Light filler material having damping function and composite material thereof

A filler material to be filled into a matrix, comprising:

• at least one mat consisting of fibers;
• and
• fine granular additives dispersed on and affixed to said at least one mat;
• said fibers and said additives having heat-resistance enough to withstand heating temperatures at which they are composited with said matrix, respectively, each of said additives having a density different from that of said matrix.

A structural material having a damping function, comprising:

• a matrix;
• and
• a filler material which comprises at least one mat consisting of fibers, and fine granular additives dispersed on and affixed to said at least one mat;
• said fibers and said additives having heatresistance enough to withstand heating temperatures at which they are composited with said matrix, respectively;
• said additives being mixed by a predetermined amount enough to provide said structural material with a desired vibration amplitude-frequency characteristic.