@article{GossmannThomasHorvathetal.2020, author = {Gossmann, Matthias and Thomas, Ulrich and Horv{\´a}th, Andr{\´a}s and Dragicevic, Elena and Stoelzle-Feix, Sonja and Jung, Alexander and Raman, Aravind Hariharan and Staat, Manfred and Linder, Peter}, title = {A higher-throughput approach to investigate cardiac contractility in vitro under physiological mechanical conditions}, series = {Journal of Pharmacological and Toxicological Methods}, volume = {105}, journal = {Journal of Pharmacological and Toxicological Methods}, number = {Article 106843}, publisher = {Elsevier}, address = {New York, NY}, doi = {10.1016/j.vascn.2020.106843}, year = {2020}, language = {en} } @article{HacklMuellerStaatetal.2016, author = {Hackl, Michael and M{\"u}ller, Lars-Peter and Staat, Manfred and Kahmann, Stephanie Lucina and Wegmann, Kilian}, title = {Proximal phalangeal neck fractures of the hand — a biomechanical comparison of three fixation techniques}, series = {Knee surgery, sports traumatology, arthroscopy}, volume = {Volume 24}, journal = {Knee surgery, sports traumatology, arthroscopy}, number = {Supplement 1}, publisher = {Springer}, address = {Berlin}, issn = {0942-2056}, doi = {10.1007/s00167-016-4080-7}, pages = {148 -- 149}, year = {2016}, abstract = {Plate osteosynthesis of displaced proximal phalangeal neck fractures of the hand allows early mobilization due to a stable internal fixation. Nevertheless, joint stiffness—because of soft tissue irritation—represents a common complication leading to high complication rates. Del Pinal et al. recently reported promising clinical results for a new, minimally invasive fixation technique with a cannulated headless intramedullary compression screw. Hence, the aim of this study was to compare plate fixation of proximal phalangeal neck fractures to less two less invasive techniques: Crossed k-wire fixation and intramedullary screw fixation. We hypothesized that these fixation techniques provide inferior stability when compared to plate osteosynthesis.}, language = {en} } @article{LinderBecklerDoerretal.2019, author = {Linder, Peter and Beckler, Matthias and Doerr, Leo and Stoelzle-Feix, Sonja and Fertig, Niels and Jung, Alexander and Staat, Manfred and Gossmann, Matthias}, title = {A new in vitro tool to investigate cardiac contractility under physiological mechanical conditions}, series = {Journal of Pharmacological and Toxicological Methods}, volume = {99}, journal = {Journal of Pharmacological and Toxicological Methods}, number = {Article number 106595}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1056-8719}, doi = {10.1016/j.vascn.2019.05.162}, year = {2019}, language = {en} } @article{StaatHeitzer2000, author = {Staat, Manfred and Heitzer, M.}, title = {Traglastanalyse - ein strukturmechanisches Verfahren zur Beurteilung von gerissenen Bauteilen und Verbindungen}, series = {Festigkeits- und Bruchverhalten von F{\"u}geverbindungen : 32. Tagung des DVM-Arbeitskreises Bruchvorg{\"a}nge ; 22. und 23. Februar 2000 in Berlin / Richard, H. A. [Hrsg]}, journal = {Festigkeits- und Bruchverhalten von F{\"u}geverbindungen : 32. Tagung des DVM-Arbeitskreises Bruchvorg{\"a}nge ; 22. und 23. Februar 2000 in Berlin / Richard, H. A. [Hrsg]}, publisher = {Deutscher Verband f{\"u}r Materialforschung und -pr{\"u}fung}, address = {Berlin}, pages = {183 -- 192}, year = {2000}, language = {de} } @article{StaatBallmann1989, author = {Staat, Manfred and Ballmann, J.