title: Defect-induced fatigue microcrack formation in cement mantle.
abstract: Acoustic emission (AE) was used to monitor the progress of the fatigue damage process in the cement mantles of two cemented femur stem constructs that contained naturally occurring defects. After the fatigue tests, morphological features of the defects were investigated using an environmental scanning electron microscope. It showed that the regions with no visible defects were mainly microcrack free, whereas the defect regions were the main sources generating microcracks. Two types of microcracks were identified: type I and type II. Signal energies associated with type I microcracks were about an order of magnitude higher than that of type II. The microstructural investigations of the defects and the areas in the vicinity of the defects suggested their categorization into stable and unstable. The accumulative energy-time relationships revealed that stable and unstable microcrack curves had convex [formula: see text], and concave [formula: see text] shapes, respectively. The progress of fatigue microcrack formation occurred over three distinct phases: initiation, transition, and stableness.
authors.affiliation: Medical Acoustic Research Laboratory, Department of Mechanical Engineering, The University of Memphis, Memphis, Tennessee 38152, USA. gangqi@memphis.edu
authors.forename: Gang
authors.initials: G
authors.lastname: Qi
authors.forename: Jihui
authors.initials: J
authors.lastname: Li
authors.forename: W Paul
authors.initials: WP
authors.lastname: Mouchon
authors.forename: Gladius
authors.initials: G
authors.lastname: Lewis
mesh_terms: D000162:Acoustics; D001696:Biomechanical Phenomena; D001843:Bone Cements / Q000737:chemistry*; D019245:Compressive Strength; D005269:Femur / Q000473:pathology / Q000648:ultrastructure; D006622:Hip Prosthesis; D006801:Humans; D008422:Materials Testing; D011475:Prosthesis Failure; D013314:Stress, Mechanical
chemical_list: D001843:Bone Cements