Adjustable Damping Research Articles

Quasi-static modeling of a full-channel effective magnetorheological damper with shunt and bending magnetic circuit

Magnetorheological dampers (MRD) are widely used in vibration control due to their rapid response and adjustable damping forces. However, conventional MRD designs with closed rectangular magnetic circuits suffer from limited effective working lengths and inadequate damping force for vehicle suspensions. To address this, a novel full-channel effective MRD with shunt and bending magnetic circuit (FEMRD_SB) is proposed. This design increases the effective working length of the damping channel by incorporating a bending motion in the magnetic circuit. Magnetic circuit shunting is integrated to mitigate magnetic leakage during bending, improving energy utilization efficiency. To better meet the practical needs of vehicle suspension, a quasi-static mathematical model aiming to explain the mechanical properties of the damper is investigated. Traditional models often overlook the uneven distribution of magnetic fields, which leads to poor modeling accuracy. To improve the precision of the quasi-static model, a multiphysical field coupling quasi-static modeling method is proposed. This method, utilizing the Takagi–Sugeno fuzzy neural network establishes the relationship between magnetic field and displacement, facilitating the integration of magnetic, flow, and solid fields for more precise modeling outcomes. Simulations and experiments validate the effectiveness of the FEMRD_SB and the quasi-static model. The real-vehicle experiments demonstrate that the FEMRD_SB effectively suppresses the sprung mass acceleration of a vehicle, improving the vehicle’s ride comfort.

CO2-based polyurethane elastomers with enhanced mechanical and tunable room-temperature damping performances

Elastomers provide excellent damping performance owing to their unique viscoelasticity, which are widely used as vibration and noise reduction materials. However, conventional rubber-based elastomers with a low glass transition temperature (Tg) and narrow damping range are difficult to adapt to room-temperature conditions. Additionally, most of petroleum-based elastomers hinder the sustainable development. In this work, a series of novel polyurethane elastomers was synthesized using carbon-fixed CO2-based polycarbonate propylene diol (PPCD). The impact of hard segment (HS) content on the thermal, mechanical, and damping properties of CO2-based polyurethane (PU) was comprehensively investigated. Increasing the HS content from 16 % to 44 % increased the Tg from −3.8 °C to 21.7 °C, covering the entire damping range at room temperature with an adjustable damping performance. Furthermore, the tensile strength increased from 7.2 MPa to 27.0 MPa. The synthesis of CO2-based PU can propel the utilization of PU in damping applications, enabling sustainable advancement of the PU industry.

Research on dynamic performance and mechanical model of a novel magnetorheological shear thickening damper with adaptive variable damping gap

Abstract Magnetorheological shear thickening fluid (MRSTF) is an intelligent composite material, which shows considerable potential in semi-active vibration control. However, the current research is mostly limited to the study of the rheological properties of materials, and there is still a lack of damper structures that can effectively utilize the dual-control characteristics of MRSTF. In this paper, a novel damper structure with adaptive adjustable damping gap length is proposed. Its unique design integrates an adaptive internal damping gap that changes with the movement of the piston and an external gap controlled by the magnetic field, providing a relatively wide range of current-controlled damping force and reliable adaptive adjustment capabilities. Based on the M-S shear stress constitutive model and structural characteristics, the mechanical model is derived from the force balance of the micro-element, and verified by performance test and curve fitting. The effectiveness of the new damper structure proposed in this paper is verified by dynamic performance test. The results show that the damper has a wide range of current controlled damping force at low speed and reliable adaptive adjustment capability at high speed. Finally, the accuracy and universality of the modified mechanical model of damper are verified by curve fitting method. All these studies can offer an effective guidance for further application of MRSTF in the field of semi-active vibration control.

