Types of Damage

Possibility of unexpected events in data. Unless the inspection occurs in well controlled environment, there is always a possibility of occurrence of unexpected events in data. These can be caused e.g. by previously unseen type of damage. Amount of unexpected data is reduced if inspection is done periodically. An experienced operator can usually correctly interpret unexpected data, but some automatic classification systems may fail and raisclassify the data. 

Aerospace struetwes made of composite. As part of the evaluation of the developed ultrasonic spectroscopy system the NSC software was tested on ultrasonic resonance spectra from composite panel samples. Spectra were collected with four different types of damages, and from flawless samples. The damages included a small cut in one of the carbon fiber... 

Backfilling with limestone or other alkahne material is an added step to protect buried structures from microbiological damage. Providing adequate drainage to produce a diy environment both above and below ground in the area of the buried structure will also reduce the risk of this type of damage. 

Types of damage can be classified as uniform or localized metal removal, corrosion cracking or detrimental effects to the environment from the corrosion products. Local attack can take the form of shallow pits, pitting, selective dissolution of small microstructure regions of the material or cracking. Detrimental effects are certainly not the case with buried pipelines, but have to be considered for environments in vessels and containers. It is usual, where different results of reactions lead... 

Fig. 2-1 Flow diagram of corrosion processes and types of damage (schematic).

Types of Damage. Hydrogen attack is characterized by three types of damage, as follows ... 

The type of damage an advanced composite sustains plays an important role in the type of repair that can be implemented. Damage to advanced composites can be... 

Local repair of delamination originally caused by non-durable surface treatment is only temporarily successful at best. The surface treatment on the unrepaired portion of the assembly remains susceptible to attack and the area of delamination will likely continue to grow once the assembly is put back into service and exposed to moist conditions. Replacement or complete remanufacture of the component is the only way to permanently address this type of damage. However, time-limited repairs using bonded or mechanical methods can be used to extend the life of the component until a major overhaul is scheduled. In some cases such as widespread disbond of fuselage doublers, mechanical repairs (rivets and fastened doublers) and continued inspection are used to extend the life of the skin indefinitely because of the high cost of replacement. 

Because of the many types of damage and damage growth in composite materials, the initial state of the material is difficult, if not impossible, to characterize. Moreover, it is much more difficult to formulate a boundary-value problem to describe crack propagation in composite materials than in metals. 

Instead of calculation of overpressure and impulse at a flxed distance, the distance at which damage can occur will be calculated. The speciflc type of damage chosen is window pane breakage. This can be expected at overpressures greater than 6 kPa (0.06 bar). 

Pressurized air can do the same type of damage as pressurized water. Treat all operations on compressed air systems with the same care taken on liquid systems. Closed valves should be slowly cracked open and both sides allowed to equalize prior to opening the valve further. 

This type of damage is dealt with comprehensively in Section 8.8. It can be particularly severe in seawater giving rise to cavitation corrosion or cavitation erosion mechanisms, and hence can be a considerable problem in marine and offshore engineering. Components that may suffer in this way include the suction faces of propellers, the suction areas of pump impellers and casings, diffusers, shaft brackets, rudders and diesel-engine cylinder liners. There is also evidence that cavitation conditions can develop in seawater, drilling mud and produced oil/gas waterlines with turbulent high rates of flow. 

Corrosion is fundamentally a problem associated with metals. Since plastics are electrically insulating they are not subject to this type of damage. Plastics are basically non-corrosive. However, there are those that can be affected when exposed to corrosive environments. It is material deterioration or destruction of materials and properties brought about through electrochemical, chemical,... 

Characterization of various types of damage to DNA by oxygen-derived species can be achieved by the technique of gas chromatography-mass spectrometry (GC-MS), which may be applied to DNA itself or to DNA-protein complexes such as chromatin (Dizdaroglu, 1991). For GC-MS, the DNA or chromatin is hydrolysed (usually by heating with formic acid) and the products are converted to volatile derivatives, which are separated by gas chromatography and conclusively identified by the structural evidence provided by a mass spectrometer. Stable isotope-labelled bases may be used as internal standards... 

A gas cylinder contains 50 lb of propane. The cylinder accidentally falls over and ruptures, vaporizing the entire contents of the cylinder. The cloud is ignited and an explosion occurs. Determine the overpressure from this explosion 100 ft away. What type of damage is expected ... 

Few in-depth studies have been made of actual furnace smelt-water explosions and, therefore, it is difficult to delineate expected overpressures and impulses. One case history is presented to indicate in a qualitative fashion the type of damage in a large explosion. 

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