subject: A Closer Look At The Rheometer [print this page] A rheometer is most often used to measure the viscoelastic properties of materials, but these measurements have to do more than measure just the material's viscosity. Specifically, it measures how particular kinds of fluids flow and how they deform under specific stresses and strains. Kinetic properties, yield stress, creed, modulus, recovery, and complex viscosity are all different types of material behavior that are measured. This is invaluable in the field of manufacturing, as just one example.
The history of rheometry
Although originally used to denote devices that measured all types of flow (including electric current), it became a term commonly used for a device that measured the flow of liquids. This was specifically prevalent in civil engineering and in medicine, in some cases until the second half of the 20th century. After that point, however, the word "rheometer" was meant to define an instrument that measured the character of a particular flow, rather than its quantity. This remains the current definition. Today, they are generally used in a lab setting, so that constants can be set and known dimensions defined.
For example, shear stress can be measured with a shear rheometer, such as a capillary version. When the party is forced into the tube under non-turbulent conditions, you can establish a constant flow rate so that pressure drop or rice can be calculated. Once you know these values, and you can calculate the shear stress.
Using an extensional product
When materials are subjected to tensile deformation, you can use an extensional type product. This can happen, for example, during extrusion, fiber spinning, or injection molding. In this type of information is useful if you want to know how liquid food products or hand soap, for example, are going to behave during handling.
When are these products commonly used?
Process models, for example, can be used for online quality control and process control, to monitor resulting stress after deformation in manufacturing. This ensures that liquid to solid products like plastics, for example, that are made will behave "properly" during the manufacturing process well in the liquid state so that they don't deform during shaping. They are also commonly used in food or household products production, for example, to predict how long a particular product's shelf life is going to be.
The rotational version is the most commonly used rheometer; it's also called a "stress/strain" products. A capillary version is the second most common type used.
Another of the most important places the rheometers used today is in the maintaining and building of roads. Pavement durability and performance can be predicted over time as it stands up to the stresses of traffic and changing climate conditions, and asphalt binders as measured by these products can help predict this.
