Tensile strength σ_UTS, or S_U measures the engineering stress applied (to something such as rope, wire, or a structural beam) at the point when it fails. It is an intensive property of the material, which not only depends on the type of material but also the preparation of the specimen and the temperature of the test. In the Physical sciences an intensive property (also called a bulk property) is a Physical property of a system that does not depend on the

Explanation

The tensile strength (TS) is the stress at the maximum on the stress-strain curve. Stress is a measure of the average amount of Force exerted per unit Area. During testing of a material sample the stress–strain curve is a graphical representation of the relationship between stress, derived from measuring the load applied on the

There are three definitions of tensile strength:

Yield strength

The stress at which material strain changes from elastic deformation to plastic deformation, causing it to deform permanently. The yield strength or yield point of a Material is defined in Engineering and Materials science as the stress at which a material

Ultimate strength

The maximum stress a material can withstand. Tensile strength \sigma_{UTS} or S_U is the Stress at which a material breaks or permanently deforms

Breaking strength

The stress coordinate on the stress-strain curve at the point of rupture. Rupture, or ductile rupture describes the ultimate failure of tough ductile materials loaded in tension

Concept

The various definitions of tensile strength are shown in the following stress-strain graph for low-carbon steel:

Stress vs. Carbon steel, also called plain carbon steel, is Steel where the main alloying constituent is Carbon. Strain curve typical of structural steel
1. Ultimate Strength
2. Yield Strength
3. The yield strength or yield point of a Material is defined in Engineering and Materials science as the stress at which a material Tensile strength
4. Strain hardening region
5. Work hardening, strain hardening, or cold work is the strengthening of a material by macroscopically speaking plastic deformation (which has the Necking region. In materials or mechanical engineering necking is a mode of Ductile flow of a material in tension.

Metals including steel have a linear stress-strain relationship up to the yield point, as shown in the figure. In some steels the stress falls after the yield point. This is due to the interaction of carbon atoms and dislocations in the stressed steel. In Materials science, a dislocation is a Crystallographic defect, or irregularity within a Crystal structure. Cold worked and alloy steels do not show this effect. Work hardening, strain hardening, or cold work is the strengthening of a material by macroscopically speaking plastic deformation (which has the For most metals yield point is not sharply defined. Below the yield strength all deformation is recoverable, and the material will return to its initial shape when the load is removed. For stresses above the yield point the deformation is not recoverable, and the material will not return to its initial shape. This unrecoverable deformation is known as plastic deformation. In Materials science, deformation is a change in the shape or size of an object due to an applied force. For many applications plastic deformation is unacceptable, and the yield strength is used as the design limitation.

After the yield point, steel and many other ductile metals will undergo a period of strain hardening, in which the stress increases again with increasing strain up to the ultimate strength. Ductility is a mechanical property used to describe the extent to which materials can be deformed plastically or "stretched" into "wires" without The M acro E xpansion T emplate A ttribute L anguage complements TAL, providing macros which allow the reuse of code across Work hardening, strain hardening, or cold work is the strengthening of a material by macroscopically speaking plastic deformation (which has the If the material is unloaded at this point, the stress-strain curve will be parallel to that portion of the curve between the origin and the yield point. If it is re-loaded it will follow the unloading curve up again to the ultimate strength, which has become the new yield strength.

After a metal has been loaded to its yield strength it begins to "neck" as the cross-sectional area of the specimen decreases due to plastic flow. When necking becomes substantial, it may cause a reversal of the engineering stress-strain curve, where decreasing stress correlates to increasing strain because of geometric effects. In materials or mechanical engineering necking is a mode of Ductile flow of a material in tension. This is because the engineering stress and engineering strain are calculated assuming the original cross-sectional area before necking. If the graph is plotted in terms of true stress and true strain the curve will always slope upwards and never reverse, as true stress is corrected for the decrease in cross-sectional area. Necking is not observed for materials loaded in compression. The peak stress on the engineering stress-strain curve is known as the ultimate strength. After a period of necking, the material will rupture and the stored elastic energy is released as noise and heat. The stress on the material at the time of rupture is known as the tensile strength.

