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Biomedical subjects

E Aernoudt

Publications and source records attributed to E Aernoudt.

10 recordsLinked to original sources
PubMed2006

Electron backscatter diffraction on pearlite structures in steel.

Electron backscatter diffraction measurements were performed on a set of pearlitic steel samples after different heat treatments. The strengths and limitations of the technique with respect to the pearlite issue are presented. Interpretation of the obtained results confirmed that more than one pearlite colony may exist inside one ferrite nodule of nearly the same crystallographic orientation. It was also found that, in most cases, a misorientation of the order of several degrees exists between pearlite colonies within one ferrite nodule. Moreover, the ferrite matrix exhibits changes of crystallographic orientation inside colonies often accompanied by a network of low angle boundaries. The mean size of the ferrite nodule in the matrix was determined by means of electron backscatter diffraction. However, determination of the mean pearlite colony size was difficult and often impossible by means of both metallographic methods and electron backscatter diffraction measurements.

Journal Article↗
PubMed1981

Fracture hip prostheses due to welding defects.

Two retrieved Moore type hip prostheses of cast Co-Cr-Mo-alloy were examined after metallic failure. The first case concerns a fatigue fracture in the stem of the prosthesis due to an abrupt change in the cross-sectional area and the presence of inappropriate welding beads in the stem. The abrupt change occurring at a transition from an I-beam into a rectangular profile gives rise to stress concentrations thus increasing change of fatigue crack initiation. The second case is a fracture of the hollow head of the prosthesis through a weld. The two parts of the cast femoral head were incompletely welded. Comparison with similar welds in other femoral heads of prostheses of the same type reveals a poor welding uniformity. Hence, both fractures are associated with the welding process. A critical investigation is needed to find optimal welding conditions for Co-Cr-Mo-alloy prostheses.

Biomechanical Phenomena↗
PubMed1980

Performance analysis of total hip prostheses: some particular metallurgical observations.

Metallurgical observations of phenomena which influence the clinically successful performance of permanent implants and implant materials are reported. The effect of casting voids in cast cobalt chromium femoral stems of total hip replacements is discussed first. Pitting corrosion occurred in a retrieved stainless-steel implant type AISI 316 containing 2.7% Mo. The fractographic pattern of this device retrieved for fatigue failure shows typical characteristics of corrosion-enhanced fatigue.

Chromium Alloys↗
PubMed1977

Microscopic fracture aspects of impact tested human bones.

The fracture aspects of impact twisted human femurs and tibias have been studied in their wet condition. The main tool used to correlate fracture behaviour with bone structure was the scanning electron microscope. Supplementary data were obtained from macroscopic fracture pattern analyses and stress coat experiments on slowly tested dried bone. The interest of the data reported concerns two major points. Firstly the analysis of the fractographic results leads to the conclusion that the fracture has presumably been initiated by shearing parallel with the torsion axis. The fracture propagates along so called spiral and oblique fracture lines. Secondly, the correlation of the macroscopic fracture pattern with microscopic fracture aspects indicates that the fracture is initiated along the cement lines, which can be considered as the weak matrix in an osteon-cement lining composite. The fracture propagates along the cement lines as well as through osteons and lamellae. Throughout the impact fracture surfaces ductile and brittle fracture aspects were observed, although the brittle fracture mode was predominant during propagation.

Bone and Bones↗
PubMed1975

Fatigue fractures of the femoral component of Charnley and Charnley-Müller type total hip prostheses.

A survey is given of the mechanical failures of the femoral component of Charnley and Charnley-Müller type total hip prostheses. Fractographic analysis reveals that all the prostheses have broken by metal fatigue. A review of the clinical data has been combined with a metallurgical and a mechanical study in order to assess the reasons of the mechanical failures. The following conclusions have been reached. The prosthesis should be inserted in varus position with regard to the axis of the intramedullary canal, and the prosthesis should be made of an alloy with appreciably higher yield stress and fatigue strength than the alloys of the investigated broken Charnley and Charnley-Müller type prostheses.

Alloys↗