}, title = {Zur Problematik tensorieller Verallgemeinerungen einachsiger nichtlinearer Materialgesetze}, series = {Zeitschrift f{\"u}r angewandte Mathematik und Mechanik : ZAMM. 69 (1989), H. 2}, journal = {Zeitschrift f{\"u}r angewandte Mathematik und Mechanik : ZAMM. 69 (1989), H. 2}, isbn = {0946-8463}, doi = {10.1515/9783112553169-006}, pages = {73 -- 81}, year = {1989}, language = {de} } @article{Staat1996, author = {Staat, Manfred}, title = {Problems and Chances for Probabilistic Fracture Mechanics in the Analysis of Steel Pressure Boundary Reliability}, series = {Technical feasibility and reliability of passive safety systems for nuclear power plants. Proceedings of an Advisory Group Meeting held in J{\"u}lich, 21-24 November 1994}, journal = {Technical feasibility and reliability of passive safety systems for nuclear power plants. Proceedings of an Advisory Group Meeting held in J{\"u}lich, 21-24 November 1994}, address = {Vienna}, pages = {43 -- 55}, year = {1996}, language = {en} } @article{ZhenLiangStaatetal.2024, author = {Zhen, Manghao and Liang, Yunpei and Staat, Manfred and Li, Quanqui and Li, Jianbo}, title = {Discontinuous fracture behaviors and constitutive model of sandstone specimens containing non-parallel prefabricated fissures under uniaxial compression}, series = {Theoretical and Applied Fracture Mechanics}, volume = {131}, journal = {Theoretical and Applied Fracture Mechanics}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0167-8442}, doi = {10.1016/j.tafmec.2024.104373}, pages = {Artikel 104373}, year = {2024}, abstract = {The deformation and damage laws of non-homogeneous irregular structural planes in rocks are the basis for studying the stability of rock engineering. To investigate the damage characteristics of rock containing non-parallel fissures, uniaxial compression tests and numerical simulations were conducted on sandstone specimens containing three non-parallel fissures inclined at 0°, 45° and 90° in this study. The characteristics of crack initiation and crack evolution of fissures with different inclinations were analyzed. A constitutive model for the discontinuous fractures of fissured sandstone was proposed. The results show that the fracture behaviors of fissured sandstone specimens are discontinuous. The stress-strain curves are non-smooth and can be divided into nonlinear crack closure stage, linear elastic stage, plastic stage and brittle failure stage, of which the plastic stage contains discontinuous stress drops. During the uniaxial compression test, the middle or ends of 0° fissures were the first to crack compared to 45° and 90° fissures. The end with small distance between 0° and 45° fissures cracked first, and the end with large distance cracked later. After the final failure, 0° fissures in all specimens were fractured, while 45° and 90° fissures were not necessarily fractured. Numerical simulation results show that the concentration of compressive stress at the tips of 0°, 45° and 90° fissures, as well as the concentration of tensile stress on both sides, decreased with the increase of the inclination angle. A constitutive model for the discontinuous fractures of fissured sandstone specimens was derived by combining the logistic model and damage mechanic theory. This model can well describe the discontinuous drops of stress and agrees well with the whole processes of the stress-strain curves of the fissured sandstone specimens.}, language = {en} } @article{KeutmannStaatLaack2018, author = {Keutmann, Sabine and Staat, Manfred and Laack, Walter van}, title = {Untersuchung der thermischen Auswirkung von therapeutischem Ultraschall}, volume = {7}, number = {10}, publisher = {Deutscher {\"A}rzte-Verl.}, address = {K{\"o}ln}, issn = {2193-5793}, pages = {518 -- 522}, year = {2018}, abstract = {Zusammenfassung: In der Orthop{\"a}die z{\"a}hlt der therapeutische Ultraschall als Mittel zur Pr{\"a}vention und Therapiebegleitung. Er hat mechanische, thermische und physiko-chemische Auswirkungen auf den menschlichen K{\"o}rper. Um mehr Erkenntnisse {\"u}ber die thermischen Auswirkungen zu erlangen, wurden Versuche an einem Hydrogel-Phantom und an Probanden durchgef{\"u}hrt. Dabei entstand eine signifikante Erw{\"a}rmung des Gewebes, welche beim Probandenversuch an der Oberfl{\"a}che und beim Hydrogelversuch in der Tiefe gemessen wurde. Summary: In orthopaedics, therapeutic ultrasound is a tool of prevention and therapy support. It has mechanical, thermal and physico-chemical effects on the human body. Tests with a hydrogel phantom and with human probands have been performed in order to obtain more knowledge about their thermal effects. Both tests measured temperature increases in cell tissue, on the surface with the human proband test and in depth with the hydrogel phantom test.