Impact Damper Research Articles

A Study on the Effect of Structural Compliance Placing in Soft Contact/Collision Properties of Multirotor Micro Aerial Vehicles

Adding compliance (softness) has been introduced as an effective way to improve the physical collision resilience characteristics of multirotor micro aerial vehicles (MAVs). This article answers the question “Where is the best place to apply compliance in a multirotor MAV to make it more collision‐resilient?” by analyzing the output data of more than 1200 drone collision tests through two sets of accelerated and nonaccelerated collision experiments for four main configurations of micro‐quadcopters each possessing a unique softness layout of physical frame. It is shown that while applying compliance to the protective propeller guards (bumpers) of a micro‐quadcopter provides a more elastic collision, it does not improve its energy‐dissipation (impact damping) characteristics. On the other hand, enhancing the inner frame of the micro‐quadcopter with a softer structure results in higher rates of impact energy damping during the collisions and an increase in the impact time, which results in lower impact accelerations the MAV experiences during the crush. A mathematical model is developed representing the contact/collision interactions as nonlinear viscoelastic forces. Comparing the results of the simulations to the experiments suggests that this model can effectively mimic the impact behavior of contacting/colliding MAVs with different structural stiffness and damping.

Experimental investigation of particle impact dampers: Vibration reduction and noise levels with varied particle numbers

Structural vibrations present significant challenges in engineering systems, and particle impact dampers (PIDs) have emerged as a promising solution for vibration control. This paper presents a comprehensive experimental investigation on the damping performance of PIDs with varying numbers of particles. The experimental setup involves subjecting a single-degree-of-freedom (SDOF) structure to base motion excitations. Frequency response analysis is conducted to assess the dynamic behavior of the primary system using different PID designs. PIDs with one mass, two masses, three masses and multiple particles are designed and analyzed using the same mass ratio. Additionally, time domain displacement responses of the top of the structure and the base are measured to capture the system's response characteristics. The frequency response analysis reveals the influence of different particle configurations on the system's response amplitude at various frequencies. Interestingly, the results show that a PID with multiple particles exhibits reduced damping performance due to excessive particle-particle collisions. These collisions decrease the energy of the particles, leading to lower velocity before impact. This highlights that the impact itself is the primary source of damping in PIDs, and any other phenomena, such as particle-particle collisions, directly affect the relative velocity before impact. The outcomes demonstrate that an optimal design of PID can reduce vibration amplitude by approximately 85 % with single mass, two masses, and three masses configurations. Conversely, the best-case scenario of PID with multiple particles provides a vibration amplitude reduction of 75 % compared to the absence of a damper. Furthermore, noise data is recorded for all cases, as noise generation is a significant concern associated with PIDs. The results indicate noise magnitudes of 62.5 dB, 70.60 dB, 73.24 dB and 78.64 dB for PIDs with single mass, two masses, three masses, and multiple particles, respectively. Overall, the relationship between the number of particles and damping performance provides valuable insights for optimizing PID designs and ensuring comfortable operation. The findings have broad implications for diverse engineering systems, leading to improved structural performance, reduced noise, and enhanced safety. This study could serve as the basis for several potential applications of PID in structural vibration control with enhanced performance and reduced noise.

Validation of a Tapered Impact Damper for Traffic Signal Structure Vibrations Using the Method of Harmonic Balance

Validation of a Tapered Impact Damper for Traffic Signal Structure Vibrations Using the Method of Harmonic Balance

The Function of Horn Ridges for Impact Damping.

This study explores the damping effects of ram horn ridges on mechanical impacts resulting from ramming. We measured the amplitudes and frequencies of ridges along the axial (pitch) direction of the ridges of ram horns obtained from eight specimens across six different species. While the horns shared a similar spiral-shaped pattern with surface ridges, our findings show variations among the horns, including ridge spacing and growth trends. Additionally, we employed finite element analysis (FEA) to compare a ridged horn model with a non-ridged counterpart to provide an understanding of the damping characteristics of the surface ridges. Our FEA results reveal that the ridged horn decreased the initial ramming pressure by 20.7%, increased the shear stress by 66.9%, and decreased the axial strain by 27.3%, the radial strain by 16.7%, and the shear strain by 14.3% at a 50 ms impact duration compared to those of the non-ridged horn. The damping ratio was increased by 7.9% because of the ridges. This study elucidates three primary functions of the different species of ram horns' spirals and ridges: (1) to transfer longitudinal waves into shear waves, (2) to filter shear waves, and (3) to stabilize the structure by mitigating excessive strain.

