Study on worn topography of bullet surface based on multi-fractal theory

摘要

The surface worn date of the bullets shot from three type guns were collected by applying collection instrument, and the worn topography of bullet surface was studied by application of fractal theory, its surface worn show the fractal characteristics. The fractal dimensions about the profile curve of bullet worn surface are calculated with multi-fractal method and the total dimension is obtained by the sum method. On the basis of this, the characteristic parameters are extracted from the multi fractal dimension spectrum and its sum value is obtained. The result shows that worn degree of bullet surface is not same, and its total dimensions and the sum value of the characteristic parameters also are not same, when bullets are shot with different types of gun. Therefore, the total value of the multi-fractal dimensions and the sum value of the characteristic parameters may be used as the index to describe the characteristic of bullet surface worn. This may help to analyze the change characteristics of worn surface topography of bullet, and provide reference for judgment of the gun that shoots such bullet. It provided an identification method for quantitative examination of bullet mark.