Shear, torsion, bending deformation is a change in the volume and shape of a body when an additional load is applied to it. In this case, the distances between molecules or atoms change, leading to the appearance of elastic forces. Consider the main types of deformations and their characteristics.
Squeeze and stretch
Tensile deformation is related to the relative or absolute elongation of the body. An example is a homogeneous rod, which is fixed at one end. When a force acting in the opposite direction is applied along the axis, the rod is stretched.
The force applied towards the fixed end of the rod leads to compression of the body. In the process of compression or stretching, the cross-sectional area of the body changes.
Stretch deformation is a change in the state of an object, accompanied by a displacement of its layers. This view can be analyzed on a model of a solid body consisting of parallel plates, which are interconnected by springs. Due to the horizontal force, the plates are shifted at some angle, while the volume of the body does not change. In the case of elastic deformations, a directly proportional relationship between the force applied to the body and the shear angle was revealed.addiction.
Bend deformation
Let's consider examples of this type of deformation. In the case of bending, the convex part of the body is subjected to some tension, and the concave fragment is compressed. Inside the body subjected to this type of deformation, there is a layer that does not experience either compression or tension. It is commonly called the neutral region of the deformable body. Near it, you can reduce the area of the body.
In engineering, examples of this type of deformation are used to save materials, as well as to reduce the weight of structures being built. Solid beams and rods are replaced with pipes, rails, I-beams.
Torsional deformation
This longitudinal deformation is a non-uniform shear. It arises under the action of forces directed parallel or opposite to the rod, which has one end fixed. Most often, various parts and mechanisms used in structures and machines undergo complex deformations. But due to the combination of several variants of deformations, the calculation of their properties is greatly facilitated.
By the way, in the process of significant evolution, the bones of birds and animals have adopted a tubular version of the structure. This change contributed to the maximum strengthening of the skeleton at a certain body weight.
Deformations on the example of the human body
The human body is subjected to serious mechanical stress from its own efforts and weight, which appear as physicalactivities. In general, deformation (shift) is characteristic of the human body:
- Compression experiences the spine, integuments of the feet, lower limbs.
- Ligaments, upper limbs, muscles, tendons are stretched.
- Bending is characteristic of the limbs, pelvic bones, vertebrae.
- The neck undergoes torsion during rotation, and the hands experience it during rotation.
But if the maximum stress is exceeded, a rupture is possible, for example, the bones of the shoulder, thigh. In ligaments, the tissues are connected so elastically that they can be stretched twice. By the way, shear deformation explains all the dangers of moving women in high heels. The weight of the body will be transferred to the fingers, which will double the load on the bones.
According to the results of medical examinations conducted in schools, out of ten children, only one can be considered he althy. How are deformities related to children's he alth? Shearing, twisting, contraction are the main causes of poor posture in children and adolescents.
Strength and deformation
Despite the diversity of the living and non-living world, the creation of numerous material objects by man, all objects and living beings have a common property - strength. It is customary to understand the ability of a material to persist for a long time period without visible damage. There is the strength of structures, molecules, structures. This characteristic is appropriate for blood vessels, human bones, brickcolumns, glass, water. Shear deformation - a variant of checking the structure for strength.
The use of different types of deformations by man has deep historical roots. It all started with the desire to connect a stick and a sharp tip to each other in order to hunt ancient animals. Already in those distant times, man was interested in deformation. Shift, compression, stretching, bending helped him create dwellings, tools, and cook food. With the development of technology, mankind has managed to use various types of deformations so that they bring significant benefits.
Hooke's Law
Mathematical calculations required in construction, engineering, made it possible to apply Hooke's law for shear deformation. The formula showed a direct relationship between the force applied to the body and its elongation (compression). Hooke used a stiffness factor to show the relationship between a material and its ability to deform.
With the development and improvement of technical means, apparatus and instruments, the development of the theory of resistance, serious studies of plasticity and elasticity were carried out. The results of the fundamental experiments carried out began to be applied in construction technology, the theory of structures, and theoretical mechanics.
Thanks to an integrated approach to the problems associated with various types of deformation, it was possible to develop the construction industry, to carry out the prevention of correct posture in the younger generation of the country.
Conclusion
Deformations considered in the course of school physics,influence the processes occurring in the living world. In human and animal organisms, torsion, bending, stretching, and compression are constantly occurring. And in order to carry out timely and complete prevention of problems associated with posture or overweight, doctors use the dependencies identified by physicists during fundamental research.
For example, before carrying out prosthetics of the lower extremities, a detailed calculation of the maximum load for which it should be calculated is performed. Prostheses are selected for each person individually, as it is important to take into account the weight, height and mobility of the latter. For violations of posture, special correction belts are used, based on the use of shear deformation. Modern rehabilitation medicine could not exist without the use of physical laws and phenomena, including without taking into account the laws of various types of deformations.