A study of soft and hard impact effects in single-particle impact dampers

Single-particle impact dampers (SPIDs) are simple, yet impactful devices that mitigate vibrations in various applications such as high-rise structures, machinery, and satellites. However, the high-intensity impact forces transmitted to the host structure pose a risk to older and vulnerable structures. Therefore, this study investigates the performance of SPIDs with soft impacts, employing viscoelastic materials to minimize the impact forces and noise levels without degrading the damping performance. Four different materials (rubber, ethylene-vinyl acetate, acrylic and poly-urethane foams) exhibiting different viscoelastic properties are studied and compared with hard impact. An approximate Voigt model for the stiffness and damping coefficient of viscoelastic material is used to conduct numerical simulations and to evaluate the damping performance of SPIDs. Dynamic mechanical analyser (DMA) tests are conducted to determine the dynamic properties of viscoelastic materials. An experimental rig which includes a single-degree-of-freedom host structure, and a prototype SPID is designed and manufactured. Experiments are conducted to determine the damping performance, impact force, and noise level with soft impacts and the results are compared with hard impacts. The results reveal a 40% reduction in vibration amplitude at resonance frequency, an impressive 96% reduction in impact force at resonance, an 11.55 dB reduction in the noise level using poly-urethane foam (softest impact) compared to steel (hard impact). Although viscoelastic materials may not be suitable in harsh environmental conditions, this study demonstrates that introducing a viscoelastic material in SPID can resolve its major drawbacks such as impact forces and noise leading to a simple, cost-effective, and safe SPID.

Reliability assessment and electromagnetic controller for semi-active impact damper in structural vibration control

This study proposes a semi-active controller for impact dampers to address the challenge of achieving ideal impacts that occur exclusively when the structure reaches to its equilibrium position. The control effectiveness and reliability of the semi-active impact damper (SAID) both over time and with parameter variations are assessed and compared with passive impact dampers. Furthermore, the performance of SAID under deviations from the ideal control strategy is investigated, considering three types of non-ideal impact time and friction effects. The mathematical solution for the ideal control strategy is derived, and a strong positive correlation is found between control efficiency and SAID parameters through theoretical analysis and numerical simulation. The corresponding suggestions are provided for addressing parameter variations and deviations from ideal control strategy of SAID. Based on the investigation of extended impact conditions, a feasible SAID controller configuration with adjustable gap clearance is proposed, effectively addressing time lag issues. Experimental results validate the numerical method and practical implementation of the proposed electromagnetic controller for SAID, which can efficiently control structural responses under random low-frequency excitations such as earthquakes.

Assessing the dissipative capacity of particle impact dampers based on nonlinear bandwidth characteristics

The dissipative capacity as quantified by the nonlinear bandwidth measure of impulsively loaded linear primary resonators or primary structures (PSs) coupled to particle impact dampers (PIDs) is assessed. The considered PIDs are designed by initially placing different numbers of spherical, linearly viscoelastic granules at various 2D initial topologies and clearances. The strongly nonlinear and highly discontinuous dynamics of the PIDs are simulated via the discrete element method taking Hertzian interactions, slipping friction caused by granular rotations into account. An extended definition of nonlinear bandwidth is used to evaluate the energy dissipation capacity of the integrated PS-PID systems. To this end, the time-bandwidth (T-B) product is defined by nonlinear bandwidth in tandem with characteristic time. The T-B product is studied as a measure of the capacity of these systems to store or dissipate vibration energy. It is found that the initial topologies of the granules in the PID drastically affect the T-B product, which, depending on shock intensity, may break the classical limit of unity of linear time-invariant dissipative resonators. The optimal PS-PID systems composed of multiple granules produce large nonlinear bandwidths, indicating strong dissipative capacity of broadband input energy by the PIDs. Moreover, the granular collect-and-collide regime yields high nonlinear bandwidth and efficient energy dissipation capacity, whereas the opposite is observed for the granular gaseous state regime. The relationship between energy dissipation by the PID and nonlinear bandwidth of the PS are discussed, and it is found that as the shock intensity increases these two measures tend to vary similarly. The implications of these findings on the study of the dissipative capacity of the PS-PID system are discussed, yielding a predictive methodology for designing PIDs to act as highly effective nonlinear energy sinks capable of rapid and efficient suppression of vibration induced by shocks.

