Chapter 3 Flashcards Preview

Manufacturing > Chapter 3 > Flashcards

Flashcards in Chapter 3 Deck (25):
1

Define: Engineering Stress

F/A ; the applied force divided by the original area of the object.

2

Define: Engineering Strain

Change in L / Original L (L = length)

3

Define: Modulus of Elasticity

Or Young's Modulus; measure of the inherit stiffness of a material

4

Define: Yield Point

Change in slope at the end of a linear region on the stress-strain diagram .

5

Define: Yield Strength

Or yield stress; property of a material that indicates the stress associated with the yield point

6

Define: Ultimate Strength

Property of a material when the applied load reaches a maximum value of engineering stress; known as tensile strength or ultimate strength.

7

Define: Necking

After reaching the tensile strength, the object begins a process of localized elongation b
Which becomes concentrated in one small section of the specimen.

8

Define: Fracture Stress

The stress calculated just prior to failure (breaking)

9

Define: Ductility

Amount of strain a material can endure before failure; measured as elongation (EL) or area reduction (AR)

10

Define: Elongation

Measure of ductility; change in Length / original length

11

Define: Area Reduction

Measure of ductility; change in Area / original Area

12

Define: True Stress

Instantaneous stress found by dividing the applied load by the instantaneous value of area

13

Define: True Strain

Instantaneous strain found be dividing "instantaneous" elongation per unit length of the material

14

Define: Work Hardening

or Strain hardening; using strain to make a metal stronger.

15

Define: Flow Curve

Stress = (K) e^n ; approximation of the behavior of metals in the plastic region, including their capacity for strain hardening

16

Define: Strength Coefficient

"K" ; units of MPa; equals the value of true stress at a true strain value of 1.

17

Define: Strain Hardening Exponent

"n" = slope of the stress vs. strain graph

18

Define: Elastic Behavior

Behavior of material completely defined by its stiffness. Fractures rather than yielding to plastic flow.

19

Define: Perfectly Plastic Behavior

Once yield strength is reached, material plastically forms at constant stress level (Y=K) and n=0.

20

Define: Strain Hardening Behavior

Material obey's Hooke's law int heat after the yield strength, deformation requires ever-increasing stress so that K>Y and n>0.

21

Define: Barreling

Consequence of friction between surfaces in that middle of the specimen is permitted to increase in area much more than that at the ends. (compression test)

22

Define: Flexure Test

or Bending Test; where beam is supported by two supports and load is applied at its center. Measures bend.

23

Define: Torsion Test

Measures shear stress and strain by torquing a tube via twisting

24

Define: Hardness (Brinell, Rockwell)

Brinell - Mostly for nonmetals and metals of low to medium hardness; conducted with steel ball placing pressure on a specimen

Rockwell - More versatile and done with a cone-shaped indentor

25

Define: Viscoelasticity

Property of polymers that determines the strain a material will experience when subjected to combinations of stress and temperature over time.