The work describes the mechanical performance of a metal rubber particles (MRP) damper design based on an auxetic (negative Poisson’s ratio) cellular configuration. The auxetic damper configuration is constituted by an anti-tetrachiral honeycomb, where the cylinders are filled with the MRP material. The MRP samples have been subjected to quasi-static loading to measure the stiffness and loss factor from the static hysteresis curve. A parametric experimental analysis has been carried out to investigate the effect of relative density and filling percentage on the static performance of the MRP, and to identify design guidelines for best use of MRP devices. An experimental assessment of the integrated auxetic-MRP damper concept has been provided through static and dynamic force response techniques.

Bolted joints play a more and more important role in the structure with lighter weight and heavier load. This paper aims to provide an overview of different experimental approaches for the dynamic behavior of structures in the presence of bolted joints, especially the energy dissipation or damping at frictional interfaces. The comprehension of energy dissipation mechanisms due to friction is provided first, while the key parameters and the measurement techniques, such as the excitation force, the preload of the bolt, or the pressure at the interfaces, are briefly introduced. Secondly, the round-robin systems aim to measure the hysteresis parameters of the frictional joints under tangential loads are reviewed, summarizing the basic theory and the strategies to apply the excitation force or acquire the response in different testing systems. Followed by parameter identification strategies for bolted structures, the test rigs with one or more simplified bolted joints are summarized to give an insight into the understanding of typical characteristics of bolted structures, which are affected by the presence of friction. More complex test rigs hosting real-like or actual engineering structures with bolted lap or flange joints are also introduced to show the identification process of the dynamic characteristics of bolted connections employed in specific applications. Based on the review paper, researchers can get the basic knowledge about the experimental systems of the bolted structures, especially several classical round robin systems, such as the Gaul resonator and widely used Brake-Reuß beam system. Readers can take advantage of this background for more creative and effective future studies, make more progress on the study of assembled structures and understand the influence of bolting frictional connections on the dynamic response better.

Aeroengines pursue high performance, and compressing blade‐casing clearance has become one of the main ways to improve turbomachinery efficiency. Rub‐impact faults occur frequently with clearance decreasing. A high‐speed rotor‐support‐casing test rig was set up, and the mechanism tests of light and heavy rub‐impact were carried out. A finite element model of the test rig was established, and the calculation results were in good agreement with the experimental results under both kinds of rub‐impact conditions. Based on the actual blade‐casing structure model, the effects of the major physical parameters including imbalance and material characteristics were investigated. During the rub‐impact, the highest stress occurs at the blade tip first and then it is transmitted to the blade root. Deformation on the impact blade tip generates easily with decreased yield strength, and stress concentration at the blade tip occurs obviously with weaker stiffness. The agreement of the computation results with the experimental data indicates the method could be used to estimate rub‐impact characteristics and is effective in design and analyses process.

As the efficiency of advanced aero engines improves, the operational speed of their rotors increases. This heightened operational speed makes the rotor dynamics highly sensitive to changes in the rotor’s mass asymmetry state, or unbalance state. During the use of a dual-spool turbofan engine, when its supercritical high-pressure rotor (HPR) exceeds a certain operational speed, the rotor’s vibration spikes and continues to increase with the operational speed until it drops sharply near the maximum operational speed. Analysis of the bolt joints in the faulty rotor reveals various phenomena such as joint interface damage, changes in bolt loosening torque distribution, and alterations in rotor initial unbalance. This paper proposes that at high operational speeds, the bolt joint of the HPR undergoes sudden angular deformation, resulting in the slanting of the principal axis of inertia of the turbine disk. This slant leads to changes in the unbalanced state of the HPR. The additional unbalance causes a sudden rotational inertia load excitation, triggering the rotor vibration failure. Subsequently, a rotor dynamic model that incorporates the angular deformation of the joints is established to simulate how this joint deformation influences the dynamic response of the rotor. The simulation results align well with the observed failure phenomenon and validate the proposed failure mechanism. Finally, troubleshooting measures are proposed and implemented in the faulty engine, effectively mitigating the vibration fault.

A novel soft magnetic entangled metallic wire material (SM-EMWM) is investigated in this article, which is manufactured using the magnetoelectric-sensitive soft magnetic wires. The mechanical properties (tangent modulus, loss factor) of SM-EMWM can be tunable in the magnetic field rapidly and reversibly, and thus can be applied to vibration control systems. The quasi-static and dynamic tests in different magnetic fields were carried out, and the results show that the tangent modulus of SM-EMWM samples in a magnetic field of 500 mT can increase 2–7 times on average compared with no magnetic field condition, while the loss factor can be improved above 50%. Therefore, with the enhancement of the intensity of the magnetic field, the resonant frequency of the system with SM-EMWM increases, the peak value of response curves decreases dramatically as well. Based on the results of dynamic tests, one suitable adaptive vibration control strategy was developed and used in the tests to avoid the resonant frequency of the system, by controlling the magnetic field condition appropriately. The results show that the peak vibration transmissibility of the controlled SM-EMWM system decreases over 50%, which reveals the excellent application prospect of the SM-EMWM for the active or semi-active control vibration control in mechanical structures.