Abstract: The paper analyses the stress wave propagating in a variable section bar using HONDO finite element computer program.It is shown that the present stress wave focussing means of electromagnetic riveter should be replaced by the focussing means with flight of steps,and its stress wave amplification rate is similar to that of the present focussing means. The analysis results of stress wave propagation in different size focussing means give out more reasonable geometric parameters, the bottom angle of the cone should be more than 45°, and the rate of the diameter of flight of steps to the diameter of cone should be greater than 5:2.

Key words: st ress w aves, focussing means, finite element