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gikiian said:Do tensile testing machines reduce the value of load in these regions? If yes, why? If no, what's happening in the graph?
The negative slope at the yield point on a tensile testing graph is due to the material undergoing plastic deformation. This means that the material has reached its maximum stress and is starting to permanently deform, causing the graph to show a decrease in stress while strain continues to increase.
The negative slope at the necking region is caused by the material undergoing significant deformation and becoming thinner at that point. This results in a decrease in cross-sectional area and an increase in strain, leading to a negative slope on the graph.
The steeper negative slope at the fracture point is due to the material rapidly losing strength and undergoing significant deformation before ultimately breaking. This results in a more drastic decrease in stress and a steeper slope on the graph.
The type of material can greatly affect the negative slope on a tensile testing graph. Materials with higher ductility, such as metals, will have a more gradual decrease in stress and a shallower negative slope, while materials with lower ductility, such as ceramics, will have a more drastic decrease in stress and a steeper negative slope.
Aside from the type of material, other factors that can influence the negative slope on a tensile testing graph include the temperature, rate of loading, and presence of impurities or defects in the material. These factors can affect the behavior of the material and alter the shape of the graph, including the negative slope regions.