Deformation is the displacement or disruption of bonds between atoms. It appears if external forces act on the object: temperature, pressure, specific load, magnetic or electric field. The main types of deformation are reversible and irreversible. Reversible deformation, in physics called elastic deformation, means that the violation of bonds between atoms is insignificant and the integrity structure is not broken. Objects having this property are called elastic. Irreversible deformation in physics is called plastic deformation and means a serious violation of bonds in atoms and, as a consequence, the integrity of the structure. Items with such properties are called plastic.
Breaking the atomic bond is not always bad. For example, damping (damping vibrations) parts must have ductility. This is necessary for the conversion of impact energy into deformation energy. The following types of deformation of solids exist: bending, tension / compression, torsion and shear. Depending on the nature of the acting forces on solids, corresponding stresses may occur. These stresses are called by the nature of the force. For example, torsion stress, compression stress, bending stress, etc. Speaking of deformation, often by default they mean deformation of solids, because structural change in them is most pronounced.
In fact, all types of deformation are the result of the influence of stress created by the acting force. In its pure form, deformation is rare. As a rule, the final deformation is the result of various stresses. As a result, they all lead to two main deformations - tension / compression and bending.
Physically, deformation is a result that is expressed in quantitative and qualitative equivalent. Quantitatively, this phenomenon is expressed in numerical value. Qualitatively - in the nature of the manifestation (direction, critical moments, such as destruction, ultimate stress ...). Possible deformation is preliminarily calculated in the strength calculation when designing any device or mechanism.
As a rule, loads and the result of deformation are displayed in the form of graphs - stress diagrams. The structure of such a graph: design scheme with applied loads, types of stresses and types of deformation. The load distribution gives an understanding of the nature of the load of the device or element, deformation. The results of deformation - tension, compression, bending, twisting - are measured in units of distance (mm, cm, m) or angular measure (degrees and radians). The main task of the calculation is to determine the ultimate strains and stresses in order to avoid disruption of working capacity - rupture, shear, fracture, etc. The nature of the voltage and the numerical value are also important, as there is the concept of fatigue deformation.
Fatigue deformation is the process of changing shape due to long loads. Over time, they develop from non-critical stresses (a constant insignificant violation of interatomic bonds) into serious consequences. This concept is called accumulated fatigue and is regulated by such a parameter (from the physical properties of the material) as fatigue strength.
In order to take into account the effect that various types of deformation have on functionality and resource, field tests of material samples are carried out. From experience, all strength characteristics for each material are obtained, which then become tabular values. In the era of computer technology, such an analysis is carried out on powerful PCs. But all the same, the properties of the material can be found only from field tests. Already laying all the characteristics and properties in the calculation model, the hard worker receives a graphic model (sometimes in the dynamics of work) of all stresses and strains.
In engineering, this calculation has already been incorporated into 3D design programs. Those. the designer implements a 3D model of all elements, each of which is reduced to a node model. Applying loads in a separate module of the program, the designer gets a three-dimensional picture of the nature of stresses and all types of deformation.