Stress, Strain, Material Properties, and CAD Basics (Video)

Vocabulary flashcards covering key terms from the video notes on stress, strain, material properties, viscoelastic behavior, and CAD concepts.

Stress (σ)

Force divided by area; units are pascals (Pa, N/m²). The formula for stress is \sigma = F/A.

Strain (ε)

Change in length divided by the original length; unitless. The formula for strain is \varepsilon = \Delta L / L_0.

Positive strain

Tensile (stretching) deformation.

Negative strain

Compressive (shortening) deformation.

Young’s Modulus (E)

Ratio of stress to strain in the elastic region; slope of the linear portion of the stress–strain curve.

Elastic region

Deformation range where stress is proportional to strain and is recoverable after unloading.

Yield strength

Stress at which permanent (plastic) deformation begins.

Ultimate strength

Maximum stress a material can withstand before fracture.

Failure strength

Stress at which the material actually breaks.

Ductile material

A material that undergoes large strains before fracture.

Brittle material

A material that fractures with little strain (low ductility).

Compressive load

A load that causes shortening of a material (negative strain).

Strain = +2 (example)

Indicates tensile (stretching) deformation.

Strain = −0.3 (example)

Indicates compressive (shortening) deformation.

Stiffest material

Material with the steepest slope on the stress–strain curve (highest Young’s modulus).

Stiffness

Resistance to deformation; related to the magnitude of Young’s modulus.

Tensile vs compressive strain signs

Positive strain = tensile; Negative strain = compressive.

Yield point

Transition from elastic to plastic deformation.

Viscoelastic

Mechanical behavior that depends on time or strain rate.

Creep

Strain increases under constant applied stress.

Relaxation

Stress decreases under constant strain.

Hysteresis

Energy loss between loading and unloading cycles.

Toe region

Non-linear, low-stress region where fibers uncrimp before stiffness increases.

Basic CAD workflow

Sketch → Dimension/Constrain → Extrude (Boss/Base or Cut).

Extruded Boss/Base

Feature that adds material by extruding a sketch.

Extruded Cut

Feature that removes material by extruding a cut.

Mates

Tools to join parts in an assembly (coincident, concentric, parallel, etc.).

Fillet

Rounded (curved) edges.

Chamfer

Beveled edges.

Drawing view requirements

Dimensions, tolerances, and multiple views (top, front, side).

Elastic deformation

Recoverable deformation that occurs below the yield point.

Plastic deformation

Permanent deformation that remains after unloading (occurs beyond yield).