Most designers are at least somewhat familiar with Failure Modes and Effects Analysis (FMEA) and Hazard and Operations Analysis (HAZOP).
These methods approach problems by assembling the available information to observe what may occur if there is a failure (absence) in delivering these functions. In other words, the analytical line of reasoning follows design intent.
Given a potential failure, the effect of the failure, the probability that it will occur, and the ability to detect it are determined. Once these parameters are quantified (often very subjectively), a calculation of risk is made.
On the surface, the process sounds logical. There are, however, serious structural weaknesses with these traditional approaches. The first weakness stems from the process used to determine failures. The process of failure determination is essentially a brainstorming exercise initiated by probing what failures "might" occur.
AFD differs from other failure-analysis techniques in several ways. But perhaps the most strategic difference is how it leads development personnel to examine failure modes.
AFD turns a process failure on its head. Rather than asking developers to look for a cause, AFD has them view the failure of interest as an intended consequence. Developers then try to devise ways of ensuring that the failure always happens. The real cause of the problem becomes obvious from the results of these studies.
The most acute drawback of traditional approaches, is the absence of an integrated problem solving mechanism to accurately pinpoint design deficiencies as a series of "inventive" problems. An inventive problem is one characterized by an inherent conflict.
Traditional techniques do not make provisions for solving difficult technological problems in an inventive way. An inventive approach recognizes system conflicts and attacks them head-on. In traditional approaches, if the design is deemed to be too risky, correction of the problem is accomplished through a number of design and redesign iterations or, as a stopgap -- redesign of the detection systems.
When the system deficiency is not defined as an inventive problem, the results are often costly over designs, or the addition of auxiliary compensating systems making the original design more complex.
In contrast, ordinary failure-analysis methods generally view failure modes in a conventional way; to theorize what might be happening. This viewpoint may indeed get one to a solution, but perhaps less quickly or directly than focusing on how the failure really occurs.
Moreover, conventional failure analysis relies on unstructured procedures such as brainstorming to come up with possible causes. AFD: a specialised branch of I-TRIZ, employs well-documented procedures that make technical innovation a rigorous process.
AFD is a far more a wide-ranging failure analysis tool than HAZOP or FMEA, because its basic methods are not based on any particular technology or industry. The methods can be used to analyze any type of process, system, or even soft issues in an organization.
Because of its wide-ranging nature, the AFD process and the steps it takes to a solution can sound extremely abstract and hard to grasp initially. That's why the technique might best be explained through an example problem solved by application of its principles.
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