Topic 4 Flashcards
Define: Physical Vs. Mechanical Properties
Physical properties do not change with the application of force, mechanical properties do
List: Physical Properties
Volume, Density, Conductivity (electrical & thermal), Thermal expansion, hardness (resistance to scratching)
List: Mechanical Properties
Strength, Stiffness, Toughness (resists the propagation of cracks), elasticity, plasticity
List: Forces
Shear, tension, compression, torsion, friction, electrical, gravitational
Smart Materials
Piezoelectric, Shaped memory alloy, photochromic, thermoelectric
Define: Grains (Metals)
Grains: The crystallization of metals, longer cooling leads to bigger grains, smaller grains means it’s stronger.
Define: Reforming (Metals)
The reheating and cooling of a metal to change its crystal make up
- Annealing: resets the structure by heat then a slow cool
- Tempering: resets the structure by heating and cooling to specific temperatures
Define: Alloy
A mixture of a least one metal and another material, often done to increase strength and hardness.
Define: Hardwood Vs. Softwood
Hardwood: slow-growing with smaller cells, the trees are angiosperms.
Softwood: Fast-growing larger cells, gymnosperms
List: Factors Affecting Strength of Wood
Moisture content, duration of loading, defects, chemical treatment.
Characteristics of manmade wood
Dimensional stability, uniformity of properties, greater availability of sizes, lower cost.
Seasoning Timber
Air Drying - Using natural environment to lower the woods moisture content
Kiln Drying - Using heat to lower moisture.
List: Properties of Glass
Biocompatibility, nonporous, chemically inert.
Annealed Glass
High tensile strength & high hardness
Tempered Glass
Designed when broken to shatter safely
Laminated Glass
Glass plastic combo when broken does not shatter.
Define: Thermoplastics vs. Thermosetting plastics
Thermoplastics: Heated and recycled many times, they have weak secondary bonds
Thermosetting: Once formed can’t be reformed through heat, strong primary bonds, more brittle than thermoplastics.
List: Natural Fibers
Vegetable: Cotton, linen, jute, hemp
Animal: Wool silk
Mineral: Asbestos
List: Manmade Fibers
Nylon, polyester, spandex/lycra
Describe: Fibers to Yarn
Blending and cleaning, Carting, Coiling, Drawing, Stretching, Spooling
Describe: Yarn to Fabric
Weaving, knitting, or braiding
Composites - Types
Laminar: Two or more layers bonded with an adhesive
Fiber-reinforced: Fibers reinforce the material (ie. MDF)
Particle-reinforced: Mixture of different particles (ie. cement)
Define: Matrix vs. Reinforcement
Matrix: Base material
Reinforcement: Added to the matrix
List: Composite Manufacturing Techniques
Filament winding, weaving, molding layup (lay composite on top of adhesive), molding spray up (spray adhesive on top of composite), compression molding, pultrusion (pulling thermoplastics through a die)
