@article{Staat2000,
  author    = {Staat, Manfred},
  title     = {Basis Reduction for the Shakedown Problem for Bounded Kinematic Hardening Material},
  year      = {2000},
  abstract  = {Limit and shakedown analysis are effective methods for assessing the load carrying capacity of a given structure. The elasto-plastic behavior of the structure subjected to loads varying in a given load domain is characterized by the shakedown load factor, defined as the maximum factor which satisfies the sufficient conditions stated in the corresponding static shakedown theorem. The finite element dicretization of the problem may lead to very large convex optimization. For the effective solution a basis reduction method has been developed that makes use of the special problem structure for perfectly plastic material. The paper proposes a modified basis reduction method for direct application to the two-surface plasticity model of bounded kinematic hardening material. The considered numerical examples show an enlargement of the load carrying capacity due to bounded hardening.},
  subject      = {Finite-Elemente-Methode},
  language  = {en}
}
@article{Staat2001,
  author    = {Staat, Manfred},
  title     = {LISA - a European project for FEM-based limit and shakedown analysis},
  year      = {2001},
  abstract  = {The load-carrying capacity or the safety against plastic limit states are the central questions in the design of structures and passive components in the apparatus engineering. A precise answer is most simply given by limit and shakedown analysis. These methods can be based on static and kinematic theorems for lower and upper bound analysis. Both may be formulated as optimization problems for finite element discretizations of structures. The problems of large-scale analysis and the extension towards realistic material modelling will be solved in a European research project. Limit and shakedown analyses are briefly demonstrated with illustrative examples.},
  subject      = {Einspielen <Werkstoff>},
  language  = {en}
}
@article{Staat2000,
  author    = {Staat, Manfred},
  title     = {Direct FEM Limit and Shakedown Analysis with Uncertain Data},
  year      = {2000},
  abstract  = {The structural reliability with respect to plastic collapse or to inadaptation is formulated on the basis of the lower bound limit and shakedown theorems. A direct definition of the limit state function is achieved which permits the use of the highly effective first order reliability methods (FORM) is achieved. The theorems are implemented into a general purpose FEM program in a way capable of large-scale analysis. The limit state function and its gradient are obtained from a mathematical optimization problem. This direct approach reduces considerably the necessary knowledge of uncertain technological input data, the computing time, and the numerical error, leading to highly effective and precise reliability analyses.},
  subject      = {Finite-Elemente-Methode},
  language  = {en}
}
@article{VuStaat2004,
  author    = {Vu, Duc-Khoi and Staat, Manfred},
  title     = {An algorithm for shakedown analysis of structure with temperature dependent yield stress},
  year      = {2004},
  abstract  = {This work is an attempt to answer the question: How to use convex programming in shakedown analysis of structures made of materials with temperature-dependent properties. Based on recently established shakedown theorems and formulations, a dual relationship between upper and lower bounds of the shakedown limit load is found, an algorithmfor shakedown analysis is proposed. While the original problem is neither convex nor concave, the algorithm presented here has the advantage of employing convex programming tools.},
  subject      = {Einspielen <Werkstoff>},
  language  = {en}
}
@article{FrotscherKochStaat2015,
  author    = {Frotscher, Ralf and Koch, Jan-Peter and Staat, Manfred},
  title     = {Computational investigation of drug action on human-induced stem cell derived cardiomyocytes},
  series = {Journal of biomechanical engineering},
  volume    = {Vol. 137},
  journal   = {Journal of biomechanical engineering},
  number    = {iss. 7},
  publisher = {ASME},
  address   = {New York},
  issn      = {1528-8951 (E-Journal); 0148-0731 (Print)},
  doi       = {10.1115/1.4030173},
  pages     = {071002-1 -- 071002-7},
  year      = {2015},
  language  = {en}
}
@article{DuongNguyenTranetal.2015,
  author    = {Duong, Minh Tuan and Nguyen, Nhu Huynh and Tran, Thanh Ngoc and Tolba, R. H. and Staat, Manfred},
