Materials Science & Technology Flashcards

The Shore A hardness scale is used to measure the hardness of which category of materials relevant to O&P?

Answer: Soft elastomers and gel liners

Shore A measures the hardness of soft rubbers, silicones, and gel materials, making it the standard for evaluating prosthetic liners and cushioning pads.

Lamination resin systems in O&P typically consist of which two components mixed before application?

Answer: Base resin and catalyst (hardener)

Lamination resins are two-part systems where the base resin crosslinks when mixed with a catalyst or hardener to form a rigid composite structure.

Silicone liner suspension for transtibial prostheses primarily functions through which mechanism?

Answer: Locking pin or shuttle lock engaging a distal receptacle

The most common silicone liner suspension uses a distal locking pin that clicks into a receiver in the socket, providing secure suspension.

Which fiber orientation in a carbon fiber layup provides the greatest resistance to bending in a single direction?

Answer: Unidirectional (0°) fibers aligned with the bending axis

Unidirectional fibers aligned with the primary load axis provide maximum stiffness and strength in that direction by fully utilizing fiber tensile modulus.

Creep in thermoplastic orthotic materials refers to:

Answer: Slow permanent deformation under sustained load over time

Creep is the time-dependent, progressive deformation of a material under constant stress, which can cause orthotics to lose their molded shape over months of use.

What is the primary purpose of a check socket in prosthetic fitting?

Answer: To evaluate fit, alignment, and function before fabricating the definitive socket

A check socket (diagnostic socket) made of clear thermoplastic allows visual inspection of pressure points and confirms fit before the definitive socket is fabricated.