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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.

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when does a design fail
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
Conventional Types of Design Failure

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]

it doesn t work broad definition
It doesn’t work [broad definition]!

Cannot find a design solution that meets

  • performance,
  • cost,
  • time,
  • etc. specifications - even after compromises.


  • Fusion reactor for power - too costly, inefficient
  • Geared turbofan
  • Electric Car - performance/cost not acceptable
it would work but
It would work, but …..!

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?

  • Theory: _______________
  • Analysis: ______________
  • Experiment: ____________
  • Simulation: _____________
it works but no one wants it
It works but no one wants it!

The operation was a success but the patient died.


  • Ford Edsel - great car, freak design
  • Sony Betamax - people wanted VHS
  • DEC PC’s - incompatible floppy

Not normally an issue for your teams, but

make sure you are doing what sponsor

wants / needs


It works,

but some unanticipated condition or reason causes it to fail.


  • Challenger Disaster - “O” rings failed below freezing temperature
  • Civic Center Roof - overloaded
  • Mianus River Bridge - mechanical failure

How do you minimize your risks?

design failure categories
Design Failure Categories


- 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

failure mechanisms
Failure Mechanisms

1. Financial 2. Performance

3. Physical 4. Process

5. People

Let’s now look at each of the above failure modes

failure mechanisms1
Failure Mechanisms

1. Financial

- Design cost too high

- Production cost too high

- Marketing unsuccessfulloss of market advantage

- Inadequate service organization

- Liabilities

failure mechanisms2
Failure Mechanisms

2. Performance

- Fails under certain environmental conditions.

- Fails under certain operating conditions

- Fails to achieve full performance specs

failure mechanisms3
Failure Mechanisms

3. Physical

- Mechanical - overstress, fracture, fatigue, over-

heating, lubrication, corrosion,


- Electrical - overheating, burnout, bad solder/

connector, tolerances, timing


failure mechanisms4
Failure Mechanisms

3. Physical [cont’d]

- Hardware/Software

  • Programming bug, timing problem, interfacing problem, too slow, not enough memory, glitches
failure mechanisms5
Failure Mechanisms

4. Process

Design is OK, but implementation a problem

- Ford Taurus ignition switch

- Firestone ATX tires (see later)

- K.C. Hyatt (see later)

5. People

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

failure mechanisms6
Failure Mechanisms

Now let’s consider some examples of

design failures that are both infamous and


design failure firestone atx tires
Design Failure: Firestone ATX Tires
  • Who was at fault, Ford or Firestone?
    • ATX tires used on trucks never had failure modes
    • Statistically greater failure of left rear tires
  • Physical

- 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

  • Process or People

- 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 failure yf102
Design Failure: YF102


  • Convair [Gen. Dyn.] delta-winged fighter
  • Unable to fly supersonically, i.e. M < 1
  • Problem diagnosed as limited by physical
  • principle not mechanical shortcoming
    • Area rule (Whitcomb, NACA)
    • blockage of wings causes excessive
    • drag rise
design failure yf1021
Design Failure: YF102
  • Solution is to reduce flow blockage
    • Coke bottle fuselage design



