TY - JOUR AU - Couture, Daniel P PY - 2022/07/20 Y2 - 2024/03/28 TI - Forensic Engineering Investigation of a High-Voltage Transmission Line Anchor Shackle Failure JF - Journal of the National Academy of Forensic Engineers JA - JotNAFE VL - 39 IS - 1 SE - DO - 10.51501/jotnafe.v39i1.65 UR - https://journal.nafe.org/ojs/index.php/nafe/article/view/65 SP - 35-46 AB - <p>A forged alloy steel anchor shackle, one of a batch of more than 2,600 produced for the project, failed catastrophically in service on a newly erected 66-kilometer high-voltage transmission line in northern Canada. A failure analysis led to a hypothesis that forging laps had created the critical crack size to initiate propaga-tion under cold weather conditions. An extensive Charpy fracture toughness test program based on CAN/CSA C83.115-96 parameters was performed on 150 shackles, but the data did not support the initial hypothesis of temperature dependence. The forensic engineering team designed experimental tensile tests at ambient tem-peratures as low as -40°C to evaluate the propagation response of lap cracks in a statistically valid sampling of shackles. The trimmed forging flash area disguised laps from the manufacturing process, and subsequent galvanizing steps prevented detection by magnetic particle inspection. A focused recommendation for removal and replacement of the shackles was issued for those bearing major loads in the tower array.</p> ER -