' subsystem:

Create components in the `Driveline' subsystem using the table below:

Component Function In Flow Out Flow Transmission (Completed) Distribute Mechanical � Rotational Torque Mechanical � Rotational Angular Velocity Driveshaft Support Mechanical � Rotational Angular Mechanical � Rotational Torque Velocity Differential Divide (Branch) Mechanical � Rotational Torque Mechanical � Rotational Angular Velocity Half Shaft (2 instances) Transmit Mechanical � Rotational Angular Mechanical � Rotational Torque (Channel) Velocity Planetary Gearbox (2 instances) Store (Provide) Mechanical � Rotational Torque Mechanical � Rotational Angular Velocity

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Session 1.8: System Modeling (Functions)

EXERCISE 1.8.3 COMPONENT FUNCTIONS AND FLOWS (CONTINUED)

Additional components required for the driveline: 2x Wheel components This requires accessing the Palette viewer:

   Search for the Wheel component
   Drag out two Wheel components to the `Driveline' system model
   Rename them to `Wheel Front' & `Wheel Rear'

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Session 1.8: System Modeling (Functions)

DISCUSSION 1.8.4 PAIR FUNCTIONS AND FLOWS

How are functions assigned for a pair?

   A part is a discrete singular unit that cannot by itself work functionally. It needs to work in combination with one
     or more other parts

Why are pair functions necessary?

   A pair is the functional use of two parts

How do pair functions relate to a component?

   Unlike the relationship between components and subsystems, part-pair functions aren't directly connected to
     their parent component's functions

   Parts represent the physical base units of a system, whereas components and above are representing the logical
     structure of the system

Note: The failure diagram (later session) will further explore relationship between parts and components

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Session 1.8: System Modeling (Functions)

EXERCISE 1.8.4 PAIR FUNCTIONS AND FLOWS

To assign a Pair Function & Flow:

  Open the system model for the `Fuel Tank' component
  Right-click the Inlet-Lining pair and select Functions
  Assign a function: Contain (Provide)
  Assign a flow: Material � Liquid
  Select the property: Flow rate

  Right-click the Lining-Outlet pair and select Functions
  Assign a function: Supply (Provide)
  Assign a flow: Material � Liquid
  Select the property: Static Pressure

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Session 1.8: System Modeling (Functions)

DISCUSSION 1.8.5 CONNECTING MODEL ITEMS

Connecting items in the system model is used for:

   Propagation of an injected failure
   Path analysis of failures for reporting outputs e.g. FMEA, FMECA
   Simulating dependencies between items using Bond Graph or FCM simulation methods

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Session 1.8: System Modeling (Functions)

EXERCISE 1.8.5 CONNECTING MODEL ITEMS

Connect the `Driveline' components as shown in the diagram below:

   The connection between the `Planetary Gearbox' and `Wheel' components can not be connected due to
     mismatched flow properties

   To resolve this, change the `Wheels' in flow properties to Angular velocity to connect the model

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Session 1.8: System Modeling (Functions)

EXERCISE 1.8.5 CONNECTING MODEL ITEMS (CONTINUED)

Connect the Power Generation' & Driveline' subsystems in the first Level of Indenture

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Session 1.8: System Modeling (Functions)

SESSION 1.8 SUMMARY

1.8.1: Functional Modeling 1.8.2: System & Subsystem Functions and Flows 1.8.3: Component Functions and Flows 1.8.4: Pair Functions and Flows 1.8.5: Connecting Model Items