Introduction
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Torsional vibration damper is a device used to dampen the vibrational energy in rotational systems. It is a combination of a spring and a damping element that is used to reduce the torsional vibrations in an engine, transmission, or other rotating component. It is also known as a torsional vibration absorber or torsional vibration attenuator. The torsional vibration damper works by reducing the amplitude of the torsional vibrations by absorbing and dissipating the energy. It is used to reduce the noise and harshness of the engine.
The torsional vibration damper is an important component of any rotating system, as it helps to reduce the vibrations caused by the engine and transmission, which can lead to premature wear and tear and even failure of the component if left unchecked. Torsional vibration dampers can be used in a variety of applications, including automotive, industrial, and marine applications.
Torsional vibration dampers work by absorbing and dissipating torsional vibrations through the use of a spring and a damping element. The spring provides a restoring force that helps to counteract the vibrations and the damping element absorbs the energy and dissipates it as heat. The torsional vibration damper is typically mounted between two rotating components, such as the engine and transmission, and is connected to both components by a flexible coupling.
Types
There are several types of torsional vibration dampers, including:
Spring-Mass-Damper:
This type of torsional vibration damper uses a combination of a spring and a damping element to reduce the amplitude of the torsional vibrations. The spring provides a restoring force that helps to counteract the vibrational energy, and the damping element absorbs and dissipates the energy as heat.
Fluid-Filled Vibration Damper:
This type of damper uses a combination of a flexible membrane and a damping fluid to reduce torsional vibrations. The flexible membrane helps to absorb the vibrational energy, while the damping fluid helps to dissipate the energy as heat.
Hydrodynamic Vibration Damper:
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This type of damper uses a combination of a cylinder, a piston, and a damping fluid to reduce torsional vibrations. The cylinder and piston are filled with a damping fluid, which helps to absorb and dissipate the vibrational energy as heat.
Applications
Torsional vibration dampers are used in a variety of applications, including automotive, industrial, and marine applications. In automotive applications, torsional vibration dampers are used to reduce the noise and harshness of the engine and transmission. They are also used to reduce the wear and tear on the engine and transmission components, as well as to improve fuel efficiency.
In industrial applications, torsional vibration dampers are used to reduce the vibration and noise in machinery and equipment. They are also used to reduce the wear and tear on the components, as well as to improve the efficiency of the machinery and equipment. In marine applications, torsional vibration dampers are used to reduce the vibration and noise in marine engines and transmissions. They are also used to reduce the wear and tear on the components, as well as to improve the efficiency of the marine engines and transmissions.
Conclusion
The torsional vibration damper is an important component of any rotating system, as it helps to reduce the vibrations caused by the engine and transmission. It is a combination of a spring and a damping element that is used to reduce the amplitude of the torsional vibrations by absorbing and dissipating the energy. There are several types of torsional vibration dampers, including spring-mass-damper, fluid-filled vibration damper, and hydrodynamic vibration damper. These dampers are used in a variety of applications, including automotive, industrial, and marine applications.
In response to the above problems, many scholars have recently improved the number of coils and coil arrangements based on previous research, thus optimizing the damper structure and improving the damper performance. Lee et al. [ 32 ] proposed a new magnetic circuit separate from the MRD piston head, as shown in Figure 3 a, where two coils are mounted at the top and bottom of the damper and surrounded by a cover plate made of ferromagnetic material. The coils separate from the piston have a higher dynamic control range, and the damping force of this structure can vary by up to 11%. However, the total stroke length limits the damping force and is suitable for small strokes with low damping. Yang et al. [ 33 ] explored the complex magnetic field distribution inside a multi-coil MRD based on a three-coil structure with an embedded Hall sensor, as shown in Figure 3 b. They proposed a magnetic field coupling model with coupling coefficients to describe the complex magnetic field distribution and coupling effects of the three-coil MRD. It can represent the magnetic field distribution of other multi-coil MRDs, laying the foundation for the optimal design of magnetic circuits and mathematical models of multi-coil MRDs. Chen et al. [ 34 ] designed a two-dimensional planar plate type MRD with bipolar coils for achieving two-dimensional damping in engineering, as shown in Figure 3 c. By controlling the windings’ direction of the coils to obtain a superimposed magnetic field in the damper’s working gap, the MRF acting on the working plate is the controllable damping force of this damper. The larger the shear rate, the more pronounced the damping should be. The maximum damping ratio of the amplitude can reach 2.5956. The proposed 2-D plate-type MRD has better damping performance. Ma et al. [ 35 ] proposed a model of a rotor-bearing system supported by an MRD as shown in Figure 3 d. It has a double coil, and the coils must be wound in opposite directions to control the rotor vibration by applying a suitable current to generate a response damping force. It provides proper damping and stiffness for the rotor system to realize the optimal control of rotor system vibration. The damper overcomes the shortcomings of the traditional squeeze film damper, such as a narrow tuning range and failure of vibration reduction due to fault or sudden unbalance.
