The smooth running of automotive gearboxes depends on automatic transmission fluids. As a fluid, they manage gear changes and transfer power; as a lubricant, they lower wear and friction between moving engine parts. A transmission can run as long as it should and be efficient only if its fluid performance is perfect.
ATF’s non-Newtonian behavior—that is, its viscosity varies with the applied shear rate—is a fundamental characteristic. Low and high temperatures emphasize this phenomenon especially.
AFTs can exhibit a notable viscosity increase at low temperatures, which would complicate the transmission’s smooth gear change.
This is because more resistance to flow produced by higher viscosity might slow down the transmission’s response time. Sometimes, the transmission can even get caught in only one gear.
At high temperatures, ATFs might show a drop in viscosity, which could cause a loss of lubricant and more wear on the transmission components.
This is so because the lower viscosity lessens the ATF’s capacity to provide a protective coating between the moving components.
Higher temperatures can also cause the ATF to malfunction, therefore impairing its lubricating qualities even more.
Several elements, including the base oil viscosity, additive package, and shear rate, affect ATF’s non-Newtonian behavior.
The main determinant of ATF low-temperature viscosity is base oil viscosity. The combination of the additives enhances the viscosity index—that is, the measurement of the viscosity change with temperature. The shear rate is the explanation for shear tension applied to the fluid.
The formulation and choice of these fluids depend heavily on an awareness of ATFs’ non-Newtonian behavior. Knowing the elements influencing this behavior helps create ATFs that satisfy the particular criteria of various transmissions and operating situations.
What Is The Non-Newtonian Behavior?
Non-newtonian behavior is a fascinating phenomenon that is observed in fluids and exhibits viscosity. It varies in response to applied force or shear stress, unlike Newtonian fluids, whose viscosity remains constant and fixed with stable properties.
Non-Newtonian fluids, which are also known as viscoelastic fluids, have the unique characteristics that set them apart from their Newtonian opposite number.
These characteristics are:
Viscosity:
Viscosity in a non-Newtonian fluid relies on the shear rate and shear stress at a particular temperature; it is not a fixed characteristic.
This implies that applying a force to the non-Newtonian fluids will change their viscosity.
Rheological behaviour
Nonlinear rheological behavior of non-Newtonian fluids is explained. Their viscosity can thus either rise or fall depending on the increasing shear force or shear rate. Unlike Newtonian fluids, whose viscosity is constant independent of the shear rate, this fluid behavior is not on such level.
Microstructures
A shear flow causes rearrangement of the microstructure of non-Newtonian fluids. Changes in the molecular or particle structure of the fluids can constitute part of this reorganizing.
Apparent viscosity:
The apparent viscosity of non-Newtonian fluids—defined as the shearing stress to shearing strain ratio—defines them most of all. Shear rate can influence the apparent viscosity of the non-Newtonian fluid.
Measurement
Since they do not offer regulated shear rate, conventional viscometers—often used to test the viscosity of Newtonian fluids—are not appropriate for precisely measuring the viscosity of non-newtonian fluids.
For this reason, special viscosimeters—rotary or capillary viscometers—that help to define the viscosity are used.
Examples of non-Newtonian fluids
There are many things around us that show fluids that are not Newtonian. Blood is one of these fluids. Its viscosity is affected by things like the number of red blood cells and the speed at which blood flows through blood channels.
Paint, shampoo, ketchup, and fire are some other examples. Due to differences in their chemical structures and make-ups, each of these behaves in a way that is not Newtonian.
Automatic Transmission Fluids Also Have Non-Newtonian Behaviour
Because they have things in them called viscosity modifiers, automatic tranmission fluids don’t behave like water under normal conditions such as like UAE. Long-chain molecules make up these chemicals. They interact with each other and connect to make a network structure in the fluid. This structure network is what makes fluids shear-thin, which means that as the shear rate goes up, their viscosity goes down.
