This paper treats the dynamic response and energy absorption of aluminum foamfilled
conical tubes under axial impact loading using non-linear finite element
techniques. The influence of geometrical, material and loading parameters on the impact
response is investigated using validated numerical models. Results are quantified in
terms of important impact response parameters and indicate that the foam filler
stabilizes the crushing process and thus improves the energy absorption capacity. The
superior performance of foam-filled conical tubes as impact energy absorbers is evident
from the results. The research information generated will be useful in developing
guidance towards the design of these devices in impact applications.

Dynamic computer simulation and energy absorption offoam-filled conical tubes under axial impact loading

Vibration present on various levels in many engineering fields and hence vibration mitigation has become a subject of intense study. The nonlinear vibration isolation devices are effective for broad frequency bandwidth and can provide better vibration isolation than linear devices. The need for nonlinearity in stiffness and damping characteristics has motivated researchers to apply the nonlinearity found in mechanisms or materials in the passive vibration control devices. This review discusses the applications of nonlinearity in the passive vibration control devices to provide an understanding of how the nonlinearity is applied and useful in the implemented system. Further, applications for nonlinearity can also be extended in the energy harvesting devices, Nonlinear energy sink, metamaterials for the purpose of vibration isolation and energy harvesting. The need for nonlinearity also encouraged research work through inspiration from the nature called bio-inspired devices. The bio-inspired devices mimic the nonlinearity of the biological system to suppress the vibrations. The nonlinear passive isolation is effective for wide frequency bandwidth than the linear isolation system. Further, the nonlinear systems also reduce transmissibility much efficiently than the linear system. The nonlinear energy harvesting system shows a great scope to harvest energy from wide ranges of excitations. The bio-inspired devices also are proven to be effective in vibration isolation. Additionally the design of the metamaterial with nonlinearity in the microstructure, proves to be promising in the vibration suppression applications. Based on the review, the nonlinearity introduced into the systems has greater benefits than the linear systems.

Applications of Nonlinearity in Passive Vibration Control: A Review

The rail–wheel interaction in a rail vehicle running at high speed results in large amplitude vibration of carbody that deteriorates the ride comfort of travellers. The role of suspension system is crucial to provide an acceptable level of ride performance. In this context, an existing rail vehicle is modelled in vertical, pitch and roll motions of carbody and bogies. Additionally, nonlinear stiffness and damping parameters of passive suspension system are defined based on experimental data. In the secondary vertical suspension system, a magneto-rheological (MR) damper is included to improve the ride quality and comfort. The parameters of MR damper depend on the current, amplitude and frequency of excitations. At different running speeds, three semi-active suspension strategies with MR damper are analysed for periodic track irregularity and the resulting performance indices are juxtaposed with the nonlinear passive suspension system. The disturbance rejection and force tracking damper controller algorithms are applied to control the desired force of MR damper. This study reveals that the vertical vibrations of a vehicle can be reduced significantly by using the proposed semi-active suspension strategies. Moreover, it naturally results in improved ride quality and passenger's comfort in comparison to the existing passive system.

https://iopscience.iop.org/article/10.1088/1361-665X/aa68f7/pdf

Ride performance of a high speed rail vehicle using controlled semi active suspension system

Cysts in the oral regions

In a railway vehicle, vibrations are generated due to the interaction between wheel and track. To evaluate the effect of vibrations on the ride quality and comfort of a passenger vehicle, the Sperl...

Ride comfort of a higher speed rail vehicle using a magnetorheological suspension system

In this article, an existing railway vehicle is modelled as a full-scale nine-degree-of-freedom system considering lateral, yaw and roll motions of the car body and the front and rear bogies. Moreo...

Disturbance rejection and force-tracking controller of nonlinear lateral vibrations in passenger rail vehicle using magnetorheological fluid damper:

This paper aims to fabricate star polygon thin walled energy absorption structure that tends to relapse the intensity of set in decelerations during impact while escalating the amount of energy absorbed. The crashworthiness topology optimization is used for structural optimization of various foam-filled tubes. The relative advantages of 14 configurations are discussed, and the effects of filling five types of foam into the best configuration of the star-shaped tube over an empty one is investigated. Specific Energy Absorption, Peak Crush Force and response of weight of the members during frontal impact are the main dimensions parameters of the member's performance. Numerical simulation is carried out using the explicit dynamics of Ansys 17.1, and obtained results are compared with experimental results conferring crash behavior and energy absorption characteristics. Based on results, the suited configuration with required performance in crashworthiness is suggested, which shall be incorporated in automobiles for safety consideration of passengers during an impact. The results show an increment of 40% in Specific Energy Absorption suggesting a better choice of a particular type of foam over a hollow tube.

Crashworthiness analysis of foam filled star shape polygon of thin-walled structure

In this paper, Bouc–Wen type magnetorheological fluid damper has been used to monitor the ride quality of a prevailing rail vehicle in lateral vibrations. Modelling of the rail vehicle is done in such a manner that it has an entire 9 degrees of freedom by significant considerations of lateral, roll and yaw motions of the car body, rear, and the front chassis. 200 km/h is considered as train speed for tracks with two varying disturbances. A system consisting of multibody in VI-rail software is provided by a track input and ergo, wheel response it obtained. SIMULINK (software) is responsible for the representation of the motions of the wheel as mathematical models. Two different types of analysis are done firstly with conventional passive lateral damper and secondly with semi-active MR lateral damper in subordinate suspension. To diminish lateral vibrations, the disturbance refusal and non-stop state controller algorithms were executed to manage the damper force. Results acquired are in the form of acceleration and displacement of the center of mass of the body under consideration is done by comparing in terms of reduction indices of their vibrations. A significant improvement in the index is seen in which a semi-active lateral damper is mounted. The results show that the proposed system significantly improves both, the vibration attenuation ability and the ride quality of the vehicle.

Sunil Kumar Sharma

Papers

Ride performance of a high speed rail vehicle using controlled semi active suspension system

Ride comfort of a higher speed rail vehicle using a magnetorheological suspension system

Disturbance rejection and force-tracking controller of nonlinear lateral vibrations in passenger rail vehicle using magnetorheological fluid damper:

Crashworthiness analysis of foam filled star shape polygon of thin-walled structure

Semi-active Control to Reduce Lateral Vibration of Passenger Rail Vehicle Using Disturbance Rejection and Continuous State Damper Controllers