@article{BhattaraiStaat2019,
  author    = {Bhattarai, Aroj and Staat, Manfred},
  title     = {A computational study of organ relocation after laparoscopic pectopexy to repair posthysterectomy vaginal vault prolapse},
  series = {Computer Methods in Biomechanics and Biomedical Engineering: Imaging \& Visualization},
  journal   = {Computer Methods in Biomechanics and Biomedical Engineering: Imaging \& Visualization},
  publisher = {Taylor \& Francis},
  address   = {London},
  issn      = {2168-1171},
  doi       = {10.1080/21681163.2019.1670095},
  year      = {2019},
  language  = {en}
}
@article{TopcuMadabhushiStaat2022,
  author    = {Top{\c{c}}u, Murat and Madabhushi, Gopal S.P. and Staat, Manfred},
  title     = {A generalized shear-lag theory for elastic stress transfer between matrix and fibres having a variable radius},
  series = {International Journal of Solids and Structures},
  volume    = {239-240},
  journal   = {International Journal of Solids and Structures},
  number    = {Art. No. 111464},
  publisher = {Elsevier},
  address   = {New York, NY},
  issn      = {0020-7683},
  doi       = {10.1016/j.ijsolstr.2022.111464},
  year      = {2022},
  abstract  = {A generalized shear-lag theory for fibres with variable radius is developed to analyse elastic fibre/matrix stress transfer. The theory accounts for the reinforcement of biological composites, such as soft tissue and bone tissue, as well as for the reinforcement of technical composite materials, such as fibre-reinforced polymers (FRP). The original shear-lag theory proposed by Cox in 1952 is generalized for fibres with variable radius and with symmetric and asymmetric ends. Analytical solutions are derived for the distribution of axial and interfacial shear stress in cylindrical and elliptical fibres, as well as conical and paraboloidal fibres with asymmetric ends. Additionally, the distribution of axial and interfacial shear stress for conical and paraboloidal fibres with symmetric ends are numerically predicted. The results are compared with solutions from axisymmetric finite element models. A parameter study is performed, to investigate the suitability of alternative fibre geometries for use in FRP.},
  language  = {en}
}
@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{NguyenRaatschenStaat2010,
  author    = {Nguyen, N.-H. and Raatschen, Hans-J{\"u}rgen and Staat, Manfred},
  title     = {A hyperelastic model of biological tissue materials in tubular organs},
  pages     = {1 -- 12},
  year      = {2010},
  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{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{GrottkeBraunschweigPhilippenetal.2010,
  author    = {Grottke, O. and Braunschweig, T. and Philippen, B. and Gatzweiler, Karl-Heinz and Gronloh, N. and Staat, Manfred and Rossaint, R. and Tolba, R.},
  title     = {A New Model for Blunt Liver Injuries in the Swine},
  series = {European Surgical Research. 44 (2010), H. 2},
  journal   = {European Surgical Research. 44 (2010), H. 2},
  isbn      = {1421-9921},
  pages     = {65 -- 73},
  year      = {2010},
  language  = {en}
}
@article{PhamVuTranetal.2010,
  author    = {Pham, Phu Tinh and Vu, Khoi Duc and Tran, Thanh Ngoc and Staat, Manfred},
  title     = {A primal-dual algorithm for shakedown analysis of elastic-plastic bounded linearly kinematic hardening bodies},
  pages     = {1 -- 7},
  year      = {2010},
  language  = {en}
}
@article{KuehnHaugnerStaatetal.2004,
  author    = {K{\"u}hn, Raoul-Roman and Haugner, Werner and Staat, Manfred and Sponagel, Stefan},
  title     = {A Two Phase Mixture Model based on Bone Observation},
  year      = {2004},
  abstract  = {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.},
  subject      = {Knochen},
  language  = {en}
}
@article{StaatVu2004,
  author    = {Staat, Manfred and Vu, Duc-Khoi},
  title     = {An Algorithm for Shakedown Analysis for Materials with Temperature Dependent Yield Stress},
  series = {Proceedings in Applied Mathematics and Mechanics (PAMM). 4 (2004), H. 1},
  journal   = {Proceedings in Applied Mathematics and Mechanics (PAMM). 4 (2004), H. 1},
  isbn      = {1617-7061},
  pages     = {231 -- 233},
  year      = {2004},
  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{TranStaat2013,
  author    = {Tran, Thanh Ngoc and Staat, Manfred},
  title     = {An Edge-Based Smoothed Finite Element Method for Primal-Dual Shakedown Analysis of Structures Under Uncertainties},
  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     = {89 -- 102},
  year      = {2013},
  language  = {en}
}
@article{ColomboDriraFrotscheretal.2022,
  author    = {Colombo, Daniele and Drira, Slah and Frotscher, Ralf and Staat, Manfred},
  title     = {An element-based formulation for ES-FEM and FS-FEM models for implementation in standard solid mechanics finite element codes for 2D and 3D static analysis},
  series = {International Journal for Numerical Methods in Engineering},
  volume    = {124},
  journal   = {International Journal for Numerical Methods in Engineering},
  number    = {2},
  publisher = {Wiley},
  address   = {Chichester},
  issn      = {1097-0207},
  doi       = {10.1002/nme.7126},
  pages     = {402 -- 433},
  year      = {2022},