Frequency-Dependent Bouc–Wen Modeling of Magnetorheological Damper Using Harmonic Balance Approach

Magnetorheological dampers (MRDs) are of great interest in engineering due to their continuously adjustable damping characteristics. Accurate models are essential for optimizing MRDs and analyzing system dynamics. However, conventional methods widely overlook the impact of excitation frequency and amplitude. To address this issue, this work proposes a modified Bouc–Wen model that can be adapted to various excitation conditions. The model’s parameters depend on the current, excitation frequency, and amplitude. The mechanical characteristics of the MRD were analyzed by the tests. The parameters in the Bouc–Wen model were identified by combining the harmonic balance method and the genetic algorithm. The modified Bouc–Wen model was established by analyzing the variation of each parameter with current, excitation frequency, and amplitude. Finally, the agreement between the modified prediction model and the test results was verified under sinusoidal excitation of 80 mm and 1 Hz. The average relative errors were 3.87%, 2.82%, 2.45%, 2.19%, and 3.27% for current excitations of 0 A, 0.5 A, 1 A, 1.5 A, and 2.0 A, respectively. Since the MRD in this paper operates from 0.5 Hz to 2 Hz, the modified model was validated in the same range. Experiments demonstrate that the modified Bouc–Wen model efficiently and accurately describes the mechanical properties of the MRD under various excitation conditions.

Novel bio-based polyurethane elastomers for adjustable room-temperature damping property

The distinctive viscoelastic behavior of elastomeres can be exploited for reducing vibrations and noise. However, the utility of conventional rubber-based elastomers is limited by low glass transition temperature (Tg) and narrow adjustable damping range, which constrain the room-temperature damping property. Moreover, the majority of rubber-based elastomers are sourced from unsustainable petroleum-based resources. Therefore, designing bio-based materials with room-temperature high-damping property to replace conventional rubber-based elastomers is crucial. Herein, a novel bio-based polyurethane (bio-PU) elastomer with an adjustable damping-temperature range and room-temperature high-damping property is successfully synthesized from bio-based poly (trimethylene ether) glycol. The effects of molecular chain structure on the thermal properties, mechanical properties, and adjustable damping-temperature range of the bio-PU elastomers, along with the mechanisms underlying these effects, are elucidated in detail. As the content of hard segment increasing, the Tg of bio-PU elastomers significantly increases from −13.0 to 29.9 °C, effectively encompassing the damping temperature range within the room-temperature working range. This promising strategy for formulating bio-based elastomers with adjustable damping-temperature range can advance the sustainable growth of PU industry and broaden the scope of PU damping applications.

Structural design and multi-objective optimization of an MR isolator based on flow valve-cone rubber structure

Due to the distinctive working environment of high precision machining and manufacturing field, it poses challenges in meeting the isolation requirements, including limited installation space, multi-dimensional vibration, and a wide range of vibration frequencies. To tackle these obstacles, this paper introduces a magnetorheological (MR) isolator that offers adjustable vertical damping characteristics while guaranteeing three-axis vibration isolation through an inclined cone structure. First, the structure of the isolator was designed by combining a flow valve damper with a conical rubber structure. Second, in pursuit of lightweight design and enhanced magnetic field strength, collaborative simulations using ANSYS and Maxwell are conducted to subject the critical components of the isolator to multi-objective optimization. The optimization results demonstrate that the mass of the isolator has been reduced by approximately 27.7%, while the magnetic field intensity has increased by around 20%. Finally, the performance of the MR isolator was verified through static testing and dynamic testing, respectively. The experimental results demonstrate that the isolator can generate a maximum damping force of approximately 778[Formula: see text]N when exposed to a current of 1.5[Formula: see text]A. Compared to the initial value of 445.06[Formula: see text]N at 0[Formula: see text]A, there has been an approximate increase of 1.74 times.

