In the plastic tensile test, the sample should pay attention to the following five requirements:
1, the test sample should be uniform, the width and thickness of the board, the length of 50mm (2in) longer than the fixed length. The sample's rated width should not exceed 5 (0.20in) and no more than 25.4mm (1). Width and thickness The ratio is at least 8. Narrow samples amplify the strain and cracks at the edges of the sample;
2. When cutting the sample, avoid the defects that may lead to premature fracture of the sample. Both sides of the sample should be parallel, the edge width should be less than 5% of the length between the two samples;
3, the thickness of the test sample should be kept constant, and the sample thickness should be less than 10% of the sample length between the clip, the material thickness is less than 0.25mm (0.010). When the material thickness is greater than 0.25mm (0.010in) is less than 1.00mm ( 0.040), the sample thickness should be less than 5% of the fixed sample length;
4. Suspicious materials are anisotropic materials and two sets of samples should be prepared separately. Its long axis should be parallel and perpendicular to the anisotropic direction;
5. When the plastic tensile testing machine measures the elastic elongation coefficient, the length of the sample is 250mm (10). This length is used to minimize the influence of the clamping on the test result. When the length is not feasible, the length of the test area can be reached. 100mm (inch) does not affect the test results. However, the 250mm length is still applied to arbitration. When testing a short sample, the test rate should be adjusted so that the strain rate is equal to the standard sample.