ADVANCED MATERIALS & PROCESSES | NOVEMBER/DECEMBER 2025 25 the investigation. Every failure is unique, and the events that lead to a failure are unique to the failure being investigated. While a particular failure mode such as fatigue fracture may be fairly easily identified, the series of events that initiated and resulted in the failure are unique to the specific case under investigation. Identifying the TRC requires a very systematic approach beginning with a clear identification and understanding of the failure mode. The next vitally important part of the process is gathering as much evidence and history as possible regarding the events leading up to the failure. When conclusions are made and corrective actions implemented prior to the TRC being positively determined only the symptoms will have been addressed. By merely treating the symptoms and not providing a remedy for the source of the failure, future failures are inevitable. This is especially true when investigating failures of components involved with complex systems. Correcting the conditions that resulted in the failure of a specific component within a system and not determining the TRC may result in a future failure that simply moves to the next weakest link in the system. Never lose sight of the fact that the primary goal of the process is to identify the TRC and eliminate it. If this is not the final result of the investigation, the investigation itself will have been a failure. INITIATE PRODUCT AND MANUFACTURING IMPROVEMENTS The second purpose for a failure investigation is to learn from the failure and implement product and manufacturing improvements. Continual improvements that lead to enhanced product performance as well as economy of design and manufacturing, are paramount to a successful business model. What worked for an original design application may not work in a new application. An unknown author is attributed with the quote “The definition of insanity is doing the same thing over and over again, but expecting different results.” Finding the TRC of a failure can very well be the baseline for continual improvement of product and design. There have been many catastrophic failures in history that have resulted in great loss of life and property. Having identified the TRC for those failures resulted in improvements to the products involved and additionally, and even more importantly, provided the failure investigation. As previously stated, the successful failure investigation goes beyond the “what” of the failure and continues to identify the source or the “why” (TRC) of the failure. THE PURPOSE OF THE FAILURE INVESTIGATION Finding the TRC for the failure may seem to be the obvious purpose of the investigative process but the purpose is actually threefold: 1. Identify the TRC of the failure and eliminate it via corrective action 2. Initiate product and manufacturing improvements 3. Protect life and property These three separate but comple- mentary reasons for the investigation comprise the “why” of a failure investigation. To fully understand the process and equip the investigator or analyst with the tools to properly conduct the failure investigation, it is helpful to begin with an explanation and understanding of the purposes for the process and the three elements that define the “why” of the process. IDENTIFY AND ELIMINATE THE TRUE ROOT CAUSE The failure of a component or product during service is never a desirable outcome especially for the customer or the end user. The failure can however be an invaluable source of information and provide a solid foundation for product improvement. Having worked in the field of metallurgy and failure analysis and being involved with failure investigations for over 35 years, this author has arrived at an indisputable conclusion regarding a failure investigation: You will learn very little from success, but the knowledge obtained from a properly conducted failure investigation is invaluable for continued improvement of products and services. Nonetheless, reaping the benefits of the knowledge obtained from the failure investigation relies on the premise that the failure’s TRC has been identified and eliminated. This must be the primary goal and purpose of GROSS PLASTIC DEFORMATION Failures come in all sizes. One example of a simple failure can be seen in the gross plastic deformation of a bolt. During service, a bolt fractured. A visual examination reveals necking of the cross-section and elongation of the threads to the left of the fracture. The threads remained intact, as evidenced after fitting a nut on the end section to the right of the fracture. The section shown on the left has threads that exhibited multiple small cracks as the material was deformed and stressed beyond its ultimate tensile strength. Photograph of a typical ductile fracture caused by tensile overload. Courtesy of surescreenmaterials.com/failure-mechanisms/ ductile-fracture.
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