Annex G (informative) Measurement of percentage elongation after fracture based on subdivision of the original gauge length

To avoid having to reject test pieces where the position of the fracture does not comply with the conditions of 11.1, the following method may be used, by agreement:

• a) before the test, sub-divide the original gauge length ( $L_{o}$ ) into $N$ equal parts;

b) after the test, use the symbol X to denote the gauge mark on the shorter piece and the symbol Y to denote it on the longer piece, the subdivision of which is at the same distance from the fracture as mark X.

If $n$ is the number of intervals between X and Y, the elongation after fracture is determined as follows:

1. if $N-n$ is an even number [see figure G.1 a)], measure the distance between X and Y and the distance from Y to the graduation mark Z located at

$\frac{N-n}{2}$ intervals beyond Y;

calculate the percentage elongation after fracture using the equation

$A=\frac{X Y+2 Y Z-L_{o}}{L_{o}} \times 100$

2. if $N-n$ is an odd number [figure G.1 b)], measure the distance between X and Y and the distance from Y to the graduation marks $\mathrm{Z}^{\prime}$ and $\mathrm{Z}^{\prime \prime}$ located respectively at

$\frac{N-n-1}{2}$ and $\frac{N-n+1}{2}$ intervals beyond Y;

calculate the percentage elongation after fracture using the equation

$A=\frac{X Y+Y Z^{\prime}+Y Z^{\prime \prime}-L_{\mathrm{o}}}{L_{\mathrm{o}}} \times 100$

Figure description:

The image shows technical diagrams (labeled a and b illustrating methods for measuring the elongated gauge length of a tensile test specimen after fracture.

Key Entities and Dimensions:

• Test Piece: A specimen showing "necking" and fracture near one end.
• Gauge Marks: Indicated by vertical tick marks along the length of the specimen.
• Point X: The gauge mark closest to the fracture on the shorter segment.
• Point Y: A gauge mark on the longer segment at a distance $n$ from $X$.
• $N$: Total original number of gauge intervals.
• $n$: Number of intervals from $X$ to $Y$.

Measurement Calculations:

• Diagram a: Used when $(N - n$ is an even number.
  • Distance between $Y$ and $Z$ is calculated as $\frac{N - n}{2}$ intervals.
• Diagram b: Used when $(N - n$ is an odd number.
  • Distance between $Y$ and $Z'$ is $\frac{N - n - 1}{2}$ intervals.
  • Distance between $Z'$ and $Z''$ is 1 interval.

NOTE — The shape of the test piece heads is given only as a guide.

Figure G.1