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Open access Jul 2026

Variable-Stiffness Targeted Energy Transfer for Wide Range Torsional Vibration Mitigation

Torsional vibrations represent a significant dynamic phenomenon in rotating mechanical systems and are often associated with increased dynamic loading, fatigue damage, noise generation, and reduced operational reliability. Conventional vibration mitigation techniques are generally effective only within a limited frequency range, which restricts their applicability in modern drivetrains operating under variable loading conditions. Consequently, increasing attention has been devoted to nonlinear vibration control concepts based on the principle of targeted energy transfer. This paper presents the development and experimental investigation of a novel TET system with variable torsional stiffness intended for torsional vibration mitigation in rotating mechanical systems. The proposed concept combines the vibration energy redistribution capability of a nonlinear absorber with adaptive stiffness tuning achieved through pneumatic elements. The torsional stiffness of the secondary subsystem can be continuously adjusted by regulating the pressure within air bellows, enabling adaptation of the system dynamics to varying operating conditions. A dedicated experimental test rig with kinematic excitation was developed to investigate the dynamic response of the coupled mechanical system and evaluate the influence of variable stiffness on the TET mechanism. The study focuses on the analysis of vibration energy redistribution, the identification of optimal operating conditions, and the assessment of the potential of variable-stiffness TET systems for wide range torsional vibration control in rotating machinery.

Lucia Žuľová, R. Grega, Jozef Krajňák et al. · 0 citations
Open access Aug 2026

Design and Analysis of a Load-Dependent Contact-Aided Compliant Joint

Passive stiffness modulation is essential for compliant robotic systems in dynamic and uncertain environments, where rigid actuators or constant stiffness designs are often insufficient to ensure safety and adaptability. This paper presents the design, modeling, optimization, and experimental validation of a Load-Dependent Contact-Aided Compliant Joint (LCCJ) that passively modulates stiffness in response to external torque. An integrated design pipeline is established, which bridges a high-fidelity analytical framework with a physically-motivated optimization strategy. The framework combines a chained pseudo-rigid-body model (CPRBM) with Karush-Kuhn-Tucker (KKT) conditions to describe the complex beam-boundary interactions. Using the distinct deformation regimes of the mechanism, the pipeline employs a two-stage optimization strategy to precisely map the desired stiffness modulation back to the physical geometric parameters. Simulation results demonstrate that, across the benchmark and optimized-design validation cases, the model predictions agree closely with finite element analysis (FEA), with maximum relative errors in the torque–deformation response of 4.02% and 3.18% in the pre- and post-contact regions, respectively. Experimental validation confirms the effectiveness of the proposed design; compared to the FEA predictions, the experimental results exhibit relative errors below 2.6% in the pre-contact region and 5.22%–6.21% in the post-contact region. The LCCJ offers a compact and monolithic solution for passive stiffness modulation in compliant joint applications.

Zhenjie Shi, Yanjun Liu, Yiran Wang et al. · 0 citations
Open access Jul 2026

Implementation and Numerical Validation of a Semi-Active Tuned Mass Damper for Vibration Mitigation in Lightweight Pedestrian Structures

The application of semi-active control systems in lightweight civil engineering structures is still limited even though several studies have shown an improvement in mitigating vibrations under uncertainty scenarios. In comparison with passive systems, a smart device is employed in a Semi-active Tuned Mass Damper (STMD) system to modify its response in real time, usually the damping force. Based on a control law, a degree of adaptability can be achieved in the smart device, leading to the desired tuning between the structure and the STMD to mitigate the vibration induced by the external force, especially when a detuned response between the structure and the control system is caused by external uncertainties. The magneto-rheological (MR) damper is the most common device used for this purpose. Thus, the practical implementation of an STMD in lightweight structures subjected to human-induced vibrations is presented in this paper. An STMD equipped with two sponge MR dampers is developed, modeled, and installed in a fiber-reinforced polymer footbridge, which fulfills the state requirements but exhibits excessive vibrations when its first vertical vibration mode is excited. Numerical simulations are also carried out considering human-structure-STMD interaction. For the analyses, a Mass-Spring-Damper system is used to depict a pedestrian, and the functioning of the MR dampers is represented through a hyperbolic tangent model. Additionally, three different phase control laws are considered for the numerical and experimental implementation of the STMD, namely: (i) an On-Off controller, (ii) a fixed gain controller, and (iii) a variable gain controller. The comparison of the numerical and test results shows that the model used for the MR damper and the STMD are adequate.

