MPD 575 Design for Failure

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MPD 575Design for Failure

• Jonathan Weaver

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Developed By

• Cohort Team 3
• Cathy Campbell
• Brandon Johnson
• Robbin McDaniel
• Britt Scott
• Updates by Anita Bersie

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Design for Failure

• Introduction to Design for Failure (DFF)
• System Engineering V-Model and DFF
• Heuristics
• How DFF fits into PD Process
• Situation to implement DFF
• Examples
• Summary

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Design for Failure

• Design
• Creative process in the Arts, Sciences and
  Technologies.
• There are many design heuristics that are derived
  from rules, relationships and experiences.

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Design for Failure

• Failure
• The many definitions of failure are
• System Failure takes place when load exceeds
  capacity by an unacceptable amount
• Different types of Failures (highly dependent on
  the individual)
• Failures which cause unacceptable damage
  (important or catastrophic)
• Failures which cause damage of little or no
  importance.

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Design for Failure

• Failure, contd
• Failure should be qualified and quantified if
  possible.
• The results of failure should be taken into
  account and fed back into the design process.
• The most important aspect is proper feedback.
• Failures are something engineers spend their life
  trying to avoid. However, there are times in
  which a failure is designed into the system as a
  function under certain conditions.
• The cause of the conditions are uncontrollable by
  the engineers but the failure under these
  conditions can be controlled.

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Design for Failure

• Teams definition of DFF
• A system or component designed to fail under
  certain conditions or circumstances

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Design for Failure

• Introduction to Design for Failure (DFF)
• System Engineering V-Model and DFF
• Heuristics
• How DFF fits into PD Process
• Situation to implement DFF
• Examples
• Summary

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Design for Failure

• The System Engineering V-Model has three phases
• Design the Product or Component
• Optimize the Design
• Validate the Design

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Design for Failure

• Key DFF Procedures in relation to the System
  Engineering V-Model
• Design the Product or Component
• Understand the System Architecture (design)
• Determine the acceptable failure criteria or
  requirements
• Conduct a DFMEA on the system or component
• Rank severity of failures
• Implement actions taken to reduce severity of
  failures identified as critical and unavoidable

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Design for Failure

• Key DFF Procedures in relation to the System
  Engineering V-Model
• Optimize the Design
• Evaluate design actions to reduce failure
  severities of unavoidable failures with minimal
  impact on cost, weight and system function

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Design for Failure

• Key DFF Procedures in relation to the System
  Engineering V-Model
• Validate the Design
• Test System for Failure
• Analyzing failure types
• Failure detection
• Verify severity of failure
• Verify that the design under the identified
  failures meets customer specification by using
  modeling and prototypes
• Retest the system

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Design for Failure

• Definition of Key DFF Procedures
• System Architecture is defined as the art and
  science of creating and building complex systems.
  That part of systems development most concerned
  with scoping, structuring, and certification
• Failure Mode Effect Analysis (FMEA) is defined as
  systematized activities intended to
• 1) recognize and evaluate potential failure of
  products/processes and its effects,
• 2) identify actions to eliminate or reduce the
  chance of the potential failure occurring, and
• 3) document the process

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Design for Failure

• Definition of failure types
• Elastic failure excessive elastic deformation
• Elastic strain resulting from the load leaves
  after the load has been removed
• Slip failure excessive plastic deformation due
  to slip.
• Plastic strain exceeds the elastic limit a
  portion of the deformation remains after the load
  is removed
• Slip plastic deformation independent of time
  duration of the applied load
• Creep failure excessive plastic deformation over
  a long period of time under constant stress
• Failure by Fracture complete separation of the
  material.

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Design for Failure

• Two approaches to detect failure
• Passive detector monitors the inputs and the
  outputs of the system and decides whether (and if
  possible what kind of) a failure has occurred.
  This is done by comparing the measured
  input-output behavior with normal behavior of
  the system.
• Active The active approach to failure detection
  consists of acting upon the system on a periodic
  basis or at critical times using a test signal,
  auxiliary signal, in order to exhibit abnormal
  behaviors which would otherwise remain undetected
  during normal operation.

