Ning Tang is a PhD student in the Department of Mechanical Engineering at the University of Sheffield. His first degree was in Mechanical Engineering in Shanghai Jiaotong Univerisity, China. After that, he was awarded the MSc degree in the University of Sheffield. His research concerned the modelling and control of structural vibration using adjustable Tuned Mass Damper. His other research interest is the modelling and characterisation of damping materials with nonlinear stiffness and amplitude-dependent damping.
Research interests:
- Adjustable Tuned Mass Damper
- Testing and modeling of viscoelastic damping materials
- Friction-based systems including particle damper, tangled metal wire material, low wave speed medium and wave springs
- Design damped components including elastomeric O-rings
Current research:
My research is about addressing on vibration control for rigid structures. The classic solutions, such as coatings and constrained-layer damper, are incorporating high damping materials to vibrating structure. This damping scheme is not always feasible for ‘rigid’ structure. Generally, a ‘rigid’ structure is likely to oscillate in a translation direction, whilst most traditional dampers implemented in mechanical structures deal with flexural oscillation including bending, torsion. Also, these damping schemes only valid for applications around room temperature.
One approach for suppressing this undesirable vibration is to develop an adjustable Tuned Mass Damper (TMD) comprising a proof mass, elastomeric O-rings and adjusting screw. The O-rings considered in this work displayed viscoelasticity and nonlinear behaviour, both in stiffness and damping. This allowed the damper to be adjustable. In order to design and optimise the damper, analytical and finite element models were developed. Subsequently, the effectiveness was demonstrated through physical experiments. It was shown that this TMD could suppress selected vibration modes.
The other option is porous metallic material. One good example is a tangled metal wire damper. Tangled metal wire (TMW) dampers are constructed from coiled metal wire through a weaving/knitting and compression process. Under cyclic loading, it provides energy dissipation from friction within the microstructure and is interesting as its performance is not sensitive to temperature. It was shown that small particles of this material that have not been subjected to the final compression process can still provide useful levels of damping to form a TMW based damper.
A wave spring can be used as an alternative for these damping elements as it reduces the complexity and difficulties in modeling of these materials. The wave spring is a circular, metal compression spring, whose coils are constructed from a fixed-width metal strip that is formed into a sinusoidal wave. The stiffness and damping of wave springs are deflection dependent due to the introduction of contacts and sliding between different layers of metal. The energy dissipation of a wave spring is considerably higher than that of a classic coil spring. The nonlinearity and damping present in wave springs give them the potential to increase the effective frequency range of a TMD when used as a combined stiffness and damping element while their metallic construction offers an increased operational temperature range.
Tangled wire metal (TWM) particles
Energy dissipation from TWM particles
Stiffness and energy dissipation for wave springs subject to different compressions.
Publications:
- Tang, N., Rongong, J., Lord, C., & Sims, N. (2016). Experimental investigation and modeling of dynamic performance of wave springs. In Proceedings of 11th International Conference on Advances in Experimental Mechanics.
- Lord, C., Tang, N., & Rongong, J. (2016). Damping of metallic wool with embedded rigid body motion amplifiers. In Proceedings of 6th European Conference on Structural Control.
- Tang, N., Sims, N., & Rongong, J. (2016). Modelling of an adjustable TMD incorporating an elastomeric O-ring. In Proceedings of 17th International Conference on Experimental Mechanics.
- Tang, N., Rongong, J. A., & Tomlinson, G. R. (2015). Nonlinear behaviour of tangled metal wire particle dampers. In International Conference on Structural Engineering Dynamics. Lagos, Portugal.