[Engineering Version] Daily Question 20180611

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Regarding the stress-strain relationship in a certain direction of an elastomer under load, which of the following statements is correct? ( ) A. Stress always implies strain, but strain does not necessarily imply stress ； B. Stress does not necessarily imply strain, and strain does not necessarily imply stress ； C. Stress does not necessarily imply strain, and strain does not necessarily imply stress ； D. Stress always implies strain, and strain always implies stress. Answer: B 【Explanation】The internal force per unit area is called stress. To avoid the influence of member length, the degree of deformation is expressed as the amount of deformation per unit length, which is called linear strain. The change in the right angle is called shear strain. Experiments show that there is a certain physical relationship between stress and strain; under certain conditions, stress is proportional to strain, which is Hooke’s law. This holds true only under certain conditions, namely when the stress area of the material is the same and the material is in the elastic deformation stage; it is not valid under any other conditions. Therefore, there is no inherent relationship between stress and strain.