Internal Biomechanics: Tissue and Muscle Mechanics Flashcards

Vocabulary-style flashcards covering internal biomechanics topics including forces, loading types, stress-strain relationships, and connective tissue properties based on lecture notes.

Stress ($\sigma$)

The intensity of the distributed internal force ($F$) over an internal area ($A$), calculated as $\sigma = \frac{F}{A}$ in units of $N/m^2$.

Strain ($\epsilon$)

The measurement of deformation relative to the original length, calculated as $\epsilon = \frac{l_f - l_i}{l_i}$, often expressed as a percentage.

Sagittal Plane

A vertical plane that divides the body into right and left parts.

Frontal Plane

Also known as the coronal plane, it divides the body into anterior and posterior parts.

Transverse Plane

Also known as the horizontal plane, it divides the body into superior and inferior parts.

Tensile Loading

A loading force applied along the longitudinal axis that pulls or stretches the body apart, resulting in tensile stress.

Compressive Loading

A loading force that pushes into the tissue and tries to squish it toward the center along the longitudinal axis.

Shear Loading

A loading applied parallel to the analysis plane where material sliding occurs as forces act parallel but in opposite directions.

Torsion

A loading produced by torque applied on the longitudinal axis at each end, resulting in a twisting form of shear stress.

Bending

A complex loading that results in tensile stress on one side of the analysis plane and compressive stress on the other side.

Young's Modulus

The slope of the linear region in a stress-strain relationship ($\text{Young's Modulus} = \frac{\Delta \sigma}{\Delta \epsilon}$), representing the stiffness of the material.

Elastic Behavior

A material property where the tissue deforms under loading but returns to its original shape and length when the stress is removed.

Yield Point

The landmark on a stress-strain curve that signifies the end of the linear/elastic region and the beginning of permanent plastic deformation.

Plastic Behavior

Occurs when stress is removed after the yield point, and the material returns to a new, permanently elongated length rather than its original shape.

Ultimate Strength

The maximum amount of stress a material is capable of withstanding.

Failure Strength

The level of stress at which the material experiences a total rupture or complete break.

Toughness

The ability of a material to absorb mechanical energy before breaking, calculated as the total area under the stress-strain curve.

Creep

A viscoelastic property where a constant compressive stress results in increasing strain over time as water is squeezed out of the tissue.

Stress Relaxation

A viscoelastic property where a constant compressive strain results in an initial increase in stress followed by a decrease/relaxation to a lower value.

Hysteresis

The phenomenon where the loading and unloading paths on a stress-strain curve are different, representing energy lost typically as heat.

Isotropic

Materials that exhibit the same mechanical properties regardless of the direction of the applied load.

Anisotropic

Biological tissues that exhibit different mechanical properties depending on the direction of loading.

Cortical Bone

Also called 'compact' bone, it is stiff and can withstand high stress but fails at a relatively low strain of about $2\%$.

Cancellous Bone

Also called 'spongy' bone, it is less stiff than cortical bone but can handle more deformation before breaking.

Toe Region

The initial part of the stress-strain curve for tendons and ligaments where the tissue is easily stretched as collagen fibers align.