This mechanical testing is demonstrated the relationship between stain and stress for a certain material while it undergoes a tension force. And define the type of factual of them, which are two metallic, copper and low carbon steel and two polymeric, acrylic and acetone.
Background Stress-strain curves show the response of material to an applied stress. It’s depend on the strain rate, temperature, and environmental conditions. They allow important information such as a material’s elastic modulus and yield stress to be determined.Elastic deformation in polymers takes place by stretching and chain aligning. And elongation of amorphous tie chains so the stress- strain behavior is brittle. For metal is plastic. Engineering stress and strain (also sometimes called nominal stress and strain) are calculated based on the original dimensions of the material in question.
True stress and strain are calculated based on the actual dimensions of the material. Method Install the given copper cylinder into the Winnfield HECK-W testing machines after measured the length and the diameter of it by using a Fernier caliper ND a ruler.Then set the X and Y vector of machine to the zero and operate the machine.
Make sure the connection between copper and the force measurement is fixed and tight before operate it. There are two value displaced on the displayer, one is the current force load and one is the maximum load. It should take a while for the elongation until it broke. Another thing is we need to measure is the elongation at fracture and the reduction in area at fracture.But for the polymeric, since they have different shape to metallic, they are clamped y a big metal clamp not just install it into the machine which mean install the metal clamp to two end of the connector and clamp the sample up. And because of the cross-section area is rectangle, we need to measure depth and width instead of the diameter. The computer will record the data for every elongation and force load.
From the breaking surface of the sample we can define the type of fracture by ease.