Dynamics of structures coupled to particle-chain impact dampers: A parametric numerical analysis

Particle impact dampers are dissipative devices that can easily be coupled to structures in order to reduce vibrations over a wide frequency range and in adverse environmental conditions. In this work, a multiple-sphere chain impact damper is coupled to a cantilever beam in order to attenuate its flexural motions. This simple configuration was chosen to better understand the energy dissipation phenomena by the device when the beam is subjected to random excitations. In addition, a parametric study of the coupled system is conducted in order to assert optimal working conditions of the damper. This study is mostly based on a numerical model of the vibro-impacting system, which was calibrated based on an experimental rig. Firstly, the computational modal basis of the bare beam was experimentally identified, and then theoretically modified taking into account the mass of the container. Secondly, calibration of the impact model was achieved by fitting the parameters of the contact formulation with respect to sphere-dropping experiments. Finally, extensive parametric computations are presented and discussed. The vibratory responses are computed using a frequency banded Gaussian random excitation, for several values of the excitation amplitude, for an increasing number of spheres and for several values of the damper clearance. The numerical results concern the r.m.s. motion of the spheres and the beam, the r.m.s. spheres/beam contact forces, the average mechanical and dissipated energies by the beam modes and the damper, as well as the effective beam modal parameters when fitted with the damper, which are essential results for understanding these damping devices. Finally, the numerical results are reduced into relevant dimensionless parameters, which prove reasonably effective in collapsing the dynamical data from such a highly nonlinear system. The present study thus highlights interesting essential features on the dynamics of structures coupled to multiple particle vibro-impact dampers under random excitation.

Development of an Impact Energy Absorption Structure by an Arc Shape Stroke Origami Type Hydraulic Damper

Cylindrical hydraulic dampers used to reduce impacts and vibrations typically have linear strokes. In this study, a new arc-shaped stroke-type origami hydraulic damper with a nonlinear damping performance was proposed. By examining the damping effect of the origami hydraulic damper, the damping force was found to be proportional to the square of the motion velocity. A nonlinear dynamics governing equation was established using the derived formula for the damping force of the origami hydraulic damper, and a numerical analysis using the Runge–Kutta method was established. An impact test device with an arc-shaped stroke was developed, and the error between the numerical analysis value of the impact displacement and the measured experimental value was confirmed to be sufficiently small. An impact verification experiment confirmed that the damping effect of the origami hydraulic damper increases with the input energy of the impact. By varying the diameter of the orifice hole, which is an important design factor for an origami hydraulic damper, the damping effect of the origami hydraulic damper was found to increase as the diameter of the orifice hole decreased. To examine the effect of the type of hydraulic oil inside the origami hydraulic damper, water and edible oil were used to conduct impact verification experiments, and it was found that the effect on the impact damping effect was relatively small.

Desenvolvimento de estrutura bioinspirada com capacidade de absorção de impacto: um estudo de caso

The development of new materials is crucial for the advancement of engineering, architecture, and design fields. This is because new materials can offer significant benefits compared to traditional materials in terms of their structural, physical, and chemical properties. In architecture and design, new materials can be used to create more durable, sustainable, aesthetically pleasing, lightweight, and resilient products. Through biomimicry, this study conducted an analysis on the structures of four tropical fruits - orange, passion fruit, cocoa, and pomegranate - to generate a new structure with damping and energy dissipation properties, aided by scanning electron microscopy (SEM), computerized microtomography (Micro-CT), and computerized three-dimensional reconstruction. As a result, a bioinspired structure was developed based on the arrangements of cell walls found in the albedo (mesocarp) of the orange - Citrus sinensis. Using this developed structure, computational tests were performed and a resin prototype was created through digital fabrication. Therefore, the development of bioinspired materials for improved impact absorption and damping is important as it can enhance the safety and effectiveness of a wide range of products, from sports equipment to medical devices, while also contributing to sustainability and energy efficiency, which are significant interests in various fields of knowledge.

