Disbond Resistant Composite Stiffener Runout

A method of controlling bondline separation between a composite stiffener and a composite structure, the method comprising:

• providing a composite stiffener comprising a web and a base flange, wherein the web terminates at a web termination point and defines a web forward edge having a curved configuration, wherein the base flange terminates at a flange termination point forward of the web termination point, and wherein the base flange comprises rounded corners;
• trimming the web from a full height at a location prior to a web termination point to a reduced height at the web termination point;
• providing a recessed notch within the base flange at the flange termination point such that the web termination point is positioned substantially at a center of the recessed notch;
• and
• bonding a bottom surface of the base flange to a top surface of the composite structure.

A stiffener runout, comprising:

• a web configured in a substantially vertical orientation and including a front surface, a rear surface, a bottom edge, and a web termination point positioned at an outermost location of the web, wherein a height of the web decreases from a full height at a location prior to the web termination point to a reduced height at the web termination point;
• and
• a base flange, comprising
• a first flange portion adjacent to the bottom edge of the web and extending substantially horizontally from the front surface of the web, and
• a second flange portion adjacent to the bottom edge of the web and extending substantially horizontally from the rear surface of the web,
• wherein the base flange includes a flange termination point positioned at an outermost location of the base flange and forward of the web termination point;
• wherein a forward edge of the web from the location prior to the web termination point to the web termination point is substantially curved.