Transducer and systems for high speed measurement of shock loads

Claim 1

An optical stress transducer for use in measuring high stresses applied at high loading rates with a time resolution of at least one microsecond, and having the ability to discern stress from nonhydrostatically applied loads, the transducer comprising: a transducer piece made of a luminescent crystalline material that exhibits a frequency shift in luminescent output as a function of stress, the transducer piece substantially comprising a single crystal within a detection area, said transducer piece being specifically positioned in a known orientation relative to the direction of at least one applied force; the transducer piece having first and second faces which are substantially flat and parallel and adapted to receive applied force, the faces being separated by a thickness dimension which is substantially uniform over the faces of the transducer piece; the transducer piece also having at least one minimum lateral dimension which defines a minimum width across the faces of the transducer piece; said minimum lateral dimension being sufficient so that a strain rarefaction wave which propagates inwardly from an outer edge of the transducer piece during high stress conditions, does not reach the detection area of the transducer piece within a time period sufficient for information indicating stress to be detected from said detection area; a first support piece having an inner face which is substantially flat and engages the transducer piece to apply an approximately uniform stress over the first face of the transducer piece; and a second support piece having an inner face which is substantially flat and engages the transducer piece to apply an approximately uniform stress over the second face of the transducer piece.

Claim 28

A system for use in measuring high stresses applied at high loading rates with a time resolution of at least one microsecond, and having the ability to discern stress from nonhydrostatically applied loads, the system comprising: an optical stress transducer comprising: a transducer piece made of a luminescent crystalline material that exhibits a frequency shift in luminescent output as a function of stress, the transducer piece substantially comprising a single crystal within a detection area, said transducer piece being specifically positioned in a predetermined orientation relative to the direction of at least one applied force; the transducer piece having first and second faces which are substantially flat and parallel and adapted to receive applied force, the faces being separated by a thickness dimension which is substantially uniform over the faces of the transducer piece; the transducer piece also having at least one minimum lateral dimension which defines a minimum width across the faces of the transducer piece; said minimum lateral dimension being sufficient so that a strain rarefaction wave which propagates inwardly from an outer edge of the transducer piece during high stress conditions, does not reach the detection area of the transducer piece within a time period sufficient for information indicating stress to be detected from said detection area; and a first support piece having an inner face which is substantially flat and engages the transducer piece to apply an approximately uniform stress over the first face of the transducer piece; a laser light source in optical communication with the detection area of the transducer piece to excite the detection area into a luminescent discharge; beam splitting means for separating incident laser light and luminescent discharge from the detection area; spectrometer means for spectrally dispersing the separated luminescent discharge; and high speed time resolving recording means for recording the spectrally dispersed luminescent discharge with a time resolution of at least one microsecond.

Claim 29

A system for use in measuring high stresses applied at high loading rates with a time resolution of at least one microsecond, and having the ability to discern stress from nonhydrostatically applied loads, the system comprising: an optical stress transducer comprising: a transducer piece made of a luminescent crystalline material that exhibits a frequency shift in luminescent output as a function of stress, the transducer piece substantially comprising a single crystal within a detection area, said transducer piece being specifically positioned in a predetermined orientation relative to the direction of at least one applied force; the transducer piece having first and second faces which are substantially flat and parallel and adapted to receive applied force, the faces being separated by a thickness dimension which is substantially uniform over the faces of the transducer piece; the transducer piece also having at least one minimum lateral dimension which defines a minimum width across the faces of the transducer piece; said minimum lateral dimension being sufficient so that a strain rarefaction wave which propagates inwardly from an outer edge of the transducer piece during high stress conditions, does not reach the detection area of the transducer piece within a time period sufficient for information indicating stress to be detected from said detection area; and a first support piece having an inner face which is substantially flat and engages the transducer piece to apply an approximately uniform stress over the first face of the transducer piece; a laser light source in optical communication with the detection area of the transducer piece to excite the detection area into a luminescent discharge; beam splitting means for separating incident laser light and luminescent discharge from the detection area; spectrometer means for spectrally dispersing the separated luminescent discharge; and high speed time resolving recording means for recording the spectrally dispersed luminescent discharge with a time resolution of at least one microsecond.

Claim 40

A method for measuring high stresses applied at high loading rates by at least one applied force loading, comprising: obtaining a transducer piece having opposing, substantially flat and parallel first and second faces; said transducer piece being made from a crystalline luminescent material which exhibits a frequency shift in luminescent output as a function of stress; selecting a detection portion of said transducer piece which comprises substantially a single crystal structure; said detection portion of said transducer piece being sufficiently spaced inwardly from outer edges of the transducer piece so that a strain rarefaction wave generated from said outer edges during stressed conditions does not reach the detection portion within a time period sufficient for information indicating stress to be detected from said detection portion; supporting the transducer piece between first and second support pieces having flat inner surfaces which bear on said first and second faces of the transducer piece; positioning the transducer piece in a predetermined orientation with respect to a direction of at least one applied force loading; stimulating the detection portion of the transducer piece with an appropriate optical beam so as to cause luminescent emissions to occur therefrom; stressing the transducer piece by subjecting it to stressed conditions throughout the detection portion; measuring the frequency of luminescent emissions occurring from the detection portion at least once during unstressed conditions and at least once during stressed conditions and prior to inpingement of said strain rarefaction wave upon said detection portion; and comparing differences in the luminescent emissions occurring during unstressed conditions and stressed conditions to achieve an indication of the stressed conditions existing in the transducer piece when the measuring step was performed.

Claim 41

A method for measuring high stresses applied at high loading rates by at least one applied force loading, comprising: obtaining a transducer piece having opposing, substantially flat and parallel first and second faces; said transducer piece being made from a crystalline luminescent material which exhibits a frequency shift in luminescent output as a function of stress; selecting a detection portion of said transducer piece which comprises substantially a single crystal structure; said detection portion of said transducer piece being sufficiently spaced inwardly from outer edges of the transducer piece so that a strain rarefaction wave generated from said outer edges during stressed conditions does not reach the detection portion within a time period sufficient for information indicating stress to be detected from said detection portion; supporting the transducer piece between first and second support pieces having flat inner surfaces which bear on said first and second faces of the transducer piece; positioning the transducer piece in a predetermined orientation with respect to a direction of at least one applied force loading; stimulating the detection portion of the transducer piece with an appropriate optical beam so as to cause luminescent emissions to occur therefrom; stressing the transducer piece by subjecting it to stressed conditions throughout the detection portion; measuring the frequency of luminescent emissions occurring from the detection portion at least once during unstressed conditions and at least once during stressed conditions and prior to inpingement of said strain rarefaction wave upon said detection portion; and comparing differences in the luminescent emissions occurring during unstressed conditions and stressed conditions to achieve an indication of the stressed conditions existing in the transducer piece when the measuring step was performed.