结构推理
What are the two methods of measuring ductility? Use formula to express the corresponding methods and indicate the meaning of each symbol in the formula. Explain how the value of ductility can be used to distinguish a ductile material from a brittle material.
【正确答案】The two methods of measuring ductility are percent elongation and percent reduction in area. /% elongation=((If-I0)×100/%)/10, where lfiS the length at fracture, lo is the original length /% reduction in area=(A0-Af)×100/%)/AO, where Af is the cross-sectional area at fracture, A0 is the original cross-sectional area. A material that has 5/% or less elongation is considered as a brittle material.