Oleh: Edi Junedi2613093051

Mukti Ali Sadikin

The rail profile is the cross sectional shape of a railway rail, perpendicular to the length of the rail. Unlike some other uses of iron and steel, railway rails are subject to very high stresses and have to be made of very high quality steel. Minor flaws in the steel that pose no problems in reinforcing rods for buildings, can, however, lead to broken rails and dangerous derailments when used on railway tracks

Double-headed

rail

In late 1830s England, railway lines had a vast range of different patterns. One of the earliest lines to use doubleheaded rail was the London and Birmingham Railway which had offered a prize for the best design. This rail was supported by chairs and the head and foot of the rail had the same profile The supposed advantage was that, when the head became worn, the rail could be turned over and re-used

Bullhead

rail

Bullhead rail is similar to double-headed rail but with a heavier profile to the top edge. It became the standard for the British railway system until the mid-20th century but has now been largely replaced by flat-bottom rail.

Flanged T

rail ( Flat Footed Rail)

Blast

furnace

Steel-making

-

Bessemer Proses Open Hearth Proses Basic Oxygen Metode Electric arc Furnace

ontinuous casting

Rolling

Straightening

Measurements

- manual inspection - ultrasonic - geometry

Hatfield Rail Crash 17th October 2000 Train speed, 115mph - rail fractured due to gross RCF 4 fatalities, 70 people injured

According

to their initiation, they can be divided into three broad groups : 1. Cracks caused by manufacturing defects (e.g. hydrogen inclusion) 2. Defects due to inappropriate handling and use (e.g. surface spalling caused by Wheelburn) 3. Rolling contact fatigue (RCF) defects

manufacturing technology has reduced the number of fatigue crack initiation sites inside the rail. However, changing service demands like increased average load, higher train speeds, shorter inspection windows and higher wear resistance have resulted in new problems. Therefore, over the last 20 years, the number of rail failures due to RCF defects has been increasing Improved

Defect Location in Rail

Bentuk

Defect

Kegagalan akibat RCF

In ultrasonic testing use is made of the basic physical property that sound waves travel at known constant velocities through any sympathetic medium. By measuring the time for a sound wave to travel through a material it can be determined how far that wave has travelled. In this way sound waves can be used to measure distances. Use can also be made of the fact that sound waves are reflected at an interface between two materials such as steel and air to detect defects

Acoustic Spectrum Ultrasonic is sound generated above human range (typically 20 kHz)

Each material unique speed of sound

Production

of Ultrasonic Wave

In ultrasonic testing sound waves are used with a frequency of 20 KHz upwards. In testing metals a range of 1 MHz to 6 MHz is generally used. To produce these high frequencies use is made of the Piezo-Electric Effect

Piezo-Electric

Effect

Certain crystalline substances change their shape slightly when an electrical potential is applied across opposite surfaces of the crystal, and conversely develop an electrical potential when they are subjected to mechanical pressure or shock.

Although the expansions and contractions will be of the same frequency as the alternating voltage, each crystal has a natural or resonant frequency at which it tends to vibrate most readily

Such devices which convert electrical energy to mechanical energy or vice-versa are termed transducers. In ultrasonic testing equipment the transducer is incorporated in a device termed an ultrasonic probe.

The simplest form of compression wave probe is the single crystal probe; this can act as the transmitter of ultrasonic waves and also as the receiver by 'listening' for the echo during the non-productive delay between emitting each pulse

The twin crystal probe is basically the same as the single crystal probe but uses one transducer for continually transmitting ultrasonic waves and one for receiving

Type

search unit

Jenis-Jenis

Probe/Transducer

Complete

transducer configuration for the inspection of one whole rail