Most of the time, Brookfield and kinematic viscosity are used to describe the rheological qualities of ATFs.
The Brookfield viscometer checks how much torque is needed to keep a wheel moving at a steady speed while it is submerged in a fluid.
Kinesthetic viscosity capillary viscometers check how long it takes for a certain amount of liquid to flow through a capillary tube when gravity is at work.
It’s important to know the Brookfield and kinematic viscosities of ATFs in order for them to work well in automatic transmission. Brookfield’s viscosity test makes sure that the fluid is the right consistency to keep the transmission parts lubricated. Fluid should be able to quickly move through the transmission’s passages and valve bodies. Kinematic viscosity makes this possible.
Several things, such as temperature, shear rate, and the addition of additives, can change the rheological properties of ATF.
Because viscosity goes down as temperature goes up, temperature and shear rate have a big impact on the viscosity of ATFs. However, chemicals are the most flexible when it comes to changing the recipe based on the temperature. They can be used to change the rheological qualities of ATFs and make them work better in certain situations. Engineers know about the rheological qualities of ATFs so that they can work well in automatic transmissions.Engineers can build and make transmissions that follow the integral process if they know about these properties.
Newtonian vs. Non-Newtonian Fluids
Newtonian fluids are characterized by a constant viscosity independent of the shear rate.
This means that the viscosity of Newtonian fluids remains the same regardless of their quick or slow flow. Examples of Newtonian fluids are water, oil, and honey.
Non-Newtonian fluids depend on the shear rate. This means that the viscosity of non-Newtonian fluids can increase or decrease as they are subjected to different shear stresses. Examples of non-Newtonian fluids include ketchup, toothpaste, and paint.
Applications of Non-Newtonian Fluids
Automatic transmission fluids are a prime example of non-Newtonian fluids that are used in the automotive industry.
Their viscosity is influenced by shear rate, which shows their shear thinning behavior. This means that their viscosity decreases under higher shear rates and allows for smooth flow and efficient lubrication within the transmission systems.
This property is important for smooth gear shifts and optimal performance during automatic transmission.
Shear-Thinning Behavior
It ensures that the properties of ATFs flow readily at high speeds and pressures in transmissions. It reduces friction and wear on the internal components.
Improved Fuel Efficiency
The reduced viscosity at high shear rates also contributes to improved fuel efficiency. It minimizes energy losses due to internal friction.
Enhanced Performance
The ability of ATFs to adapt their viscosity is based on operating conditions to make sure consistent performance and responsiveness in automatic transmission.
Atlantic ATFs Exhibit The Non-Newtonian Bahaviour
Automatic transmission fluids (ATFs) are required for the perfect operation of cars with automatic gearboxes. Our ATF’s are designed to carry out many vital tasks; and consist of the following:
In an automatic transmission, ATFs help to lower friction between the brake bands and drums. This lessens brake band wear and tear and helps to stop overheating of the transmission.
- The torque converter moves power from the engine to the transmission. ATFs help to guarantee effective and seamless operation of the torque converter.
- ATFs lubricate the valves in an automatic transmission that they open and close smoothly. This helps to stop the wildly shifting transmission.
- ATFs lubricate the gears in an automatic transmission, therefore lowering wear and tear and extending the life of the gearbox.
- ATFs are designed on base oils, additives, and detergents. The base oils give the required viscosity and lubricity; the additives enhance the fluid’s performance and protect the transmission from wear and tear. Detergents help to maintain the transmission free of deposits and clean.
Non-Newtonian fluid research has important ramifications for materials science and engineering, among other disciplines. For instance, ketchup and toothpaste are common examples of non-Newtonian fluids. Many suppliers and manuafcturers exhibit these charactersitics in their automatic transmission fluids.
Atlantic grease and Lubricant researchers understand the behavior of these fluids and create systems that maximize the processes involving the flow and management of these fluids. Our products exhibit the non-Newtonian behaviour and are suitable in any climatic conditions.