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Design for Failure

• Introduction to Design for Failure (DFF)
• System Engineering V-Model and DFF
• Heuristics
• How DFF fits into PD Process
• Situation to implement DFF
• Examples
• Summary

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Design for Failure

• Heuristics
• P Prescriptive, D Descriptive
• (D) It is better to be aware of the failures than
  not.
• (P) You want to design a less expensive
  component to fail in order to protect a more
  expensive component.
• (P) Understand planned failures fail as they are
  planned.
• (P) Failure is defined by the beholder, not by
  the architect. (Modification of Maier/Rechtin,
  270)

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Design for Failure

• Heuristics (continued)
• (P) Dont confuse the functioning of the parts
  for the functioning of the system.
  (Maier/Rechtin, 269)
• (D) Some of the worst failures are system
  failures. (Maier/Rechtin, 271)
• (P) Choose the elements so that they are as
  independent as possible that is, elements with
  low external complexity (low coupling) and high
  internal complexity (high cohesion).
  (Maier/Rechtin, 273)
• (P) The principles of minimum communications and
  proper partitioning are key to system testability
  and fault isolation. (Maier/Rechtin, 275)
• (D) Knowing a failure has occurred is more
  important than the actual failure.
  (Maier/Rechtin, 276)

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Design for Failure

• Introduction to Design for Failure (DFF)
• System Engineering V-Model and DFF
• Heuristics
• How DFF fits into PD Process
• Situation to implement DFF
• Examples
• Summary

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Design for Failure

• How DFF fits into PD Process
• Gather raw data from the customers
• Interpret the data in terms of customers needs.
• Organize and establish the importance
• Establish target specifications
• Identify any potential products that require safe
  failure modes
• Determine the strategy
• Establish warranty guidelines
• Include the failure strategy in overall system
  architecture boundaries for failure

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Design for Failure

• How DFF fits into PD Process
• 9. Set-up design requirements and targets
• 10. Define validation requirements
• 11. Establish assembly, service and maintenance
  guidelines

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Design for Failure

• How DFF fits into PD Process
• You can identify potential design for failure
  opportunities through multiple ways
• Upfront Design
• Customer wants and needs (surveys)
• Focus Groups
• Competitive product analysis
• Aftermarket product analysis
• Review product requirements and restrictions
• Review assembly, serviceability and maintenance
  requirements

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Design for Failure

• How DFF fits into PD Process
• You can identify potential design for failure
  opportunities through multiple ways
• Design Phase
• Analyzing overall system architecture
• Conducting DFMEAs on product or system
• Simulating critical system interactions and
  interfaces

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Design for Failure

• How DFF fits into PD Process
• You can identify potential design for failure
  opportunities through multiple ways
• Design and Release
• Analyzing a component/system that has failed
• The Product Design and Development team reviews
  the data and decides on the overall system
  architecture.

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Design for Failure

• Introduction to Design for Failure (DFF)
• System Engineering V-Model and DFF
• Heuristics
• How DFF fits into PD Process
• Situation to implement DFF
• Examples
• Summary

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Design for Failure

• Situations to implement DFF
• The main purpose of designing for failure is the
  prevention of injury or harm to a system,
  component or person in the event of a potential
  system or component failure (either catastrophic
  or minor).
• The following systems were developed to meet the
  above criteria
• Air Bag Deployment System
• Electrical Circuit Protection
• Whiplash Protection Seating System (WHIPS)

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Design for Failure

• Situations to implement DFF
• Collapsible Steering Column
• Windshield Breakage
• Run Flat Tire
• Paper Shredder

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Design for Failure

• Concepts in Planning for Failure
• Single Point Failure Example If system
  operations depend on knowing the time and there
  is only one watch, it becomes a single point
  failure mechanism. (Smead)
• Redundant Systems Example Having 2 watches
  there is a back-up device to tell time. However,
  you must have a way to resolve inconsistencies
  between the two watches to determine the correct
  time. (Smead)
• Failsafe describes a device which if (or when)
  it fails, fails in a way that will cause no harm
  or at least a minimum of harm to other devices or
  danger to personnel. (Wikipedia)
• Failover / Switchover a device that takes over
  for a failed mechanism only after the point of
  failure (Smead)
• Ping-pong devices that take turns operating, so
  as not to get overloaded, (also beware of
  inconsistencies) (Smead)

