A Weibull model describes the failure distribution of a component that has not yet been manufactured. The mortality curve is drawn before birth. The shape parameter $\beta$ indicates whether failures are early, random, or wear-out. The scale parameter $\eta$ sets the horizon. The component does not exist. Its death is already modelled.
Every design decision is a negotiation with this curve. Wall thickness, alloy selection, surface treatment, assembly tolerance: everything is sized so that the failure distribution falls within an acceptable window. The MTBF is not a prediction. It is a boundary condition that the design process must satisfy.
Doctrine
Failure is not what happens at the end. It is what is set at the beginning. The reliability curve is the first specification. Everything else follows from it.
One does not design a machine that works. One designs a machine that fails at the right moment.
Vecteur ouvert
If future failure is the initial parameter of design, then the machine is a process whose terminal condition is fixed before its initial condition. The question is whether this is a peculiarity of engineering, or the structure of every manufactured object.
