By providing a tube of deformable material which can be located within a hollow cavity of a blade it is possible to provide an element which through friction engagement can absorb vibration energy and therefore damp vibration in a hollow blade. The tube incorporates a number of cuts and/or grooves in an appropriate pattern in order to define a deformation profile once the tube is expanded in location. The tube is secured in position internally upon an expandable element which is typically an inflatable device. Once in position the tube is retained in its expanded deformable profile and the engagement between the tube and the hollow cavity wall surface results in energy absorption through vibration episodes. It is possible to provide a tube formed from a shape memory alloy which will expand in location to engage the hollow cavity wall surfaces for energy absorption during vibration episodes.