The **materials mechanics** studies the responses of objects to applied external loads. The knowledge of such answers depends on the more efficient design of machines, mechanisms and structures.

For a design to be adequate, it is necessary to consider the forces and deformations that act on the object. Each material has its own response, according to its characteristics.

The mechanics of materials is based in turn on statics, since it must make use of its methods and concepts, such as the different charges or forces and the moments to which bodies can be exposed during their operation. It is also necessary to consider the equilibrium conditions of an extended body.

In this way the resistance, rigidity, elasticity and stability of bodies are studied conscientiously.

Mechanics of materials is also known as strength of materials or mechanics of solids.

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**History of mechanics of materials**

Since the beginning of humanity, people checked, by trial and error, the characteristics of the materials in their environment. It’s not hard to imagine the industrious artisans of the stone age choosing the right rocks to carve their arrowheads.

With the sedentary lifestyle, structures began to be built that over time evolved into the monumental buildings of the peoples of Ancient Egypt and Mesopotamia.

These builders were well acquainted with the response of the materials they used, to the point that even today the temples, pyramids and palaces they left behind continue to amaze.

The same can be said of the engineering of the ancient Romans, notable for its design in which they applied arches and vaults, as well as the correct use of materials.

**Modern mechanics of materials**

The formalism of the mechanics of materials arose centuries later, thanks to the experiments of the great Galileo Galilei (1564 – 1642), who studied the effects of loads on bars and beams made of different materials.

Galileo recorded in his book *two science caves* their conclusions about failures in structures such as cantilever beams. Subsequently, Robert Hooke (1635-1703) laid the foundations of the theory of elasticity, with the famous Hooke’s law, which states that the deformation, as long as it is small, is proportional to the effort.

Isaac Newton (1642-1727) established the laws of motion that define the action of forces on objects, and independently with Gottfried Leibnitz, invented mathematical calculus, a fundamental tool for modeling the effects of forces.

Later, beginning in the 18th century, several notable French scientists carried out experiments with materials: Saint-Venant, Coulomb, Poisson, Lame, and Navier, the most notable. The latter is the author of the first text on the modern mechanics of materials.

At the same time, mathematics evolved to provide tools for solving more complex mechanical problems. Notable are the experiments of Thomas Young (1773-1829), who determined the stiffness of different materials.

To this day, many problems are solved by numerical methods and computer simulations, as advanced research in materials science continues.

**Field of study**

The mechanics of materials studies real solids, those that can be deformed under the action of forces, unlike ideal solids, which are non-deformable. From experience it is known that real materials can fracture, stretch, compress or flex, depending on the load they experience.

For this reason, the mechanics of materials can be considered as the next step to statics. In this it was considered that solids were non-deformable, what follows is to find out how they deform when external forces act on them, because thanks to these forces, internal forces are developed inside the objects in response.

The deformation of the body and eventual rupture depend on the intensity of these efforts. So the mechanics of materials provides the basis for an effective design of parts and structures, regardless of the material they are made of, since the theory developed applies to all of them.

**Strength and rigidity**

The response of the materials depends on two fundamental aspects:

-Endurance

-Rigidity

The resistance of an object is understood to be its ability to withstand stress without breaking or fracturing. However, in this process, the object can be deformed and its functions within the structure are diminished, according to its rigidity.

The stiffer the material, the less it tends to deform under stress. Of course, whenever an object is under stress, it is going to undergo some type of deformation, which may or may not be permanent. The idea is that this object does not stop working properly despite this.

**types of efforts**

The mechanics of materials contemplates the effects of various efforts, which it classifies by its form or by its duration. Due to its shape, the efforts can be:

Traction, is a normal effort (acts perpendicular to the cross section of the object) and produces its elongation.

Compression is also a normal effort, but favors shortening.

Shear consists of forces in the opposite direction applied to the cross section of the body, the effect of which is to produce a cut, dividing it into sections.

Bending, perpendicular forces that tend to bend, curve or buckle the element on which they act.

-Torsion, are torques applied to the object that twist it.

And for its speed, the efforts are:

Static, which act very slowly on the body.

Impact, they are short-lived and intense effect.

Fatigue, which consist of repetitive stress-strain cycles that end up fracturing the element.

**Applications of mechanics of materials**

Whenever you have a structure, machinery or any object, it will always be subjected to numerous efforts derived from its use. As previously mentioned, these stresses cause deformations and eventual breakage: the beams can buckle, with the risk of collapse, or the gear teeth break.

So the materials used in various utensils, machinery and structures must be appropriate, not only to guarantee their proper functioning, but also to be safe and stable.

In general, material mechanics works like this:

**Analysis**

In the first instance, the structure, whose geometry is known, is analyzed, determining the stresses and deformation, to find the maximum load that can be applied and that does not exceed a pre-established deformation limit.

**Design**

Another option is to determine the dimensions of the structure, given certain loads and allowable stress and strain values.

In this way, the mechanics of materials is applied indistinctly to various areas:

**civil Engineering**: for the design of buildings according to the type of loads they must support.

**Automotive and aeronautical mechanics:** in the design of parts for cars, planes and boats.

**Medicine:** Biomaterials is a very interesting area, in which the principles described are applied in the design of various prostheses and as tissue substitutes, for example.

In this way, the mechanics of materials is positioned as the basis of materials science and engineering, a multidisciplinary branch with spectacular advances in recent times.

**References**

Beer, F. 2010. Mechanics of Materials. 5th. Edition. McGraw Hill.

Cavazos, J. Introduction to the mechanics of materials. Recovered from: youtube.com.

Fitzgerald, R. 1996. Mechanics of Materials. Alpha Omega.

Hibbeler, R. 2011.Mechanics of Materials. 8th Edition. pearson.

Engineering and Teaching. Materials mechanics. Retrieved from: ingenieriaydocencia.wordpress.com.

Mott, R. 1996. Strength of Applied Materials. 3rd. Edition. Prentice Hall.