Report a QuestionPlease email hello@efficientengineer.com. Question 38 Material Properties | Stress-strain curves | difficulty level 2A circular steel bar with a length of 200 mm and a radius of 2 cm is strained in a tensile test to point B on the stress-strain curve shown below, and is then unloaded. What is the permanent change in the length of the bar compared to its original length? The bar has increased in length by 5 mm No change in length The bar has decreased in length by 5 mm The bar has increased in length by 2 mm Report this questionExplanationWhen a material is loaded beyond the elastic limit, there will be some permanent plastic deformation after the load has been removed. After the load is removed there will be the recovery of the elastic strain, so the material will unload along a curve which has a slope equal to Young's modulus, as shown in the image below. The permanent plastic strain after unloading is 1.0% in this case, which means that the 200 mm long bar has permanently increased in length by 2 mm.Your Results Restart with New Questions Change Quiz Settings Review the Questions