(1) The coil embeds in the piston, and the piston bore connects the wire to an external power supply, thus generating a magnetic field. The advantage of this arrangement is the simplicity of the design and the better magnetic utilization. However, there are the following problems: By the coil being in direct contact with the MRF, the fluid will leak through it; and the seals will complicate the manufacturing process. In addition, the internal temperature rise may make the viscosity of MRF decrease significantly, leading to the attenuation of the output performance of the MRD.
The piston of a general MRD consists of a piston head, a piston rod, and an embedded coil. When the force of the applied load transmits through the piston rod into the damper, the piston rod moves relative to the damper cylinder. When the coil energizes, it generates a magnetic field. The MRF in the gap between the piston and the cylinder enters a flow or shear mode of operation, resulting in a controlled damping force due to the magnetorheological effect. The conventional piston structure is simple, but the size of the damper limits its piston stroke, thus limiting the damping force and the range of adjustment, and the magnetic utilization of the simple piston structure is low. To optimize the design of the piston so that the damper can produce a sizeable damping force and dynamic range even with restricted dimensions and to improve the overall damper performance, researchers have recently improved or replaced the piston of the MRD.
Jiang et al. [ 36 ] designed an MRD with an inner piston channel, as shown in Figure 4 a, that integrates the magnetic circuit in the piston assembly without passing through the cylinder. The damper is lightweight, electromagnetic compatible, and highly integrated. They optimized the structure by a non-explicit ranking genetic algorithm version II with the maximum dynamic range and a minimum number of turns of the solenoid coil as the optimization objectives. This optimization can provide a reference for the optimal design of related damping devices. Oh et al. [ 37 ] compared two types of MRD, as Figure 4 b shows, one with two different bypass holes in the piston, and the MRD with the bypass hole had the central hole and two additional bypass holes in the runners. A simulation study concluded that the MRD with the bypass hole in the low piston speed region had less damping force, better energy dissipation performance in body resonance (1–2 Hz), and superior ride quality in passenger mode (3–10 Hz). Li et al. [ 38 ] developed a mathematical model that can efficiently predict the damping force of MRDs with non-magnetized channels in the piston. These studies show that it works better over various piston velocities, indicates damping force, and evaluates performance. Further, Liu et al. [ 39 ] validated the advantages of MRD with multi-grooves through experiments for the first time. Compared with MRD without multi-grooves, a MRD with multi-grooves has a more significant damping force and controllable force range and less increment of fluid viscous force while keeping the same increase in field-dependent force.
In addition, the piston rod’s length and the damper cylinder’s size limit the movement stroke of the piston. Recent research has utilized a new internal damping adjustment structure instead of the usual piston structure to eliminate the limit, allowing for a compact damper structure. Yu et al. [ 40 41 ] developed a spiral-flow rotating MRD with an optimized flux path, as shown in Figure 5 . The inner cylinder of it consists of a conductive ring and a non-magnetic conductive ring, and the maximum torque increases from 0.15 N*m to 17 N*m when the current increases from 0 to 4 A, providing better magnetic field distribution, higher torque, and dynamic adjustment range compared to previous dampers. To ensure significant angular variable stiffness of the MRD output, Yu et al. [ 42 ] proposed a new compact rotating MRD with variable damping and stiffness containing two drive discs and one active rotating disc, as shown in Figure 6 . They compared those with one drive disc and no drive disc, showing that the dampers have greater angular controllable stiffness.