Cavitation Modeling and the Hysteretic Behavior Investigation on Twin-Tube Hydraulic Adjustable Damper

Cavitation Modeling and the Hysteretic Behavior Investigation on Twin-Tube Hydraulic Adjustable Damper

Effect of Lower Body Negative Pressure (LBNP) on Blood Pressure in Awake Rats and Effects of Anesthesia

Lower body negative pressure (LBNP) has been used for decades in a variety of settings and species to model orthostatic challenge (OC) and baroreceptor unloading. However, due to physical constraints, measurements of blood pressure (BP) during LBNP have always been made in anesthetized animals, where cardiovascular reflexes are blunted or even blocked. In terminal procedures, for example, urethane is often used in an attempt to preserve some measure of autonomic reflex function during OC. More recently, investigators have used isoflurane in animals fitted with BP telemeters in order to perform longitudinal studies, but the extent to which various cardiovascular reflexes may be preserved is unknown. Here we have developed a novel method to apply lower body negative pressure in awake rats instrumented for BP measurement. Rats were placed into a tubular restraining device (5 cm diameter X 21 cm length), that is divided into an upper and lower chamber by two adjacent latex septa with small holes (~ 2 cm). Rats were positioned so that the septa form a seal at the lower margin of the thorax, thereby creating independent upper and lower chambers. Negative pressure was then applied to the lower chamber using a high-volume vacuum and the pressure controlled using an adjustable damper. BP measurements in response to progressive levels of LBNP (-3 to -15 mmHg) were first made in awake rats, followed by induction of anesthesia and repetition of the LBNP protocol. The effects of pentobarbital (50mg/kg), ketamine/xylazine (70/6 mg/kg) and isoflurane (3%) were determined on separate days. BP and heart rate (HR) responses are shown in the Table. We found that BP was remarkably preserved in awake rats up to at least -9 mmHg LBNP, and thereafter (at -12 and -15 mmHg) decreased modestly. There was a robust baroreceptor-mediated increase in HR beginning at -6 mmHg. By contrast, under each anesthetic, blood pressure decreased dramatically and progressively with increasing LBNP, and the reflex increases in HR were entirely blocked (and actually inverted). These data indicate that the awake rat has robust mechanisms to preserve cardiovascular function during OC, and that these mechanisms are severely compromised during anesthesia. University of Cincinnati College of Medicine Innovation Seed Grant. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Column-based programmable damper for impact protection and vibration suppression of jacket structures

Steel jacket structures subjected to environmental impacts exhibit severe dynamic responses, potentially causing local fatigue failure, plastic damage, and even catastrophic collapse. Therefore, a structure with adjustable stiffness and large damping is ideal for coping with complex environmental loads and dissipating kinetic energy. A novel programmable damper was designed by connecting N-layer coupling elements composed of a linear spring, wire ropes, and an asymmetric column. Analytical models for the elastic buckling behavior of the damper were derived and mutually verified with finite element analysis (FEA). Based on the analytical models, the dependence of the mechanical responses of the damper on the number of elements and the spring stiffness was investigated for design guidance. The results indicate that the N-layer damper has 2N different stiffnesses, and the total dissipation capacity increases by approximately 2.6N times compared with a single asymmetric column. For potential applications, the dynamic decay responses of representative jacket structures assembled with the damper were simulated using the FE software ABAQUS combined with user-defined-material (UMAT) code, which demonstrated that the programmable damper is an advanced device that simultaneously achieves adjustable stiffness and significant damping.

Topology optimization of gradient lattice structure filling with damping material under harmonic frequency band excitation

With the rapid development of 3D printing technology, lattice structures have been widely utilized in structural designs aimed at vibration resistance due to their excellent performance. In this study, considering the moderate improvement of vibration suppression property of existing graded lattice, we introduce high-damping material into the optimization framework and further enhance the vibration resistance ability of gradient lattices. This framework extends the existing framework of stiffness and mass distribution to incorporate the distribution of stiffness, mass, and damping, which allows us to consider the damping changes with the cell configuration. Initially, the lattice cells are assigned with two different constitutive materials, one with high stiffness and the other with excellent damping properties. Different from traditional lattice units, we can obtain a series of lattice units with adjustable stiffness , mass and damping in a certain range. Via the homogenization method on the frequency domain, the complex elastic matrices about distribution of these lattice cells controlled by three parameters are obtained. In the meantime, the loss factor of these lattice cells is also obtained. A polynomial-based interpolation technique is employed to characterize the graded lattice units, which is integrated into an optimization process aimed at minimizing the lattice structures’ vibration responses. Several numerical examples are presented to illustrate this framework’s effectiveness, and experimental tests on 3D printed specimens are conducted to validate the numerical results. It’s worth noting that under the condition that the total weight of the structure remains unchanged, this weakens the overall stiffness of the structure (the reduction of first-order natural frequency), but greatly increases the damping of the structure (with a widened resonance peak) to resist the vibration of the structure. For the lattice structures induced by damping materials, the average loss factor is 0.114, which is almost doubled to the average value of those not including the damping material. When comparing the results of the mean displacement amplitude with and without damping materials, the reduction of displacement amplitude of lattice structures is above 25 %. The methodology expands the scope of optimization design for lattice structures, moving beyond stiffness maximization to include vibration mitigation by determining the appropriate distribution of stiff and damping materials, showcasing the practical applicability of the presented methods in engineering practice.

