PSI - Issue 19

Xavier Hermite et al. / Procedia Structural Integrity 19 (2019) 130–139 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 1. FMEA support for test strategy

2.2. Discrimination of failure mode/mechanism through HALT – HASS strategies

FMEA allows identification of every failure modes, which could occur on a component. In practice, there is a failure mode competition. Efforts should be put on the reduction of highest occurrence probabilities, considering that lowest ones are acceptable. Consideration of the component environment may highlight variables, which could have positive or negative influence on a failure mechanism and therefore on the failure probability. Component environment involves: - the material and manufacturing process, - the assembly boundary conditions, - the climate and, - the mechanical load spectra including usage and user variability. Analysis of these variables allows to retain a set of controllable influence factors to manage in the frame of a HALT – HASS design of experiment. HALT – HASS strategies consist to sever the test conditions in order to reach degradation or failure as quickly as possible, without focus on a specific mechanism. The aim of these strategies is identification of the weaknesses of a system and the most like ly degradation/failure mechanisms. They are also called “burn - in tests”. Design of experiment (DoE) is the best way to lead these test strategies, by defining a range of variation for each influence factor to manage and the experimental set-up to apply to benefit of all the looked-for information with the best test optimization [2] .