}, language = {de} } @article{MichaelMayerWeberetal.2017, author = {Michael, Hackl and Mayer, Katharina and Weber, Mareike and Staat, Manfred and van Riet, Roger and Burkhart, Klau Josef and M{\"u}ller, Lars Peter and Wegmann, Kilian}, title = {Plate osteosynthesis of proximal ulna fractures : a biomechanical micromotion analysis}, series = {The journal of hand surgery}, volume = {42}, journal = {The journal of hand surgery}, number = {10}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0363-5023}, doi = {10.1016/j.jhsa.2017.05.014}, pages = {834.e1 -- 834.e7}, year = {2017}, language = {en} } @article{HacklBuessKammerlohretal.2021, author = {Hackl, Michael and Buess, Eduard and Kammerlohr, Sandra and Nacov, Julia and Staat, Manfred and Leschinger, Tim and M{\"u}ller, Lars P. and Wegmann, Kilian}, title = {A "comma sign"-directed subscapularis repair in anterosuperior rotator cuff tears yields biomechanical advantages in a cadaveric model}, series = {The american journal of sports medicine}, volume = {49}, journal = {The american journal of sports medicine}, number = {12}, publisher = {Sage}, address = {London}, issn = {1552-3365}, doi = {10.1177/03635465211031506}, pages = {3212 -- 3217}, year = {2021}, abstract = {Background: Additional stabilization of the "comma sign" in anterosuperior rotator cuff repair has been proposed to provide biomechanical benefits regarding stability of the repair. Purpose: This in vitro investigation aimed to investigate the influence of a comma sign-directed reconstruction technique for anterosuperior rotator cuff tears on the primary stability of the subscapularis tendon repair. Study Design: Controlled laboratory study. Methods: A total of 18 fresh-frozen cadaveric shoulders were used in this study. Anterosuperior rotator cuff tears (complete full-thickness tear of the supraspinatus and subscapularis tendons) were created, and supraspinatus repair was performed with a standard suture bridge technique. The subscapularis was repaired with either a (1) single-row or (2) comma sign technique. A high-resolution 3D camera system was used to analyze 3-mm and 5-mm gap formation at the subscapularis tendon-bone interface upon incremental cyclic loading. Moreover, the ultimate failure load of the repair was recorded. A Mann-Whitney test was used to assess significant differences between the 2 groups. Results: The comma sign repair withstood significantly more loading cycles than the single-row repair until 3-mm and 5-mm gap formation occurred (P≤ .047). The ultimate failure load did not reveal any significant differences when the 2 techniques were compared (P = .596). Conclusion: The results of this study show that additional stabilization of the comma sign enhanced the primary stability of subscapularis tendon repair in anterosuperior rotator cuff tears. Although this stabilization did not seem to influence the ultimate failure load, it effectively decreased the micromotion at the tendon-bone interface during cyclic loading. Clinical Relevance: The proposed technique for stabilization of the comma sign has shown superior biomechanical properties in comparison with a single-row repair and might thus improve tendon healing. Further clinical research will be necessary to determine its influence on the functional outcome.