Towards a Unified Model-Based Formalism for Supporting Safety Assessment activities

Safety assessment is a rational and systematic process for assessing the risk associated with the usage of a product. While the safety assessment process is important even when making a simple product, the true importance of this process comes into light when designing for example an aircraft, where a failure could possibly lead to the loss of human lives. However,even though this process is vital for certain industries, it is plagued by a lack of tools. The existing tools are focused on specific parts of the process and do not make use of work done in earlier steps of the process which often means that the safety engineer needs to manually do work that could have been calculated automatically from information that is already present from an earlier step in the process. This thesis shows that by creating a model of the product that can be present and augmented throughout every step in the process, many calculations that are currently done by hand can be automated or semi-automated by examining this shared model. The thesis proposes a specification for a modeling formalism that is simple enough to be used as early as the requirements phase of a project, but powerful enough to provide important information all the way throughout the safety assessment process. The thesis also specifically shows how this model can be used to help in the creation and updating process of Failure Mode and Effects Analysis (FMEA) documents as a proof-of concept implementation based on Sörman Information AB’s product “Uptime BPC Standard”.Algorithms for synchronizing between the model and the FMEA representation, as well as algorithms for automatically calculating the next level effect and global level effect of failure modes based on the hierarchy and connections made in the model are also presented. The prototype implementation shows that even though the entire safety assessment process cannot be automated it is possible to extract information from the model by analyzing its hierarchy and connections. While more work still needs to be done before the entire safety assessment process can be encompassed, the initial results shows that the proposed modeling formalism allows us to create models from which relevant information that can be used to support the safety assessment process can be calculated