  title     = {Influence of refrigerated storage on tensile mechanical properties of porcine liver and spleen},
  series = {International biomechanics},
  volume    = {Vol. 2},
  journal   = {International biomechanics},
  number    = {Iss. 1},
  publisher = {Taylor \& Francis},
  address   = {London},
  issn      = {2333-5432},
  doi       = {10.1080/23335432.2015.1049295},
  pages     = {79 -- 88},
  year      = {2015},
  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{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{HacklKahmannWegmannetal.2016,
  author    = {Hackl, Michael and Kahmann, Stephanie Lucina and Wegmann, Kilian and Ries, Christian and Staat, Manfred and M{\"u}ller, Lars-Peter},
  title     = {Shortening osteotomy of the proximal radius — a treatment option for isolated osteoarthritis of the lateral column of the elbow joint?},
  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     = {128 -- 129},
  year      = {2016},
  abstract  = {Treatment of posttraumatic osteoarthritis of the radial column of the elbow joint remains a challenging yet common issue. While partial joint replacement leads to high revision rates, radial head excision has shown to severely increase joint instability. Shortening osteotomy of the radius could be an option to decrease the contact pressure of the radiohumeral joint and thereby pain levels without causing valgus instability. Hence, the aim of this biomechanical study was to evaluate the effects of radial shortening on axial load distribution and valgus stability of the elbow joint.},
  language  = {en}
}
@article{HacklLeschingerStaatetal.2016,
  author    = {Hackl, Michael and Leschinger, T. and Staat, Manfred and M{\"u}ller, Lars-Peter and Wegmann, Kilian},
  title     = {Reconstruction of the interosseous membrane in the Essex Lopresti lesion — a biomechanical evaluation},
  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     = {130 -- 131},
  year      = {2016},
  abstract  = {Surgical reconstruction of the interosseous membrane (IOM) could restore longitudinal forearm stability to avoid persisting disability due to capituloradial and ulnocarpal impingement in Essex Lopresti lesions. This biomechanical study aimed to assess longitudinal forearm stability of intact specimens, after sectioning of the IOM and after reconstruction with a TightRope construct using either a single or double bundle technique.},
  language  = {en}
}
@article{WegmannHacklStaatetal.2016,
  author    = {Wegmann, Kilian and Hackl, Michael and Staat, Manfred and Mayer, Katharina and M{\"u}ller, Lars-Peter},
  title     = {Double plate osteosynthesis of proximal ulna fractures: biomechanical and clinical results},
  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/s00167-016-4079-0},
  pages     = {58 -- 59},
  year      = {2016},
  abstract  = {While plate fixation of proximal ulna fractures might lead to superior clinical results compared to tension band wiring, regular plates represent an established risk factor for wound complications. The olecranon double plates (Medartis, Basel, CH) might decrease complications related to the osteosynthesis because of their low profile and better anatomical fit. This study aimed to evaluate the biomechanical performance and clinical results of the olecranon double plates.},
  language  = {en}
}
@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{HacklAndermahrStaatetal.2017,
  author    = {Hackl, M. and Andermahr, J. and Staat, Manfred and Bremer, I. and Borggrefe, J. and Prescher, A. and M{\"u}ller, L. P. and Wegmann, K.},
  title     = {Suture button reconstruction of the central band of the interosseous membrane in Essex-Lopresti lesions: a comparative biomechanical investigation},
  series = {The Journal of Hand Surgery (European Volume)},
  volume    = {42},
  journal   = {The Journal of Hand Surgery (European Volume)},
  number    = {4},
  publisher = {Sage},
  address   = {London},
  issn      = {2043-6289 (Online)},
  doi       = {10.1177/1753193416665943},
  pages     = {370 -- 376},
  year      = {2017},
  language  = {en}
}
@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{HacklWegmannKahmannetal.2017,
  author    = {Hackl, Michael and Wegmann, Kilian and Kahmann, Stephanie Lucina and Heinze, Nicolai and Staat, Manfred and Neiss, Wolfram F. and Scaal, Martin and M{\"u}ller, Lars P.},
  title     = {Radial shortening osteotomy reduces radiocapitellar contact pressures while preserving valgus stability of the elbow},
