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Like I said, it is the work done by the sample. The force exerted by the sample on its surroundings is directed toward the sample, and the displacement at the boundary where the work is being done is directed toward the sample. So the work done by the sample is positive. The work done on the sample is negative.KevMilan said:What about the area under the loading curve? Is it the workdone on the sample or by the sample?
Yes. The force we apply and the displacement are in the same direction.KevMilan said:For the area under the loading curve, shouldn't it be the workdone ON the sample?
Because we are the one putting force/stress on it? Could you clarify? Thankyou.
Work done ON the sample, but that area is the sum of the shaded area and the "white" sliver.KevMilan said:What about the area under the loading curve? Is it the workdone on the sample or by the sample?
KevMilan said:One more thing, why is it the workdone BY the sample (not ON)? (Is it because we're not putting any force/tension on the sample when unloading?) Any simple explanation would be very helpful!
We are applying a force on the sample during unloading. But that force is opposite to the displacement so we are doing negative work. If you interpret the dark area as negative, then it represents the work done ON the sample during unloading.KevMilan said:One more thing, why is it the workdone BY the sample (not ON)? (Is it because we're not putting any force/tension on the sample when unloading?)
'On' or 'By' is not necessarily obvious and it's actually a bit anthropomorphic, imo.KevMilan said:One more thing, why is it the workdone BY the sample (not ON)?
Strain energy is the potential energy stored in a material when it is deformed or stretched. It is the work done on the material to cause the deformation and is usually measured in joules (J).
When a sample is loaded, strain energy is stored in the material as it is deformed. When the load is removed and the sample is unloaded, the stored strain energy is released. The amount of strain energy stored and released depends on the material's properties and the amount of deformation.
There may be confusion because strain energy is often not directly measured but is instead calculated using other parameters such as stress and strain. Additionally, the amount of strain energy stored and released can vary depending on the testing conditions and the material's behavior.
Strain energy is an important factor in understanding a material's behavior under loading and unloading. It can affect the material's strength, stiffness, and ability to withstand repeated loading cycles. Materials with higher strain energy may be more prone to failure or fatigue, while materials with lower strain energy may be more resilient.
Understanding strain energy is crucial in designing and testing materials for various applications. It can help engineers determine the maximum load a material can withstand without failure, predict the material's behavior under different loading conditions, and optimize the material's properties for specific uses. Strain energy is also important in fields such as biomechanics, where it is used to study the behavior of biological tissues and structures.