Structural fracture mechanics is the field of
structural engineering
Structural engineering is a sub-discipline of civil engineering in which structural engineers are trained to design the 'bones and joints' that create the form and shape of human-made Structure#Load-bearing, structures. Structural engineers also ...
concerned with the study of load-carrying structures that includes one or several failed or damaged components. It uses methods of analytical
solid mechanics
Solid mechanics (also known as mechanics of solids) is the branch of continuum mechanics that studies the behavior of solid materials, especially their motion and deformation (mechanics), deformation under the action of forces, temperature chang ...
, structural engineering,
safety engineering
Safety engineering is an engineering Branches of science, discipline which assures that engineered systems provide acceptable levels of safety. It is strongly related to industrial engineering/systems engineering, and the subset system safety en ...
,
probability theory
Probability theory or probability calculus is the branch of mathematics concerned with probability. Although there are several different probability interpretations, probability theory treats the concept in a rigorous mathematical manner by expre ...
, and
catastrophe theory
In mathematics, catastrophe theory is a branch of bifurcation theory in the study of dynamical systems; it is also a particular special case of more general singularity theory in geometry.
Bifurcation theory studies and classifies phenomena chara ...
to calculate the load and stress in the structural components and analyze the safety of a damaged structure.
There is a direct analogy between
fracture mechanics
Fracture mechanics is the field of mechanics concerned with the study of the propagation of cracks in materials. It uses methods of analytical solid mechanics to calculate the driving force on a crack and those of experimental solid mechanics t ...
of solid and structural fracture mechanics:
There are different causes of the first component failure:
#
mechanical overload,
fatigue (material)
In materials science, fatigue is the initiation and propagation of cracks in a material due to cyclic loading. Once a fatigue crack has initiated, it grows a small amount with each loading cycle, typically producing striations on some parts of ...
, unpredicted scenario, etc.
# “human intervention” like unprofessional behavior or a terrorist attack.
There are two typical scenarios:
#A localized failure does NOT cause immediate collapse of the entire structure.
#The entire structure fails immediately after one of its components fails.
If the structure does not collapse immediately there is a limited period of time until the catastrophic
structural failure
Structural integrity and failure is an aspect of engineering that deals with the ability of a structure to support a designed structural load (weight, force, etc.) without breaking and includes the study of past structural failures in order to ...
of the entire structure. There is a critical number of structural elements that defines whether the system has reserve ability or not.
Safety engineers use the failure of the first component as an indicator and try to intervene during the given period of time to avoid the catastrophe of the entire structure. For example, “Leak-Before-Break”
methodology means that a leak will be discovered prior to a catastrophic failure of the entire piping system occurring in service. It has been applied to pressure vessels, nuclear piping, gas and oil pipelines, etc.
The methods of structural fracture mechanics are used as checking calculations to estimate sensitivity of a structure to its component failure.
The failure of a complex system with parallel redundancy can be estimated based on probabilistic properties of the system elements.
See also
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References
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Structural engineering
Continuum mechanics
Fracture mechanics
Solid mechanics