#4 - Material, Structural and Tissue Mechanics

What is the formula for calculating stress (σ)?

Stress (σ) = Force / Area

How is stress (σ) measured?

Measured in Pascals (Pa) or MegaPascals (MPa); 1 Pa = 1 N/m².

What does a stress riser refer to?

A discontinuity that leads to uneven distribution of stresses, increasing the chance of tissue failure.

What are the primary material properties in the study of biological tissues?

Mass, density, stiffness, and strength.

What are the two categories of properties studied in biological materials?

Material properties and structural properties.

What is the measure of deformation known as?

Strain (ε).

What does 'toughness' refer to in the context of stress-strain curves?

Toughness is the total failure energy, which is the area under the stress-strain curve.

What does isotropic mean in terms of material properties?

Loading characteristics/properties of a material are the same in all directions.

What does anisotropic mean with respect to biological tissues?

Loading characteristics/properties are directionally dependent.

What is the consequence of having reduced strain-to-failure in tendons?

Decreased stiffness and a smaller region of plastic deformation, making them more brittle.

How does plastic deformation affect clinical outcomes?

It may lead to decreased stiffness and increased risk of tissue failure.

What is the meaning of viscoelasticity in biological tissues?

Biological tissues exhibit both viscous (fluid-like) and elastic (solid-like) behavior.

What happens to tissue mechanics when loading rates are increased?

Internal tissue stresses increase due to alterations in viscosity.

What is Reynolds number related to in fluid mechanics?

It describes the flow regimes in fluid dynamics, determining whether the flow is laminar or turbulent.

What clinical implications arise from altered interstitial fluid viscosity?

Changes in viscosity due to factors like inflammation or age can significantly impact tissue health and function.

What is the expected effect of aging on biological tissues?

Increased glycation and altered macromolecular structure leading to altered tissue mechanics.