design failure dc10 cargo door1
Design Failure: DC10 Cargo Door
  • All commercial aircraft are pressurized while flying
  • Outside air is at low pressure compared to cabin
  • Inward opening door plug tight against door frame
  • Cargo door open outward so as not to lose interior cargo storage space
  • DC10 door locking procedure [baggage handler]
    • Pull down top-hinged door and shut it
    • Swing down lever on outside or door
    • Press and hold button operating electric motor
    • Put ear to fuselage until hear click, then hold for 7 more seconds till motor stops
design failure dc10 cargo door2
Design Failure: DC10 Cargo Door
  • DC10 flight on June 12, 1972 from Detroit to Buffalo
  • DC10 baggage handler has difficulty closing door, but forces lock which gives false signal of locking
  • After takeoff, cargo door blows out sucking out rear galley and damaging hydraulic cables and cables to tail
  • Pilot deviates from accepted procedures and successfully landed plane; design changes recommended
  • Turkish Airlines inspection paperwork stamped with quality control approval [indicating cargo door repaired]; plane crashed in 1974 due to cargo door failure, killing 346.
design failure k c hyatt atrium
Design Failure: K.C. Hyatt Atrium
  • Background
  • Plush hotel complex with atrium inter
  • connecting 3 buildings
  • 2 / 1 pedestrian walkways for the 2-4 / 1
  • floors
  • At evening tea dance in atrium (1981)
  • with people dancing on walkways; 2-4
  • floor walkways collapsed
    • Worst structural disaster in U.S.
    • History
    • 114 dead, 200 injured
  • Owner (D. Hall) settled more than 90%
  • of claims out of court as a sense of
  • duty and civic responsibility
design failure k c hyatt atrium1
Design Failure: K.C. Hyatt Atrium
  • Observation: failure site noted at 4th floor box beam hanger on walkway
    • Walkway sliding (bearing) support chosen to allow beam to expand / contract with temperature changes
  • Brainstorming of Failure Causes
    • People dancing on walkways sets up a resonance
    • Quality of material used in construction
    • Construction crew skill level
    • On-site contractor (as-built) modification of final design

Design changes approved by architects and structural engineers

As built 4th floor support takes twice the designed load

design failure k c hyatt atrium2
Design Failure: K.C. Hyatt Atrium

Box Beam Hanger-as Built

Box Beam Hanger-as Designed

design failure k c hyatt atrium3
Design Failure: K.C. Hyatt Atrium
  • Actual dead load (weight of all components) of walkway was 8% greater than designed dead load
  • Live load (required by K.C code was 72,000 lbs/walkway), but with 63 people on 2 walkways, actual live load = 63 (150 lbs) = 9450 lbs << 72,000 lbs
  • Load per 6 supports therefore was 72,000 * 2 / 6 = 24,000

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.

design failure boston hancock building
Design Failure: Boston Hancock Building
  • Background
  • 60 story floor-to ceiling reflective glass panels
  • Glass panels started blowing out from the
  • beginning of construction (1973). At times
  • more than 1/3 of panels were out.
  • Cause not certain due to legal agreement of
  • “nondisclosure in perpetuity”
  • Design satisfied all governing codes
  • Some information gleaned from construction
  • grapevine
  • Window design
  • Double-glazed, doubled pane panels
  • Lead spacer at edges to separate panels
  • Design allowed for view of continuous glass
design failure boston hancock building1
Design Failure: Boston Hancock Building
  • Brainstorming
  • Large wind storm correlated to panel blowout
  • Lateral deflection of structure due to wind effect
  • not verified in tests
  • Twisting motion (short direction) observed by
  • tenants (had to be damped out)
    • 600 tons of lead dampers added near
    • roof
design failure boston hancock building2
Design Failure: Boston Hancock Building
  • Failure Cause Analysis
  • Glass panels were correctly installed
  • Thermal stress cycles induced by compression
  • / expansion of air between panes
  • Most panes cracks found in outer panes first
  • Lead solder overconstrains glass causing
  • premature fatigue
  • Replace all 10,344 panels with single pane glass
guarding against failure
Guarding Against Failure


  • Management Plan
  • Financial Plan
  • Marketing Plan
  • Engineering
guarding against failure1
Guarding Against Failure


  • Modeling / Simulation
  • Design Review [CDR, Tiger Teams]
  • Prototyping
  • Testing
  • Maintenance Plan
  • Failsafe Design - Redundancy
  • Documentation
what are your teams doing to ensure success
What are your teams doing to ensure success?
  • Theory: _______________
  • Analysis: ______________
  • Experiment: ____________
  • Simulation: _____________
what are your teams doing to ensure success1
What are your teams doing to ensure success?

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.