@article{JungStaatMueller2018, author = {Jung, Alexander and Staat, Manfred and M{\"u}ller, Wolfram}, title = {Corrigendum to "Flight style optimization in ski jumping on normal, large, and ski flying hills" [J. Biomech 47 (2014) 716-722]}, series = {Journals of Biomechanics}, journal = {Journals of Biomechanics}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0021-9290}, doi = {10.1016/j.jbiomech.2018.02.001}, pages = {313}, year = {2018}, 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{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{StaatBallmann1988, author = {Staat, Manfred and Ballmann, J.}, title = {Computation of impacts on elastic solids by methods of bicharacteristics}, series = {Computational Mechanics '88 : theory and applications ; proceedings of the International Conference on Computational Engineering Science April 10-14, 1988, Atlanta, GA, USA ; vol. 2}, journal = {Computational Mechanics '88 : theory and applications ; proceedings of the International Conference on Computational Engineering Science April 10-14, 1988, Atlanta, GA, USA ; vol. 2}, pages = {1719 -- 1722}, year = {1988}, abstract = {Shock waves, explosions, impacts or cavitation bubble collapses may generate stress waves in solids causing cracks or unexpected dammage due to focussing, physical nonlinearity or interaction with existing cracks. There is a growing interest in wave propagation, which poses many novel problems to experimentalists and theorists.}, subject = {Bicharakteristikenverfahren}, 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{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} } @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} } @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{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{Staat1987, author = {Staat, Manfred}, title = {Anisotrope Wellenausbreitung in isotropen hyperelastischen Scheiben}, series = {Zeitschrift f{\"u}r angewandte Mathematik und Mechanik : ZAMM. 67 (1987), H. 4}, journal = {Zeitschrift f{\"u}r angewandte Mathematik und Mechanik : ZAMM. 67 (1987), H. 4}, isbn = {0946-8463}, pages = {T241 -- T243}, year = {1987}, language = {de} } @article{StaatBallmann1985, author = {Staat, Manfred and Ballmann, J.}, title = {Anisotrope Ausbreitung und Fokussierung von Beschleunigungswellen in vorgespannten nichtlinearelastischen Scheiben}, series = {Wellenfokussierung, Kolloquium des SFB 27, RWTH Aachen}, journal = {Wellenfokussierung, Kolloquium des SFB 27, RWTH Aachen}, address = {Aachen}, pages = {140 -- 158}, year = {1985}, 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{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} } @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} }