11.18 Structural Monitoring Flashcards
What is damage tolerance?
The ability of an aircraft structure to sustain damage without catastrophic failure
What type of damage is monitored?
Stress corrosion, cracks, accidental damage, impact damage, delaminating, dis-bonding, water ingress, damage due to loads and strain
Why is damaged tolerance used?
while cracks due to fatigue and corrosion will develop in the aircraft structure, the process can be understood and controlled
What is structural health monitoring (SHM)?
Structural health monitoring (SHM) involves a non-destructive testing (NDT) system with sensors integrated into the aircraft’s structure to enable continuous or periodic inspection, this can tell you when parts need to be replaced
How do you measure fatigue?
Fatigue meters, strain gauges, intelligent skins
Why does the greater the age of the aircraft mean it has been fatigued more?
It has been exposed to atmospheric pressure turbulence and other harsh elements for longer
What are fatigue meters used for?
Fatigue meters are used to record overall, accumulated stress levels on aircraft
What can the fatigue meter measure?
Can measure/indicate when the aircraft nears or exceeds the design limits imposed on it
What do strain gauges measure?
They measure the deformation or strain caused by stress acting upon the component
What happens if you replace a resistor in a Wheatstone bridge?
If we replace one of the resistors in a balanced Wheatstone bridge with a wire strain gauge, the resistance will be a function of the deformation of the material
How are intelligent skins constructed?
These are constructed with fibre optic sensors embedded in the material which are connected to signal processing units
