Fatigue and Stress | Strains and Stresses

Question 1

The largest changes take place in the __ axis

Answer 1

vertical

Question 2

Accelerations can be measured with ___

Answer 2

accelerometers

Question 3

An accelerometer can measure ___

Answer 3

Gravity, accleration

Question 4

A basic accelerometer might consist of ___

Answer 4

• Mass attached to strings

- Restrained by a motor (torquer)

Question 5

An accelerometer involving E and I bars works on the principle that ___

Answer 5

The alternating current produces a magnetic field that is disturbed when the coils move relative to the armature, the changing field produces a signal in the outer coils

Question 6

Piezoelectric accelerometers use crystal structures which generate a ___ when they are stressed

Answer 6

voltage

Question 7

Capacitance accelerometers work on the principle that ___

Answer 7

There is a certain amount of voltage between 2 capacitors, if one is moved by an accelerative force, the value will change.

Question 8

Micro Electro-Mechanical Systems are used in:

Answer 8

• Solid state accelerometers
• Rate sensor gyroscopes
• Magnetometers

Question 9

The strength of a material lies in its ability to ___.

Answer 9

resist the application of a force without breaking

Question 10

The general term for the force of attraction between molecules of the same time is ___

Answer 10

cohesion

Question 11

The general term for the force of attraction between molecules of different kinds is ___

Answer 11

adhesion

Question 12

Something’s tensile strength depends upon its ___

Answer 12

cohesion

Question 13

Tensile strength is the maximum amount of ___ ___ that a material can be subjected to before it fails.

Answer 13

tensile stress

Question 14

The ___ ___ is stress that a material can withstand without permanent deformation.

Answer 14

yield strength

Question 15

Ductile metals other than steel have no defined ____

Answer 15

yield point

Question 16

Metals that can be hammered or rolled into sheets, are ___

Answer 16

malleable

Question 17

An object’s ability to return to its original size or shape when stress forces are removed is called ____

Answer 17

elasticity

Question 18

When a substance is on the verge of permanent change, it has reached its ___ limit.

Answer 18

elastic

Question 19

The strain remaining after a rubber band has been overstretched is called the ___

Answer 19

permanent set

Question 20

With the elastic limit having been reached, the substance will be ___. This is ___ behaviour.

Answer 20

permanently deformed plastic

Question 21

Stress is the amount of ___

Answer 21

force per unit area

Question 22

The units of stress are ___

Answer 22

Pascals

Question 23

1 pascal is equal to _ Netwon(s) per metre squared

Answer 23

1 Newton

Question 24

Stress arises from the ___ ___ in a body which resist ___ ___

Answer 24

internal forces internal forces

Question 25

The stress required to produce the first signs of plastic strain is the ___ stress

Answer 25

yield

Question 26

Direct stress is ___ to the line of action of the external forces, as with tension or compression

Answer 26

perpendicular

Question 27

___ is the distortion in a body caused by the stress forces acting on it, from extension, contraction, and shear or slide

Answer 27

Strain

Question 28

Strain =

Answer 28

Change in length / Original Length

Question 29

Within the elastic limit of a material, any change in shape is ___ proportional to the applied for producing it

Answer 29

directly

Question 30

Turbine blades might suffer from ___

Answer 30

creep

Question 31

Creep can be affected by the ____

Answer 31

• Material used
• Load applied
• Duration of stress
• Temperature

Question 32

___ temperature can make a material more pliable

Answer 32

Higher

Question 33

A sudden increase in strain is called ___ ___

Answer 33

shock loading