Design Failure. When Does a Design Fail?. A failed design is a design process which one does not achieve the specified design goals. In this class, failure could be project cancellation due to nonperformance or no support for next year’s project. Conventional Types of Design Failure.
A failed design is a design process which one does not achieve the specified design goals.
In this class, failure could be project cancellation due to nonperformance or no support for next year’s project
1. It doesn’t work!
2. It would work, but ……..!
3. It works, but no one wants it!
4. Ooops [we’ll see what this means]
Cannot find a design solution that meets
All the theory, analysis, experiment and simulation says it should work, but it doesn’t.
Example: F-102 delta wing pursuit plane [We will
see about this shortly].
What are your teams doing to ensure success?
The operation was a success but the patient died.
Not normally an issue for your teams, but
make sure you are doing what sponsor
wants / needs
but some unanticipated condition or reason causes it to fail.
How do you minimize your risks?
- Serious damage to life, property;
- Serious financial loss; etc.
- Design goals not met but nobody hurt,
- Missed opportunity
- No UCONN support for next year
- No job offers to graduates
1. Financial2. Performance
3. Physical4. Process
Let’s now look at each of the above failure modes
- Design cost too high
- Production cost too high
- Marketing unsuccessfulloss of market advantage
- Inadequate service organization
- Fails under certain environmental conditions.
- Fails under certain operating conditions
- Fails to achieve full performance specs
- Mechanical - overstress, fracture, fatigue, over-
heating, lubrication, corrosion,
- Electrical - overheating, burnout, bad solder/
connector, tolerances, timing
3. Physical [cont’d]
Design is OK, but implementation a problem
- Ford Taurus ignition switch
- Firestone ATX tires (see later)
- K.C. Hyatt (see later)
Design is OK, but people can be a problem
- skill level of workers (Firestone Decatur plant)
- supervision of workers (PW TF30 for F111)
- interest level of workers
Now let’s consider some examples of
design failures that are both infamous and
- shoulder pockets (for traction in mud and snow) cut too deep, leaving too little rubber on edge
- shoulder pockets cut at right angles to tread increasing strain on shoulder
- Manufacturing standards at Decatur plant were inconsistent
- Decatur plant used too much lubricant to keep rubber compounds from sticking together during manufacturing. Belts from this plant did not stick to each other as well as in other plants.
Design changes approved by architects and structural engineers
As built 4th floor support takes twice the designed load
Box Beam Hanger-as Built
Box Beam Hanger-as Designed
Notes do not say what design should be able to take
Principal manager and project manager fro m structural firm had
Missouri license revoked for not calculating whether support would work.
Finally remember to document your failures for you and others to learn from….
But if someone has to be blamed for a project failure, blame your advisor.