These tensile test specimens are made up of thin strips of translucent PVC plastic, which are wider at each end and pinch to a narrow, straight neck in the middle. The dimensions of the test specimens are standardised, to allow for machine compatibility and easy comparison between other materials. Tensile tests like this are destructive; the material is pulled apart until it breaks. These test specimens are, clearly, yet to be tested. These materials properties are vital for materials scientists, designers and engineers to choose the best material for a particular purpose or predict how materials will perform in use, and can be crucial for safety and performance.
The test specimens are designed to be used in a tensile test to measure how materials behave in tension. In the experiment, the wider sections of the specimen are gripped on each side by a machine, which slowly pulls the material apart lengthways. The instrument measures the force required to pull the material apart by a certain distance. With these data, a stress-strain curve may be plotted, and characteristics like the material’s ultimate tensile strength, Young’s Modulus, Poisson’s ratio and yield strength can be determined.
Plastic materials like PVC will often stretch when put under tension, making the sample longer but the cross-section narrower. Eventually, one section will become much thinner – called necking – and it’s here that the sample usually breaks. Different plastics will perform differently in these tests; polyethylene stretches many times its own length before breaking, but PVC only stretches a small amount. A brittle plastic like Perspex would show much less elongation
Sample ID: 111
Particularities
- State
- Solid
- Compound
- Donated by
- King's College London
- Selections
- Categories
- Polymer
- Curiosities
- Destructive
- Relationships
- Elastic | Poisson's ratio | Rigid | Strength | Stress-strain | Tensile | Translucent | Yield strength | Young's Modulus
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