Hybrid model predictive control for vehicle trajectory tracking with integrated attitude adjustment

This paper presents a vehicle trajectory tracking method that integrates attitude adjustment. The method utilizes the asymmetric adjustment of the damping of the adjustable damping shock absorber to lift the left and right vehicle body and carry out the attitude adjustment of the vehicle. Additionally, it actively tilts toward the inside of the curve during turning. In order to address the nonlinear constraints of damping asymmetry regulation and the mixed logic relationship between suspension asymmetry damping switching and left and right body lifting during body attitude regulation, a mixed logic dynamic system (MLD) for vehicle attitude adjustment is established. Subsequently, the vehicle trajectory tracking controller is designed using the hybrid model predictive control theory (HMPC), which integrates active steering control and attitude adjustment. The optimal control problem of hybrid systems is transformed into a hybrid integer quadratic programming problem and solved through finite time domain rolling optimization. The effectiveness of the proposed integrated controller is confirmed through Simulink simulation. Compared with pure tracking control and roll tracking control with zero roll angle as the control target, this controller demonstrates its ability to effectively track the reference trajectory and enhance the vehicle’s dynamic performance.

The self-tuning fuzzy sliding mode control method for the suspension system with the LSTM network road identification

As an important component of semi-active suspension (SAS) systems, the built-in solenoid valve adjustable damper (BSVAD) is now widely used in the field because of its advantages of fast response, continuously adjustable damping, and lightweight design. However, only a few studies have discussed the BSVAD-modeling method. Hence, this study proposes a method for constructing an agent model using a feedforward neural network (FNN) for an equivalent BSVAD regulation mechanism. Meanwhile, a new control strategy, i.e., a fuzzy sliding mode control method based on road conditions (RC-FSMC), is proposed for calculating the required damping force. The proposed method identifies and analyzes unsprung mass acceleration characteristics using a long short-term memory network to obtain the road condition of the moving vehicle and inputs the output results into the designed fuzzy rules to adjust the sliding mode switching gain and finally realize road condition-based adaptive control. Finally, through simulation test analysis, the results show that the designed RC-FSMC strategy can effectively reduce vehicle body acceleration and vehicle dynamic load under different road conditions to improve the adaptability of the vehicle to different roads.

Structural design and multi-objective optimization of a novel asymmetric magnetorheological damper

The MRD with continuously adjustable damping, small compression, and large extension for asymmetric output may improve all-terrain vehicle impact resistance and vibration reduction performance in a variety of conditions. A novel conical flow channel asymmetric MRD (CFC-MRD) is proposed to solve the structure complexity stroke sacrifice, and lack of failure protection concerns in currently studied asymmetric MRD structures. In the design, the non-parallel plate magnetic circuit characteristics of CFC-MRD are investigated, including theoretical analysis and finite element modeling, and the correctness of the model is proved by testing. Considerations in multi-objective optimization include special performance imposing extra restrictions, and making the work more complicated and prone to local optima. To address this, the Nelder–Mead approach is utilized, which decreases the complexity of the optimization model while simultaneously managing performance conflicts. And a collaborative optimization strategy employing Comsol and Matlab tools is applied to improve optimization efficiency. The greatest difference between theoretical optimized values and real values is less than 6.77% in the experiments, showing the efficiency of the CFC-MRD structure design and optimization process.

