用专业英语给出抗拉强度、屈服强度、比例极限、弹性极限、延伸率、断面收缩率的定义

抗拉强度 compressive strength
Compressive strength is the capacity of a material or structure to withstand loads tending to reduce size.

屈服强度 yield strength
A yield strength of a material is defined in engineering and materials science as the stress at which a material begins to deform plastically.

比例极限 proportionality limit
Up to this amount of stress, stress is proportional to strain (Hooke's law), so the stress-strain graph is a straight line, and the gradient will be equal to the elastic modulus of the material.

弹性极限 elastic limit
Beyond the elastic limit, permanent deformation will occur. The elastic limit is therefore the lowest stress at which permanent deformation can be measured.

延伸率 stretch ratio
The stretch ratio or extension ratio is a measure of the extensional or normal strain of a differential line element, which can be defined at either the undeformed configuration or the deformed configuration.

断面收缩率 shrinkage ratio
When the material tensioning fracture section decreased, the ratio of cross-sectional area reduced to the original area of the section is called shrinkage ratio.

抗拉强度：Ultimate tensile strength (UTS),
often shortened to tensile strength (TS) or ultimate strength,[1][2] is the maximum stress that a material can withstand while being stretched or pulled before failing or breaking. Tensile strength is distinct fromcompressive strength.
https://en.wikipedia.org/wiki/Ultimate_tensile_strength

屈服强度：yield strength
A yield strength or yield point of a material is defined in engineering and materials scienceas the stress at which a material begins to deform plastically. Prior to the yield point the material will deform elastically and will return to its original shape when the applied stress is removed. Once the yield point is passed, some fraction of the deformation will be permanent and non-reversible. In the three-dimensional space of the principal stresses (), an infinite number of yield points form together ayield surface.
https://en.wikipedia.org/wiki/Yield_(engineering)

延伸率：ductility is a solid material's ability to deform undertensilestress; this is often characterized by the material's ability to be stretched into a wire.
https://en.wikipedia.org/wiki/Ductility

断面收缩率：The percentage decrease in the cross- sectional area of a tensile test piece caused by wasting or necking of the specimen. It is expressed as a percentage of the original area of the test piece and is a measure of ductility.

在维基百科里面，比例极限，弹性极限，屈服强度，都指向屈服强度（yield strength)