In Callister it says, "two modes of failure are possible ductile and brittle." Why not malleable?Furthermore why is uniaxial tensile test chosen for predicting failure?
Ductile ("able to be drawn out into a thin wire") makes sense as the failure method, because the test is stretching the sample. Malleable ("able to be hammered or pressed into shape without breaking or cracking") doesn't make sense here, since the sample is not under compression! You could describe a three-point bend failure as Malleable, however. When @blacksmith37 states that "Malleable is the same as ductile", this is what he's referring to. They are somewhat analogous, where "Ductile" is in tension, and "Malleable" in compression. It's important to note, however, that they are not the same physical property. For example, Zinc and Lead both exhibit much higher malleability than they do ductility.
Malleable is the same as ductile. The uniaxial tensile test provides a uniform method to measure the mechanical properties of materials. It only predicts failure of uniaxial test bars. There are a variety of techniques / methods to predict failures or structures ; Such as L E F M , linear elastic fracture mechanics.
Ductile: The capacity of materials to allow large deformations or large extension without failure is termed as ductility. The materials with high ductility are termed as ductile materials. Normally if the elongation exceeds 15% the material is ductile. Brittle: A brittle material is one which exhibit a relatively small extensions or deformations to fracture and failure occur suddenly without any warning. If the elongation is less than 5% the material is considered to be brittle. Malleable:It is a special case of ductility where it can be rolled into thin sheets but it is not necessary to be so strong.