Page 328 - Design for Six Sigma a Roadmap for Product Development

298 Chapter Nine

9.3.3 Solution generation
After problem classification, there are usually many TRIZ methods
available for solving the problem, so many alternative solutions could
be found. These solutions will be evaluated in the next step.

9.3.4 Concept evaluation
There are many concept evaluation methods that can be used to eval-
uate and select the best solution. These methods are often not TRIZ
related. The frequently used concept evaluation methods include
Pugh concept selection, value engineering, and the axiomatic design
method.

9.4 Physical Contradiction
Resolution/Separation Principles
Usually, when we first encounter a contradiction, it often appears as a
technical contradiction. After digging deeper into the problem, the fun-
damental cause of the technical contradiction is often a physical con-
tradiction. A physical contradiction is a situation in which a subject or
an object has to be in mutually exclusive physical state. A physical con-
tradiction has the typical pattern: “To perform function F 1 , the element
must have property P, but to perform function F 2 , it must have
property –P, or the opposite of P.”

9.4.1 Analyze the physical contradiction
In order to identify the physical contradiction that causes the techni-
cal contradiction, the following three steps are recommended to pre-
analyze the conflict:
Step 1: Capture the functions involved in the conflict and establish
the functional model for the contradiction
Step 2: Identify the physical contradiction. Physical contradiction
often happens when a useful action and a harmful action coexist on
the same object.
Step 3: Identify the zones of conflict (Domb 1997). There are two
“zones” of conflict in a problem, spatial and temporal. In other words,
the two “zones” are the location properties of conflict and the time
properties of conflict. The identification of the zones can help to
determine what separation principles can be used to resolve the
physical contradiction.

We will use the following example to illustrate the above three steps.