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