  series = {Knee Surgery, Sports Traumatology, Arthroscopy},
  volume    = {25},
  journal   = {Knee Surgery, Sports Traumatology, Arthroscopy},
  number    = {7},
  publisher = {Springer},
  address   = {Berlin},
  issn      = {1433-7347},
  doi       = {10.1007/s00167-017-4468-z},
  pages     = {2280 -- 2288},
  year      = {2017},
  language  = {en}
}
@article{CiritsisHorbachStaatetal.2018,
  author    = {Ciritsis, Alexander and Horbach, Andreas and Staat, Manfred and Kuhl, Christiane K. and Kraemer, Nils Andreas},
  title     = {Porosity and tissue integration of elastic mesh implants evaluated in vitro and in vivo},
  series = {Journal of Biomedical Materials Research: Part B: Applied Biomaterials},
  volume    = {106},
  journal   = {Journal of Biomedical Materials Research: Part B: Applied Biomaterials},
  number    = {2},
  publisher = {Wiley},
  address   = {New York, NY},
  issn      = {1552-4981},
  doi       = {10.1002/jbm.b.33877},
  pages     = {827 -- 833},
  year      = {2018},
  abstract  = {Purpose In vivo, a loss of mesh porosity triggers scar tissue formation and restricts functionality. The purpose of this study was to evaluate the properties and configuration changes as mesh deformation and mesh shrinkage of a soft mesh implant compared with a conventional stiff mesh implant in vitro and in a porcine model. Material and Methods Tensile tests and digital image correlation were used to determine the textile porosity for both mesh types in vitro. A group of three pigs each were treated with magnetic resonance imaging (MRI) visible conventional stiff polyvinylidene fluoride meshes (PVDF) or with soft thermoplastic polyurethane meshes (TPU) (FEG Textiltechnik mbH, Aachen, Germany), respectively. MRI was performed with a pneumoperitoneum at a pressure of 0 and 15 mmHg, which resulted in bulging of the abdomen. The mesh-induced signal voids were semiautomatically segmented and the mesh areas were determined. With the deformations assessed in both mesh types at both pressure conditions, the porosity change of the meshes after 8 weeks of ingrowth was calculated as an indicator of preserved elastic properties. The explanted specimens were examined histologically for the maturity of the scar (collagen I/III ratio). Results In TPU, the in vitro porosity increased constantly, in PVDF, a loss of porosity was observed under mild stresses. In vivo, the mean mesh areas of TPU were 206.8 cm2 (± 5.7 cm2) at 0 mmHg pneumoperitoneum and 274.6 cm2 (± 5.2 cm2) at 15 mmHg; for PVDF the mean areas were 205.5 cm2 (± 8.8 cm2) and 221.5 cm2 (± 11.8 cm2), respectively. The pneumoperitoneum-induced pressure increase resulted in a calculated porosity increase of 8.4\% for TPU and of 1.2\% for PVDF. The mean collagen I/III ratio was 8.7 (± 0.5) for TPU and 4.7 (± 0.7) for PVDF. Conclusion The elastic properties of TPU mesh implants result in improved tissue integration compared to conventional PVDF meshes, and they adapt more efficiently to the abdominal wall. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 827-833, 2018.},
  language  = {en}
}
@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{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{BhattaraiJabbariAndingetal.2018,
  author    = {Bhattarai, Aroj and Jabbari, Medisa and Anding, Ralf and Staat, Manfred},
  title     = {Surgical treatment of vaginal vault prolapse using different prosthetic mesh implants: a finite element analysis},
  series = {tm - Technisches Messen},
  volume    = {85},
  journal   = {tm - Technisches Messen},
  number    = {5},
  publisher = {De Gruyter},
  address   = {Berlin},
  issn      = {2196-7113},
  doi       = {10.1515/teme-2017-0115},
  pages     = {331 -- 342},
  year      = {2018},
  abstract  = {Particularly multiparous elderly women may suffer from vaginal vault prolapse after hysterectomy due to weak support from lax apical ligaments. A decreased amount of estrogen and progesterone in older age is assumed to remodel the collagen thereby reducing tissue stiffness. Sacrocolpopexy is either performed as open or laparoscopic surgery using prosthetic mesh implants to substitute lax ligaments. Y-shaped mesh models (DynaMesh, Gynemesh, and Ultrapro) are implanted in a 3D female pelvic floor finite element model in the extraperitoneal space from the vaginal cuff to the first sacral (S1) bone below promontory. Numerical simulations are conducted during Valsalva maneuver with weakened tissues modeled