Ultimate failure


Ultimate failure

In mechanical engineering, ultimate failure describes the breaking of a material. In general there are two types or failure: fracture and buckling. Fracture of a material occurs when either an internal or external crack elongates the width or length of the material. In ultimate failure this will result in one or more breaks in the material. Buckling occurs when compressive loads are applied to the material and instead of cracking the material bows. This is undesirable because most tools that are designed to be straight will be inadequate if curved. If the buckling continues the material will create tension on the inner side of the material and compression on the outer part, thus fracturing the material.

In engineering there are multiple types of failure based upon the application of the material. In many machine applications any change in the part due to yielding will result in the machine piece needing to be replaced. Although this deformation or weakening of the material is not the technical definition of ultimate failure, the piece has failed. In most technical applications pieces are rarely allowed to reach their ultimate failure or breakage point, instead for safety factors they are removed at the first signs of significant wear.

There are two different types of fracture brittle and ductile. Each of these types of failure occur based on the material's ductility. Brittle failure occurs with little to no plastic deformation before fracture. An example of this would be stretching a clay pot or rod, when it is stretched it will not neck or elongate merely break into two ore more pieces. While applying a tensile stress to a ductile material, instead of immediately breaking the material will instead elongate. The material will begin by elongating uniformly until it reaches the yield (engineering) point, then the material will begin to neck. When necking occurs the material will begin to stretch more in the middle and the radius will decrease. Once this begins the material has entered a stage called plastic deformation. Once the material has reached its ultimate tensile strength it will elongate more easily until it reaches ultimate failure and breaks.

There are numerous methods to improve the strength of a material and therefore increase its ultimate failure point. Cold working a material is done by plastically deforming a material below its recrystallization temperature. This is most commonly seen by manufacturers hammering a material at room temperature. Hot working is any plastic deformation that is done above the recrystallization temperature. Cold working remains less effective because it is done below the recrystallization factor, but also remains more accurate. Because of thermal expansion and contraction of a material when heated hot working adds additional strength but also adds a rougher surface due to oxidization.

Heat treatment of a material is when the material is heated to extreme temperatures and quenching the material in water to cool it quickly. By heating the material to these very high temperatures the materials atomic structure is capable of being altered into a stronger material. This will also hopefully remove any cracks or deformations that will weaken a material. These cracks will weaken a material because they focus the stress or strain of a material to a particular point.

ee also

* Failure mode
* Material Strength
* Fabrication (metal)

References

*Manufacturing Processes for Engineering Materials Fifth Edition


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Failure theory (material) — v · d · e Materials failure modes Buckling · Corro …   Wikipedia

  • failure — noun 1 lack of success ADJECTIVE ▪ complete, total ▪ abject, humiliating ▪ The attempt ended in abject failure. ▪ inevitable …   Collocations dictionary

  • Ultimate Warrior (comics) — Warrior was a comic book based on the Ultimate Warrior, starting in 1996. It was written by Warrior with art by Jim Callahan (Issues #1 through 3, Christmas Special) and The Sharp Brothers (issue #4).HistoryThe comics sold well in the first two… …   Wikipedia

  • ultimate — ul|ti|mate1 W3 [ˈʌltımıt] adj [only before noun] [Date: 1600 1700; : Late Latin; Origin: ultimatus last , from ultimare to come to an end, be last , from Latin ultimus farthest, last , from ulter; ULTERIOR] 1.) someone s ultimate aim is their… …   Dictionary of contemporary English

  • Failure causes — are defects in design, process, quality, or part application, which are the underlying cause of a failure or which initiate a process which leads to failure. Where failure depends on the user of the product or process, then human error must be… …   Wikipedia

  • ultimate load — noun (aeronautics) The maximum load that a structure is designed to withstand without a failure • • • Main Entry: ↑ultimate …   Useful english dictionary

  • Failure mode and effects analysis — A failure modes and effects analysis (FMEA) is a procedure for analysis of potential failure modes within a system for classification by severity or determination of the effect of failures on the system. It is widely used in manufacturing… …   Wikipedia

  • Ultimate Duck Hunting — Infobox VG title = Ultimate Duck Hunting developer = Mid Carolina Media publisher = Mid Carolina Media (PC) Detn8 Games (Wii) designer = engine = released = May 2, 2006 (PC) October 19, 2007 (Wii) genre = Sports game modes = Single player,… …   Wikipedia

  • failure of proof — Inability or failure to prove the cause of action or defense in its entire scope and meaning. Breslin Griffitt Carpet Co. v. Asadorian, Mo.App., 145 S.W.2d 494, 496. Where evidence is such as would support either of two contradictory inferences,… …   Black's law dictionary

  • failure of proof — Inability or failure to prove the cause of action or defense in its entire scope and meaning. Breslin Griffitt Carpet Co. v. Asadorian, Mo.App., 145 S.W.2d 494, 496. Where evidence is such as would support either of two contradictory inferences,… …   Black's law dictionary


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.