Acoustic Emission Monitoring of Push-Out Testing for Early Microcrack Detection: A Proof-of-Concept on Strut-Structured Surrogate Samples

Conventional push-out tests detect bone–implant failure only at the point of macroscopic instability, leaving earlier damage stages unresolved. Here we present a proof-of-concept for a push-out test stand combined with acoustic emission (AE) monitoring, aimed at capturing crack initiation before the macroscopic load drop. To provide a controlled failure process, samples were fabricated from SLA resin with defined breaking points, serving as mechanical surrogates rather than biological models. Four sample types with varying strut number and thickness were tested while recording AE, and post-processing was applied to remove friction and noise signals. A four-stage fracture model—initial, pre-fracture, fracture, and post-fracture—was defined, with the pre-fracture stage showing AE activity prior to any macroscopic load response. Increasing strut thickness and contact area raised maximum load resistance and AE activity, and Principal Component Analysis confirmed a progressive, intensity-driven separation of stages. The results demonstrate that AE monitoring resolves a pre-fracture regime inaccessible to conventional load measurement, establishing a methodological basis for future application to bone–implant samples.