Lesson 10: Types of Loading
Area Moment of Inertia
1) A measure of a body's resistance to bending 2) Combines the first two factors: - Cross-sectional area - Distribution of the material around the neutral axis
Types of Loading
1) Axial. 2) Bending. 3) Shear.
Load
1) Externally applied force
Factors that determine Load
1) Magnitude 2) Location 3) Direction 4) Duration 5) Frequency 6) Variability 7) Rate
Neutral Axis
1) The line along which there is neither compressive nor tensile loading on a body during loading . Ex. - Symmetrical body: Located in the geometric centroid
Polar Moment of Inertia
1) The resistance to torsional loading 2) Increases with the distance away from the neutral axis.
3- Point Bending
1) Three forces applied 2) Create two moments
Bending Loading
A load applied perpendicular to the longitudinal axis of a body causing it to curve. 1) 3-point bending 2) 4-point bending
Shear Loading
A load that causes one part of a body to move parallel past another part 1) Forces --> directed towards each other, just not along the same line 2) Parallel to the surface of a structure, opposite directions Ex. - Cutting a paper with your hands - Femur: Greater trochanter --> increase hip fracture.
Tension
A load that pulls the parts of a body apart Ex. - Bone is resistant - Tendons - Ligaments resist elongation
Compression
A load that squeezes the parts of a body together EX. Bone is resistant to compression
4-point Bending
Four forces applied.
Torsion Loading
The type of loading that exists when there is a twist around the neutral axis . Ex. Knee: - Meniscus tear due to torsion of lower leg. Depends of Polar Moment of Inertia
Effects of Bending on a body
Three factors: 1) Cross-sectional area 2) Distribution of the material around the neutral axis 3) Length of the body
Material Mechanics
- Focus on the internal effects of forces and moments. - Tissue mechanics.
Tissue Mechanics
- The mechanics of materials of human connective tissue 1) Bones. 2) Ligaments. 3) Cartilage. 4) Tendons.
Axial Load
Acts along a line, which is the longitudinal axis of a body. 1) Compression. 2) Tension.