}, language = {en} } @article{LeschingerBirgelHackletal.2019, author = {Leschinger, Tim and Birgel, Stefan and Hackl, Michael and Staat, Manfred and M{\"u}ller, Lars Peter and Wegmann, Kilian}, title = {A musculoskeletal shoulder simulation of moment arms and joint reaction forces after medialization of the supraspinatus footprint in rotator cuff repair}, series = {Computer Methods in Biomechanics and Biomedical Engineering}, journal = {Computer Methods in Biomechanics and Biomedical Engineering}, number = {Early view}, publisher = {Taylor \& Francis}, address = {London}, doi = {10.1080/10255842.2019.1572749}, year = {2019}, language = {en} } @article{JungMuellerStaat2019, author = {Jung, Alexander and M{\"u}ller, Wolfram and Staat, Manfred}, title = {Optimization of the flight technique in ski jumping: the influence of wind}, number = {Early view}, publisher = {Elsevier}, address = {Amsterdam}, doi = {10.1016/j.jbiomech.2019.03.023}, year = {2019}, language = {en} } @article{HorbachDuongStaat2017, author = {Horbach, Andreas and Duong, Minh Tuan and Staat, Manfred}, title = {Modelling of compressible and orthotropic surgical mesh implants based on optical deformation measurement}, series = {Journal of the mechanical behavior of biomedical materials}, volume = {74}, journal = {Journal of the mechanical behavior of biomedical materials}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1751-6161}, doi = {10.1016/j.jmbbm.2017.06.012}, pages = {400 -- 410}, year = {2017}, language = {en} } @article{DuongNguyenStaat2015, author = {Duong, Minh Tuan and Nguyen, Nhu Huynh and Staat, Manfred}, title = {Physical response of hyperelastic models for composite materials and soft tissues}, series = {Asia pacific journal on computational engineering}, volume = {2}, journal = {Asia pacific journal on computational engineering}, number = {3 (December 2015)}, issn = {2196-1166}, doi = {10.1186/s40540-015-0015-x}, pages = {1 -- 18}, year = {2015}, language = {en} } @article{StaatHeitzer1999, author = {Staat, Manfred and Heitzer, M.}, title = {FEM-computation of load carrying capacity of highly loaded passive components by direct methods. Heitzer, M. ; Staat, M.}, series = {Nuclear Engineering and Design. 193 (1999), H. 3}, journal = {Nuclear Engineering and Design. 193 (1999), H. 3}, isbn = {0029-5493}, pages = {349 -- 358}, year = {1999}, language = {en} } @article{Staat1991, author = {Staat, Manfred}, title = {Versagenswahrscheinlichkeit der Prim{\"a}rkreisdruckumschließung eines HTR-Moduls zur Prozeßw{\"a}rmegewinnung unter St{\"o}rfallbedingungen}, series = {Jahrestagung Kerntechnik '91 / Kerntechnische Gesellschaft e.V. ; Deutsches Atomforum e.V}, journal = {Jahrestagung Kerntechnik '91 / Kerntechnische Gesellschaft e.V. ; Deutsches Atomforum e.V}, publisher = {INFORUM}, address = {Bonn}, pages = {123 -- 126}, year = {1991}, language = {de} } @article{TranStaat2010, author = {Tran, Thanh Ngoc and Staat, Manfred}, title = {Shakedown analysis of two dimensional structures by an edge-based smoothed finite element method}, pages = {1 -- 7}, year = {2010}, language = {en} } @article{LeschingerBeschAydinetal.2019, author = {Leschinger, Tim and Besch, Katharina and Aydin, Cansu and Staat, Manfred and Scaal, Martin and M{\"u}ller, Lars Peter and Wegmann, Kilian}, title = {Irreparable rotator cuff tears: a biomechanical comparison of superior capsuloligamentous complex reconstruction techniques and an interposition graft technique}, series = {The Orthopaedic Journal of Sports Medicine}, volume = {7}, journal = {The Orthopaedic Journal of Sports Medicine}, number = {8}, doi = {10.1177/2325967119864590}, pages = {1 -- 5}, year = {2019}, language = {en} } @article{LaackLeversStaat2013, author = {Laack, Walter van and Levers, A. and Staat, Manfred}, title = {Gonarthrosetherapie auf Kernspinresonanzbasis mit MBST-Vierjahresbeobachtungen}, series = {Orthop{\"a}dische Nachrichten : Zeitung f{\"u}r Orthop{\"a}die und Unfallchirurgie. 2013, H. 7/8}, journal = {Orthop{\"a}dische Nachrichten : Zeitung f{\"u}r Orthop{\"a}die und Unfallchirurgie. 