  abstract  = {Edge-based and face-based smoothed finite element methods (ES-FEM and FS-FEM, respectively) are modified versions of the finite element method allowing to achieve more accurate results and to reduce sensitivity to mesh distortion, at least for linear elements. These properties make the two methods very attractive. However, their implementation in a standard finite element code is nontrivial because it requires heavy and extensive modifications to the code architecture. In this article, we present an element-based formulation of ES-FEM and FS-FEM methods allowing to implement the two methods in a standard finite element code with no modifications to its architecture. Moreover, the element-based formulation permits to easily manage any type of element, especially in 3D models where, to the best of the authors' knowledge, only tetrahedral elements are used in FS-FEM applications found in the literature. Shape functions for non-simplex 3D elements are proposed in order to apply FS-FEM to any standard finite element.},
  language  = {en}
}
@article{AbelKahmannMellonetal.2020,
  author    = {Abel, Alexander and Kahmann, Stephanie Lucina and Mellon, Stephen and Staat, Manfred and Jung, Alexander},
  title     = {An open-source tool for the validation of finite element models using three-dimensional full-field measurements},
  series = {Medical Engineering \& Physics},
  volume    = {77},
  journal   = {Medical Engineering \& Physics},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1350-4533},
  doi       = {10.1016/j.medengphy.2019.10.015},
  pages     = {125 -- 129},
  year      = {2020},
  abstract  = {Three-dimensional (3D) full-field measurements provide a comprehensive and accurate validation of finite element (FE) models. For the validation, the result of the model and measurements are compared based on two respective point-sets and this requires the point-sets to be registered in one coordinate system. Point-set registration is a non-convex optimization problem that has widely been solved by the ordinary iterative closest point algorithm. However, this approach necessitates a good initialization without which it easily returns a local optimum, i.e. an erroneous registration. The globally optimal iterative closest point (Go-ICP) algorithm has overcome this drawback and forms the basis for the presented open-source tool that can be used for the validation of FE models using 3D full-field measurements. The capability of the tool is demonstrated using an application example from the field of biomechanics. Methodological problems that arise in real-world data and the respective implemented solution approaches are discussed.},
  language  = {en}
}
@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{VuStaatTran2007,
  author    = {Vu, Duc Khoi and Staat, Manfred and Tran, Ich Thinh},
  title     = {Analysis of pressure equipment by application of the primal-dual theory of shakedown},
  series = {Communications in Numerical Methods in Engineering. 23 (2007), H. 3},
  journal   = {Communications in Numerical Methods in Engineering. 23 (2007), H. 3},
  isbn      = {1069-8299},
  pages     = {213 -- 225},
  year      = {2007},
  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{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{HorbachStaatPerezVianaetal.2020,
  author    = {Horbach, Andreas and Staat, Manfred and Perez-Viana, Daniel and Simmen, Hans-Peter and Neuhaus, Valentin and Pape, Hans-Christoph and Prescher, Andreas and Ciritsis, Bernhard},
  title     = {Biomechanical in vitro examination of a standardized low-volume tubular femoroplasty},
  series = {Clinical Biomechanics},
  volume    = {80},
  journal   = {Clinical Biomechanics},
  number    = {Art. 105104},
  publisher = {Elsevier},
  address   = {Amsterdam},
  doi       = {10.1016/j.clinbiomech.2020.105104},
  year      = {2020},
  abstract  = {Background Osteoporosis is associated with the risk of fractures near the hip. Age and comorbidities increase the perioperative risk. Due to the ageing population, fracture of the proximal femur also proves to be a socio-economic problem. Preventive surgical measures have hardly been used so far. Methods 10 pairs of human femora from fresh cadavers were divided into control and low-volume femoroplasty groups and subjected to a Hayes fall-loading fracture test. The results of the respective localization and classification of the fracture site, the Singh index determined by computed tomography (CT) examination and the parameters in terms of fracture force, work to fracture and stiffness were evaluated statistically and with the finite element method. In addition, a finite element parametric study with different position angles and variants of the tubular geometry of the femoroplasty was performed. Findings Compared to the control group, the work to fracture could be increased by 33.2\%. The fracture force increased by 19.9\%. The used technique and instrumentation proved to be standardized and reproducible with an average poly(methyl methacrylate) volume of 10.5 ml. The parametric study showed the best results for the selected angle and geometry. Interpretation The cadaver studies demonstrated the biomechanical efficacy of the low-volume tubular femoroplasty. The numerical calculations confirmed the optimal choice of positioning as well as the inner and outer diameter of the tube in this setting. The standardized minimally invasive technique with the instruments developed for it could be used in further comparative studies to confirm the measured biomechanical results.},
  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}
}