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 periodicals archive ?
And cracks are dividing into different grades (grading standard is shown in Table-1).
Mild anodization (MA) is slower while the hard anodization (HA) is faster process; however the drawback of the HA is the cracks on the surface of alumina.
A panel of dimension 100 X 100 mm is considered for analysis with a hole of diameter 10mm to simulate the effect of damages like dents, cracks, gouges and scratches critical being the crack, thickness of the panel is 20mm.
Shear cracks can run completely through the stem and separate it into two halves.
The slip that occurs between the concrete and reinforcing steel will introduce the strain incompatibility near the cracks [7].
It was found that the interaction between cracks affected the initiation rather than the growth of cracks.
For the nonlinear dynamic investigation of crack structures, many researchers considered cracks as open-crack models.
The cracks affected the barangay road along Purok 1 in Sitio Taytay leading to the barangay proper of Cantuyoc, rendering it impassable to motorists and isolating a sitio.
For example, in most new builds and extensions it is common to see shrinkage cracks around windows and doors and at wall and ceiling junctions which are often associated with the drying out of new building materials.
This paper addresses two goals: first of all, to experimentally characterize the layer of zinc applied during the hot-dip galvanization process, in order to obtain necessary information about the uniformity of the zinc layer and the number of cracks and their length, and finally to estimate the behaviour of the cracks located in zinc layer when the mechanical loading is imposed.
Look for cracks on the cover near its pivot point with the receiver.