Yu et al. [ 43 ] prepared a shear-thickening MRF with a shear-thickening effect and magnetorheological effect, and designed a magnetic rate-controlled stage damper based on it. The central working part consists of the main piston and an auxiliary piston. The main piston has the function of shock resistance and energy dissipation; the auxiliary piston consists of permanent magnets and coils, which can realize energy dissipation of continuous variable damping. The dampers have been tested and proven to have an adjustable output range of 192.8–250.2 KN at large displacements and a flexible damping force range of approximately 1.3. They are suitable for various vibration excitation environments and resist shock energy dissipation. Elsaady et al. [ 44 ] have proposed a piston design to enhance the magnetic properties of MRDs, mainly by improving the piston fluid region and the type of piston magnetic material.The piston consists of four magnetic coils connected in parallel, separated by five magnetic spacers made of Vacoflux-50, wound on a non-magnetic cartridge tube made of nylon-66 and surrounded by an isolator made of the same material. The piston rod is fitted with a magnetic core, also made of Vacoflux-50, with a damping channel between the core’s outer surface and the magnetic spacer. The improved design proposed in this study results in a significant increase in the magnetic field and fluid yield stress, a 50% increase in maximum damping force, and a high magnetic field at low input currents. It is suitable for the development of large MRDs ideal for higher loads.
In addition to innovative designs for piston structures, some researches based on general piston structures use optimizing techniques and tools to optimize the shape, dimensions, etc. Nie et al. [ 45 ] investigated the influence of the form of the piston slot and the magnetic insulators at the ends of the piston on their operating performance. The MRD with chamfered piston slot edges and the magnetic insulators’ inclined edges had better damping force and dynamic range by simulation analysis. Optimizing the piston slot’s boundaries could reduce the magnetic circuit’s magnetic flux density and increase the working gap. The optimized damping force and dynamic range increased by 12.7% and 12%, respectively, and the structural volume reduced to 34.6%. Based on the double-ended MRD piston prototype, Gao et al. [ 46 ] optimized the piston shape using the Bezier, one of the typical parametric curves. The transition between the front and rear piston heads and the intermediate piston in the prototype is not smooth at right angles, resulting in flux loss and reduced flux density in the ring gap. That significantly reduces the output damping force; the optimized piston can successfully solve the problem of regional magnetic saturation in the transition between the front and rear piston and the intermediate piston. The regional magnetic saturation in the transition area between the front and rear pistons and the intermediate piston can be successfully solved, resulting in a greater flux density in the ring gap and a more excellent controllable damping force range than the pre-optimized piston. Devikiran et al. [ 47 ] designed a single-tube shear mode MRD for a two-wheeled vehicle. The piston size was optimized using the optimizing function ‘Optimization Toolbox’ of MATLAB to achieve an extended dynamic range and high damping force. However, they did not specify the particularities of the design of this damper structure for a two-wheeled vehicle. Hu et al. [ 48 ] used a multi-objective genetic algorithm to optimize the critical structural parameters of a built-in double-ended MRD, resulting in a 43% reduction in power consumption and a 30% increase in the damping force of the MRD. This multi-objective optimization method, which maximizes the output damping force at low power consumption and minimizes the piston volume, was shown to provide new ideas for optimizing other dampers. Yoon et al. [ 49 ] proposed a new core model that considers gap edge effects and B-H curve nonlinearity to give an accurate model for MRD core design, producing high controllable forces over a wide dynamic range without using the finite element method. Patel et al. [ 50 ] developed a MRD for washing machine applications, using a generalized, simplified gradient (GRG) and grey relational analysis (GRA) optimization techniques for shear MRD design parameters (e.g., magnetic coil height, width, piston path radius, and optimum fluid volume). The method had a significant effect on reducing the cost of the damper.
Lee et al. [ 51 52 ] designed a new permanent magnet-based MRD that uses two materials with different reluctances to provide flux dispersion in two magnetic circuits, as shown in Figure 7 . The MRD achieves a controlled damping force through the motion of the permanent magnet piston rather than through the magnitude of the input coil current. However, the response time is relatively slow compared to MRDs using electromagnetic coils. Building on previous research, the triangular cylinder was replaced by a rectangular column to achieve a stepped input response of the damping force based on switching state logic. They carried out experimental tests to measure the response time of the damper by considering three influencing factors: the material of the magnetic circuit, the magnitude of change in the damping force, and the excitation frequency of the piston. The results show that the damper has a faster-than-normal shortening response time and is suitable for specific applications where a fast response time of the damping force is required.
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