By use of a non-contact laser vibrometer

experiments were made on an L-shaped beam with a cavity attached to the free end

so as to investigate the damping properties of particle damping for a two-dimensional vibrating structure under different cavity sizes.The experimental results show that: (1)the nonlinear particle damping

which is at least one order of magnitude higher than the intrinsic material damping of metals

can significantly suppress the vibration of structures. (2)The features of two-dimensional particle damping are almost the same in each direction;with the increasing of dimensionless acceleration amplitude

particle damping firstly increases and then decreases

meaning that there is a critical dimensionless acceleration amplitude causing the highest damping. (3)Particle damping as well as the critical dimensionless acceleration amplitude corresponding to the damping peak increases with the cavity sizes.The experimental results could provide a reliable basis for numerical simulation of particle damping in two-dimensions.