Mechanical Stress

Also found in: Wikipedia.

Stress, Mechanical


a measure of internal forces that arise in a body being deformed as a result of external forces. When studying the stress at any point, a section is cut through the point (Figure 1). The interaction of contiguous parts of the body along the section is replaced by forces. If a force ∆P acts on the elementary area ∆S surrounding point M, the limiting value of the quotient lim (∆P/∆S) ═ is called the stress at the point M on the surface ∆S; it is a vector quantity. The components of the vector of stress are the normal stress σ along the normal to the section and the tangential stress τ, in which case 2 ═ σ2 + τ2. The totality of vectors of stress for all sections cut through point M characterizes the stressed state at the point. The stressed state is completely defined by the tensor of stresses, whose components σx, σY, σZ, τxy ═ τyx, τyz ═ τzy, and τzxτxz are precisely the stresses on the faces of an infinitely small parallelipiped formed in the vicinity of the given point (Figure 2).

Figure 1

Figure 2

The relationship between stress and deformations is described by relationships of elasticity theory within the elasticity limits of the material. Equations of plasticity theory apply in the elastoplastic state. Experimental studies of stress are conducted using the method of tensometry (strain measurement), as well as optical methods (for example, the optical polarization method of stress study).

References in periodicals archive ?
They are functional, resistant to impact, mechanical stress and weathering, and can be made to fit curves.
The new ie3 premium efficiency gearmotors offer increased efficiency over standard IE1 models throughout the speed range and initiate less mechanical stress, which directly translates into long-term energy savings.
In both instances, the results showed an increase in bone formation and density without causing any mechanical stress to the construct or surrounding tissue.
This family of fluoropolymers is said to combine many outstanding properties, notably flame and smoke resistance, service temperatures to 150[degrees]C, and resistance to abrasion, chemical attack, sunlight and UV, radiation and mechanical stress, all resulting in a material said to have exceptional long-term stability.
In piezoelectric materials, mechanical stress results in electrically charged materials.
Intensive mechanical stress could cause micro-cracks to the card body structure.
Christ Basu, a PhD student in the Structure and Motion Lab said that giraffes were heavy animals but had unusually skinny limb bones for an animal of this size which means that their leg bones were under high levels of mechanical stress.
Mechanical Stress Evaluation by Neutrons and Synchrotron Radiation VI; select papers
This unique capability, which is already available on previous-generation EVG resist processing platforms, has been used in production to reduce mechanical stress and improve electrical performance of these advanced-packaging interconnect structures.
Ward and his research team have discovered a new signaling pathway that links mechanical stress during muscle contraction to calcium and reactive oxygen signaling dysregulation in DMD heart and skeletal muscle.
The PVDF has an excellent resistance to abrasion and UV exposure, it resists creep and fatigue under mechanical stress and load, and is autoclavable with wide temperature range: -80[degrees]F to 226[degrees]F.
Consistently, LbGp inhibited skin expansion under mechanical stress, which in this model depends on the activity of MMP-1.

Full browser ?