Cracks


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compressor blade damage

compressor blade damageclick for a larger image
Various types of damages that compressor blades can sustain. Only one or two may take place simultaneously though these have been combined in this illustration.
The various types of damages to compressor blades and their appearances are as follows:
i. Bend. The blade gives the appearance of ragged edges. Smooth repair of the edges or surface in question can be carried out, but the extent of the damage that can be repaired is limited.
ii. Bow. The main source of this type of damage is a foreign object. The blade is bent at the tips and the edges.
iii. Burning. The damage is caused by overheating. The surface of the blade is discolored. If the overheating is severe, there may be some flow of material as well.
iv. Burr. A ragged or turn-out edge is indicative of this type of damage. This takes place during the grinding or cutting operation of the blade at the manufacturing stage.
v. Corrosion. Oxidants and corrosive agents, especially moisture present in the atmosphere, are the main reasons for the corrosion or pitting of the blades. Normally, regular washing is sufficient to prevent it. The blade gives a pitted appearance, and there is some breakdown of the surface of the blade. Also called pitting.
vi. Cracks. Excessive stress from shocks, overloading, or faulty processing of blades during manufacturing can cause cracks and result in their fracture.
vii. Dent. These can be caused by FOD (foreign-object damage) or strikes by dull objects like those in bird strikes. Minor dents can be repaired.
viii. Gall. This type of damage is from the severe rubbing of blades, in which a transfer of metal from one surface to another takes place.
ix. Gouging. The blade gives the appearance of displacing material from its surface, and a tearing effect is prominently visible. This type of damage is from the presence of a comparatively large cutting material or foreign body between moving parts.
x. Growth. The damage manifests itself in the form of elongation of the blades. Growth type of damage takes place because of continued and/or excessive heat and centrifugal force.
xi. Score. Deep scratches are indicative of scoring, which is caused by the presence of chips between surfaces.
xii. Scratch. Narrow and shallow scratches are caused by sand or fine foreign particles as well as by mishandling the blades.
xiii. Pitting. Pitting takes place because of atmospheric corrosion, especially seawater. The surface of the blade shows signs of pitting.
References in classic literature ?
"'Tis he that hath but now so soundly cracked the crown of Eric of Lincoln," was the reply.
Little John stooped and peered through the hole to see what food lay within reach, when crack! went the steward's keys upon his crown, and the worthy danced around him playing a tattoo that made Little John's ears ring.
Then Eric stepped back to gather his wits, while a great shout went up and all were glad that Nottingham had cracked Lincoln's crown; and thus ended the first bout of the game.
"Who is yon stranger clad all in scarlet?" said some, and others answered, "It is he that hath but now so soundly cracked the crown of Eric o' Lincoln." Thus the people talked among themselves, until at last it reached even the Sheriff's ears.
Suddenly there was a rending, tearing sound, and the earth split into another great crack just beneath the spot where the horse was standing.
"I wonder if hot sunshine is liable to crack pumpkins," said Jack, with an anxious ring in his voice.
where [S.sub.c] is the flexibility of the cantilever beam without cracks; [k.sub.c] is the bending stiffness of the cantilever beam without cracks; [k.sub.a] is the bending stiffness caused by the local flexibility.
I've started to spot cracks in the walls of my home.
Penang Chief Minister Chow Kon Yeow has ordered state exco Zairil Khir Johari to conduct an investigation into the cracks that appeared on a newly repaired road heading to Balik Pulau.
Initially, small cracks appeared on the walls along with a leakage from the drain in the office of a senior officer and other rooms but the cracks started increasing day by day.
Los Angeles, CA, May 18, 2018 --(PR.com)-- The patent covers the novel structural crack repair apparatus and method which facilitates the repair of cracks in walls, floors and surfaces of a variety of above-ground structures as well as various subterranean structures such as swimming pools.
[9] set up a flow-stress-damage (FSD) coupling model for heterogeneous rocks based on a statistical model that considers the growth of existing cracks and the formation of new cracks.