Determining fracture mode transition behavior of solid materials using miniature specimens

A process of determining the fracture mode transition behavior (FMTB) of solid material, by loading the material, comprising:

• (a) providing a miniature specimen, having a plurality of sides and ends, of material having a volume and smallest dimension sufficient to establish continuum behavior in all directions, and with a volume not more than 10.sup.7 times said sufficient volume, said specimen having a notch intermediate the ends on one side;
• (b) modifying the stress field of the specimen by providing grooves on two sides opposite to the notch at a position intersecting the notch, so as to induce stress in the specimen in a pre-selected field of orientation in the notch;
• (c) deforming the specimen by applying a load on the specimen in a direction different than the orientation of the modified stress field;
• (d) measuring at least one key variable in step c;
• and
• (e) determining the FMTB of the material from the measurements taken according to the principles of the finite element method and/or the principles of linear or nonlinear material mechanics.

A process of determining the ductile-brittle transition temperature (DBTT) of solid materials, by loading the material comprising:

• (a) providing a specimen, having a plurality of sides and ends, of the material having a volume and smallest dimension sufficient to establish continuum behavior in all directions, and with a volume not more than 10.sup.7 times said sufficient volume, said specimen having a notch and/or crack intermediate the ends on one side;
• (b) modifying the stress field of the specimen by providing grooves on the two sides opposite to the notch and or cracks to provide overlapping stress field that include transverse stress components which are approximately equal throughout the thickness of the side with the notch, resulting in a measurable DBTT;
• (c) deforming the specimen by applying a load on the specimen in a direction different than the orientation of the modified stress field;
• (d) measuring at least one key variable in step c;
• and
• (e) determining the DBTT of the material from the measurements taken according to the principles of the finite element method and/or the principles of linear or nonlinear material mechanics.

A process of determining the ductile-brittle transition temperature (DBTT) of solid material, comprising:

• (a) providing a miniature specimen, having a plurality of sides and ends, of the material having a volume and smallest dimension sufficient to establish continuum behavior in all direction, and with a volume not more than 10.sup.7 times said sufficient volume, said specimen having a notch and/or crack intermediate the ends on one side;
• (b) modifying the stress field of the specimen by providing grooves on the two sides opposite to the notch at a position intersecting the notch, and/or crack so as to induce stress in the specimen in a preselected field of orientation in the notch;
• (c) deforming the specimen by applying a load on the specimen in a direction different than the orientation of the modified stress field;
• (d) measuring at least one key variable in step c;
• and
• (e) determining the DBTT of the material from the measurements taken according to the principles of the finite element method and/or the principles of linear or nonlinear material mechanics.