Serial High-Throughput Tensile Testing of Additively Manufactured Composites: From Direct Coupling to Stiffness-Augmented (STASH) Testing

Abstract

Characterizing the lower tail of strength distributions is essential for reliability assessment of advanced materials, such as additively manufactured (AM) composites. Yet conventional single-specimen tensile testing is inefficient for probing rare-event failures. To address this challenge, we present a STiffness-Augmented Serial High-throughput (STASH) tensile testing framework that leverages automated 3D printing with serial sample coupling to encode the material strength distribution directly into the system-level load–displacement response. By decoding this global response, the method enables large-scale statistical characterization of strength from a single test for brittle and quasi brittle materials. An analytical model is developed to work in tandem with the STASH system and guide the experimental design. A key feature of this approach is its ability to mitigate hysteresis caused by nonuniform cyclic loading, which arises inevitably from the serial coupling of samples. This is achieved by implementing controlled partial unloading after each individual sample failure, rather than fully unloading the system. STASH tests on 3D-printed chopped carbon-fiber- reinforced polylactic acid (PLA–CF) specimens fabricated at 0∘ orientations relative to the loading direction show strong agreement with conventional dog-bone testing. By directly sampling the weakest specimens, the STASH test substantially enhances efficiency in resolving lower-tail failure probabilities. The frame work is scalable to hundreds of samples per run and provides a promising route toward rapid probabilistic failure characterization in quasi-brittle materials, including but not limited to fiber composites, geomaterials (such as shale), and ceramics.