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Christopher Harrington
Christopher Harrington

A Novel Magnetic Fluid Shock Absorber with a Composite Magnet Structure: Experimental and Numerical Analysis

Magnetic Shock Absorbers: What Are They and How Do They Work?

Shock absorbers are devices that reduce the impact of bumps and vibrations on vehicles. They are essential for ensuring a smooth and safe ride, as well as protecting the vehicle components from damage. Shock absorbers work by converting the kinetic energy of the suspension movement into heat, which is then dissipated into the environment.

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Magnetic shock absorbers are a type of shock absorber that use magnetic forces to generate damping force. Unlike conventional shock absorbers that rely on mechanical or hydraulic elements, magnetic shock absorbers use electric motors or magnetic fluids to adjust the damping properties according to the road conditions and driver preferences. Magnetic shock absorbers have several advantages over conventional ones, such as:

  • They can provide variable and controllable damping force, which can improve the ride comfort and handling performance of vehicles.

  • They can harvest vibration energy and convert it into useful electricity, which can reduce fuel consumption and emissions.

  • They have fewer moving parts and less friction, which can reduce wear and tear and maintenance costs.

However, magnetic shock absorbers also have some disadvantages, such as:

  • They require complex control systems and sensors, which can increase the cost and weight of the vehicle.

  • They may generate electromagnetic interference or noise, which can affect other electronic devices or human health.

  • They may have limited power output or efficiency, which can limit their performance or applicability.

Types of Magnetic Shock Absorbers

There are two main types of magnetic shock absorbers: electromagnetic shock absorbers and magnetic fluid shock absorbers. They differ in the way they use magnetic forces to generate damping force.

Electromagnetic Shock Absorbers

Electromagnetic shock absorbers use linear or rotary electric motors to generate damping force. The electric motor is connected to a mechanical or hydraulic system that amplifies the speed of the suspension movement. The electric motor acts as a generator when the suspension moves, producing electric current that flows through a resistive load. The resistive load converts the electric current into heat, which creates a damping force that opposes the suspension movement. The damping force can be adjusted by changing the resistance value or switching between different resistive loads.

Magnetic Fluid Shock Absorbers

Magnetic fluid shock absorbers use magnetic fluids to adjust the damping properties. Magnetic fluids are liquids that contain tiny magnetic particles that can change their viscosity or flow behavior when exposed to a magnetic field. The magnetic fluid is filled in a cylinder that has a piston and a coil. The piston is attached to the suspension and moves up and down with the road vibrations. The coil is connected to a power source and generates a magnetic field when electric current passes through it. The magnetic field changes the viscosity of the magnetic fluid, which creates a damping force that resists the piston movement. The damping force can be adjusted by changing the current or frequency of the coil.

Comparison Table of Electromagnetic and Magnetic Fluid Shock Absorbers





- High damping force and power output- Good energy harvesting capability- Simple structure and easy control

- High cost and weight- Electromagnetic interference or noise- Mechanical or hydraulic losses

Magnetic Fluid

- Low cost and weight- No electromagnetic interference or noise- No mechanical or hydraulic losses

- Low damping force and power output- Poor energy harvesting capability- Complex structure and difficult control

Applications of Magnetic Shock Absorbers

Magnetic shock absorbers have various applications in different fields of engineering and science. Some of the most common and promising applications are:

Automotive Suspensions

Magnetic shock absorbers can improve the ride comfort and handling performance of vehicles by providing variable and controllable damping force. They can also reduce the fuel consumption and emissions of vehicles by harvesting vibration energy and converting it into useful electricity. Some examples of vehicles that use magnetic shock absorbers are:

  • The Bose Active Suspension System uses linear electromagnetic motors to provide smooth and stable ride quality for cars.

  • The Audi eROT System uses rotary electromagnetic motors to recover kinetic energy from the suspension movement and store it in a battery for later use.

  • The MagneRide System uses magnetic fluid dampers to adjust the damping properties according to the road conditions and driver preferences.

Energy Harvesting

Magnetic shock absorbers can convert vibration energy into useful electricity, which can be used for powering other devices or systems. This can reduce the dependence on external power sources or batteries, which can save energy and resources. Some examples of devices or systems that use magnetic shock absorbers for energy harvesting are:

  • The Regenerative Shock Absorber uses a rack-and-pinion mechanism and a DC brushless motor to generate electricity from the suspension movement.

  • The Energy-Harvesting Damper uses a magnetic interaction system to produce electricity from the relative motion between magnets.

  • The Hybrid Electromagnetic Shock Absorber uses a combination of electromagnetic and piezoelectric elements to harvest vibration energy from multiple directions.

Other Fields

Magnetic shock absorbers have potential uses in other fields of engineering and science, such as:

  • Aerospace: Magnetic shock absorbers can improve the landing performance and safety of aircrafts or spacecrafts by providing adaptive damping force.

  • Biomedical: Magnetic shock absorbers can enhance the comfort and functionality of prosthetic limbs or orthotic devices by providing adjustable stiffness or damping.

  • Robotics: Magnetic shock absorbers can increase the mobility and agility of robots or machines by providing variable compliance or damping.

Design and Analysis of Magnetic Shock Absorbers

The design and analysis of magnetic shock absorbers involve several aspects, such as:

Design Principles

The design principles of magnetic shock absorbers are based on the following factors:

  • The required damping force and power output: The size, shape, and material of the electric motor or magnetic fluid, as well as the mechanical or hydraulic system, should be chosen to provide sufficient damping force and power output for the application.

  • The control strategy and algorithm: The resistive load, coil current, or frequency should be controlled by a suitable strategy and algorithm to achieve the desired damping properties.

  • The optimization criteria and constraints: The design parameters should be optimized according to certain criteria, such as weight, cost, efficiency, or performance, while satisfying certain constraints, such as space, safety, or reliability.

Analysis Methods

Analysis Methods

The analysis methods of magnetic shock absorbers are based on the following tools and techniques:

  • The characteristic diagrams: The characteristic diagrams (Force-Displacement, Velocity-Acceleration) are graphical representations of the relationship between the input and output variables of the shock absorber. They can be constructed