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COMPONENT FAILURE MUSEUM

The main sections of the museum are listed below;

Metal Fatigue
Manufacturing Faults
Bicycle Components
Corrosion
Polymers
Composite Materials

Tools of the trade, some ways to investigate problems;
Photoelasticity
Dye penetrant testing

Glossary
of materials engineering terms


Glossary of materials engineering terms - 2

Edax, EDS- Energy Dispersive Analysis

Method of elemental analysis of materials by scanning backscattered X-rays from high volyage electron bombardment usually in a Scanning Electron Microscope. Characteristic emission peaks enable identification of most elements.

Endurance limit (fatigue)

In fatigue testing, the number of cycles which may be withstood without failure at a particular level of stress.

ESEM - Environmental Scanning Electron Microscope;

A ESEM is capable of operating as a conventional high-vacuum SEM, or under low-vacuum in ESEM mode for the imaging of 'wet' and non conductive samples, utilizing the ESEM's special Secondary Electron Detector. The ESEM can be equipped with a range of Secondary Electron (SE) and Back Scattered Electron (BSE) detectors.
Though a certain degree of resolution has been compromised, microscopists are able to investigate specimens in their natural state or under natural environmental conditions - without the need for conventional preparation techniques that may produce unwanted artefacts in the sample. Magnifications up to 50,000 times are possible in such environments. This performance compares favourably with that from many conventional scanning electron microscopes. The main attraction is the ability to image materials without coating or other preparation.

Fast fracture;

when a crack propagates instantaneously at a critical level of stress. The crack may arrest later but usually does not, especially if the applied stress level is constant or increases.

Fatigue;

follow this link for an explanation of fatigue.

Fractography;

an important investigative method in forensic engineering. The study of fracture surfaces of materials to determine the nature and origin of product failure, e.g. whether brittle or ductile, single or multiple origns, association with stress concentrations, and the nature of crack propagation. Analysis usually starts with macrography, then micrography, often using scanning electron microscopy.

FTIR - Fourier Transform-InfraRed Spectroscopy;

This technique is used to examine the chemical bond types present in a polymer (or other IR-absorbent materials) by taking advantage of the fact that chemical bonds can be stimulated to vibrate by IR radiation of particular wavelengths. In doing so, these bonds absorb energy. The strength of the absorption, and the wavelength at which it occurs, is characteristic of the presence of a given bond in the structure. Each different bond type has a characteristic wavelength at which it is stimulated to vibrate in a number of different modes e.g. stretching, bending or wagging.
By scanning across the IR radiation spectrum and measuring how much of the supplied energy is transmitted through the sample at each wavelength, a spectrum is evolved showing a series of absorbance peaks (areas of low energy transmission), the position of which is directly related to the nature of the chemical bonds present in the sample. By examining this pattern of peaks, conclusions can be drawn about the structure and identity of the sample, often by reference to correlation charts or spectral libraries.

HAZ - Heateffected zone ;

Whenever welding, brazing and soldering is used to join metals the neighbouring parent material is effected. It may be remelted, recrystallised, annealed or stress-relieved due to the energy input. Material properties such as hardness and yield strength can be changed (usually reduced) in this region. Low energy and concentrated heat sources minimise the extent of the zone, such as electron beam or laser welding compared to gas torch processes.

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© 2005 Materials Engineering - Page last modified 18-Dec-2007