Passive strain gauge

A method for determining a stress exerted upon a structure, said method comprising the steps of,

• aligning acoustic emitters along a line for emitting acoustic emissions when stressed along the line,
• encapsulating the acoustic emitters within a matrix to form the strain gauge having length along the line of the acoustic emitters, the acoustic emitters preserves a state representing peak stress induced upon the acoustic emitters, the acoustic emitters emit acoustical emissions when stressed along the line when stressed above prior stresses along the length of the strain gauge,
• mounting the strain gauge on the structure, the length of the strain gauge in mounted direction relative to the structure, the stress exerted upon the structure along the mounted direction is induced along the line of the acoustical emitters,
• removing the strain gauge from the structure,
• applying a test load in increasing amount upon the strain gauge along the line of the acoustic emitters, and
• determining when the strain gauge begins to emit acoustical emissions when applying the test load in increasing amounts along the length to indicate the stress exerted upon the structure along the mounted direction.