(Micro-mechanical characterization of fatigue fracture in brittleconstruction materials) FWO-project G088920N: PhD MAT

During their lifetime, structures are commonly subjected to cyclic loading such as traffic loads, wind and wave loading, or thermal loading. For brittle construction materials like masonry, concrete, or mortars, cyclic loading can give rise to a fatigue-induced fracture process. The fatigue behavior of brittle construction materials will become increasingly important as structural engineers design structures for optimal durability and material use. This generally results in an increase of stress amplitudes and makes designs susceptible to fatigue. Fatigue in construction materials is commonly characterized using stress-cycle (S/N) curves. S/N curves provide an empirical relationship between the number of cycles to failure for a corresponding maximum (normalized) stress level, but require a lot of time-consuming high-cycle fatigue tests to calibrate. We aim to develop an alternative approach based on low-cycle fatigue tests with advanced techniques for micro-fracture detection and quantification. Novel, realistic fracture models are developed and calibrated based on a limited number of low-cycle fatigue tests, resulting in an approach that accurately predicts high-cycle fatigue limits under a variety of loading conditions. This would strongly reduce the number of experiments to calibrate S/N curves, allowing for a fast assessment of the remaining lifetime of aging infrastructure and speeding up the development of durable materials. The aim of this project is to gain an improved insight into the fatigue behavior of brittle building materials, based on recent innovations in numerical modeling and experimental characterization of cracks on a micro and macro scale. For this purpose, low-cyclic fatigue tests are carried out with advanced techniques for detecting and quantifying micro-cracks. These tests are further used to develop and calibrate realistic fracture models.This PhD focuses on experimental characterization (micro-CT, acoustic emission, digital image correlation).