@article{KnoxBruggemannGossmannetal.2020,
  author    = {Knox, Ronald and Bruggemann, Andrea and Gossmann, Matthias and Thomas, Ulrich and Horv{\´a}th, Andr{\´a}s and Dragicevic, Elena and Stoelzle-Feix, Sonja and Fertig, Niels and Jung, Alexander and Raman, Aravind Hariharan and Staat, Manfred and Linder, Peter},
  title     = {Combining physiological relevance and throughput for in vitro cardiac contractility measurement},
  series = {Biophysical Journal},
  volume    = {118},
  journal   = {Biophysical Journal},
  number    = {Issue 3, Supplement 1},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0006-3495},
  doi       = {10.1016/j.bpj.2019.11.3104},
  pages     = {570a},
  year      = {2020},
  abstract  = {Despite increasing acceptance of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in safety pharmacology, controversy remains about the physiological relevance of existing in vitro models for their mechanical testing. We hypothesize that existing signs of immaturity of the cell models result from an improper mechanical environment. We cultured hiPSC-CMs in a 96-well format on hyperelastic silicone membranes imitating their native mechanical environment, resulting in physiological responses to compound stimuli.We validated cell responses on the FLEXcyte 96, with a set of reference compounds covering a broad range of cellular targets, including ion channel modulators, adrenergic receptor modulators and kinase inhibitors. Acute (10 - 30 min) and chronic (up to 7 days) effects were investigated. Furthermore, the measurements were complemented with electromechanical models based on electrophysiological recordings of the used cell types.hiPSC-CMs were cultured on freely-swinging, ultra-thin and hyperelastic silicone membranes. The weight of the cell culture medium deflects the membranes downwards. Rhythmic contraction of the hiPSC-CMs resulted in dynamic deflection changes which were quantified by capacitive distance sensing. The cells were cultured for 7 days prior to compound addition. Acute measurements were conducted 10-30 minutes after compound addition in standard culture medium. For chronic treatment, compound-containing medium was replaced daily for up to 7 days. Electrophysiological properties of the employed cell types were recorded by automated patch-clamp (Patchliner) and the results were integrated into the electromechanical model of the system.Calcium channel agonist S Bay K8644 and beta-adrenergic stimulator isoproterenol induced significant positive inotropic responses without additional external stimulation. Kinase inhibitors displayed cardiotoxic effects on a functional level at low concentrations. The system-integrated analysis detected alterations in beating shape as well as frequency and arrhythmic events and we provide a quantitative measure of these.},
  language  = {en}
}
@incollection{GohTopcuMadabhushietal.2023,
  author    = {Goh, Kheng Lim and Top{\c{c}}u, Murat and Madabhushi, Gopal S. P. and Staat, Manfred},
  title     = {Collagen fibril reinforcement in connective tissue extracellular matrices},
  series = {Handbook of the extracellular matrix},
  booktitle = {Handbook of the extracellular matrix},
  editor    = {Maia, Fatima Raquel Azevedo and Miguel Oliveira, J. and Reis, Rui L.},
  publisher = {Springer Nature},
  address   = {Cham},
  isbn      = {978-3-030-92090-6 (Print)},
  doi       = {10.1007/978-3-030-92090-6_6-1},
  pages     = {1 -- 20},
  year      = {2023},
  abstract  = {The connective tissues such as tendons contain an extracellular matrix (ECM) comprising collagen fibrils scattered within the ground substance. These fibrils are instrumental in lending mechanical stability to tissues. Unfortunately, our understanding of how collagen fibrils reinforce the ECM remains limited, with no direct experimental evidence substantiating current theories. Earlier theoretical studies on collagen fibril reinforcement in the ECM have relied predominantly on the assumption of uniform cylindrical fibers, which is inadequate for modelling collagen fibrils, which possessed tapered ends. Recently, Top{\c{c}}u and colleagues published a paper in the International Journal of Solids and Structures, presenting a generalized shear-lag theory for the transfer of elastic stress between the matrix and fibers with tapered ends. This paper is a positive step towards comprehending the mechanics of the ECM and makes a valuable contribution to formulating a complete theory of collagen fibril reinforcement in the ECM.},
  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}
}
@inproceedings{BirgelLeschingerWegmannetal.2017,
