Typically, failure analysis is performed by a forensic engineering professional. This process examines, tests and analyzes why a particular structure failed. The focus is on gathering information about the faulty component and its history. A detailed visual examination provides more thorough understanding of what went wrong.A series of tests are also performed:
Nondestructive testing – magnetic particle test, dye penetrant
Fatigue damage is the most common reason structures fail. Sources of the fatigue can come from restrained thermal expansion, internal vibratory sources and outside forces. A stress analysis and strain gage test can reveal the exact stressed area where the failure originated.In addition, the material’s properties determine if a low cycle fatigue or high cycle fatigue initiated the failure. Testing will also determine if a catastrophic failure occurred because the crack grew too big.Industries That Use Failure AnalysisSome of the industries that use failure analysis include:
Automotive, Transportation and Marine Industries
Manufacturing and Construction
Power, Utilities and Boilers
Steps to Performing the AnalysisThere are eight crucial steps that must be performed to have full analysis to reveal the cause of structural damage after a catastrophic incident.
Step 1: Collect background information, including service history, of the failed component.
Step 2: Visually examine all failed components and related parts in the failed state. Low magnification examinations are also performed during this step to locate areas that need further analysis or testing.
Step 3: Analyze all degraded or fractured surfaces at high magnification with a Scanning Electron Microscope (SEM).
Step 4: Use the SEM to determine the origin of the failure by investigating the initiation site. The purpose is to look for contributing factors or any unusual conditions. The failure mechanism is identified and characterized as an overload, fatigue, etc. the engineer will also investigate to see if any unusual stress risers exist.
Step 5: The cross-section microstructure is selected, prepared, examined and analyzed in the area where the failure initiated. Conditions of manufacturing processes reflected in the microstructure are also analyzed and investigated for potentially flawed conditions. Material quality and heat treat conditions are also investigated.
Step 6: The failed component, coatings or platings undergo a chemical component analysis.
Step 7: Tests for hardness, strength, and mechanical are performed.
Step 8: All tests results and gathered evidence are analyzed to formulate an opinion and conclusion for why the structure failed.
The careful analysis through extensive forensic examination helps to provide a conclusive explanation of the root cause for the failure.