ISO 16842:2021 pdf download – Metallic materials — Sheet and strip — Biaxial tensile testing method using a cruciform test piece.
6.2 Measurement method of force and strain 6.2.1 General This subclause specifies the method for measuring the tensile forces (F x , F y ) and nominal strain components (e x , e y ) applied to the x and y directions of a cruciform test piece. 6.2.2 Measurement method of force For measurement of F x and F y , load cells shall be used in the x and y directions. The force-measuring system of the testing machine shall be calibrated in accordance with ISO 7500-1, class 1, or better. 6.2.3 Measurement method of strain For measurement of e x and e y , strain gauges or other methods (e.g. an optical measurement system) shall be used. Measure e x and e y to the nearest 0,000 1 or better. 6.2.4 Strain measurement positions Figure 2 shows the position(s) of a strain gauge (or strain gauges) for measuring e x and e y . e x and e y shall be measured at a position, with a distance of (0,35 ± 0,05)B from the centre of test piece, on the centreline parallel to the maximum tensile force. The strain measurement position can also be determined according to the agreement between parties involved in transaction. NOTE According to the finite element analyses of the cruciform test piece as recommended in Clause 5 and the strain measurement position as specified in Figure 2, the stress calculation error is estimated to be less than 2,0 % [2][3] .
8 Test report 8.1 Information in the report The test report shall contain at least the following information unless otherwise agreed by the parties concerned: a) identification of the test piece; b) specified material, if known; c) thickness of the original sheet sample; d) dimensions of the test piece: arm width, B; grip length, C; slit length, L; corner radius at the junctions of arms to the gauge area, R; slit width, w S ; thickness of the test piece, a (see Figure 1); e) location and direction of sampling of the test pieces, if known, and the fabrication method of the test pieces; f) strain measurement method; g) test temperature; h) testing machine; i) loading conditions (force ratio, true stress ratio, strain-rate ratio, or grip displacement ratio for the link type biaxial tensile testing mechanism shown in Figure C.2, strain-rate, etc.); j) test results: data specified according to the agreement between the parties involved in transaction (force-time diagram, strain-time diagram, contour of plastic work, stress path in stress space, strain path in strain space, etc.). 8.2 Additional note It is recommended that the record of the following items is added in the test report: a) sample mill sheet; b) photo of overall appearance of the test piece after test.