Fatigue and Stress | Strains and Stresses Flashcards
The largest changes take place in the __ axis
vertical
Accelerations can be measured with ___
accelerometers
An accelerometer can measure ___
Gravity, accleration
A basic accelerometer might consist of ___
- Mass attached to strings
- Restrained by a motor (torquer)
An accelerometer involving E and I bars works on the principle that ___
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
Piezoelectric accelerometers use crystal structures which generate a ___ when they are stressed
voltage
Capacitance accelerometers work on the principle that ___
There is a certain amount of voltage between 2 capacitors, if one is moved by an accelerative force, the value will change.
Micro Electro-Mechanical Systems are used in:
- Solid state accelerometers
- Rate sensor gyroscopes
- Magnetometers
The strength of a material lies in its ability to ___.
resist the application of a force without breaking
The general term for the force of attraction between molecules of the same time is ___
cohesion
The general term for the force of attraction between molecules of different kinds is ___
adhesion
Something’s tensile strength depends upon its ___
cohesion
Tensile strength is the maximum amount of ___ ___ that a material can be subjected to before it fails.
tensile stress
The ___ ___ is stress that a material can withstand without permanent deformation.
yield strength
Ductile metals other than steel have no defined ____
yield point
Metals that can be hammered or rolled into sheets, are ___
malleable
An object’s ability to return to its original size or shape when stress forces are removed is called ____
elasticity
When a substance is on the verge of permanent change, it has reached its ___ limit.
elastic
The strain remaining after a rubber band has been overstretched is called the ___
permanent set
With the elastic limit having been reached, the substance will be ___. This is ___ behaviour.
permanently deformed plastic
Stress is the amount of ___
force per unit area
The units of stress are ___
Pascals
1 pascal is equal to _ Netwon(s) per metre squared
1 Newton
Stress arises from the ___ ___ in a body which resist ___ ___
internal forces internal forces
The stress required to produce the first signs of plastic strain is the ___ stress
yield
Direct stress is ___ to the line of action of the external forces, as with tension or compression
perpendicular
___ is the distortion in a body caused by the stress forces acting on it, from extension, contraction, and shear or slide
Strain
Strain =
Change in length / Original Length
Within the elastic limit of a material, any change in shape is ___ proportional to the applied for producing it
directly
Turbine blades might suffer from ___
creep
Creep can be affected by the ____
- Material used
- Load applied
- Duration of stress
- Temperature
___ temperature can make a material more pliable
Higher
A sudden increase in strain is called ___ ___
shock loading
