Page 19 - Failure Analysis Case Studies II

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Fig. 5. Top view of failed silo, showing remaining filling level.

2.2. Tests for traces of an explosion
Specimens F were subjected to laboratory tests to detect possible traces of heat influence by fire
or explosion. No such traces could be found. Thus, one can conclude that failure was not caused
by the explosion of methane or any other gas produced in the silo by fermentation.

2.3. Tensile tests
The sheet metal was tested using specimens BR, CR, BP and CP, as shown in Fig. 6 and
Table 2.

Fig 6. Specimens for mechanical tests.

Table 2. Results of tensile tests on sheet material from silo
Yield Tensile Reduction Elongation Uniform
strength strength of area (5 diameters) elongation
Specimen Orientation (N~II-~) (N~II-~) (”/) (”/I (”/)
BR I to joint 288 341 18 44.5 25
CR I to joint 261 316 I1 47.5 24
BP 11 to joint 300 345 IS 43 24
CP 1) to joint 278 313 70 46.3 29