Research On Mechanical Responses Of An Internal Bypass Magnetorheological Shock Absorber

Magnetorheological(MR)fluid is a kind of magnetic field effect intelligent material with controlled rheological properties.Its fast response property make the controllable damping actuator based on MR fluid have potential application in high-speed impact buffer control system.In this dissertation,the principle and structure of an internal bypass magnetorheological shock absorber(MRSA)under high speed impact excitation are presented,which can be used to absorb energy in a timely and efficient in high-speed impact.The principle and mechanical properties of internal bypass MRSA are deeply analyzed,simulated and experimentally verified.The magnetic field distribution of internal bypass MRSA under different current excitation conditions is analyzed in static magnetic field.The response time of internal bypass MRSA under transient current excitation and transient voltage excitation is obtained by transient electromagnetic simulation.Based on the theory of fluid flow characteristics and the finite element simulation software ANSYS/Fluent,the mathematical of mechanical properties and the finite element model of flow field of MRSA are established respectively under different excitation conditions.The mechanical properties of the conventional unicoil MRSA,the multicoil MRSA and the internal bypass MRSA are compared and analyzed.To verify the decoupling of the piston and the electromagnetic coil makes the internal bypass MRSA has better controllable mechanical performance,including controllable damping force range,dynamic range and constant stroking load velocity range.Based on the impact of the self-built test platform and the Heron Palace servo hydraulic excitation test system,experiments and analyzes of mechanical response characteristics under high speed impact and sinusoidal displacement excitation with the internal bypass MRSA are carried out.The time response characteristics of internal bypass MRSA prototype under the condition of triangular wave displacement excitation are tested on the Heron Palace servo hydraulic excitation test system,including the response time when the current source and the voltage source are used as the excitation power driver,respectively.The feasibility of semi-active buffering of internal bypass MRSA in impact buffer system is analyzed and discussed when the current source is used as an excitation current driver.