2013, H. 7/8}, publisher = {Biermann}, address = {K{\"o}ln}, issn = {1437-2193}, pages = {13}, year = {2013}, language = {de} } @article{TranStaat2020, author = {Tran, Ngoc Trinh and Staat, Manfred}, title = {Direct plastic structural design under lognormally distributed strength by chance constrained programming}, series = {Optimization and Engineering}, volume = {21}, journal = {Optimization and Engineering}, number = {1}, publisher = {Springer Nature}, address = {Cham}, issn = {1573-2924}, doi = {10.1007/s11081-019-09437-2}, pages = {131 -- 157}, year = {2020}, abstract = {We propose the so-called chance constrained programming model of stochastic programming theory to analyze limit and shakedown loads of structures under random strength with a lognormal distribution. A dual chance constrained programming algorithm is developed to calculate simultaneously both the upper and lower bounds of the plastic collapse limit and the shakedown limit. The edge-based smoothed finite element method (ES-FEM) is used with three-node linear triangular elements.}, language = {en} } @article{StaatHeitzerHicken1998, author = {Staat, Manfred and Heitzer, M. and Hicken, E.F.}, title = {LISA, ein europ{\"a}isches Projekt zur direkten Berechnung der Tragf{\"a}higkeit duktiler Strukturen.}, year = {1998}, language = {de} } @article{Staat2012, author = {Staat, Manfred}, title = {Limit and shakedown analysis under uncertainty}, series = {Tap chi Khoa hoc \& ung dung - Dai hoc Ton Duc Thang}, volume = {19}, journal = {Tap chi Khoa hoc \& ung dung - Dai hoc Ton Duc Thang}, pages = {45 -- 47}, year = {2012}, language = {en} } @article{Staat1992, author = {Staat, Manfred}, title = {Probabilistische Bewertung des bruchmechanischen Verhaltens der Prim{\"a}rkreisdruckumschließung eines HTR-Moduls}, year = {1992}, language = {de} } @article{LeversStaatLaack2016, author = {Levers, A. and Staat, Manfred and Laack, Walter van}, title = {Analysis of the long-term effect of the MBST® nuclear magnetic resonance therapy on gonarthrosis}, series = {Orthopedic Practice}, volume = {47}, journal = {Orthopedic Practice}, number = {11}, pages = {521 -- 528}, year = {2016}, language = {en} } @article{UllrichGrottkeRossaintetal.2010, author = {Ullrich, Sebastian and Grottke, Oliver and Rossaint, Rolf and Staat, Manfred and Deserno, Thomas M. and Kuhlen, Torsten}, title = {Virtual Needle Simulation with Haptics for Regional Anaesthesia}, pages = {1 -- 3}, year = {2010}, language = {en} } @article{CiobanuStaatRahimi2008, author = {Ciobanu, Octavian and Staat, Manfred and Rahimi, Alireza}, title = {The use of open source software in biomechanical finite element analysis}, series = {Buletinul Institutului Politehnic din Ia{\c{s}}i / Universitatea Tehnică Gh. Asachi, Ia{\c{s}}i Secţia 5, Construcţii de ma{\c{s}}ini = Machine construction = Bulletin of the Polytechnic Institute of Jassy = Izvestija Jasskogo Politechničeskogo Instituta}, volume = {54}, journal = {Buletinul Institutului Politehnic din Ia{\c{s}}i / Universitatea Tehnică Gh. Asachi, Ia{\c{s}}i Secţia 5, Construcţii de ma{\c{s}}ini = Machine construction = Bulletin of the Polytechnic Institute of Jassy = Izvestija Jasskogo Politechničeskogo Instituta}, number = {7/8}, issn = {1011-2855}, pages = {213 -- 220}, year = {2008}, language = {en} } @article{Staat1996, author = {Staat, Manfred}, title = {Probabilistic assessment of the fracture mechanics behaviour of an HTR-module primary circuit pressure boundary}, series = {Nuclear Engineering and Design. 160 (1996), H. 1-2}, journal = {Nuclear Engineering and Design. 160 (1996), H. 1-2}, isbn = {0029-5493}, pages = {221 -- 236}, year = {1996}, language = {en} } @article{StaatHeitzer2000, author = {Staat, Manfred and Heitzer, M.}, title = {Reliability Analysis of Elasto-Plastic Structures under Variable Loads}, series = {Inelastic analysis of structures under variable loads : theory and engineering applications / Maier, G.; Weichert, D. [ed]}, journal = {Inelastic analysis of structures under variable loads : theory and engineering applications / Maier, G.; Weichert, D. [ed]}, publisher = {Kluwer Academic Publ.