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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

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Polymer failure - Battery case

Click on pictures below for full size image.

 

Plate 1

We were approached by the makers of large lead-acid traction batteries for powering the locos on the railway system in Hong Kong, to investigate a fire which had occurred in one of the batteries. The base of the battery (Plate 1) showed a large hole with a brittle crack running through the middle (Optical Micro Plate 2).

 

The hole was surrounded by burnt plastic. SEM was crucial in determining the cause of the fire, by using EDX analysis. Plate 3 shows the SEM image taken of the section, and Figure 1 and Figure 2 the EDX analysis of the surface in the hole. In addition to lead and sulphur peaks, there were also two peaks from aluminium and silicon.

 

Since the latter peaks only occurred in the hole, and not elsewhere, we were able to infer that the battery had landed on an aluminium stud already on the floor of the holder where the battery sat normally. The stud had impacted the base, cracked the case, and created a short circuit with the internal battery plates (Fig 3). The cause of the fire was not the battery manufacturer, but rather the installer of the battery who had not checked that the floor of the holder was clear of debris.

 

Plate 2

 

Plate 3

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ed: PRL 17/12/01

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