Effect of Ageing on Constrained Damping Structure of Viscoelastic Material

This paper studied the effects of 4 kinds of accelerated ageing methods: high-low temperature cycles, freeze-thaw cycles, saturated Ca (OH)(2) solution and salt fog on the damping properties of constrained damping structure. The damping properties such as the complex loss factor and the vibration acceleration level are studied. The micro ageing mechanism for viscoelastic damping materials was studied by means of infrared spectrum (FTIR). The results show that after being exposed to the above ageing conditions for 90 days, the complex loss factor of this constrained damping structure fell by 3.81%, 4.07%, 4.48% and 4.02% respectively, with total vibration level value increased by 1.82%, 2.33%, 3.24% and 2.87%, respectively. After 120 days, the material still remains good damping performance in ageing environment. FTIR spectra analysis revealed that the cause of the degradation is due to the break of N-H, C=O and C-H bond of the viscoelastic damping material. The change of chemical bond is small and its effect on shear energy dissipation capacity is marginal, so the damping property of constrained damping structure has just been slightly reduced. When the viscoelastic damping material was directly exposed to the above four kinds of ageing conditions for 120 days, the mechanical properties such as tensile strength, elongation at break and hardness fell sharply, showing that this material is not suitable for direct service in ageing environment.