Irreversible energy transfers in systems with particle impact dampers

Irreversible energy transfers in systems with particle impact dampers

Experimental study on rotational impact dampers

Integrating the benefits of rotational nonlinear energy sinks (NESs) and impact NESs while eliminating the negative effects of impacts, rotational impact dampers (RIDs) are proposed in this study. RIDs consist of multiple eccentric masses that rotate in the same horizontal plane about a common pivot, with impacts occurring between adjacent rotators to facilitate fast and effective energy dissipation. First, the development of the RID system is presented. Subsequently, experiments are conducted on a two-story frame structure under impulse excitation to validate the feasibility of RIDs. The impacts of the RIDs with two, three, and four rotators are identified and their control effectiveness is analyzed. The experimental results demonstrate that the RIDs can effectively attenuate the vibration of the structure, with the number of rotators being the main factor affecting the control capacity. With physical validation provided, this short communication highlights the great potential of RIDs as a viable solution for control problems involving different types of uncertainties.

Design optimization of a single-mass impact damper

This research article presents a numerical approach to establish an optimal design methodology for a single-mass impact damper (SMID), which is a passive energy dissipation device with robust performance. Due to the nonlinear characteristics of SMID and a lack of analytical models, designing a single-mass impact damper with optimal combination of the parameters has been challenging. Furthermore, an uncontrolled mass of the SMID on a vibrating structure may lead to chaotic vibration responses. This study identifies a range of design parameters of the SMID to ensure non-chaotic responses and validates the optimal design combinations using an experimental prototype. The results show that a single-mass impact damper designed with the optimal combination of design parameters can provide better vibration damping and relatively steady response. This study also compares the performance of an optimized single-mass impact damper with an optimized tuned mass damper and finds that the single-mass impact damper can work more effectively than the tuned mass damper in damping free vibrations of a single-degree-of-freedom primary structure. Although the SMID cannot suppress forced vibration amplitude as effectively as a tuned mass damper (TMD) at resonance, it has the advantages of lower cost and easier installation than the TMD. Overall, this study provides a basis for the optimal design of a single-mass impact damper and resolves the issues related to design methodology and chaotic vibration response with a single-mass impact damper.

Experimental Study on Performance of Impact Damper For Various Mass Ratios

Vibration plays a vital role in many structural elements. Excessive vibration can cause failure due to resonance and fatigue, malfunctioning of critical components, etc. Vibration can be controlled using passive, active and hybrid control systems. This paper presents the experimental studies carried out on the behaviour of impact dampers, which belong to the category of passive vibration control devices that are used to attenuate vibration of discrete and continuous systems. Impact damping is a technique for improving damping of a dynamic system by means of dissipation of energy due to collision of a free mass on the main mass.
 Experimental studies are carried out for forced vibration conditions by giving sinusoidal varying forcing function to the cantilever beam system using an exciter system and the time/frequency response function is determined. Impact mass is placed at free end of cantilever beam and the system is given constant base excitation and the damping of the system is studied by varying the frequency. Experiments are conducted for various mass ratios with different impact mass materials and the results are compared with theoretical predictions.

Finite Element Simulation of a Passive Damper System Using Contact Algorithm

Impact dampers are passive devices wherein a moving mass impacts with the primary structure. The vibrations caused due to these impacts are random in nature. During these impacts, exchange of momentum occurs resulting in dissipation of energy. Here, theoretical model of an impact damper system is modelled as MDOF system using Hertzian contact algorithm. Numerical simulation of the above problem was created using ANSYS Finite Element Analysis (FEA) package. Augmented Lagrangian method with Newmark’s time integration scheme is used for simulations. The problem being studied is highly nonlinear in nature with contacts being established during impact. Normal contact force generated due to impact of ball are used to get the transient response of the system.
 Detailed study was carried out with various mass ratio at low frequency and high amplitudes of excitation. Not much studies have been carried out earlier using MDOF systems with contact algorithm. Above modelling and simulation study was helpful to visualise and accurately capture the transient movement of the impact mass within the confined space.

