TY - JOUR A1 - Sponagel, Stefan A1 - Adbay, U. A1 - Becker, E. A1 - Krozer, S. T1 - A possible cause of viscoelastic turbulence JF - Rheology : proceedings of the 8th International Congress of Rheology, held in Naples, Italy, September 1 - 5, 1980 / Hrsg. von Giovanni Astarita, Vol. 2 Y1 - 1980 SN - 0-306-40465-6 SP - 79 EP - 84 PB - Plenum Pr. CY - New York ER - TY - JOUR A1 - Kühn, Raoul-Roman A1 - Haugner, Werner A1 - Staat, Manfred A1 - Sponagel, Stefan T1 - A Two Phase Mixture Model based on Bone Observation N2 - An optimization method is developed to describe the mechanical behaviour of the human cancellous bone. The method is based on a mixture theory. A careful observation of the behaviour of the bone material leads to the hypothesis that the bone density is controlled by the principal stress trajectories (Wolff’s law). The basic idea of the developed method is the coupling of a scalar value via an eigenvalue problem to the principal stress trajectories. On the one hand this theory will permit a prediction of the reaction of the biological bone structure after the implantation of a prosthesis, on the other hand it may be useful in engineering optimization problems. An analytical example shows its efficiency. KW - Knochen KW - Knochenbildung KW - Knochenchirugie KW - Strukturanalyse KW - Schwammknochen KW - Knochendichte KW - Wolffsches Gesetz KW - bone structure KW - bone density KW - Wolff's Law KW - cancellous bone Y1 - 2004 ER - TY - JOUR A1 - Sponagel, Stefan A1 - Lutz, T. T1 - Aggregatelager JF - Kautschuk Gummi Kunststoffe. 43 (1990), H. 5 Y1 - 1990 SN - 0022-9520 SP - 397 EP - 406 ER - TY - JOUR A1 - Staat, Manfred A1 - Kühn, R. A1 - Hauger, W. A1 - Sponagel, Stefan T1 - An Interpretation of Wolff’s Law JF - Biomedizinische Technik. 49 (2004) Y1 - 2004 SN - 0932-4666 N1 - Ergänzungsband 2, Teil 2 SP - 1020 EP - 1021 ER - TY - JOUR A1 - Sponagel, Stefan T1 - Analytische Berechnung von Gummi- Metall- Verbindungen JF - Konstruktion : Zeitschrift für Produktentwicklung. 39 (1987), H. 4 Y1 - 1987 SN - 0373-3300 SP - 151 EP - 158 ER - TY - JOUR A1 - Sponagel, Stefan A1 - Baroud, G. A1 - Falk, R. A1 - Crookshank, M. T1 - Corrigendum to “Experimental and theoretical investigation of directional permeability of human vertebral cancellous bone for cement infiltration”. Baroud, G.; Falk, R.; Crookshank, M.; Sponagel, S.; Steffen, T. JF - Journal of Biomechanics. 37 (2004), H. 2 Y1 - 2004 SN - 0021-9290 SP - 1802 ER - TY - JOUR A1 - Sponagel, Stefan T1 - Der Mensch als Läufer JF - Orthopädie und Sport : [Bericht zum Stolberger Orthopädietag, 13. Juni 1998] Y1 - 1999 SN - 978-3-89124-540-8 N1 - Inhaltsverzeichnis unter http://www.m-m-sports.com/mm_objects/previews/978-3-89124-540-8p.pdf SP - 15 EP - 21 PB - Meyer & Meyer CY - Aachen ER - TY - JOUR A1 - Sponagel, Stefan A1 - Lutz, Th. T1 - Ein Beitrag zur Bestimmung der Haertewerte von Elastomeren JF - Kautschuk Gummi Kunststoffe. 43 (1990), H. 10 Y1 - 1990 SN - 0022-9520 SP - 861 EP - 865 ER - TY - JOUR A1 - Sponagel, Stefan A1 - Groling, G. T1 - Eine Bemerkung zum Beweis des π Theorems. G. Groling, S. Sponagel JF - Zeitschrift für angewandte Mathematik und Mechanik: ZAMM. 63 (1983) Y1 - 1983 SN - 0044-2267 N1 - weitere ISSN: 0946-8463 SP - T258 EP - T259 ER - TY - JOUR A1 - Sponagel, Stefan A1 - Müller, H. T1 - Exakte instationäre Lösungen der Navier-Stokes-Gleichung. H. Müller, S. Sponagel JF - Zeitschrift für angewandte Mathematik und Mechanik: ZAMM. 63 (1983) Y1 - 1983 SN - 0044-2267 N1 - weitere ISSN: 0946-8463 SP - T273 EP - T275 ER - TY - JOUR A1 - Staat, Manfred A1 - Sponagel, Stefan A1 - Nguyen, Nhu Huynh T1 - Experiment and material model for soft tissue materials JF - Constitutive models for rubber VI : proceedings of the sixth European Conference on Constitutive Models for Rubber, Dresden, Germany, 7 - 10 September 2009 / eds. Gert Heinrich ... Y1 - 2010 SN - 978-0-415-56327-7 SP - 465 EP - 470 PB - CRC Press CY - Boca Raton [u.a.] ER - TY - JOUR A1 - Sponagel, Stefan A1 - Baroud, G. A1 - Falk, R. A1 - Crookshank, M. T1 - Experimental and theoretical investigation of directional permeability of human vertebral cancellous bone for cement infiltration. G. Baroud, R. Falk, M. Crookshank, S. Sponagel, T. Steffen JF - Journal of Biomechanics. 