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Christian Schroeder Thomas M. Grupp Bernhard Fritz Christoph Schilling Yan Chevalier Sandra Utzschneider Volkmar Jansson 《Journal of materials science. Materials in medicine》2013,24(5):1319-1325
The reduced intraoperative visibility of minimally invasive implanted unicondylar knee arthroplasty makes it difficult to remove bone and cement debris, which have been reported on the surface of damaged and retrieved bearings. Therefore, the aim of this study was to analyze the influence of bone and cement particles on the wear rate of unicompartmental knee prostheses in vitro. Fixed bearing unicompartmental knee prostheses were tested using a knee-wear-simulator according to the ISO standard 14243-1:2002(E) for 5.0 million cycles. Afterwards bone debris (particle size 671 ± 262 μm) were added to the test fluid in a concentration of 5 g/l for 1.5 million cycles, followed by 1.5 million cycles blended with cement debris (particle size 644 ± 186 μm) in the same concentration. Wear rate, knee-kinematics and wear-pattern were analyzed. The wear rate reached 12.5 ± 1.0 mm3/million cycles in the running-in and decreased during the steady state phase to 4.4 ± 0.91 mm3/million cycles. Bone particles resulted in a wear rate of 3.0 ± 1.27 mm3/million cycles with no influence on the wear rate compared to the steady state phase. Cement particles, however, lead to a significantly higher wear rate (25.0 ± 16.93 mm3/million cycles) compared to the steady state phase. The careful removal of extruded cement debris during implantation may help in reducing wear rate. Bone debris are suggested to have less critical influence on the prostheses wear rate. 相似文献
105.
Three-dimensional chemo-thermomechanically coupled simulation of curing adhesives including viscoplasticity and chemical shrinkage 总被引:1,自引:1,他引:0
Christoph Liebl Michael Johlitz Bülent Yagimli Alexander Lion 《Computational Mechanics》2012,49(5):603-615
Based on the one-dimensional material model developed by Liebl et al. (Arch Appl Mech, 2011) a three-dimensional viscoelastic-viscoplastic material model for small deformations of curing adhesives on the basis of
continuum mechanics is proposed in this contribution. The model describes the most relevant phenomena which occur during curing
processes in the automotive industry and includes the effects of temperature and degree of cure on the mechanical properties
of the material. Thermal expansion as well as chemical shrinkage are also contained. The yield stress for the viscoplastic
part of the model goes back to the work of Schlimmer and Mahnken (Int J Numer Meth Eng 63:1461–1477, 2005), but is formulated in reference to the degree of cure and the temperature. Therefore this model considers chemo-thermomechanical
coupling and extends the plasticity approach of Schlimmer and Mahnken, which is devised for cured adhesives, to the whole
curing range, from the uncured to the fully cured adhesive. A peculiar focus is hereby laid on epoxy resins used in the automotive
industry as structural adhesives. 相似文献
106.
Lars Büttner Christoph Leithold Jürgen Czarske 《International Journal of Optomechatronics》2014,8(1):1-13
Flow measurements often take place under difficult conditions. Optical flow measurement techniques are affected by variations of the refractive index, caused e.g., by temperature, concentration, or pressure gradients. This will give rise to an increased measurement uncertainty or cause the measurement to fail. To overcome these limitations, we propose the employment of adaptive optics. In this contribution we present interferometric flow velocity measurements through a fluctuating air-water interface by the use of adaptive optics. Using the adaptive optics, the rate of valid measurement signals can be improved from 28% to 83%. The results are promising to enable measurements in difficult environments affected by refractive index variations which were not accessible so far. 相似文献
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Lisa Meier-Dinkel Johanna Trautmann Luc Frieden Ernst Tholen Christoph Knorr Ahmad Reza Sharifi Mark Bücking Michael Wicke Daniel Mörlein 《Meat science》2013
This study aimed to assess the influence of two label conditions on the acceptance of boar meat. A central location test was conducted with 145 consumers each assessing 4 pieces of pork loin. 相似文献
109.
Pierre Carmier Oleksii Shevtsov Christoph Groth Xavier Waintal 《Journal of Computational Electronics》2013,12(2):175-187
We investigate the effect of spin-orbit coupling on the band structure of graphene-based two-dimensional Dirac fermion gases in the quantum Hall regime. Taking monolayer graphene as our first candidate, we show that a quantum phase transition between two distinct topological states—the quantum Hall and the quantum spin Hall phases—can be driven by simply tuning the Fermi level with a gate voltage. This transition is characterized by the existence of a chiral spin-polarized edge state propagating along the interface separating the two topological phases. We then apply our analysis to the more difficult case of bilayer graphene. Unlike in monolayer graphene, spin-orbit coupling by itself has indeed been predicted to be unsuccessful in driving bilayer graphene into a topological phase, due to the existence of an even number of pairs of spin-polarized edge states. While we show that this remains the case in the quantum Hall regime, we point out that by additionally breaking the layer inversion symmetry, a non-trivial quantum spin Hall phase can re-emerge in bilayer graphene at low energy. We consider two different symmetry-breaking mechanisms: inducing spin-orbit coupling only in the upper layer, and applying a perpendicular electric field. In both cases, the presence at low energy of an odd number of pairs of edge states can be driven by an exchange field. The related situation in trilayer graphene is also discussed. 相似文献
110.