Ductile metals do not have a well defined yield point. The yield strength is typically defined by the "0. 2% offset strain". The yield strength at 0. 2% offset is determined by finding the intersection of the stress-strain curve with a line parallel to the initial slope of the curve and which intercepts the abscissa at 0. 002. A stress-strain curve typical of aluminum along with the 0. 2% offset line is shown in the figure below.

Stress vs. Strain curve typical of aluminum
1. Ultimate Strength
2. Yield strength
3. The yield strength or yield point of a Material is defined in Engineering and Materials science as the stress at which a material Proportional Limit Stress
4. Tensile strength
5. Offset Strain (typically 0. 002).

Brittle materials such as concrete and carbon fiber do not have a yield point, and do not strain-harden which means that the ultimate strength and breaking strength are the same. Concrete is a construction material composed of Cement (commonly Portland cement) as well as other cementitious materials such as Fly ash and Slag A most unusual stress-strain curve is shown in the figure below. Typical brittle materials do not show any plastic deformation but fail while the deformation is elastic. One of the characteristics of a brittle failure is that the two broken parts can be reassembled to produce the same shape as the original component. A typical stress strain curve for a brittle material will be linear. Testing of several identical specimens will result in different failure stresses. The curve shown below would be typical of a brittle polymer tested at very slow strain rates at a temperature above its glass transition temperature. Some engineering ceramics show a small amount of ductile behaviour at stresses just below that causing failure but the initial part of the curve is a linear.

Stress vs. Strain curve of a very untypical brittle material
1. Ultimate Strength
2. Tensile strength.

Tensile strength is measured in units of force per unit area. In Physics, a force is whatever can cause an object with Mass to Accelerate. Area is a Quantity expressing the two- Dimensional size of a defined part of a Surface, typically a region bounded by a closed Curve. In the SI system, the units are newtons per square metre (N/m²) or pascals (Pa), with prefixes as appropriate. The newton (symbol N) is the SI derived unit of Force, named after Isaac Newton in recognition of his work on Classical M^2 redirects here For other uses see M². CM2 redirects here An SI prefix (also known as a metric prefix) is a name or associated symbol that precedes a unit of measure (or its symbol to form a Decimal multiple or The non-metric units are pounds-force per square inch (lbf/in² or PSI). The pound per square inch or more accurately pound-force per square inch (symbol psi or lbf/in² or lbf/in²) is a unit of Engineers in North America usually use units of ksi which is a thousand psi.

The breaking strength of a rope is specified in units of force, such as newtons, without specifying the cross-sectional area of the rope. A rope is a length of Fibers twisted or Braided together to improve strength for pulling and Connecting. This is often loosely called tensile strength, but this is not a strictly correct use of the term.

In brittle materials such as rock, concrete, cast iron, or soil, tensile strength is negligible compared to the compressive strength and it is assumed zero for many engineering applications. Glass fibers have a tensile strength stronger than steel[1], but bulk glass usually does not. This is due to the Stress Intensity Factor associated with defects in the material. Stress Intensity Factor, K is used in Fracture mechanics to more accurately predict the stress state ("stress intensity" near the tip of a crack caused As the size of the sample gets larger, the size of defects also grows. In general, the tensile strength of a rope is always less than the tensile strength of its individual fibers. Fiber or fibre is a class of Materials that are continuous filaments or are in discrete elongated pieces similar to lengths of thread.

Tensile strength can be defined for liquids as well as solids. Liquid is one of the principal States of matter. A liquid is a Fluid that has the particles loose and can freely form a distinct surface at the boundaries of For example, when a tree draws water from its roots to its upper leaves by transpiration, the column of water is pulled upwards from the top by capillary action, and this force is transmitted down the column by its tensile strength. A tree is a perennial Woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or Transpiration is the Evaporation of water from the aerial parts of Plants especially leaves but also stems Flowers and Roots Capillary action, capillarity, capillary motion, or wicking is the ability of a substance to draw another substance into it Air pressure from below also plays a small part in a tree's ability to draw up water, but this alone would only be sufficient to push the column of water to a height of about ten metres, and trees can grow much higher than that. (See also cavitation, which can be thought of as the consequence of water being "pulled too hard". Cavitation is defined as the phenomenon of formation of vapour bubbles of a flowing liquid in a region where the pressure of the liquid falls below its vapour pressure )

Typical tensile strengths

Some typical tensile strengths of some materials:

