Although ceramic prostheses have been successfully used in conventional total hip arthroplasty (THA) for many decades, ceramic materials have not yet been applied for hip resurfacing (HR) surgeries. The objective of this study is to investigate the mechanical reliability of silicon nitride as a new ceramic material in HR prostheses. A finite element analysis (FEA) was performed to study the effects of two different designs of prostheses on the stress distribution in the femur-neck area. A metallic (cobalt-chromium-alloy) Birmingham hip resurfacing (BHR) prosthesis and our newly designed ceramic (silicon nitride) HR prosthesis were hereby compared. The stresses induced by physiologically loading the femur bone with an implant were calculated and compared with the corresponding stresses for the healthy, intact femur bone. Here, we found stress distributions in the femur bone with the implanted silicon nitride HR prosthesis which were similar to those of healthy, intact femur bone. The lifetime predictions showed that silicon nitride is indeed mechanically reliable and, thus, is ideal for HR prostheses. Moreover, we conclude that the FEA and corresponded post-processing can help us to evaluate a new ceramic material and a specific new implant design with respect to the mechanical reliability before clinical application.
This paper provides a contribution to the understanding of both the vibroacoustical behavior and the influence of passive constrained layer damping (PCLD) applications on the sound radiation of a grid-stiffened panel. A test specimen is manufactured and an experimental set-up with a synthetic turbulent boundary layer excitation is developed. In addition, a numerical model is created and updated with the results of an experimental modal analysis. Further, the acoustic effect of PCLD applied to the ribs and to the skin fields of the grid panel is assessed by measurement of the radiated sound power. It is shown that the ribs are suitable for an efficient application of PCLD. Generally, additional damping of the grid panel is achieved with PCLD for frequencies above 300 Hz. By partially covering the ribs with PCLD, a reduction of the radiated sound power of up to 2 dB in third-octave bands is achieved. In case of a total coverage of the grid panel, a reduction of up to 4 dB in third-octave bands is attained.
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