FTA Questions on Medini usage for Fusa analyses

medini_1060717213

Hello, We are
performing some trials of Functional Safety analyses with Medini tool.   By kind of analysis, we have some notes and questions:    FTA Missing gates: « Priority AND » => equation to be used (but the formula has to be checked) “Inhibit” => not available “Null” => not available   Missing events: House event   => not available Undevelopped event  => not available   Dormant  => not available Conditional  => not available   Repeat
mode for events: Use “Alt” and drag&drop the gate to be duplicated If an event implemented with the same name (Id) than a previous one is duplicated, no warning!   Quantitative
FTA: no issue   Using
of existing safety analysis: Impossible to open analysis file (like FTA) out of the complete project space in Medini => archiving issue for FuSa work products in our own project space. Is there a solution of workaround?   Failure
rate calculation: For calculation :  why the environment factor (called E4 in ICE 61709 standard) is not seeable in the Medini formula? Where does come the default value of the “base failure rate” in the calculation parameters in Medini from? Export of a BOM components with their physical parameters (stress, rate, Power, dissipation) in Excel or Word format possible => OK BUT Import issue of component parameter (stress, rate, Power, dissipation) : is there a dedicated template with an csv/Excel file (specificity of format)?   Miscellaneous:  è Certification ISO26262 for Medini tool? Thanks a lot for your replies, Best Regards,  Laurent garrouste FuSa & Cybersecurity line manager Veoneer France

medini_1059007410

Hello Laurent, Welcome and thanks for sharing the questions here in the forum. This way your colleagues can see the answers also later, and we would like to see as many people as possible reading and participating in the forum. I'll respond to the first part of your questions, and Krasimira will reply to the remaining ones. I have a few counter-questions for you, marked with an underline. FTA Generally gates and events are described in the help here: User Guide > Safety Analysis > Fault Tree Analysis (FTA) > FTA Diagram Editor  Priority AND gate Indeed, we do not have a priority AND gate. Instead, we recommend to model such sequential order constraints with an additional fixed probability (=0.5 for two events) event below a normal AND gate. This way you can reach the same probabilistic result. In other domains (e.g. Aero, ARP4761) this is specifically declared a "Required Order Factor (ROF)". Inhibit gate Medini does not have a dedicated inhibit gate, but as it is basically just another graphical representation of an AND gate with a conditional event (that's available, see below), you can just use a normal AND gate. The presence of a conditional event then clarifies that you are talking about an inhibition. Null gate Null gates do not have an effect on the tree logic, but provide space for more descriptions. This is possible in medini with a normal (intermediate) event: Medini allows gates (with an actual logic like AND/OR) and also intermediate events at the branches of the tree. Intermediate events store failure rate results as well as descriptions, so just add an event to a connection line: House event Medini has a house event - if you added an event, you can set "Kind" to HOUSE in the Properties (if you don't see that windows, right-click and click "Show Properties View") At the moment please use 0 and 1 as fixed probability input. From version 2022 R1 onwards, the setting TRUE/FALSE will be available as additional probability model, which better fits to house events. Undeveloped event Same as above, set "Kind" to UNDEVELOPED Conditional event Same as above, set "Kind" to CONDITIONAL Dormant event This is available and defined in the "Probability" tab of the Properties view. There you can choose the "Model" for the probability calculation, and for a dormant (or latent) event you can choose "Exponential" and then in under "Cycle kind" select "Monitored". This tau value represents the monitoring time or dormancy for the event, and will be shown as tau=...h below the event. "If an event implemented with the same name (Id) than a previous one is duplicated, no warning!" Yes, this feature is different in medini than in some other FTA tools. Medini identifies the events internally with unique identifiers, so it does not depend on the user-defined IDs. This freedom was implemented on user requests years ago, although others prefer unique IDs. The autocounters used for new events support the feature "avoid duplicated IDs" (available in Project Settings > Auto-counter Patterns since 2021 R2.1) for creating new events. Still one can manually change the IDs to existing ones. To validate uniqueness of the event IDs, you can run the "Validate" action on the project (via "Project" in the menu bar, or context menu of the project in the Model Browser). With Dynamic Constraint 0031 active (part of the BestPracticeTemplate, can be checked via Project Settings > Dynamic Constraints) this will otherwise lead to error shown. Additional counter-question: Which FTA tool are you migrating from? Usage of existing safety analysis "Impossible to open analysis file (like FTA) out of the complete project space in Medini => archiving issue for FuSa work products in our own project space. Is there a solution or workaround?" I do not fully understand the question. Is this about import from other tools into medini, or use of medini data across medini projects? And do you mean with "project space" the Model Browser, or the project folder on the drive (files and folders)? Can you please explain a bit more? Generally, projects should be (stored and) archived as .mprx files, which can be also handled by version management systems (with medini itself as comfortable diff&merge tool). Failure rate calculation "Why the environment factor (called E4 in ICE 61709 standard) is not seeable in the Medini formula?" I couldn't find the E4 factor in IEC 61709:2017. Can you please hint me to the position in the standard, where it is described? Krasimira will reply for the remaining questions. Regards, Nils