Material Failure Analysis: A Deep Dive
Material Failure Analysis
Concept of Failure
The term “failure” is defined as a material defect that reduces its resistance, deviates from expected performance, or contains a flaw that compromises its integrity.
Methodology
Failure analysis methodology includes three key stages:
- Search: Identifying the elements or reasons that affected the material’s performance.
- Integration: Evaluating the impact of the identified defect on the material’s strength or integrity. Establishing the relationship between cause and effect is crucial for the next stage.
- Decision-Making: Determining the corrective actions to eliminate the root causes of the failure. This stage relies heavily on the findings from the previous two stages.
Failure analysis can be defined as the discipline of finding the primary cause(s) of failure and implementing corrective measures to prevent recurrence.
Originating in the 1950s with British investigations into the Comet aircraft disasters, failure analysis emerged as a multidisciplinary approach developed by the aviation industry.
Disciplines Involved in Failure Analysis
From an engineering perspective, failure analysis primarily involves the following disciplines:
- Chemical Analysis: Determines material compositions, corrosion products, and electrochemical parameters to define corrosion mechanisms.
- Mechanical Design: Employs experimental stress analysis methods, manufacturing processes, and assembly techniques.
- Fractography and Fractomechanics: Connects the morphological features of fracture surfaces with the mechanisms causing these phenomena, considering the size, distribution, and shape of defects.
- Metallurgy: Provides knowledge about materials, structural conditions, heat treatments, examination methods, and testing procedures.
- Other Disciplines: As required by the specific characteristics of the failure being investigated.
Objectives of Failure Analysis
The fundamental objective is to prevent future failures by thoroughly investigating the causes and implementing preventive measures.
Often, new techniques and experimental development are required to determine the contributing factors to a failure.
Failure analysis is not merely a technique but a methodology that often requires an interdisciplinary approach and a broad range of criteria.
Scope of Failure Analysis
Two main drivers for conducting failure analysis are:
- Technical Reasons: Motivated by good engineering practices.
- Legal Reasons: For legal investigations and liability purposes.
From an engineering standpoint, proper application of failure analysis helps resolve design problems and material limitations.
Optimal design aims for component or structural capacity to slightly exceed requirements under all operating conditions. Due to the complexity of predicting all potential stresses, thorough failure analysis is crucial for preventing recurrence and optimizing design.