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Design for Failure

• Fail-safe mechanism failure examples
• Therac 25 Computerized radiation therapy
  machine (Leveson)
• 1985-87 Injuries and deaths from radiation
  overexposure
• Model had replaced several mechanical interlocks
  for safety with software algorithms.
• Operators were able to retry administering doses
  after a dose-rate malfunction was indicated
  incorrectly by the software.
• A safety analysis of the device in 1983 by
  manufacturer excluded software in the fault tree
  analysis.
• Christus St. Joseph Hospital Elevator
  Decapitation (Greene)
• August 2003, Surgical Intern, Hitoshi Nikaidoh
  pinned in elevator doors while closing,
  decapitated when elevator raised
• Nikaidoh had expected the elevator doors to
  retract when an obstacle (his body) was
  encountered but they did not.
• Lesson Fail safe devices, poke-yokes and safety
  mechanisms must be fully tested for proper
  designed function. Dont assume they work
  properly, or will continue to work properly over
  time.

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Design for Failure

• Introduction to Design for Failure (DFF)
• System Engineering V-Model and DFF
• Heuristics
• How DFF fits into PD Process
• Examples
• Summary

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Airbag Deployment System
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• How does it relate to DFF?
• The air bag system is designed to deploy in the
  event of an accident (failure of a system or
  component).
• Consistent deployment is vital in airbag designs.
  This means consistent failure of components that
  contain airbags is vital.

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• How does it work?
• Internal seam in steering wheel covers allows for
  uniform failure in order for airbag to inflate in
  an consistent time and manner.
• Seats and Headliners
• Some designs have a panel that opens like a door
  in order to have controlled deployment of the
  seat side air bags.
• Headliners typically have a weak point in the
  design that will break during the deployment.

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Electrical Circuit Protection
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• How does it relate to DFF?
• The electrical circuit system is designed for
• One Time Applications
• Once failed the component cannot be reused.
• Bolt-In Fuse
• J-Case Fuses
• Maxi/Mini Fuses

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• How does it work?
• The circuit protection system is designed to fail
  when the conditions (listed below) are over
  exerted.
• Following parameters are part of circuit
  protection selection.
• Ambient Temperature
• Breaking Capacity
• Operating Voltages in Volts
• Operating Current in Amperes
• Required Failure Time
• Re-settable or One-Time

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• Re-Settable Breakers
• Once the component fails, it can be manually
  reset and used again. Some reset themselves
  after failed condition is stopped.
• Blade Design
• 120240V AC Single pole breaker (typically used in
  residential wiring)
• High Speed Fuse Applications
• Used with Allen-Bradley Controllers and Drivers.
• Manufacturing Equipment Application

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Volvo Whiplash Protection Seating System (Whips)
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• How does it relate to DFF?
• The WHIPS system, unique to Volvo, is designed to
  provide markedly better protection from neck and
  back injuries in the event of a rear impact.
• How does it work?
• In the event of a rear impact, the WHIPS seat
  responds immediately.
• The seatback/headrest assembly moves back and
  then tilts down, absorbing the impact.
• In laboratory tests acceleration forces on the
  neck are reduced by up to 50.
• Under normal condition this would be a failure of
  the seat system.

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Collapsible Steering Column
NASCAR Steering Column
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• How does it relate to DFF?
• Volvo has designed a steering column that
  collapses down and away from the driver during a
  severe crash (system failure).
• How does it work?
• Upon impact, the steering column structure fails
  in order to protect the customer.

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Windshield Breakage
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• How does it relate to DFF?
• The windshield is designed to provide a clear and
  undistorted view to the driver and passenger AND
  minimize danger in the event of a collision.
• The windshield in a vehicle is designed to stay
  in place upon impact. The glass will not
  shatter into a lot of small pieces. This
  protects the vehicle occupants from serious
  injury.
• The safest place to be during a car accident is
  in the car. Your windshield is an important
  barrier that keeps you in the car. A cracked
  windshield can fail during a collision or roll
  over, allowing you or your passenger to be
  ejected. A passenger ejected from a car or truck
  is much more likely to experience a serious
  injury or death.

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• How does it relate to DFF?
• An automobile's windshield is designed to prevent
  the roof from crushing you in a roll over
  accident. A windshield can be significantly
  weakened by cracks and may fail to support the
  roof if the car flips over, causing severe injury
  or death to occupants.

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• How does it work?
• Windshield glass is made by fabricating ordinary
  glass (flat) into high-grade shaped and tempered
  glass.
• Two primary types of safety glass
• Laminated (Front Windshields)
• Tempered (Side/Rear Windshields)
• Many people don't realize that front-seat
  passenger airbags deploy against the windshield.
• In the event of a front-end collision, a cracked
  windshield can fail, allowing passengers who
  aren't seat-belted properly to be ejected from
  the vehicle through the windshield.

