Damage and Microcrack Detection in Metals and Biomaterials using Numerical and Experimental Methods
thesisposted on 24.10.2013 by Akshay Kalmesh Bilagi
In order to distinguish essays and pre-prints from academic theses, we have a separate category. These are often much longer text based documents than a paper.
This study is intended to facilitate the damage detection and microcrack propagation analysis to predict the quality and healthy mechanical behavior of metal elements and biomaterials. The study focuses on the dual experimental and numerical methods applied to extract morphological information and to analyse the damage and cracks in the materials. First, a complete numerical model of a ball bearing is built to obtain the fault frequencies characteristic of a spall crack in the outer bearing and to analyse the effect of the spall crack increasing length on the first three harmonic frequencies of the numerised experimental testing system. Second, an efficient visualisation technique is also developed for observing the cartilagenous and bony vertebral endplate morphology and for detecting different microdamages present in this human tissue. Additionally, the spacial distribution of the chondrocyte cells is analysed by Fast Fourier Transform image processing and its influence on the disc degeneration and nutrient supply. Finally, an idealised Monte Carlo model based on non-interpenetrable elliptical cylinders is applied to generate synthetic cortical bone microstructures and compared with explicit in silico in situ models of human Haversian cortical bone tissues from elderly women. This study estimate the mechanical reliability of idealised structures at the tissue scale and their limitations at the osteonal level. All the presented studies relies on dual concomitant experimental and numerical methods.