Christian A. Barrera-Vargas, C. Gallegos-Calderón, Iván M. Díaz · 0 citations
Open access Aug 2026

Electromechanical Coupling Modeling and LQG Active Vibration Control of CFRP Cantilever Plates Using MFCs

This study addresses the inherently low damping and vibration susceptibility of carbon fiber reinforced polymer (CFRP) laminated cantilever plates by developing a comprehensive dynamic modeling and active vibration control framework. An electromechanical coupling model incorporating macro-fiber composite (MFC) actuators and sensors is established using the first-order shear deformation theory (FSDT) and the assumed mode method, with virtual springs introduced to account for non-ideal clamped boundary conditions. A reduced-order state-space model is then derived through model reduction, and a linear quadratic Gaussian (LQG) controller is designed for optimal state estimation and feedback control. The theoretical model is systematically validated via convergence analysis, ANSYS finite element simulations, and LMS impact hammer testing. The results demonstrate that, with the relative errors of the first four natural frequencies controlled within 2%, the theoretical mode shapes are highly consistent with those obtained from ANSYS simulations. An active vibration control experimental platform is established, and the effectiveness of the control strategy is verified under dual-spectrum harmonic and impact excitations. The results show that the designed LQG controller can effectively suppress multi-modal vibrations, substantially attenuating the response amplitudes of dominant modes and significantly accelerating the transient vibration convergence. This study addresses the challenge of precisely characterizing actual non-ideal clamped boundary conditions. Through model order reduction and closed-loop LQG control experiments, it provides a comprehensive set of theoretical methodologies, numerical solution strategies, and engineering-oriented experimental schemes for the electromechanical coupling dynamic modeling and optimal vibration suppression of CFRP thin-walled composite structures.

Dong-Yang Song, Peng-Yue Na, Yulai Zhao et al. · 0 citations
Aug 2026

Design and control of a variable-stiffness maglev vibration isolation system under broadband excitation

Broadband stochastic vibrations have become a critical bottleneck limiting the measurement accuracy and operational stability of precision equipment in marine engineering and resource exploration. Conventional passive isolation and linear feedback control methods suffer from limited bandwidth and insufficient robustness under low-frequency broadband excitations. To address these challenges, a magnetically levitated vibration isolation system based on adaptive nonsingular terminal sliding mode control (ANTSM-MI) is proposed. The system adopts a symmetric contactless maglev configuration with a dual-armature structure to enhance electromagnetic force output. A nonlinear dynamic model is established, and the electromagnetic force is parameterized as an explicit nonlinear function of current and air gap. An adaptive nonsingular terminal sliding mode controller is developed to ensure finite-time convergence without requiring prior knowledge of disturbance bounds, while avoiding singularity issues. By exploiting electromagnetic nonlinear coupling, the system achieves real-time regulation of equivalent stiffness, enabling a unified realization of high static stiffness and low dynamic stiffness. Results show that the proposed method enables targeted vibration suppression in the dominant energy input band and maintains stable isolation performance over a broadband range. The transmissibility remains below −20 dB within 1–35 Hz without introducing additional resonance peaks. The proposed approach provides a robust solution for vibration isolation under complex stochastic excitations.

Bo Zhou, Changming Dai, Wenxin Yi et al. · 0 citations
Conference Aug 2026

Development and control experiments of low-impact high-frequency variable-stroke reciprocating linear actuator

Linear actuators represent an important category of contemporary electromechanical devices, which are widely use d in industrial automation, medical equipment, household appliances, and automotive fields. This paper proposes an electromagnetic-mechanical coupled linear actuator characterized by low impact, high operating frequency and high-precision displacement control. Based on the Euler-Lagrange equation, a dynamic model of the mechanical transmission component is established, and the equivalent moment of inertia and driving torque of the mechanical transmission can be calculated. The electromagnetic characteristic s of the electromagnetic drive module are obtained via finite element simulation. Moreover, a closed-loop control strategy for the proposed electromagnetic-mechanical linear actuator (EMLA) is constructed combining PID control, feedforward compensation and dynamic parameter tuning. Experimental results demonstrate that the EMLA system exhibits excellent positioning capability, low velocity at the end of motion, and stable continuous operation under various operating modes, with a positioning error of less than 0.24 mm and a velocity of less than 0.2m/s at the end of motion.

Eryong Zhang, Yong Lu, Fengshuo He et al. · 0 citations