The correct answer is: D. Can be less than 1
The plastic section modulus is a measure of the ability of a beam to resist plastic deformation. It is calculated by dividing the area of the beam by the distance from the neutral axis to the extreme fiber. The elastic section modulus is a measure of the ability of a beam to resist elastic deformation. It is calculated by dividing the area of the beam by the second moment of inertia of the cross-section.
The ratio of the plastic section modulus to the elastic section modulus is a measure of the ductility of the material. A material with a high ductility will have a high ratio of plastic section modulus to elastic section modulus. This means that the material will be able to deform plastically before it fails.
The ratio of the plastic section modulus to the elastic section modulus can be less than 1 if the material is not ductile. This means that the material will fail before it has a chance to deform plastically.
Here are some additional details about each option:
- Option A: Is equal to 1. This is not always the case. The ratio of the plastic section modulus to the elastic section modulus can be less than 1 if the material is not ductile.
- Option B: Is always less than 1. This is not always the case. The ratio of the plastic section modulus to the elastic section modulus can be greater than 1 if the material is ductile.
- Option C: Is always greater than 1. This is not always the case. The ratio of the plastic section modulus to the elastic section modulus can be less than 1 if the material is not ductile.
- Option D: Can be less than 1. This is the correct answer. The ratio of the plastic section modulus to the elastic section modulus can be less than 1 if the material is not ductile.