}, address = {Dordrecht}, isbn = {0-7923-6645-X}, pages = {269 -- 288}, year = {2000}, language = {en} } @article{Staat1995, author = {Staat, Manfred}, title = {Reliability of an HTR-module primary circuit pressure boundary Influences, sensitivity, and comparison with a PWR}, series = {Nuclear Engineering and Design. 158 (1995), H. 2-3}, journal = {Nuclear Engineering and Design. 158 (1995), H. 2-3}, isbn = {0029-5493}, pages = {333 -- 340}, year = {1995}, language = {en} } @article{Staat1991, author = {Staat, Manfred}, title = {Versagenswahrscheinlichkeit der Prim{\"a}rkreisdruckumschließung eines HTR-Moduls zur Prozeßw{\"a}rmegewinnung unter St{\"o}rfallbedingungen bei verschiedenen Versagensmoden}, year = {1991}, language = {de} } @article{PhamStaat2013, author = {Pham, Phu Tinh and Staat, Manfred}, title = {An Upper Bound Algorithm for Limit and Shakedown Analysis of Bounded Linearly Kinematic Hardening Structures}, series = {Limit State of Materials and Structures : Direct Methods 2. Saxc{\´e}, G{\´e}ry de (Hrsg.)}, journal = {Limit State of Materials and Structures : Direct Methods 2. Saxc{\´e}, G{\´e}ry de (Hrsg.)}, publisher = {Springer}, address = {Dordrecht}, isbn = {978-94-007-5424-9}, pages = {71 -- 87}, year = {2013}, language = {en} } @article{StaatVu2012, author = {Staat, Manfred and Vu, Duc Khoi}, title = {Limit analysis of flaws in pressurized pipes and cylindrical vessels Part II: Circumferential defects}, series = {Engineering Fracture Mechanics ; 97(2013), H. 1}, volume = {97}, journal = {Engineering Fracture Mechanics ; 97(2013), H. 1}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0013-7944}, doi = {10.1016/j.engfracmech.2012.05.017}, pages = {314 -- 333}, year = {2012}, abstract = {Upper and lower bound theorems of limit analyses have been presented in part I of the paper. Part II starts with the finite element discretization of these theorems and demonstrates how both can be combined in a primal-dual optimization problem. This recently proposed numerical method is used to guide the development of a new class of closed-form limit loads for circumferential defects, which show that only large defects contribute to plastic collapse with a rapid loss of strength with increasing crack sizes. The formulae are compared with primal-dual FEM limit analyses and with burst tests. Even closer predictions are obtained with iterative limit load solutions for the von Mises yield function and for the Tresca yield function. Pressure loading of the faces of interior cracks in thick pipes reduces the collapse load of circumferential defects more than for axial flaws. Axial defects have been treated in part I of the paper.}, language = {en} } @article{SchierenKleinschmidtSchmutzetal.2019, author = {Schieren, Mark and Kleinschmidt, Joris and Schmutz, Axel and Loop, Torsten and Gatzweiler, Karl-Heinz and Staat, Manfred and Wappler, Frank and Defosse, Jerome}, title = {Comparison of forces acting on maxillary incisors during tracheal intubation with different laryngoscopy techniques: a blinded manikin study}, series = {Anaesthesia}, volume = {74}, journal = {Anaesthesia}, number = {12}, publisher = {Wiley-Blackwell}, address = {Oxford}, isbn = {1365-2044}, doi = {10.1111/anae.14815}, year = {2019}, language = {en} } @article{Staat2021, author = {Staat, Manfred}, title = {An extension strain type Mohr-Coulomb criterion}, series = {Rock mechanics and rock engineering}, volume = {54}, journal = {Rock mechanics and rock engineering}, number = {12}, publisher = {Springer Nature}, address = {Cham}, issn = {1434-453X}, doi = {10.1007/s00603-021-02608-7}, pages = {6207 -- 6233}, year = {2021}, abstract = {Extension fractures are typical for the deformation under low or no confining pressure. They can be explained by a phenomenological extension