Where the Conjunction of Factors gives Original & Incredible Failures : the Effects of Secundary Order Influences !

Industrial machineries are very often much more complex as what they look ! While dealing with the different potential physical phenomenon that may appear and take the seat within their machine components, it is worth to say that the complexity shows there its beautiful sight and may also be at its ... paroxism ! As the Design Process is a true "inverse problem" (Considered as of the most complex ones of our Mother Nature), the Designer has a very hardly difficult task to try to prognosticate what could potentially be their Mode of Failure and, by this, to prevent for any kind of failure. In some machineries, the combinatory action of different physical phenomenon is so complex to understand and/or simply to imagine (Meaning that it needs a deep specialized knowledge also of different disciplines), that some very original Failures may appear : the fundamentals ("Influences of the First Order", e.g. Strength, Deformation, Resilience, ...) on which the Designer has usually taken the necessary preventive safeties are then overwhelmed by the combinatorial action of "Secondary Order Influences", which combined can give a strong negative effect leading to very unpredictable and, therefore, original Failures. A case study dedicated to industrial blowers involving factors as important as vibration noise, the nature of the stresses and their distribution, the dynamics of two-phase (loaded) compressible flow fluids, speed and pressure fields, manufacturing practices, welding processes and local effects, long term slow corrosion action and its combined effects with multiple stress raisers will here illustrate the point !