onstruction, tensile stress · esfuerzo de tensión.

Para medir el esfuerzo de una pieza que este sometida bajo una carga, en el sistema ingles (SI), la carga P esta expresada en newton y A en metros cuadrados “m2”. El esfuerzo σ se expresara en “N/m2”. Esta unidad se denomina pascal Pa. Sin embargo, el pascal es una unidad muy pequeña por lo cual se utiliza múltiplos de esta.

Seeing as 'esfuerzo' is measured in Pascals, then the translation would have to be 'stress'.

http://es.scribd.com/doc/12873096/esfuerzo-de-ingenieria#scr...

The pascal (symbol: Pa) is the SI derived unit of pressure, internal pressure, stress, Young's modulus and ultimate tensile strength, and is defined as one newton per square metre.[1] It is named after the French polymath Blaise Pascal.

https://en.wikipedia.org/wiki/Pascal_(unit)

Esfuerzos biaxiales: Círculo de Mohr.

www.uclm.es/area/ing_rural/calculoestructuras/temas/tema1.p...

biaxial stress
biaxial stress[bī′ak·sē·əl ‚stress]
(mechanics)
The condition in which there are three mutually perpendicular principal stresses; two act in the same plane and one is zero.

http://encyclopedia2.thefreedictionary.com/biaxial stress

Mohr's circle, named after Christian Otto Mohr, is a two-dimensional graphical representation of the transformation law for the Cauchy stress tensor.

After performing a stress analysis on a material body assumed as a continuum, the components of the Cauchy stress tensor at a particular material point are known with respect to a coordinate system. The Mohr circle is then used to determine graphically the stress components acting on a rotated coordinate system, i.e., acting on a differently oriented plane passing through that point.

https://en.wikipedia.org/wiki/Mohr's_circle



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Note added at 2 hrs (2016-01-28 15:52:10 GMT)
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In continuum mechanics, stress is a physical quantity that expresses the internal forces that neighboring particles of a continuous material exert on each other, while strain is the measure of the deformation of the material. For example, when a solid vertical bar is supporting a weight, each particle in the bar pushes on the particles immediately below it. When a liquid is in a closed container under pressure, each particle gets pushed against by all the surrounding particles. The container walls and the pressure-inducing surface (such as a piston) push against them in (Newtonian) reaction. These macroscopic forces are actually the average of a very large number of intermolecular forces and collisions between the particles in those molecules.

Strain inside a material may arise by various mechanisms, such as stress as applied by external forces to the bulk material (like gravity) or to its surface (like contact forces, external pressure, or friction). Any strain (deformation) of a solid material generates an internal elastic stress, analogous to the reaction force of a spring, that tends to restore the material to its original non-deformed state. In liquids and gases, only deformations that change the volume generate persistent elastic stress. However, if the deformation is gradually changing with time, even in fluids there will usually be some viscous stress, opposing that change. Elastic and viscous stresses are usually combined under the name mechanical stress.

https://en.wikipedia.org/wiki/Stress_(mechanics)

Force:
Related concepts to force include: thrust, which increases the velocity of an object; drag, which decreases the velocity of an object; and torque, which produces changes in rotational speed of an object. In an extended body, each part usually applies forces on the adjacent parts; the distribution of such forces through the body is the so-called **mechanical stress**. Pressure is a simple type of stress. Stress usually causes deformation of solid materials, or flow in fluids.

https://en.wikipedia.org/wiki/Force