  author    = {Birgel, Stefan and Leschinger, Tim and Wegmann, Kilian and Staat, Manfred},
  title     = {Calculation of muscle forces and joint reaction loads in shoulder area via an OpenSim based computer calculation},
  series = {2nd YRA MedTech Symposium 2017 : June 8th - 9th / 2017 / Hochschule Ruhr-West},
  booktitle = {2nd YRA MedTech Symposium 2017 : June 8th - 9th / 2017 / Hochschule Ruhr-West},
  editor    = {Erni, Daniel and Fischerauer, Alice and Himmel, J{\"o}rg and Seeger, Thomas and Thelen, Klaus},
  publisher = {Universit{\"a}t Duisburg-Essen},
  address   = {Duisburg},
  organization    = {MedTech Symposium},
  isbn      = {978-3-9814801-9-1},
  doi       = {10.17185/duepublico/43984},
  pages     = {116 -- 117},
  year      = {2017},
  language  = {en}
}
@inproceedings{TranStaatKreissig2007,
  author    = {Tran, Thanh Ngoc and Staat, Manfred and Kreißig, R.},
  title     = {Calculation of load carrying capacity of shell structures with elasto-plastic material by direct methods},
  year      = {2007},
  abstract  = {Proceedings of the International Conference on Material Theory and Nonlinear Dynamics. MatDyn. Hanoi, Vietnam, Sept. 24-26, 2007, 8 p. In this paper, a method is introduced to determine the limit load of general shells using the finite element method. The method is based on an upper bound limit and shakedown analysis with elastic-perfectly plastic material model. A non-linear constrained optimisation problem is solved by using Newton's method in conjunction with a penalty method and the Lagrangean dual method. Numerical investigation of a pipe bend subjected to bending moments proves the effectiveness of the algorithm.},
  subject      = {Finite-Elemente-Methode},
  language  = {en}
}
@inproceedings{BhattaraiFrotscherStaat2015,
  author    = {Bhattarai, Aroj and Frotscher, Ralf and Staat, Manfred},
  title     = {Biomechanical study of the female pelvic floor dysfunction using the finite element method},
  series = {Conference proceedings of the YIC GACM 2015 : 3rd ECCOMAS Young Investigators Conference and 6th GACM Colloquium on Computational Mechanics , Aachen , Germany, 20.07.2015 - 23.07.2015 / ed.: Stefanie Elgeti ; Jaan-Willem Simon},
  booktitle = {Conference proceedings of the YIC GACM 2015 : 3rd ECCOMAS Young Investigators Conference and 6th GACM Colloquium on Computational Mechanics , Aachen , Germany, 20.07.2015 - 23.07.2015 / ed.: Stefanie Elgeti ; Jaan-Willem Simon},
  publisher = {RWTH Aachen University},
  address   = {Aachen},
  organization    = {ECCOMAS Young Investigators Conference <3, 2015, Aachen>},
  pages     = {1 -- 4},
  year      = {2015},
  language  = {en}
}
@inproceedings{JabbariBhattaraiAndingetal.2017,
  author    = {Jabbari, Medisa and Bhattarai, Aroj and Anding, Ralf and Staat, Manfred},
  title     = {Biomechanical simulation of different prosthetic meshes for repairing uterine/vaginal vault prolapse},
  series = {2nd YRA MedTech Symposium 2017 : June 8th - 9th / 2017 / Hochschule Ruhr-West},
  booktitle = {2nd YRA MedTech Symposium 2017 : June 8th - 9th / 2017 / Hochschule Ruhr-West},
  editor    = {Erni, Daniel and Fischerauer, Alice and Himmel, J{\"o}rg and Seeger, Thomas and Thelen, Klaus},
  publisher = {Universit{\"a}t Duisburg-Essen},
  address   = {Duisburg},
  organization    = {MedTech Symposium},
  isbn      = {978-3-9814801-9-1},
  doi       = {10.17185/duepublico/43984},
  pages     = {118 -- 119},
  year      = {2017},
  language  = {en}
}
@inproceedings{KahmannUschokWegmannetal.2018,
  author    = {Kahmann, Stephanie Lucina and Uschok, Stephan and Wegmann, Kilian and M{\"u}ller, Lars-P. and Staat, Manfred},
  title     = {Biomechanical multibody model with refined kinematics of the elbow},
  series = {6th European Conference on Computational Mechanics (ECCM 6), 7th European Conference on Computational Fluid Dynamics (ECFD 7), 11-15 June 2018, Glasgow, UK},
  booktitle = {6th European Conference on Computational Mechanics (ECCM 6), 7th European Conference on Computational Fluid Dynamics (ECFD 7), 11-15 June 2018, Glasgow, UK},
  pages     = {11 Seiten},
  year      = {2018},
  abstract  = {The overall objective of this study is to develop a new external fixator, which closely maps the native kinematics of the elbow to decrease the joint force resulting in reduced rehabilitation time and pain. An experimental setup was designed to determine the native kinematics of the elbow during flexion of cadaveric arms. As a preliminary study, data from literature was used to modify a published biomechanical model for the calculation of the joint and muscle forces. They were compared to the original model and the effect of the kinematic refinement was evaluated. Furthermore, the obtained muscle forces were determined in order to apply them in the experimental setup. The joint forces in the modified model differed slightly from the forces in the original model. The muscle force curves changed particularly for small flexion angles but their magnitude for larger angles was consistent.},
