Fastener, method of attaching a fastener to a panel and fastener and panel assembly

A method of attaching a fastener element to a panel, comprising the following steps:

• forming a fastener element having a generally cylindrical shank portion, a first radial flange portion integral and coaxially aligned with said shank portion having an annular face surrounding said shank portion and a frustoconical outer surface inclined inwardly from an outer edge, and a second radial flange portion integral and coaxially aligned with said first radial flange portion having an annular face surrounding said first radial flange portion including a plurality of circumferentially spaced radial ribs each having a top face inclined inwardly from an outer surface of said second radial flange to adjacent said frustoconical outer surface of said first radial flange portion;
• forming an opening in said panel having a diameter equal to or greater than a diameter of said first radial flange portion but less than said second radial flange portion;
• inserting said shank portion and said first radial flange portion through said opening in said panel and locating said annular face of said second radial flange portion opposite a first face of said panel;
• and
• deforming said annular face of said first radial flange portion radially outwardly to overly and engage a second face of said panel, and substantially simultaneously driving said annular face of said second radial flange portion against said first face of said panel and deforming said radial ribs into said first face of said panel, deforming said panel beneath said frustoconical outer surface of said first radial flange portion and preventing rotation of said fastener element relative to said panel.