This article will focus on rheology. You will learn what it is, get acquainted with the main provisions of this component of physics and much more.
Rheology as a branch of physics
Rheology is part of physical science that studies the phenomenon of deformation. Engaged in the study of the characteristics and properties of real objects, rheology is between the theory of elasticity and hydrodynamics. Rheological properties are the characteristics of substances that can be detected under a certain influence of certain forces or speeds. The very concept of rheology was introduced into circulation by the American chemist Eugene Bingham.
Introducing Newtonian Fluid
Newtonian fluid is a viscous medium, which during its flow obeys Newton's law of viscous friction. This fluid occupies a key place in rheology, since the viscosity in it is independent of the deformation process.
The second important concept is a perfectly elastic body. In this body at any moment in time, the deformation force depends on the applied force. The rheological properties of solutions in Newtonian fluids are measurable parameters, and the information obtained as a result of studies of such substances allows us to make a large number of practically useful conclusions. These terms were introduced for objects that at one time can show both plastic and elastic properties.
Deformation in rheology
Various applications of rheology are used in practice to study the various properties of metals under pressure or flow. Each crystal in any of its states can be changed plastically, that is, to deform. Deformation occurs due to the directed motion of the dislocation and the vacancy. Due to the action of various forces in the body of the crystal, a stress is formed, which disappears due to the appearance of various cracks and deformations. If the force of influence becomes more admissible, then the destruction of the body occurs. In fact, the rheological properties of materials are described precisely in rheology, which is very important for a person in everyday life.
Properties of the rheological type and their significance
Rheological properties - these are the features of substances that determine the creation of the possibility of various exploitation of the studied objects. Almost all substances are characterized by complex rheological characteristics. Their condition is influenced by many factors that affect the outside of the body, such as pressure force, time, temperature. Medications and their properties are affected by stability, concentration and composition.
The influence of rheological properties is noticeable in all areas of industry and technological processes, from development to determining the quality of the initial product. The main examples of such changes are:
- Analysis of food and personal care cosmetics on the possibility of changing their condition.
- Characterization of binding systems, search for suitable materials for medicines and pharmaceuticals.
Features of the process
The standard process of the rheological type can be called the relative flow of substances in a sluggish state. In this case, the presence of elasticity, resilience and plasticity of the substance itself is necessary. In the most diverse soils, rheological processes constantly occur that occur as a result of mixing solid-type soil particles together with soil aggregates that are separated by a coherent fluid, namely water.
The above process causes a violation of structural bonds and leads to the creation of viscous contacts, as well as the reorientation of soil particles. Here, the deformation process is considered as creep and can be of volumetric or shear type. The first type (volumetric) arises as a result of particle compaction, and its main determining factor is the filtration and change in the creep characteristics of the soil skeleton. By nature, this phenomenon can be divided into two types: undamped and damped.
Subsections in Rheology
Rheological science in its arsenal has a subset of sections. The first is macroreology, otherwise called theoretical. It is often considered along with mechanics. Rheological properties are the ability of a body to deform, and it is from this angle that macro-rheology considers such features of substances. This part of rheology deals with the establishment of an indicator of the dependence of the current stress on a specific object and the magnitude of the deformation, as well as a change in this indicator of deformation as a result of the passage of time. The solution of boundary value problems on the deformation and flow of solids, as well as liquid and other solids is the main goal of theoretical rheology. This science does not have a clear equation for determining the material state, but there are variations of formulas for a wide variety of cases.
Another part of rheology is the modeling of a mechanical nature. Differential equations are created for him, which include a combination of both viscous and elastic qualities. Such models are used to study the qualitative characteristics of polymeric substances, internal-type friction of solids, etc.
Rheometry is an experimental branch of science that determines the various properties of objects using special instruments and machines.
Microreology is engaged in the study of the deformation of objects over time in a microvolume.
Bioreological studies study the characteristics of liquids and their course. We consider liquids of a biological nature. For example, a violation of the rheological properties of blood and the timely detection of this incident will avoid unnecessary problems in the body of the subject. The results of deformation of various tissues are also considered here.
Rheology and its phenomena are present in most natural processes and in a large part of technological and industrial activities. The most commonly studied substances in such processes, as a rule, parts of the earth’s crust, various types of rocks, magma, oil and clay, concrete and asphalt concrete, oil-type paints, various solutions, alloys of polymers. The rheological properties of products, such as dough and the like, which is used to make sweets and other confectionery products, also come under the influence of studies of their qualitative parameters in rheology.
Rocket fuels and hygiene products, toothpaste, creams, and even muscle tissue, which are made up of protein bodies, are all tested and studied in this science. Such an incomplete list of rheological processes even includes substances such as concrete, initially solid and liquid, and even oil. The rheological properties of drilling fluids are especially important for oil production, because if you do not reduce the parameters of the rheological type of flushing fluids used in pumps for oil production, then their technical indicators will drop.
How to discover evidence of rheology in everyday life
A simple experience is found in everyday life, it occurs when, when contaminated with glue, resin or sugar syrup, a person tries to open his fingers. This leads to the appearance of strings that are created from a seemingly fluid medium. Thus, a web and various threads are obtained.
Rheology gives us the opportunity to understand that with high-speed impacts on the body, substances can manifest themselves as solid, and with slow exposure - as liquid. For example, a blow to the surface of the water at a speed of 150 km / h is no different, from a blow to a concrete wall, in this case the water manifests itself as a solid and does not have time to manifest its fluidity. A concrete pillar can become curved over time (the substance flows), various strings on musical instruments periodically lose their tension, they have to be pulled, due to the slowed flow, their length increases.
The range of relay processes can range from a few seconds to billions of years. Rocks that form entire mountain systems crumple over several geological periods, which can be billions of years. The characteristics and features of various rheological media are different and depend on the conditions of the load exerted on them. By nature and properties close to Bingham fluids can be called toothpastes, sludges, drilling fluids.
Some research (bioreology)
Based on studies of the rheological characteristics of the blood and the factors influencing it, we can conclude that the state of the aggregate nature in which the blood is located is the basis from which to draw conclusions. Improving the rheological properties of blood, it is possible to achieve its better circulation and ability to transfer the constituent elements of the internal environment of the body. In modern times, researchers pay great attention to the micro-rheological characteristics of the blood. However, viscometry has not lost its significance to this day. Determination of the rheological properties of blood using viscometry can be divided into two main types: capillary and rotational. The first type can occur inside a tube, the dimensions of which are known in advance, and the process itself is exposed to the specified size of the pressure difference at its different ends.
Conclusion
Rheological properties are the characteristics of various substances that can occur as a result of exposure to a specific nature, such as speed or pressure. Rheology itself is an important science and an integral part of physics, and also finds its application even in biology. This science has many subsections, which, although they work in the same field, however, can have the most diverse conclusions in research.