by reduced tissue stiffness. Tissues are modeled as incompressible, isotropic hyperelastic materials whereas the meshes are modeled either as orthotropic linear elastic or as isotropic hyperlastic materials. The positions of the vaginal cuff and the bladder base are calculated from the pubococcygeal line for female pelvic floor at rest, for prolapse and after repair using the three meshes. Due to mesh mechanics and mesh pore deformation along the loaded direction, the DynaMesh with regular rectangular mesh pores is found to provide better mechanical support to the organs than the Gynemesh and the Ultrapro with irregular hexagonal mesh pores. Insbesondere {\"a}ltere, mehrgeb{\"a}hrende Frauen leiden h{\"a}ufiger an einem Scheidenvorfall nach einer Hysterektomie aufgrund der schwachen Unterst{\"u}tzung durch laxe apikale B{\"a}nder. Es wird angenommen, dass eine verringerte Menge an {\"O}strogen und Progesteron im h{\"o}heren Alter das Kollagen umformt, wodurch die Gewebesteifigkeit reduziert wird. Die Sakrokolpopexie ist eine offene oder laparoskopische Operation, die mit prothetischen Netzimplantaten durchgef{\"u}hrt wird, um laxe B{\"a}nder zu ersetzen. Y-f{\"o}rmige Netzmodelle (DynaMesh, Gynemesh und Ultrapro) werden in einem 3D-Modell des weiblichen Beckenbodens im extraperitonealen Raum vom Vaginalstumpf bis zum Promontorium implantiert. Numerische Simulationen werden w{\"a}hrend des Valsalva-Man{\"o}vers mit geschw{\"a}chtem Gewebe durchgef{\"u}hrt, das durch eine reduzierte Gewebesteifigkeit modelliert wird. Die Gewebe werden als inkompressible, isotrop hyperelastische Materialien modelliert, w{\"a}hrend die Netze entweder als orthotrope linear elastische oder als isotrope hyperlastische Materialien modelliert werden. Die Positionen des Vaginalstumpfs, der Blase und der Harnr{\"o}hrenachse werden anhand der Pubococcygeallinie aus der Ruhelage, f{\"u}r den Prolaps und nach der Reparatur unter Verwendung der drei Netze berechnet. Aufgrund der Netzmechanik und der Netzporenverformung bietet das DynaMesh mit regelm{\"a}ßigen rechteckigen Netzporen eine bessere mechanische Unterst{\"u}tzung und eine Neupositionierung des Scheidengew{\"o}lbes, der Blase und der Urethraachse als Gynemesh und Ultrapro mit unregelm{\"a}ßigen hexagonalen Netzporen.},
  language  = {en}
}
@article{BirgelLeschingerWegmannetal.2018,
  author    = {Birgel, Stefan and Leschinger, Tim and Wegmann, Kilian and Staat, Manfred},
  title     = {Calculation of muscle forces and joint reaction loads in the shoulder area via an OpenSim based computer model},
  series = {tm - Technisches Messen},
  volume    = {85},
  journal   = {tm - Technisches Messen},
  number    = {5},
  publisher = {De Gruyter},
  address   = {Berlin},
  issn      = {2196-7113},
  doi       = {10.1515/teme-2017-0114},
  pages     = {321 -- 330},
  year      = {2018},
  abstract  = {Using the OpenSim software and verified anatomical data, a computer model for the calculation of biomechanical parameters is developed and used to determine the effect of a reattachment of the Supraspinatus muscle with a medial displacement of the muscle attachment point, which may be necessary for a rupture of the supraspinatus tendon. The results include the influence of the operation on basic biomechanical parameters such as the lever arm, as well as the calculated the muscle activations for the supraspinatus and deltoid. In addition, the influence on joint stability is examined by an analysis of the joint reaction force. The study provides a detailed description of the used model, as well as medical findings to a reattachment of the supraspinatus. Mit der Software OpenSim und {\"u}berpr{\"u}ften anatomischen Daten wird ein Computermodell zur Berechnung von biomechanischen Parametern entwickelt und genutzt, um den Effekt einer Refixierung des Supraspinatusmuskels mit einer medialen Verschiebung des Muskelansatzpunktes zu ermitteln, wie sie unter anderem nach einem Riss der Supraspinatussehne notwendig sein kann. Die Ergebnisse umfassen hierbei den Einfluss der Operation auf grundlegende biomechanische Parameter wie den Hebelarm sowie die berechneten Muskelaktivierungen f{\"u}r den Supraspinatus und Deltoideus. Zus{\"a}tzlich wird der Einfluss auf die Gelenkstabilit{\"a}t betrachtet und durch eine Analyse der Gelenkreaktionskraft untersucht. Die Studie bietet eine detaillierte Beschreibung des genutzten Modells, sowie medizinische Erkenntnisse zu einer Refixierung des Supraspinatus.},
  language  = {en}
}