Adjustable damping properties of the AlCrFe2Nix medium entropy alloys by tuning phase constituent

The effects of Ni content on the phase constituent, mechanical properties and damping capacity of the AlCrFe2Nix (x = 1.0, 1.5, 1.7, 2.1, 2.2 and 2.3) medium entropy alloys (MEAs) were studied. When x = 2.1, the microstructure of the MEA consists of BCC phase as the matrix and FCC phase as the second phase with the corresponding volume fractions of 87.7, 12.3 vol%, respectively. The combination of hard BCC matrix and soft FCC secondary phase, especially, the BCC phase is isolated by the circular FCC phase, results in a very high damping capacity up to 0.06936 for the AlCrFe2Ni2.1 MEA at the corresponding strain amplitude of 2.55 × 10−4. Both the BCC matrix and the peculiar microstructure play a key role in increasing the damping capacity of the AlCrFe2Ni2.1 MEA. Excellent damping performance and comprehensive tensile properties of AlCrFe2Ni2.1 MEA indicate that it has potential applications as the candidate of damping materials.

A new energy-feeding variable damping control strategy for electromagnetic hybrid suspension systems

Traditional energy-feeding suspensions exhibit a non-adjustable damping characteristic during energy recovery, which can compromise the dynamic performance of the suspension system. To overcome this issue, this paper proposes an energy-feeding variable damping control strategy (EFVD) predicated on an electromagnetic hybrid suspension system. This strategy aims to achieve adjustable damping during energy recovery, reducing energy losses while ensuring optimal suspension performance. Building on a half-vehicle suspension model, we construct a dynamic model of the electromagnetic hybrid suspension. By leveraging an enhanced hybrid-skyhook and ground-hook control algorithm (HSGH), we solve for the target control force. We then design a force distribution controller based on the EFVD strategy, aiming to optimize suspension dynamic performance and energy feeding efficiency. And we conduct a simulation study, measuring power supply efficiency and suspension dynamic performance as key evaluation metrics. The results demonstrate the superiority of the proposed EFVD strategy over conventional passive and active suspension control strategies, highlighting its effectiveness and reliability in maintaining dynamic performance while enhancing energy efficiency. This underscores the potential of the EFVD strategy as a practical solution for future suspension system design and energy management.

Design and verification of low-friction and high-performance monotube magnetorheological damper

The frictional force of the suspension damper is an essential factor affecting vehicle ride comfort. As an important basic component of intelligent suspension, magnetorheological (MR) damper has the advantages of simple structure and adjustable damping performance. However, the frictional force of the MR damper is excessively high, due to the high-pressure gas to avoid the cavitation effect. If the frictional force of MR damper can be reduced, the vibration isolation performance of the intelligent suspension based on the MR damper will be further improved. In this study, a monotube MR damper with low friction and high performance is proposed and investigated. Firstly, the structural design of the low-friction MR damper is carried out, and the mathematical model of its controllable damping force and uncontrollable damping force is established. Secondly, the key structural parameters of the MR piston are optimized, and the valve system is matched based on the optimized mechanical characteristics of the piston to avoid the cavitation effect. Thirdly, bench tests are carried out on the developed low-friction MR damper. The experimental results show that the frictional force of the MR damper is very low, and no cavitation effect occurs. Finally, the system performance simulation analysis is carried out on the 1/4 vehicle semi-active suspension using the MR damper, and the influence of frictional force on the performance evaluation indexes of passive and semi-active suspensions is investigated. The simulation results indicate that the influence of frictional force on semi-active suspension is higher than that of passive suspension, and reducing the frictional force of the MR damper is of great significance to improve the performance of the semi-active suspension.