  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}
}
@misc{StaatHorbachGatzweiler2019,
  author    = {Staat, Manfred and Horbach, Andreas and Gatzweiler, Karl-Heinz},
  title     = {Biaxiales Materialpr{\"u}fsystem und Verfahren zu dessen Anwendung},
  year      = {2019},
  abstract  = {System und Verfahren zur Durchf{\"u}hrung von Messungen biaxialer und kreuzf{\"o}rmiger Zugversuche, wobei ein Weg oder eine Kraft auf eine Materialprobe {\"u}ber mindestens zwei Nadelarme mit Nadeln geleitet wird, die in einem Geh{\"a}use gelagert sind, wobei die Arme und/oder Nadelarme f{\"u}r eine ungehinderte Querkontraktion bei gleichm{\"a}ßiger Lasteinleitung um eine Achse drehbar gelagert und seitlich auslenkbar sind.},
  language  = {de}
}
@incollection{StaatHeitzer2003,
  author    = {Staat, Manfred and Heitzer, M.},
  title     = {Basis reduction technique for limit and shakedown problems},
  series = {Numerical Methods for Limit and Shakedown Analysis. Deterministic and Probabilistic Approach. NIC Series Vol. 15 / Ed. by Staat, M.; Heitzer, M.},
  booktitle = {Numerical Methods for Limit and Shakedown Analysis. Deterministic and Probabilistic Approach. NIC Series Vol. 15 / Ed. by Staat, M.; Heitzer, M.},
  publisher = {John von Neumann Institute for Computing (NIC)},
  address   = {J{\"u}lich},
  isbn      = {3-00-010001-6},
  url       = {http://nbn-resolving.de/urn:nbn:de:0001-2018112115},
  pages     = {1 -- 55},
  year      = {2003},
  language  = {en}
}
@inproceedings{FrotscherRaatschenStaat2012,
  author    = {Frotscher, Ralf and Raatschen, Hans-J{\"u}rgen and Staat, Manfred},
  title     = {Application of an edge-based smoothed finite element method on geometrically non-linear plates of non-linear material},
  series = {Proceedings European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2012)},
  booktitle = {Proceedings European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2012)},
  editor    = {Eberhardsteiner, J.},
  year      = {2012},
  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{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{LeversStaatLaack2011,
  author    = {Levers, A. and Staat, Manfred and Laack, Walter van},
  title     = {Analyse der Langzeitwirkung der MBST® KernspinResonanzTherapie bei Gonarthrose},
  year      = {2011},
  abstract  = {Originalausgabe: Orthop{\"a}dische Praxis Jg. 47. 2011 H. 11; S. 536-543. Mit freundlicher Genehmigung des Verlags Zusammenfassung: Auf der Basis von Patientenabfragen mittels Fragebogen zum Schmerzempfinden und zur Einschr{\"a}nkung bei Aktivit{\"a}ten des allt{\"a}glichen Lebens wird die Langzeitwirkung der MBST® KernspinResonanz-Therapie bei Gonarthrose untersucht. An der Studie nahmen 39 Patienten teil, bei denen die Therapie bis zu vier Jahre zur{\"u}ckliegt. Neben einer Gesamtbetrachtung wird der Erfolg auch in Abh{\"a}ngigkeit von Alter, Geschlecht und sportlicher Aktivit{\"a}t analysiert. Insgesamt weist die Studie auf eine anhaltende Verbesserung des Gesundheitszustands mit zum Teil deutlicher Schmerzlinderung auch noch nach vier Jahren hin, jedoch mit einer leichten Schmerzzunahme gegen Ende des Untersuchungszeitraums von vier Jahren. Eine tendenziell positivere Wirkung bei Frauen, {\"a}lteren Menschen oder auch sportlich nicht-aktiven Patienten l{\"a}sst auf eine m{\"o}gliche Beeinflussung des Erfolgs der Therapie durch ({\"U}ber-)Belastung im Alltag schließen. Ein zus{\"a}tzlich positiver Effekt der Therapie auf die Knochendichte ist ebenfalls denkbar, dies bleibt jedoch offen.},
  subject      = {Kniegelenkarthrose},
  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{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{StaatKuehnHaugeretal.2004,
  author    = {Staat, Manfred and K{\"u}hn, R. and Hauger, W. and Sponagel, Stefan},
  title     = {An Interpretation of Wolff's Law},
  series = {Biomedizinische Technik. 49 (2004)},
  journal   = {Biomedizinische Technik. 49 (2004)},
  isbn      = {0932-4666},
  pages     = {1020 -- 1021},
  year      = {2004},
  language  = {de}
}
@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{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}
}