• Note: Multiwalled carbon nanotubes have the highest tensile strength of any material yet measured, with labs producing them at a tensile strength of 63 GPa, still well below their theoretical limit of 300 GPa. See also Graphene, Buckypaper Carbon nanotubes (CNTs are Allotropes of carbon with a nanostructure that can have a length-to-diameter However as of 2004, no macroscopic object constructed of carbon nanotubes has had a tensile strength remotely approaching this figure, or substantially exceeding that of high-strength materials like Kevlar. Kevlar is the registered Trademark for a light strong para-aramid Synthetic fiber, related to other Aramids such as Nomex and
• Note: many of the values depend on manufacturing process and purity/composition.

(Source: A. Annealing, in Metallurgy and Materials science, is a Heat treatment wherein a material is altered causing changes in its properties such as strength In Solid mechanics, Young's modulus (E is a measure of the Stiffness of an isotropic elastic material The yield strength or yield point of a Material is defined in Engineering and Materials science as the stress at which a material WikipediaNaming Copper (ˈkɒpɚ is a Chemical element with the symbol Cu (cuprum and Atomic number 29 Gold (ˈɡoʊld is a Chemical element with the symbol Au (from its Latin name aurum) and Atomic number 79 Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 Characteristics Lead has a dull luster and is a dense, Ductile, very soft highly Nickel (ˈnɪkəl is a metallic Chemical element with the symbol Ni and Atomic number 28 Silicon (ˈsɪlɪkən or /ˈsɪlɪkɒn/ silicium is the Chemical element that has the symbol Si and Atomic number 14 Silver (ˈsɪlvɚ is a Chemical element with the symbol " Ag " (argentum from the Ancient Greek: ἀργήντος - argēntos gen Tantalum (ˈtæntələm (formerly tantalium /tænˈtæliəm/ is a Chemical element with the symbol Ta and Atomic number 73 Tin is a Chemical element with the symbol Sn (stannum and Atomic number 50 Titanium (taɪˈteɪniəm is a Chemical element with the symbol Ti and Atomic number 22 Tungsten (ˈtʌŋstən also known as wolfram (/ˈwʊlfrəm/ is a Chemical element that has the symbol W and Atomic number 74 Zinc (ˈzɪŋk from Zink is a Metallic Chemical element with the symbol Zn and Atomic number 30 M. Howatson, P. G. Lund and J. D. Todd, "Engineering Tables and Data" p41)

See also

• Tension (mechanics)
• Toughness
• Deformation
• Tensile structure
• Universal Testing Machine
• Specific strength
• Strength of materials
• Ultimate Failure

Sources

• A. In Physics String Tension is the magnitude of the pulling force exerted by a string cable chain or similar object on another object Toughness, in Materials science and Metallurgy, is the resistance to Fracture of a material when stressed. In Materials science, deformation is a change in the shape or size of an object due to an applied force. A tensile structure is a Construction of elements carrying only Tension and no Compression or Bending. A Universal Testing Machine otherwise known as a materials testing machine/ test frame is used to test the tensile and compressive properties of materials The specific strength is a material strength divided by its Density. In Materials science, the strength of a material refers to the material's ability to resist an applied force M. Howatson, P. G. Lund and J. D. Todd, "Engineering Tables and Data"
• Giancoli, Douglas. Physics for Scientists & Engineers Third Edition. Upper Saddle River: Prentice Hall, 2000.
• Köhler, T. and F. Vollrath. 1995. Thread biomechanics in the two orb-weaving spiders Araneus diadematus (Araneae, Araneidae) and Uloboris walckenaerius (Araneae, Uloboridae). Journal of Experimental Zoology 271:1-17.
• Edwards, Bradly C. "The Space Elevator: A Brief Overview" http://www.liftport.com/files/521Edwards.pdf
• T Follett "Life without metals"
• Min-Feng Yu et. al (2000), Strength and Breaking Mechanism of Multiwalled Carbon Nanotubes Under Tensile Load, Science 287, 637-640

References

• http://www.albarrie.com/Filtration/fil-basalt.html

External links

• Tensile Strength Test
• January 2003 sci.physics thread on water tensile strength and trees
• Theory re the discrepancy in static vs dynamic measurements of water's tensile strength
• Engineering Stress-strain Curve
• Systems for measuring tensile strength