Design, analysis and optimization of a hybrid fluid flow magnetorheological damper based on multiphysics coupling model

Magnetorheological (MR) dampers are widely used in industrial applications due to its simple structure, fast response and adjustable damping performance. However, the volume of the MR damper will be limited by the installation space, which hinders the application to some extent. In this paper, a hybrid fluid flow MR damper which can be used in antiseismic building is designed to achieve better damping performance under constrained volume size. The multiphysics coupling simulation model and circuit simulation model are also established. Numerical results show the output damping force is 6.367 kN, the dynamic adjustable range is 50.768, and the current input time is 31 ms under the applied current of 2.0 A. In order to improve the dynamic performance of the designed MR damper under constrained volume size, a multi-objective structural optimization method based on theoretical calculation model is proposed. Experiments are also conducted to investigate the dynamic performance of the initial and optimal MR damper. Compared with the initial MR damper, the output damping force and the dynamic adjustable range of the optimal damper are improved by 6.6 % and 46.3 %, while the energy consumption is reduced by 10.7 %, respectively.

Research on Two-Stage Semi-Active ISD Suspension Based on Improved Fuzzy Neural Network PID Control.

To better improve the ride comfort and handling stability of vehicles, a new two-stage ISD semi-active suspension structure is designed, which consists of the three elements, including an adjustable damper, spring, and inerter. Meanwhile, a new semi-active ISD suspension control strategy is proposed based on this structure. Firstly, the fuzzy neural network's initial parameters are optimized using the grey wolf optimization algorithm. Then, the fuzzy neural network with the optimal parameters is adjusted to the PID parameters. Finally, a 1/4 2-degree-of-freedom ISD semi-active suspension model is constructed in Matlab/Simulink, and the dynamics simulation is carried out for the three schemes using PID control, fuzzy neural network PID control, and improved fuzzy neural network PID control, respectively. The results show that compared with adopting PID control and fuzzy neural network PID control strategy, the vehicle body acceleration and tire dynamic loads are significantly reduced after using the grey wolf optimized fuzzy neural network PID control strategy, which shows that the control strategy proposed in this paper can significantly improve the vehicle smoothness and the stability of the handling.

An Improved Model for Hysteretic Behavior Investigation on the Twin-tube Hydraulic Adjustable Damper

The damper, as an integral constituent of the automotive suspension system, assumes a critical function in determining the suspension’s overall performance. To enhance the ride comfort and stability of automobiles, further research on the performance of dampers is particularly important. In this paper, an improved mathematical model with a twin-tube hydraulic adjustable damper (THAD) was developed to analyze the hysteretic behavior. The cavitation process of THAD was studied by studying the compressibility of oil and the structure of the valve port. Mathematical model results and published data under compression stroke and rebound stroke are compared for different working situations. The simulation results consistently illustrate the correctness of the model.

Design and validation of a dual-functional damper based on a stepper motor for energy harvesting and vibration control

Dampers are widely used to reduce undesired vibrations. In recent decades, they have been developed from the energy dissipation strategy to the energy harvesting strategy. Dual-functional dampers, which convert part of vibration energy into electrical energy, are intensively studied. DC motors are the most applied electromagnetic transducers in these studies. In this paper, two-phase stepper motors are applied as adjustable electrical dampers and energy harvesters. Dual-functional dampers using stepper motors inherently have higher damping density than those using DC motors, as stepper motors have more pole pairs than DC motors. The nonlinear theoretical electrical damping coefficient of two-phase stepper motors is derived and compared with that of DC motors. A dual two-stage Energy Harvesting Circuit (EHC) is proposed to realize the function of adjustable electrical damping through resistance emulation and the function of harvesting energy. A test bench is built to experimentally verify the adjustable electrical damping and energy harvesting performance of a selected two-phase hybrid stepper motor with the proposed dual two-stage energy harvesting circuit. The numerical solution from the identified model shows a high agreement with the experimental results. The energy harvesting efficiency in the electrical domain has reached about 85%. This tested dual-functional damper using a stepper motor has been successfully integrated into a full-scale demonstrator of the distributed-Multiple Tuned Facade Damping (d-MTFD) system.