Performance of tuned particle impact damper and tuned mass damper seismic control systems considering mainshock-aftershock

Generally, seismic structural design codes have been defined in accordance with a single shock or mainshock. Also, seismic control systems are usually designed and studied based on single events. considering that ground motions in seismic zones are not a single event and usually several remarkable aftershocks accompany a mainshock, the seismic behavior of controlled structures and performance of the seismic control systems are not clear under real seismic sequences. The current study investigates the seismic behavior of a 3D seismic controlled steel structure and the performance of the seismic control systems under seven real mainshock-aftershocks using non-linear implicit analysis. A tuned particle impact damper (TPID) was used that combines a passive TMD and a particle impact damper (PID) to increase efficiency and performance by working out-of-phase with the main structure and increasing energy absorption. The efficiency of the TPID and TMD seismic control systems was studied by comparing the seismic behavior of the TPID-controlled, TMD-controlled and uncontrolled structures under seismic sequences. The parameters of the frequency response, top-story maximum relative displacement, structural damage (residual displacement) and inter-story drift ratio were studied. Additionally, by considering the structural system as a closed adiabatic isolated system with ground motion energy as the only system input energy, the absorbed kinetic and potential (inelastic dissipated energy) energies in seismic control systems were calculated and compared. Results showed that both TPID and TMD seismic control systems are efficient under seismic sequences. But the TPID system is a more efficient seismic control system compared to the TMD system. Also, this case showed that because of the high performance of the TPID and TMD seismic controlled systems, unlike the moment-resisting uncontrolled structures, there is no need to consider seismic sequences in the design of TPID- and TMD-controlled structures.

Optimizing the performance of nonlinear impact damper connected to beam in forced vibrations with hybrid metaheuristic method

Optimizing the performance of nonlinear impact damper connected to beam in forced vibrations with hybrid metaheuristic method

Establishment of theoretical models for beam structures with particle impact damper

Over the past few decades, research on impact dampers has grown significantly, leading to numerous analytical and experimental investigations in that field. Vibrations can harm industrial equipment and cause process errors. Particle impact damper has a significant impact on lowering vibration and has been broadly implemented in various engineering applications. This work deals with the theoretical modeling for cantilever beam and fixed-fixed beam attached with a cylindrical enclosure filled with particles. Transient and forced excitations are considered to trace the motion of the primary mass with respect to time. Also, theoretical modeling of particle arrangement in enclosure, condition for particles to detach from base or ceiling of enclosure, motion of particle after detachment from enclosure, and mechanism of collision and friction of particles are discussed and presented in detail. Theoretical models proposed in this study can be used to generate theoretical readings for practical engineering applications.

Momentum transfer on impact damping by liquid crystalline elastomers

The effect of elastomeric damping pads, softening the collision of hard objects, is investigated comparing the reference silicone elastomer and the polydomain nematic liquid crystalline elastomer, which has a far superior internal dissipation mechanism. We specifically focus not just on the energy dissipation, but also on the momentum conservation and transfer during the collision, because the latter determines the force exerted on the target and/or the impactor—and it is the force that does the damage during the short time of an impact, while the energy might be dissipated on a much longer time scale. To better assess the momentum transfer, we compare the collision with a very heavy object and the collision with a comparable mass, when some of the impact momentum is retained in the target receding away from the collision. We also propose a method to estimate the optimal thickness of an elastomer damping pad for minimising the energy in impactor rebound. It has been found that thicker pads introduce a large elastic rebound and the optimal thickness is therefore the thinnest possible pad that does not suffer from mechanical failure. We find good agreement between our estimate of the minimal thickness of the elastomer before the puncture through occurs and the experimental observations.

The prototype, mathematical model, sensitivity analysis and preliminary control strategy for Adaptive Tuned Particle Impact Damper

The paper presents a novel approach for prototyping and modelling of the Adaptive Tuned Particle Impact Damper (ATPID). After introducing the operation and potential disadvantages of the classical Particles Impact Dampers (PIDs) the authors propose the concept of single-grain controllable damper, which can adapt to actual dynamic excitation by a real-time change of the container height. The investigations focus on the methodology of simplified mathematical modelling of the ATPID damper based on grain physical properties, nonlinear soft contact theory, and control function of the absorber height being a novel component used to optimize dynamic response of the system. The proposed ATPID model is positively verified against the experimental results obtained from the developed test stand including a vibrating beam equipped with the proposed innovative attenuator. The conducted analyses clearly reveal the operating principles of the ATPID damper, the types of grain movement, the influence of shock absorber parameters on the vibrating system response and the energy balance of the system. The solution of the formulated optimization problem aimed at minimization of vibration amplitudes allows to find the optimal damper height for various physical parameters of the grain and the external excitation and to achieve a high efficiency of the proposed damper reaching 90%. In addition, a real-time control strategy providing adaptation of the ATPID damper to changing amplitude of kinematic excitation and effective mitigation of steady-state vibrations is proposed and verified experimentally.