# Stress Concentration

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## stress concentration

[′stres ‚kän·sən‚trā·shən]
(mechanics)
A condition in which a stress distribution has high localized stresses; usually induced by an abrupt change in the shape of a member; in the vicinity of notches, holes, changes in diameter of a shaft, and so forth, maximum stress is several times greater than where there is no geometrical discontinuity.

## Stress Concentration

(in elasticity theory), the concentration of large stresses on small areas adjacent to points of abrupt changes in the shape of the surface or cross section of a deformed body. The factors leading to stress concentration (”stress concentrators”) may be openings, cavities, cracks, grooves, incisions, corners, protrusions, sharp edges, or engraving, as well as various surface irregularities, such as notches, scratches, markings, and irregularities of welded seams.

The distribution of stresses σ (see Figure 1) is characterized by a sharp change in the stressed state, accompanied by rapid attenuation of stresses with increasing distance from the stressed zone. The higher the maximum stress at the site of concentration relative to the nominal stress (the average normal tensile stress at the narrowest cross section of the specimen), the more pronounced the attenuation of stress with increasing distance from the most highly stressed zone.

Figure 1. Stress concentration under tension of force P on a band of width b with a circular opening of diameter d

A measure of stress concentration is the stress concentration factor, ασ = σmaxn and ατ= τmaxn, where σn and τn are the nominal normal and tangential stresses, respectively. The values of ασ and αT are not related to the properties of the material but rather depend on the type of stress concentrator, on its sharpness, absolute size, and size relative to the specimen, and on the type of deformation and stressed state. In addition to the geometric stress concentration factors (those given above), there is also a technical stress concentration factor, which takes into account the structure and plastic properties of the material.

The nature of stress distribution and the values of stress at concentration sites are determined by using the theory of elasticity and plasticity only for a few types of concentrators, because of the great difficulty of solving such problems. In most cases, stress concentration is studied using the methods of photoelas-ticity or lacquer coatings or by tensometry. Stress-relief notches, reinforcement of the edges of openings and recesses, and stiffen-ers in plates are used to reduce or eliminate stress concentration. Strengthening of the material in the stress concentration zone is achieved by various types of treatment.

## stress concentration

Localized stress (usually as a result of localized loading or changes in geometry) which is significantly higher than the average stress.
References in periodicals archive ?
The regions where stress concentration may occur, such as the fillets and possible contact areas, are discredited by a finer mesh (Figs.
Figure 3 shows that the fault zone stress is much lower than the original rock stress, which is due to several factors such as the ease with which the fault zone coal rock mass is broken, low strength, low cohesion, low tensile strength and the difficulty of forming stress concentration.
Caption: Figure 4: Dent study stress concentration factors.
Inclusions into the matrix lead to stress concentration around them resulting in a multiaxial state of stress, even under axial loading.
Sharp internal corners in particular can produce stress concentration that inherently reduces the apparent ductility of the material.
The stress concentration factor decreases as the particle loading increases as can be seen in Fig.
Obviously, for the actions of such stresses, especially impulse, stress concentration significantly differs from those occurring under conditions of quasi-static deformation.
A problem of optimizing spatially varying fiber paths in a symmetric, linear orthotropic composite laminate with a cutout, so as to achieve minimum stress concentration under remote unidirectional tensile loading is of interest in this study.
Furthermore, the stress concentration caused by changes in cross section can affect the distribution of the stress of flexure hinges.

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