Failure Modes Effects Analysis process modelling

The goal of risk analysis is to identify events that may have one or several undesirable consequences on a system, and to assess the likelihood and severity of these consequences. A lot of methods can be used to conduct risk analysis (Flaus, 2013a) such as Preliminary Hazard Analysis (PHA) and Failure Mode Effects Analysis (FMEA) (Papadopoulos et al., 2004). In most of these methods, the obtained information may be used to build a risk model. The next step after risk analysis is to study the behavior of the system, when the undesirable events occur, in order to evaluate its performance in degraded conditions, and its robustness or resilience. An approach to allow integrated risk analysis and simulation has been proposed for business process management (Tjoa et al., 2011). 

A conprehensive product release process ensures that products are very mamre when released. Parallel to the comprehensive quality management process the safety process starts with general safety requirements which are checked for applicability and allocated to the project respectively. It continues with several tasks like performance of an Functional Hazard Assessment, production of an hardware RAM Modelling and Prediction Report and a Failure Modes, Effects and Criticality Analysis for a typical configuration and the use of the previously mentioned hazard checklist. Finally all issues of the product release checklist are to be fulfilled to get the official release. 

There are four main reliability engineering processes that are carried over at the very early phases of a design project and updated during the development phase of the project. Those are modeling, allocation, prediction and Failure Modes Effects and Criticality Analysis (FMECA). MIL-STD-785B can be used as a reference for conducting a reliability program. (Department of Defense 1980, Aydm < etin 2009, Demirel Cretin 2010). 

The magnitude of risk from some event depends on the product of how often the analyst thinks an event will occur and how seriously the event impacts on the overall process. Therefore, it is. incumbent on the scientist to develop a quantitative sense of where the risks in an analysis exist, and how serious they are. The best systems analyst cannot perform this function only the person who the is most knowledgeable about the analytical procedure can function as the risk assessor. This person is normally the research chemist who developed the methodology and not the analyst who may run the procedure routinely. He or she is most familiar with the emerging methodology and has a basis (whether it be historical, intuitive or reasoned) to assign a factor of risk to the individual components of the analysis. Typical mechanisms for risk assessment studies include either the use of a "Fault Tree", which uses lists of major failures and associated minor failures which might cause them, or a "Failure Modes and Effects Analysis Model" (21) which uses lists of the ways a system can fail and the results of each failure. For this study, the "Failure Modes and Effects Analysis Model" was chosen. 

The hazard identification and evaluation of a complex process by means of a diagram or model that provides a comprehensive, overall view of the process, including its principal elements and the ways in which they are interrelated. There are four principal methods of analysis failure mode and effect, fault tree, THERP, and cost-benefit analysis. Each has a number of variations, and more than one may be combined in a single analysis. See also Cost-Benefit Analysis Failure Mode and Effects Analysis (FMEA/FMECA) Fault Tree Analysis (FTA) THERP (Technique for Human Error Rate Probability). 

Reliability, Maintainability, and Quality Control. Inclusion of these organizations in the system safety process, from concept through disposal, will aid in the identification of safety-critical components for reliability analysis. A failure mode(s) and effect(s) analysis (FMEA), as well as other common reliability models, can be used to identify critical and noncritical failure points. The quality assurance element can be extremely usefid in the overall system safety process. Quality engineers should participate in the inspection of safety-critical components, serve on certification boards, audit any corrective-action requirements, and identify any safety impacts associated with implementation of such requirements. 

For this paper we treat hazard assessment as a combination of two interrelated concepts hazard identification, in which the possible hazardous events at the system boundary are discovered, and hazard analysis, in which the likelihood, consequences and severity of the events are determined. The hazard identification process is based on a model of the way in which parts of a system may deviate fi om their intended behaviour. Examples of such analysis include Hazard and Operability Studies (HAZOP, Kletz 1992), Fault Propagation and Transformation Calculus (Wallace 2005), Function Failure Analysis (SAE 1996) and Failure Modes and Effects Analysis (Villemeur 1992). Some analysis approaches start with possible deviations and determine likely undesired outcomes (so-called inductive approaches) while others start with a particular unwanted event and try to determine possible causes (so-called deductive approaches). The overall goal may be safety analysis, to assess the safety of a proposed system (a design, a model or an actual product) or accident analysis, to determine the likely causes of an incident that has occurred. 

---