Vetokokeella

Vetokokeella is the process of assessing a material’s mechanical properties by performing a tensile test. In this test, a specimen is gripped at both ends and pulled under controlled conditions until failure. The resulting force–displacement data are converted to a stress–strain curve, from which properties such as yield strength, ultimate tensile strength, elongation at break, and the elastic modulus can be determined. The term is used in Finnish engineering literature to describe results obtained through a tensile test.

Procedure and equipment: Tensile tests are conducted with a universal testing machine equipped with a load cell, grips, and often an extensometer. Specimens follow standardized geometries and sizes (for example dog-bone shapes for metals or flat specimens for plastics). The test is performed at a specified crosshead speed or strain rate and sometimes at controlled temperature. Force and displacement are recorded continuously, and stress is calculated by dividing force by the original cross-sectional area while strain is the change in gauge length divided by the original gauge length.

Standards and interpretation: Standards such as ISO 6892 and ASTM E8 (metals) or ASTM D638 (plastics) specify specimen shape, testing speed, and data handling. The stress–strain curve provides yield strength, tensile strength, and elongation at break; the modulus of elasticity is obtained from the elastic region. Depending on material, yield may be defined by a 0.2% offset. Results can be influenced by grip slip, specimen alignment, or rate effects.

Applications: Vetokokeella supports material development, quality control, and failure analysis, informing material selection, design safety factors, and performance predictions. The method complements other mechanical tests that assess toughness, fatigue, and impact resistance.