the nature of failure
DESCRIPTION
TugasTRANSCRIPT
The Nature of FailureFathiya Karimah 1306368734Irfan Ramajati 1306368740Teuku M. Iqbal Iftikar 1306368721
“There will always be failures or disasters as engineers and designers push the
boundaries by building taller buildings, longer bridges, or by reaching further into
space. Each time there is a failure or disaster, changes are made and regulations introduced only to be
outstripped by further developments.”(Hard Lessons, by Nick
Spurrier, 20 April 2009, The Institution of Engineering
and Technology).
The Nature of Failure
What it can do
What we want it to do
Equipment fail when “can” drops below “want”(when the ability to resist stress drops below applied stress)
What it can do (resistance to stress)
What we want it to do(applied stress)
LIFE
Point at which failure occurs
In reliability theory, failure is defined as the event when a required function is terminated.
DefinitionA failure occurs when and only when a structure or system does not perform according to design specification.
An item is considered to have failed under one of the following conditions:1. When it becomes completely inoperable2. When it is still operable, but no longer able to perform a required function3. When a serious deterioration makes the item unsafe for its continued use
Causes of Failure1. Deficiencies in design2. Improper selection of process and manufacturing technique3. Lack of knowledge and experience4. Errors of assembly5. Improper service conditions
Source: http://www.machinerylubrication.com/Read/23904/human-factors-engineering-reliability, Drew Troyer (diakses 00.23 WIB)
Failure Rateratio of number of failures (f) during a specific test interval to the total test time of items undergoing test.
P-F IntervalRepresents the second (middle) phase in a three-phase life cycle model and deterioration model of assets. 1. Pre-P Period (<P)2. P-F Interval (P-F)3. Post-F Period (>F)
P-F Interval"Potential Failure" ("P") is first detected on an asset, or component, until it has reached "Functional Failure" ("F")
P-F curve helps the owner determine which types of asset replacement policy is most appropriate to their tolerance for risk.
Application of the P-F IntervalFunctional Failure (F) is a bearing seazing in a fan motor and causing the fan to stop. Partial failure, or potential failure (P), is a worn impeller in a pump that still pumps fluid but not to the required level.
Potential Failure (P) is the loss of some protective granules from the cap sheet of an SBS roof. Functional Failure (F) is the leakage through a roof system into the occupied space below as a result of systemic delamination and blistering of the waterproofing membrane.
Referenceshttp://www.assetinsights.net/Glossary/G_P-F_Curve.html (diakses 14.28 WIB)
Telsang, Martand. 2006. Industrial Engineering And Production Management. S.Chand. New Delhi
Inkster, Ian. 2005. History of Technology Volume 26. Continuum. New York.