strain failure criterion. In the past, a simple empirical criterion for fracture initiation in brittle rock has been developed. In this article, it is shown that the simple extension strain criterion makes unrealistic strength predictions in biaxial compression and tension. To overcome this major limitation, a new extension strain criterion is proposed by adding a weighted principal shear component to the simple criterion. The shear weight is chosen, such that the enriched extension strain criterion represents the same failure surface as the Mohr-Coulomb (MC) criterion. Thus, the MC criterion has been derived as an extension strain criterion predicting extension failure modes, which are unexpected in the classical understanding of the failure of cohesive-frictional materials. In progressive damage of rock, the most likely fracture direction is orthogonal to the maximum extension strain leading to dilatancy. The enriched extension strain criterion is proposed as a threshold surface for crack initiation CI and crack damage CD and as a failure surface at peak stress CP. Different from compressive loading, tensile loading requires only a limited number of critical cracks to cause failure. Therefore, for tensile stresses, the failure criteria must be modified somehow, possibly by a cut-off corresponding to the CI stress. Examples show that the enriched extension strain criterion predicts much lower volumes of damaged rock mass compared to the simple extension strain criterion.}, language = {en} } @article{BhattaraiStaat2018, author = {Bhattarai, Aroj and Staat, Manfred}, title = {Computational comparison of different textile implants to correct apical prolapse in females}, series = {Current Directions in Biomedical Engineering}, volume = {4}, journal = {Current Directions in Biomedical Engineering}, number = {1}, publisher = {De Gruyter}, address = {Berlin}, doi = {10.1515/cdbme-2018-0159}, pages = {661 -- 664}, year = {2018}, abstract = {Prosthetic textile implants of different shapes, sizes and polymers are used to correct the apical prolapse after hysterectomy (removal of the uterus). The selection of the implant before or during minimally invasive surgery depends on the patient's anatomical defect, intended function after reconstruction and most importantly the surgeon's preference. Weakness or damage of the supporting tissues during childbirth, menopause or previous pelvic surgeries may put females in higher risk of prolapse. Numerical simulations of reconstructed pelvic floor with weakened tissues and organ supported by textile product models: DynaMesh®-PRS soft, DynaMesh®-PRP soft and DynaMesh®-CESA from FEG Textiletechnik mbH, Germany are compared.}, language = {en} } @article{HorbachStaat2018, author = {Horbach, Andreas and Staat, Manfred}, title = {Optical strain measurement for the modeling of surgical meshes and their porosity}, series = {Current Directions in Biomedical Engineering}, volume = {Band 4}, journal = {Current Directions in Biomedical Engineering}, number = {1}, publisher = {De Gruyter}, address = {Berlin}, issn = {2364-5504}, doi = {10.1515/cdbme-2018-0045}, pages = {181 -- 184}, year = {2018}, abstract = {The porosity of surgical meshes makes them flexible for large elastic deformation and establishes the healing conditions of good tissue in growth. The biomechanic modeling of orthotropic and compressible materials requires new materials models and simulstaneoaus fit of deformation in the load direction as well as trannsversely to to load. This nonlinear modeling can be achieved by an optical deformation measurement. At the same time the full field deformation measurement allows the dermination of the change of porosity with deformation. Also the socalled effective porosity, which has been defined to asses the tisssue interatcion with the mesh implants, can be determined from the global deformation of the surgical meshes.}, language = {en} }