A steel beam in a building cracked after 10 years. Which of the following is the best first step in failure analysis?
AReplace the beam immediately
BExamine the crack to determine where and how it started
CBlame the construction crew
DRedesign the entire building
Failure analysis begins with examining the failure itself -- where did the crack start, what direction did it grow, what does the fracture surface look like? This evidence reveals whether the cause was overloading, fatigue, corrosion, a material defect, or something else.
Question 2 True / False
If an engineer finds the root cause of a failure, they should fix that one product and move on.
TTrue
FFalse
Answer: False
Finding the root cause should lead to systemic fixes -- changing the design, updating manufacturing procedures, revising inspection schedules, or modifying requirements -- to prevent the same failure in all similar products, not just the one that failed.
Question 3 Short Answer
What is the difference between the symptom of a failure and its root cause?
Think about your answer, then reveal below.
Model answer: The symptom is what you observe (a crack, a leak, a collapse). The root cause is the underlying reason it happened (a material was too weak for the load, a joint was improperly welded, a design did not account for vibration). Fixing the symptom without addressing the root cause means the failure will likely recur.
Effective failure analysis digs past symptoms to find root causes. A cracked beam (symptom) might have failed because of metal fatigue from vibration (root cause). Replacing the beam fixes the symptom; adding vibration dampening fixes the root cause.