Extensometer

Claim 2

An extensometer comprising a pair of spaced apart substantially coextensive arms, support means connected between said arms adjacent first ends of said arms, said support means including a first resilient strip element extending in a first direction between said arms and being rigidly coupled to said arms, and a second resilient strip element extending transverse to said first resilient strip element and being rigidly coupled to said arms, the planes of said first and second strip elements intersecting and forming a cross flexure connection between said arms to permit the arms to pivot relative to each other in the region where said planes intersect, means at second ends of said arms to Engage a specimen to be tested whereby said second ends of said arms will move when said specimen is subjected to strain to thereby subject the resilient strip elements to bending strain, means to measure the strain in said support means, cooperating overlapping members fixed to each of said arms, respectively, and removable means engaging said overlapping member to fix the position of said overlapping members to establish a preset gage length for said extensometer.

Claim 3

The combination as specified in claim 1 wherein said overlapping members comprise a lug mounted on a first of said arms, and a bracket mounted on a second of said arms, said bracket having a pair of legs and a cross bar positioned between said legs, said lug being positioned between said pair of legs and positioned to strike said cross bar when the arms are separated a preselected amount and to strike said legs to prevent substantial transverse movement of said arms relative to each other.

Claim 4

The combination as specified in claim 2 and wherein said removable means comprises a pin, and opening means defined in said lug and in said legs whereby the pin can be inserted in said opening means when the opening means in the lug and legs are aligned.

Claim 5

The combination as specified in claim 1 wherein said means on said arms to engage said specimen comprise removably mounted knife-edge blade means on each of said arms.

Claim 6

The combination as specified in claim 4 and hook means extending on opposite sides of said knife-edge blade means, an elastic band, said hook means being of size to receive and retain said elastic band when said band is positioned around said specimen to elastically urge said knife-edge blade means toward said specimen.

Claim 7

The combination as specified in claim 4 and adapter means to change the distance between said knife-edge blade means, said adapter means comprising a column, means to mount said column on one of said arms in the place of one of the knife-edge blade means, and knife-edge blade means at the outer end of said column positioned to engage said specimen.

Claim 8

The combination as specified in claim 1 wherein said first element comprises a strip of material having an opening in the center portions thereof, and said second element comprises a strip of material which extends through said opening in said first element and at substantially right angles thereto.

Claim 9

The combination as specified in claim 1 wherein first and second elements comprise strips of material and the planes of said first and second elements are at substantially 90* to each other.

Claim 10

An extensometer comprising a pair of separated arms, a first resilient strip rigidly attached at its ends to said arms and extending between said arms, a second resilient strip positioned transversely to the first resilient strip, the ends of said second resilient strip being on opposite sides of the plane of said first resilient strip, means to rigidly attach the ends of said second strip to said arms at locations spaced from the attachment of the first strip to said arms respectively, said resilient strips being positioned adjacent first ends of said arms, means to engage a specimen to be tested and to move with said specimen at second ends of said arms, said resilient strips permitting said arms to pivot as the second ends of said arms move, said resilient strips flexing to permit said movement, means to measure the strain in at least one of said resilient strips, and stop means adjacent the second ends of said arms comprising a lug mounted on a first of said arms, and a bracket mounted on a second of said arms, said bracket having a pair of legs and a cross bar positioned between said legs and spaced from the second arm, said lug being positioned between said pair of legs and positioned between the second arm and the cross bar to thereby engage said cross bar when the arms are separated a preselected amount and to engage said legs to prevent substantial transverse movement of the second ends of said arms relative to each oTher.

Claim 11

An extensometer comprising a pair of separated arms, a first resilient strip rigidly attached at its ends to said arms and extending between said arms, a second resilient strip positioned transversely to the first resilient strip, the ends of said second resilient strip being on opposite sides of the plane of said first resilient strip, means to rigidly attach the ends of said second strip to said arms at locations spaced from the attachment of the first strip to said arms respectively, said resilient strips being positioned adjacent first ends of said arms, means to engage a specimen to be tested and to move with said specimen at second ends of said arms, said resilient strips permitting said arms to pivot as the second ends of said arms move, said resilient strips flexing to permit said movement, means to measure the strain in at least one of said resilient strips, and stop means adjacent the second ends of said arms comprising a lug mounted on a first of said arms, and a bracket mounted on a second of said arms, said bracket having a pair of legs and a cross bar positioned between said legs and spaced from the second arm, said lug being positioned between said pair of legs and positioned between the second arm and the cross bar to thereby engage said cross bar when the arms are separated a preselected amount and to engage said legs to prevent substantial transverse movement of the second ends of said arms relative to each oTher.

Claim 12

The combination as specified in claim 9 wherein said first resilient strip has an opening in the center portions thereof, and said second resilient strip extending through said opening in said first element and at substantially right angles thereto.

Claim 13

The combination of claim 9 wherein said arms have coplanar end surfaces at the first ends thereof, said first strip being positioned to extend between said arms, said means to rigidly connect the ends of said first strip to said arms comprising means to clamp said strip against end surfaces of said arms, spacer blocks fixed to each of said arms and extending toward the opposite arm, said spacer blocks having coplanar end surfaces defining a plane at substantially right angles to said arm end surfaces, and wherein said means to rigidly connect the ends of said second strip to said arm comprises means to clamp the ends of said second strip against the end surfaces of said spacer blocks.