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Dealing with Problems of Biomedical and Regulatory Interest
Published in Guigen Zhang, Introduction to Integrative Engineering, 2017
In this section, we demonstrate the use of the computational modeling technique to perform mechanical testing of a femoral stem of a hip implant according to ISO 7206-4:2010(E) and compare the results with those of the ASTM round-robin test. Note that a round-robin test is a test (including measurement, analysis, and experiment) in which several participating laboratories perform their independent tests by following the same set of conditions and compare the interlaboratory testing results. The CAD geometric model for the femoral stem used here is the one used for the ASTM round-robin test that is available for download at http://www.astm.org/committee/F04.htm. Figure 16.6 shows the hip stem model after being imported into COMSOL.
The Biodegradability Testing of Lubricants
Published in Leslie R. Rudnick, Synthetics, Mineral Oils, and Bio-Based Lubricants, 2020
Peter Lohmann, Ben Müller, Gerhard Gaule
Methods for testing biodegradation are biological tests. Almost every biological test method has a weak spot: biology itself. For instance, behavioral tests in neuroscience entail variations due to the individualism of test participants. Biodegradation tests also implicate variabilities due to an unpredictable composition of the inoculum used. Consequently, compared to usual methods in engineering, biodegradation tests are not very precise. To determine the precision of test methods, round robin tests are carried out. In these tests, several laboratories measure the same sample and compare their results. The results of such interlaboratory comparisons are two major statistical values, repeatability (r) and reproducibility (R). Repeatability refers to a single laboratory performing measurements under the same conditions, i.e. the same measurement procedure, the same observer, the same measuring instrument, used under the same conditions, and the same location (JCGM 100:2008). Reproducibility is defined as the closeness of the agreement between individual results obtained in the normal and correct operation of the same method on identical test material carried out under different conditions of measurement, e.g. different operator, different apparatus, and different laboratories (EN ISO 4259-2 2017). To compare different test methods, absolute reproducibility can be expressed as relative reproducibility, which can be calculated by absolute reproducibility related to typical results of the test method. The smaller the value of R, the more reliable is the result. For example, density and viscosity are very precise laboratory test methods in the lubricant industry with a relative reproducibility of about 0.2% and 0.6%, respectively (ASTM D7042-16 2016). In contrast, the four-ball test rather represents an imprecise test method expressed by a relative reproducibility of 30% (DIN 51350-2 2015).
A round-robin finite element analysis of human femur mechanics between seven participating laboratories with experimental validation
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
Daniel Kluess, Ehsan Soodmand, Andrea Lorenz, Dieter Pahr, Michael Schwarze, Robert Cichon, Patrick A. Varady, Sven Herrmann, Bernhard Buchmeier, Christian Schröder, Stefan Lehner, Maeruan Kebbach
A round-robin test requires a coordinator, a precisely defined task, specific and equal samples, and at least two participating laboratories. Although FEA is a common method in musculoskeletal research, we are not aware of any published round-robin test that considers the mechanics of long human bones. Helgason et al. have already proposed the development of a benchmark study in 2008 (Helgason et al. 2008). Only one comparative study on a different type of bone—the lumbar spine—has been published yet (Dreischarf et al. 2014). However, all the FE models compared in that study rely on different specimens; therefore, a direct comparison as desired in a round-robin test is not possible. Owing to this gap in the numerical biomechanical research on human bone, we decided to conduct a round-robin FEA that was organized within the Cluster “Numerical Simulation” of the Musculoskeletal Biomechanics Network (MSB-Net), which is a part of the Basic Research Section of the German Society for Orthopaedics and Traumatology (DGOU). The participating labs were asked to set up FE models and calculate a common task without knowing the experimental results a priori, using a human femur as the ground truth for geometry and mechanics.