Configuration Panel
The Simulation Settings report appears at the top of the Configuration panel. The component settings for every selected component appear below the Simulation Settings outline. Configuration settings for selected events and actions appear below the block shape to which the action or event belongs.
Simulation Settings
Alter the settings for the simulation in the Simulation Settings report, which is available in the Configuration panel. The following settings are available:
Duration
The length of time that is simulated in each iteration.
Time Unit
The unit of time to use for the simulation.
Note: Recurring events and non-immediate actions use the Time Unit specified in Simulation Settings.
N Simulations
The number of iterations in the simulation.
Seed
(Optional) A random seed that ensures the reproducibility of simulation results. By default, the Seed is set to zero, which does not produce reproducible results. When you save the analysis to a script, the random seed that you enter is saved to the script.
Caution: If you run a simulation by right-clicking and selecting Run Multithreaded Simulation, the results are not reproducible, even if you specify a random seed.
Block Settings
Select a block shape in the System Diagram to see its settings in the Configuration panel.
Each block shape, except the knot block, has a Turn On System Exemption option. If this option is selected for a block, the block is not turned on when the Turn On System action is invoked.
Each block shape, except the knot block, has a failure distribution that determines the rate at which the block shape’s individual components randomly fail. The failure distribution for a basic block determines the rate at which the block fails, because basic blocks represent only one component. For more information about the available failure distribution options, see Distribution Options. Under the Distribution option, you can specify the Time Unit and distribution-dependent parameters for the block.
Series and Parallel
A series block fails when one of its components fails. A parallel block fails when all of its components fail. The following option is available for series and parallel blocks:
N
Specifies the number of identical components contained in the block.
K-out-of-N
K-out-of-N blocks contain n identical components. The block fails when fewer than k of the components are functional. The following options are available for K-out-of-N blocks:
K
Specifies the minimum number of functional components required for the block to remain functional.
N
Specifies the number of identical components contained in the block.
Standby
Standby blocks have secondary components, called standby components, that are inactive. Active components perform work within a standby block. Inactive components do not perform work within a standby block, and are activated one at a time as active components fail. Occasionally, the activation process is not successful. A component switch might fail when activating a standby component. A standby block fails when less than k of its n identical components are active. The following options are available for standby blocks:
K
Specifies the number of components that are initially active. This is also the minimum number of active components that is required for the block to remain functional.
N
Specifies the total number of identical components within the block. The difference between k and n is equal to the number of standby components.
Switch Type
Specifies the mechanism that activates a single standby component if any active component fails.
Single Switch
A single switch exists in the block. If the activation of a standby component fails, then the block also fails.
Individual Switches
A switch exists for each standby component. If the activation of a standby component fails, that standby component cannot be activated. The standby block attempts to activate the next standby component until a standby component is activated. If no remaining switches are functional and fewer than k of the components are active, then the block fails.
Switch Reliability
Specifies the probability of success of activating a standby component when any active component fails.
Standby Type
Specifies the state and failure distribution of the standby components.
Cold
Standby components do not age until they are activated.
Warm
Standby components age according to a secondary failure distribution while they are inactive. When standby components are activated, they age according to the primary failure distribution. Use the secondary failure distribution to mimic reduced stress on standby components that are not performing work in the standby block.
Stress Sharing
A stress sharing block distributes stress equally among its components. As components fail, the components that remain functional experience increased stress and subsequently fail at an increased rate.
N
Specifies the total number of identical components contained in the block.
Switch Reliability
Specifies the probability of successfully reallocating stress among the remaining functional components. The block fails if the reallocation of stress fails.
Stress Sharing Type
Specifies how stress is shared among functional components.
Basic (default)
Specifies that stress is shared equally among the remaining functional components. This type of stress sharing is referred to as Load Sharing. The characteristic life of individual components is proportional to the number of components that share the work load.
Custom
Specifies that components share stress according to the JSL code that appears in the Sharing Formula option. The Sharing Formula defines how stress changes when components fail.
Knot
Knot blocks do not have a failure distribution. Knot blocks fail only if the number of connected blocks shapes that are functional falls below the specified minimum number. The following option is available for knot blocks:
Minimum Available
Specifies the minimum number of functional blocks that must point to the knot block for the knot block to remain functional.