This also applies to the defensive design of child car seats
Between the 1940s and 1950s, a USAF colonel named John Paul Stapp was in charge of investigating the effects that acceleration had on US Air Force pilots. In these experiments, in which he himself was the dummy, he reached accelerations of about 40 Gs, and the first mechanisms were developed to calculate the deceleration, stresses and strains resulting from an impact.
When presenting the impact biomechanics work, Stapp was asked how no one had been seriously injured in these experimental trials, and his answer was that they had applied Murphy’s law. It was the first time this law had ever been mentioned in public.
Edward Murphy was an engineer on Stapp’s team who postulated that “If something can go wrong, it will”. Colonel Stapp’s trials took into account all the things that could go wrong, and he worked on concrete solutions to each of them, so that, in the event that something actually did go wrong, the consequences would be bearable.
As we can see, contrary to what we may think, Murphy’s law was not initially used as a phrase to confirm fait accompli, but was instead used for the application of what is known as defensive design.
Defensive design takes into account all possible aspects of what could fail, so that nothing does actually go wrong. Today, the theory of defensive design is still being applied and is especially valuable in products intended to save lives.
The engineers in charge of developing child restraints, like Murphy’s engineering colleagues, apply all possible variables when developing child restraints, both in tests and in terms of accident typology, to ensure that child restraints do not fail if there is a collision, because this potential failure has already been taken into account.
In this way, tests are carried out with greater loads than would be permitted, without an anti-rotational system, or with thermally conditioned samples.
It is clear that the product’s most efficient result is achieved when all the protection, fixation and absorption elements work the way they have been designed and, therefore, the installation of the child seat must be as perfect as possible. But it is reassuring to think that the design process of these devices intended to save lives has taken into account more adverse conditions than those in which the device actually performs its function.
Thanks to pioneers like Colonel Stapp and engineer Murphy, many of the products we have today have been designed by applying the theories of defensive design, in other words, Murphy’s law.