Engine

Tensile Strength of a Material

(Maximum Load experienced during test) / (original area)

Work Hardening

(Strain Hardening) The increase in strength in metals that occurs when they are strained

Accuracy in Measurement

Accuracy is the degree to which the measured value agrees with the true value of the quantity of interest

Complicating factor that occurs in compression test

Barreling of test specimen due to friction caused at the interfaces with the testing machine plates.

shear elasticity G to tensile E

G = 0.4 E on average

State Hooks Law

Hooke's law defines the stress-strain relationship for an elastic material. spiral thing = Ee where E is a constant of proportionality called the modulus of elasticity.

shear S to TS tensile

S = 0.7 TS

Engineering Stress

The engineering stress and strain in a tensile test are defined relative to the original area and length of the test specimen original value onto applied load F/Original

Yield Strength of a Material

The stress at which a material begins to plastically deform. usually measured at 0.2% offset value stress strain curve relationship (right at curve)

True Stress

The true stress and strain in a tensile test defined relative to the instantaneous area and length of the test specimen as it decreases through the duration of the test instantaneous value onto applied load F/Actual

Capital Good

Those purchased by firms to produce goods and services construction equipment

Unilateral Tolerance

Tolerance variation is only permitted in one direction: increasing or decreasing but not both

Bi-Lateral Tolerance

Tolerance variation is permitted in both direction (increasing, decreasing)

A tolerance

Total amount by which a specified dimension is permitted to vary tolerance is total max minus min

Newtonian Fluid

Viscosity is same at given temp water, oil

problems with hardness measurment

different hardness of surfaces very hard cant be used for very soft

Why are surfaces important

aesthetics safety friction and wear/tear effect on mechanic (sliding part) and physical (uneven) properties electrical contacts

manufacturing process with best surface finish

b. grinding

Why cannot a direct conversion be made between the ductility measures of elongation and reduction in area using the assumption of constant volume?

because of necking that occurs in the test specimen.

How does the change in cross-sectional area of a test specimen in a compression test differ from its counterpart in a tensile test specimen?

compression test - cross sectional area increases as test progresses tensile test - cross sectional area decreases as test progresses

Changes / Injuries that occur at or just below the surface of a metal

cracks craters variations in hardness at the surface intergranular attack metallurgical changes resulting from heat

Thermal Energy changes in altered layer

hardness variation, heat affected zone, recrystalization

product variety v product quantity

large variety = small quantity large quantity = small variety

batch production

make group, lots, or batches of a production part before moving onto next assembly step small or medium production might need to change machine set up for next step

manufacturing support departments

manufacturing engineering production planning and control quality control

basic categories of materials

metals ceramics polymers

2 subclasses of assembly processes

permanent joining - welding, adhesive mechanical fastening - nuts, bolts, rivets

primary, secondary, and tertiary industries

primary - exploits natural resources (agriculture, mining) secondary - takes outputs of primary industries and turns them into consumer and capital goods (electronics, textiles) tertiary - service sector (banking , education)

process layout v product layout

process layout it where different production functions are split. more unique and smaller amount of products with increased travel time product layout - reduced travel time, arranged by general production of product makes stuff go faster

viscosity

resistance to flow of a fluid material thicker more viscosity

Hardness

resistance to indentation pressing hard object into surface and measuring indentation

shaping process v surface process

shaping - changes the geometry of the material surface - only alters surface

Surface Roughness

small fine made deviations from the nominal surface (perfect) made by process that created the surface average vertical deviations from nominal surface

nominal surface

surfaces that are geometrically perfect to the specification of an engineering design drawing. perfectly everything (round, straight, etc.)

manufacturing capability

tech process capabilities physical size and weight production capactity technical and physical limitations of firm

recrystallization temperature

temperature at which metal forms new grains (recrystallization) rather than work hardens

What are the three types of static stresses to which materials are subjected?

tensile, compressive, shear

measure for strength of ceramics

three-point bending test. provides the transverse rupture strength

strength coefficient = yield coeffecient

when a material is perfectly plastic and does not strain harden