## The difference between three types of curves for non-Newtonian fluids

Non-newtonian fluids have different rheological properties under force, and according to the change of their rheological properties, they can be divided into three types of curves: shear stress-shear rate curves, also known as rheological curves. Here are the differences between the three types of curves for non-Newtonian fluids:

**Plastic Fluid:**

Plastic fluids behave as solids at low shear rates and need to exceed a certain shear stress (critical shear stress) to start flowing. When the shear stress exceeds the critical value, there is a linear relationship between the shear rate and the shear stress.

When the shear stress is below the critical value, the plastic fluid behaves as a rigid solid without fluidity. Only when the shear stress exceeds the critical value can plastic deformation occur and flow start.

The flow curve of plastic fluid shows two distinct stages: one is that the shear stress remains basically constant, and the other is that the relationship between shear stress and shear rate is linear.

Examples of plastic fluids include some greases, plastic pastes, etc.

**The difference between three types of curves for non-Newtonian fluids**

**Pseudo Plastic Fluid: Pseudo plastic fluid**

The pseudoplastic fluid exhibits high viscosity at low shear rates, but its viscosity decreases gradually with increasing shear rates. In pseudoplastic fluids, there is a nonlinear relationship between shear stress and shear rate, and an increase in shear stress leads to an increase in shear rate.

The rheological curve of the pseudoplastic fluid shows a gradually decreasing trend, and its slope becomes smaller and smaller, and the relationship between shear stress and shear rate is not linear.

Examples of pseudoplastic fluids include some colloidal solutions, paints, certain food pastes, etc.

**The difference between three types of curves for non-Newtonian fluids**

**True plastic Fluid (Dilatant Fluid)The difference between three types of curves for non-Newtonian fluids**

True plastic fluids exhibit low viscosity at low shear rates, but their viscosity gradually increases with increasing shear rates. In a true plastic fluid, there is a nonlinear relationship between shear stress and shear rate, and an increase in shear stress leads to a decrease in shear rate.

The rheological curve of the true plastic fluid shows a gradual increasing trend with a larger and larger slope, and the relationship between shear stress and shear rate is not linear.

Examples of true plastic fluids include concrete, particulate suspended solids, etc.

Different non-Newtonian fluids may have different rheological properties and characteristics, and the above description is a generalization in a general case. In the specific application, it is also necessary to analyze and judge according to the rheological properties of actual materials and experimental data.