37 (2004), H. 2 Y1 - 2004 SN - 0021-9290 SP - 189 EP - 196 ER - TY - BOOK A1 - Sponagel, Stefan T1 - Gummi-Metall-Bauteile Y1 - 1987 N1 - Universität Kaiserslautern, Dissertation CY - Kaiserslautern ER - TY - JOUR A1 - Sponagel, Stefan A1 - Spaltofski, R. A1 - Steinhilper, W. T1 - Hochmolekulare Additive für die Gleitlagerschmierung. Spaltofski, R.; Sponagel, S.; Steinhilper, W. JF - Tribologie und Schmierungstechnik. 35 (1988), H. 5 Y1 - 1988 SN - 0036-6218 SP - 236 EP - 241 ER - TY - JOUR A1 - Sponagel, Stefan A1 - Spaltofski, R. T1 - Hochmolekulare Zusätze verbessern die Leichtlaufeigenschaft und die Tragfähigkeit von Schmierfilmen / Sponagel, S. ; Spaltofski, R. JF - Mineralöltechnik. 32 (1987), H. 3 Y1 - 1987 SN - 0341-1893 SP - 28 S. ER - TY - JOUR A1 - Baroud, G. A1 - Wu, J.Z. A1 - Bohner, M A1 - Sponagel, Stefan A1 - Steffen, T. T1 - How to determine the permeability for cement infiltration into osteoporotic cancellous bone JF - Medical Engineering & Physics. 25 (2003), H. 4 N2 - Cement augmentation is an emerging surgical procedure in which bone cement is used to infiltrate and reinforce osteoporotic vertebrae. Although this infiltration procedure has been widely applied, it is performed empirically and little is known about the flow characteristics of cement during the injection process. We present a theoretical and experimental approach to investigate the intertrabecular bone permeability during the infiltration procedure. The cement permeability was considered to be dependent on time, bone porosity, and cement viscosity in our analysis. In order to determine the time-dependent permeability, ten cancellous bone cores were harvested from osteoporotic vertebrae, infiltrated with acrylic cement at a constant flow rate, and the pressure drop across the cores during the infiltration was measured. The viscosity dependence of the permeability was determined based on published experimental data. The theoretical model for the permeability as a function of bone porosity and time was then fit to the testing data. Our findings suggest that the intertrabecular bone permeability depends strongly on time. For instance, the initial permeability (60.89 mm4/N.s) reduced to approximately 63% of its original value within 18 seconds. This study is the first to analyze cement flow through osteoporotic bone. The theoretical and experimental models provided in this paper are generic. Thus, they can be used to systematically study and optimize the infiltration process for clinical practice. KW - Osteoporose KW - Permeabilität KW - Viskose Strömung KW - Viskosität KW - Vertebroplastie KW - Cement infiltration KW - Vertebroplasty KW - Osteoporosis KW - Permeability KW - Experiment KW - Analysis KW - Viscous flow Y1 - 2003 SN - 1350-4533 SP - 283 EP - 288 ER - TY - JOUR A1 - Sponagel, Stefan A1 - Unger, J. A1 - Spies, K. H. T1 - Härtebegriff im Zusammenhang mit Vernetzung, Bruchdehnung und Dauerfestigkeit eines Elastomers JF - Kautschuk Gummi Kunststoffe. 56 (2003), H. 11 Y1 - 2003 SN - 0948-3276 SP - 608 EP - 613 ER - TY - JOUR A1 - Sponagel, Stefan A1 - Akbay, U. A1 - Becker, E. T1 - Instability of plane Couette flow of viscoelastic liquids JF - Journal of non-Newtonian fluid mechanics. 18 (1985), H. 2 Y1 - 1985 SN - 0377-0257 SP - 123 EP - 141 ER - TY - JOUR A1 - Sponagel, Stefan A1 - Akbay, U. A1 - Becker, E. A1 - Krozer, S. T1 - Instability of slow viscometric flow JF - Mechanics Research Communications. 7 (1980), H. 4 Y1 - 1980 SN - 0093-6413 SP - 199 EP - 204 ER - TY - PAT A1 - Sponagel, Stefan A1 - Masberg, Mariane A1 - Hartmann, Jochen T1 - Kraftfahrzeugkühlwasserpumpe : Offenlegungsschrift DE19803739A1 ; Veröffentlichungstag im Patentblatt: 12.08.1999 Y1 - 1999 PB - Deutsches Patent- und Markenamt CY - München ER -