The tensile strength can be used to characterise structural elements (brackets, ropes) subject to tensile stress. When designing them, we need to know the load they can withstand and the force that will cause them to break. In addition to force, the cross-section must also be taken into account.
Tensile strength (e-learning with AR)
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| Tearing apart |
|---|---|
During the measurement, the test piece made of the tested material must actually be torn. The test piece is stretched more and more while measuring how the pulling force changes. The tensile strength (Rm) is the ratio of the maximum force (f) measured and the starting cross-section (A0). Its unit is N/mm2, i. e. MPa. | |
Principle of measurement
| The Machine | ||
| A machine capable of applying very high forces and measuring force and displacement is required. The splitting machine can move the crossheads on two columns by hydraulic, mechanical, or electromechanical means. On the crossheads is the gripping device to which the test piece is to be fixed. The loading speed must be set to a specified value depending on the material. |
The machine has already done its job
| The Test Body | ||
| The tensile test is carried out on a workpiece of known cross-section and length. The test piece is usually circular or rectangular in cross-section, with two ends either plain or threaded, depending on the type of grip. The middle test section is smaller in crosssection and is used to test for elongation and tensile strength. When gripping, it is necessary to ensure uniaxiality, so that the machine loads the specimen only with tensile stress, as twisting and bending would modify the final result. |
| The Result | ||
| During the measurement, a computer checks the stretching force as a function of elongation. The resulting curve is the tensile diagram. From its initial linear section, the modulus of elasticity of the material can be calculated: in this range, the specimen would recover its original length without the load. The upper and lower yield strengths can then be read and the tensile points calculated. |
