Marker load method for durability testing of additively manufactured Ti–6Al–4V under random load spectra

This study investigates a marker load method suitable for durability testing of Laser-Directed Energy Deposition (LDED) Ti-6Al-4V material. By evaluating the Equivalent Initial Damage Size (EIDS) associated with pore-induced failures and incorporating crack growth simulation methods that account for the effects of both air and pseudo-vacuum environments, a systematic approach for determining marker load parameters is established. After fatigue tests, distinct marker lines are observed on both SEM and optical images of the fracture surfaces. After extracting the ( a , T ) data, the influence of initial defects on marker load parameter determination is analyzed. A comparison is made between the Murakami model and the EIDS derived from durability testing, and the causes of missing marker lines during the small crack growth stage are discussed.