The normal stress of an electrorheological fluid in compression mode

Abstract

This work studied the normal stress of an ER fluid in compression mode through both experiment and simulation. The TiO 2 based ER fluid was used to test the normal stress under different DC voltages and compressive speeds. The normal stress reached about tens of kPa and was affected by the applied voltage and compressive parameters. Then, a simulation model was presented to investigate the influencing factors on the normal stress. The computational normal stresses agreed well with the experimental results. Typically, the shear action was also found to be very important for the normal stress during the compression. When the shear rate is small, the shear action showed little effect on normal stress. When the shear rate exceeded a critical value, the normal stress oscillated within a certain range. At last, an ideal 2D simulation was conducted to investigate the relation between the mechanical property and the structure transformation.

Electrorheological Fluids with High Shear Stress Based on Wrinkly Tin Titanyl Oxalate

“…The electrostatic interaction is responsible for the maintenance of the ER chain structure and hinders the flow, whereas the hydrodynamic interaction forces tend to destroy the chain structure and enhance the flow. Hence, the high and stable shear stress of W-TTO ER fluids further confirms that W-TTO particles possess not only large polarizability but also the fast response time to keep the structures and rheological properties stable. − Comparing the flow curves of TTO ER fluids with those of W-TTO ER fluids (Figures S8, S10, and a,c), it is observed that the shear stresses of both low-concentration (19%) ER fluids remain stable during the entire shear rate range under different electric field strengths. When the concentration increases to 32%, the shear stress of W-TTO ER fluids still maintains a stable level but for TTO ER fluids, the shear stress reaches a maximum value and then decreases rapidly.…”

1D and 2D hybrid polymers based on zinc phenylphosphates: synthesis, characterization and applications in electroactive materials

“…For example, smart uids responding to electric elds (EFs), are formed by electricallypolarizable particles dispersed in a non-conducting liquid medium, [40][41][42][43] and may be utilized in dampers, valves, engine mounts, hydraulic actuators, squeeze mounts, medicine (e.g., in drug delivery or haptic medical devices), and food processing. [44][45][46][47] The industrial applications of currently known electrorheological (ER) uids are based on a positive ER effect, 44,47,48 resulting from the EF-controlled orientation of dispersed particles (e.g., metal oxides, 41,42 metal salts, 43 and modied polymeric particles 40 ) into chain-like structures accompanied by a transition of uid from liquid to viscoelastic system. However, there are many applications in which a controllable decrease in viscosity would be desirable (e.g., hydrostatic journal bearing for controlling rotor vibrations or squeeze lm damper for actively controlling rotor dynamics).…”

Squeeze damping of giant electrorheological fluid tuned by pulse width modulation

“…This technique can effectively predict the force-displacement and force-velocity curves with high accuracy. Wang et al [30] assumed that the number of ERF particles was constant during the squeeze process and obtained the normal stress according to the particle motion equation and particle interaction relationship. They investigated the effect of shear rate on the normal stress during compression.…”