Process for the shear testing of testpieces, comprising the use of a testing apparatus for testpieces having two opposite lateral faces, comprising two jaw systems between which the testpieces are compressed, each of said jaw systems comprising two jaws, each of said jaws having a bearing surface for bearing one of the respective lateral faces of the testpieces, means being placed on each of said jaw systems in order to move one of said jaws of each jaw system towards and away from the other of said jaws of the same jaw system, characterized in that one of the jaws of each jaw system also has an abutment surface for the testpieces, the testpieces being provided with two notches on the lateral faces and surrounding a median zone of the testpieces and being compressed between their end faces by the abutment surfaces.