Load sensing system including RFID tagged fasteners

A fastener adapted for wireless monitoring of an applied tensile load, comprising:

• a body;
• a head at one end of the body with a face distal to the body, wherein a hole is provided in the body and the head that extends from the face of the head to an end in the body;
• an RFID transponder comprising an antenna and an RFID chip positioned on the face of the had;
• an electrical grounding pin attached to the body at the end of the hole, the grounding pin being spaced apart from the RFID transponder when at least a minimum tensile load is applied to the fastener and contacting the RFID transponder to disrupt operation of the RFID transponder when the fastener is tightened to less than the minimum tensile load;
• and
• a mounting bore of smaller diameter than the hole provided in the body at the end of the hole and wherein the grounding pin has a first end inserted into the mounting bore to attach the grounding pin to the body and a second end proximate to head that is unattached to the body, whereby the grounding pin remains substantially constant in length and the second end is positioned relative to the RFID transponder based on deformation of the body.

A system for wireless monitoring of fasteners, comprising:

• a plurality of fasteners joining components in a structural assembly, wherein the fasteners comprise:
• a body;
• a head at one end of the body with a face distal to the body, wherein a hole is provided in the body and the head that extends from the face of the head to an end in the body;
• an RFID transponder comprising an antenna positioned on the face of the head;
• and
• an electrical grounding pin attached to the body at an end of a bore hole extending through the head and into the body, the grounding pin being spaced apart from the RFID transponder when the fasteners are tightened to at least a minimum tensile load and contacting the RFID transponder to ground the antenna when the fastener is tightened to less than the minimum tensile load;
• and
• RFID readers transmitting read signals to the RFID transponders of the fasteners, wherein each of the RFID transponders is powered by one of the read signals and transmits a response signal comprising identification data when the grounding pin is in the spaced apart position and wherein the RFID readers are positioned relative to the structural assembly such that each of the RFID transponders on the fasteners can receive at least one of the read signals from the RFID readers.

A system for wireless monitoring of fasteners, comprising:

• a plurality of fasteners joining components in a structural assembly, wherein the fasteners comprise:
• a body;
• a head at one end of the body with a face distal to the body, wherein a hole is provided in the body and the head that extends from the face of the head to an end in the body;
• an RFID transponder comprising an antenna positioned on the face of the head;
• and
• an electrical grounding pin attached to the body at an end of a bore hole extending through the head and into the body, the grounding pin being spaced apart from the RFID transponder when the fasteners are tightened to at least a minimum tensile load and contacting the RFID transponder to ground the antenna when the fastener is tightened to less than the minimum tensile load;
• and
• at least one RFID reader transmitting read signals to the RFID transponders of the fasteners, wherein each of the RFID transponders is powered by one of the read signals and transmits a response signal comprising identification data when the grounding pin is in the spaced apart position;
• wherein the fasteners each further comprises a mounting bore of smaller diameter than the hole provided in the body at the end of the hole and wherein the grounding pin has a first end inserted into the mounting bore to attach the grounding pin to the body and a second end proximate to head that is unattached to the body, whereby the grounding pin remains substantially constant in length and the second end is positioned relative to the RFID transponder antenna based on deformation of the body.