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Run Flat Tire
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• How does it relate to DFF?
• The run flat tire is a system that is designed
  to allow the driver to continue to drive their
  vehicle in the event of a tire blowout (product
  failure).
• How does it work?
• When the tire loses pressure, it rests on a
  support ring attached to the wheel.
• Majority of the run-flat capability is on the
  wheel versus the tire. The wheel does not wear
  out whereas, the tire does wear out and require
  replacement.
• Benefit of Run Flat Tire
• Eliminate the need for spare tire reduce the
  weight of vehicle increase fuel efficiency
• Allow more luggage space by eliminating the spare
  tire
• Increase driver security and confidence in their
  vehicles
• Promise better ride quality because their
  sidewall's stiffness can be equivalent to today's
  standard tires versus the other technologies that
  are on the market (self sealing and self
  supporting)

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Design for Failure

• Paper Shredder (Jam Mechanism)

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Design for Failure

• Paper Shredder (Jam Mechanism)
• How does it relate to DFF?
• The paper shredder is designed to shred paper. If
  too many sheets or a non-paper object (metal,
  thick plastic) are fed through it the failure
  mode is to jam or stop working before damaging
  the product.
• How does it work?
• There are several shredder designs available
  (electrical or battery operated) to accept
  different quantities ( 1 thru 140 sheets) of
  paper. The paper is then fed thru the shredder
  opening.
• If the quantity or thickness is too great the
  shredder jams.
• If a non-paper object is placed in the shredder
  it jams.
• Once the extra sheets or object is removed, the
  shredder reset button can be activated.

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Design for Failure

• Introduction to Design for Failure (DFF)
• System Engineering V-Model and DFF
• Heuristics
• How DFF fits into PD Process
• Situation to implement DFF
• Case Study
• Examples
• Summary

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Design for Failure

• Summary
• Incorporate the DFF procedures into each design
• Define useful life of product and its failures
• Challenge engineering to develop customer
  satisfaction criteria for all types of uses/
  misuses (additional failures)
• Develop products or processes that meet the
  failure mode and is robust against different
  sources of variation
• Address new technology or existing technology in
  new environments against the failure modes
• Design for failure may prevent more damage by
  making the system inoperable.

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Design for Failure

• Summary
• Gain an understanding of a systems failure
  sensitivity
• Meet the global challenge of incorporating
  product failure modes on all components or
  systems
• Look at the big picture, address a component or
  sub-component that is part of the product system
  design

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Design for Failure

• References
• The Art of System Architecting, M. Maier
  Rechtin, 2nd edition, CRC Press, 2000
• Systems Architecting of Organizations, CRC Press,
  2000
• Product Design and Development, Karl T. Ulrich
  and Steven Eppinger, 2nd edition
• Mechanics of Materials, A. Higdon, E. Ohlsen, W.
  Stiles, J. Weese, W. Riley John Wiley Sons,
  Inc, 4th Edition, 1985
• Mechanical Engineering Design, Joseph Edward
  Shigley, Charles Mischke McGraw-Hill, Inc, 5th
  Edition, 1989

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References

• www.fpds.ford.com/fpds2k/index.html
• www.ford.com
• www.destroyit-shredders.com
• www.bestbuy.com
• www.helmets.org
• http//www.be.ford.com/safety/training/general20a
  irbags/airbag101/links.htm
• www.ask.com/main/metaAnswer.

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References (Cont)

• Smead, David. Vessel Networking 2. On-line
  posting. 8 May, 2007. Available
  http//www.amplepower.com/dave_blog/2/vessel_netwo
  rking_2.pdf
• Greene M.D., Alan. A Tragic Lesson. On-line
  posting. 20 Aug, 2003. Available
  http//www.drgreene/com/21_1660.html
• Failsafe. Wikipedia On-line. 26 Oct, 2007.
  Available http//en.wikipedia.org/wiki/Failsafe
• Leveson, Nancy Clark Turner. An Investigation
  of the Therac-25 Accidents. IEEE Computer, Vol.
  26, No. 7, July 1993, pp. 18-41.

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QUESTIONS ????
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Design for Failure

• Thank You