The sources of failure

One of the practical aspects of materials selection in the design, development and production of new components (or parts/ structures) is the possibility of failure of the component (or parts/ structures) under normal operation. Classify and analyse all the sources of failure that must be considered before designing a component (or parts / structures).

Answer

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1)        Deficiencies in design,

§  Safety factors are usually included in the design to account for uncertainties in the operational conditions.

§  The designer consider the possible failure mechanisms that could be induced during service

2)        Deficiencies in materials

§  Selection of an inadequate material during the design process (design deficiency).

§  The deliberate or accidental substitution of an alternate material

§  The presence of defective material.

3)        Service conditions that have been modified from those considered in design,

§  Modifying service condition includes changes in

ü  Temperature and/ or pressure,

ü  ambient environment,

ü  speed,

ü  power or loading,

ü  lubricant, and process stream.

§  If it cannot be determined that the modified conditions were included in the design process,

ü  a systematic evaluation of the potential effects of the modification should be undertaken.

4)        Errors in assembly or maintenance.

§  Service failures often result from errors in original assembly, errors in maintenance procedures or errors in reassembly following maintenance.

§  Failures due to assembly or maintenance errors are most often found in the moving parts of mechanical assemblies.