Final answer:
The structural features formed from deformation include changes in length through tension and compression, shear stress, and torsion or twisting. Within the elastic limit, materials deform elastically and return to their original shape. Beyond this limit, materials may deform plastically and not recover their initial form.
Step-by-step explanation:
The question pertains to the types of deformations and the structural features that form as a result of these deformations. Deformations can occur in different ways, such as changes in length which involve tension (stretching) and compression (squeezing), shear (sideways stress), and volume changes. Another type of deformation mentioned is torsion or twisting, which behaves similarly to shear stress.
When a material is subjected to stress within its elastic limit, it behaves elastically, meaning it will return to its original shape once the stress is removed. Beyond the elastic limit, however, a material may exhibit plastic behavior, leading to irreversible deformation. This can result in either a ductile manner, commonly seen in metals where the material becomes easier to deform as it reaches its breaking point, or brittle manner, such as breaking like glass under a hammer's blow. The term elastic modulus is used to describe the proportionality between stress and strain in these deformation scenarios.