What is a plastic deformation of bone?
Plastic deformation refers to the deformation of a bone, without fracture of its cortices, that persists once the deforming force has been removed. It is not a common condition but is seen more frequently in children than in adults.
What causes plastic deformation in polymers?
A ductile material shows a characteristic yield point followed by a drop in strength and break at lower stress but much higher strain. At this point, the material starts to undergo plastic deformation.
Why is it called plastic deformation?
This type of deformation involves stretching of the bonds, but the atoms do not slip past each other. When the stress is sufficient to permanently deform the metal, it is called plastic deformation.
What is plastic deformation of ulna?
Acute plastic deformation of a bone refers to traumatic bending or bowing without a detectable cortical defect. We present a case that is unusual in that bowing of the ulna occurred in a skeletally mature individual and was associated with injury to the distal radioulnar joint.
What is polymer deformation?
At a microscopic level, deformation in polymers involves stretching and rotating of molecular bonds. More commonly, one distinguishes the deformation mechanisms in polymers as brittle, ductile (with or without necking), and elastomeric.
What is mechanism of plastic deformation?
Slip is the prominent mechanism of plastic deformation in metals. It involves sliding of blocks of crystal over one other along definite crystallographic planes, called slip planes. • it is analogous to a deck of cards when it is pushed from one end. Slip occurs when shear stress applied exceeds a critical value.
What is plastic deformation material?
Plastic deformation is the permanent distortion that occurs when a material is subjected to tensile, compressive, bending, or torsion stresses that exceed its yield strength and cause it to elongate, compress, buckle, bend, or twist.
What is plastic and elastic deformation?
Elastic deformation is the deformation that disappears upon removal of the external forces causing the alteration and the stress associated with it. Plastic deformation is a permanent deformation or change in shape of a solid body without fracture under the action of a sustained force.
Is a torus fracture the same as a buckle fracture?
Torus fractures, also known as buckle fractures, are incomplete fractures of the shaft of a long bone that is characterized by bulging of the cortex. They result from trabecular compression due to an axial loading force along the long axis of the bone.
Which type of the Salter-Harris fracture is most commonly encountered and which part of the bone is involved?
Type II is the most common type of Salter-Harris fracture and refers to a bone fracture through the growth plate and part of the metaphysis.
What is a Salter 3 fracture?
Type 3. This fracture occurs when a force hits the growth plate and the rounded part of the bone, but doesn’t involve the bone shaft. The fracture may involve cartilage and enter into the joint. This type usually happens after age 10. About 10 percent of Salter-Harris fractures are type 3.
Is polymer elastic or plastic?
The green curve is a class of polymers known as elastomers. These materials exhibit rubber-like elasticity and will return to their original shape and form unless they are extended to the point of fracture. Mechanical properties of polymers: stress-strain behavior.
What are the factors affecting plastic deformation?
(c) Plastic deformation depends upon (i) applied stress, (ii) temperature and (iii) strain rate. (d) Plastic deformation involves distortion of the crystal and microstructure. (e) When stresses increase beyond yield strength, the plastic deformation starts and the metal at this point begins to soften.
Why do dislocations cause plastic deformation?
The Dislocation motion causes plastic deformation of the material. The passage of a single dislocation completely across the slip plane displaces the material above the plane by b with respect to material below the plane.