@article{Staat2004, author = {Staat, Manfred}, title = {Plastic collapse analysis of longitudinally flawed pipes and vessels}, year = {2004}, abstract = {Improved collapse loads of thick-walled, crack containing pipes and vessels are suggested. Very deep cracks have a residual strength which is better modelled by a global limit load. In all burst tests, the ductility of pressure vessel steels was sufficiently high whereby the burst pressure could be predicted by limit analysis with no need to apply fracture mechanics. The relative prognosis error increases however, for long and deep defects due to uncertainties of geometry and strength data.}, subject = {Druckbeh{\"a}lter}, language = {en} } @article{Staat2005, author = {Staat, Manfred}, title = {Local and global collapse pressure of longitudinally flawed pipes and cylindrical vessels}, year = {2005}, abstract = {Limit loads can be calculated with the finite element method (FEM) for any component, defect geometry, and loading. FEM suggests that published long crack limit formulae for axial defects under-estimate the burst pressure for internal surface defects in thick pipes while limit loads are not conservative for deep cracks and for pressure loaded crack-faces. Very deep cracks have a residual strength, which is modelled by a global collapse load. These observations are combined to derive new analytical local and global collapse loads. The global collapse loads are close to FEM limit analyses for all crack dimensions.}, subject = {Finite-Elemente-Methode}, language = {en} } @article{Staat2005, author = {Staat, Manfred}, title = {Direct finite element route for design-by-analysis of pressure components}, year = {2005}, abstract = {In the new European standard for unfired pressure vessels, EN 13445-3, there are two approaches for carrying out a Design-by-Analysis that cover both the stress categorization method (Annex C) and the direct route method (Annex B) for a check against global plastic deformation and against progressive plastic deformation. This paper presents the direct route in the language of limit and shakedown analysis. This approach leads to an optimization problem. Its solution with Finite Element Analysis is demonstrated for mechanical and thermal actions. One observation from the examples is that the so-called 3f (3Sm) criterion fails to be a reliable check against progressive plastic deformation. Precise conditions are given, which greatly restrict the applicability of the 3f criterion.}, subject = {Einspielen }, language = {en} } @article{Staat2003, author = {Staat, Manfred}, title = {Shakedown and ratchetting under tension-torsion loadings: analysis and experiments}, year = {2003}, abstract = {Structural design analyses are conducted with the aim of verifying the exclusion of ratchetting. To this end it is important to make a clear distinction between the shakedown range and the ratchetting range. The performed experiment comprised a hollow tension specimen which was subjected to alternating axial forces, superimposed with constant moments. First, a series of uniaxial tests has been carried out in order to calibrate a bounded kinematic hardening rule. The load parameters have been selected on the basis of previous shakedown analyses with the PERMAS code using a kinematic hardening material model. It is shown that this shakedown analysis gives reasonable agreement between the experimental and the numerical results. A linear and a nonlinear kinematic hardening model of two-surface plasticity are compared in material shakedown analysis.}, subject = {Einspielen }, 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{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{StaatBaroudTopcuetal.2008, author = {Staat, Manfred and Baroud, G. and Topcu, M. and Sponagel, Stefan}, title = {Soft Materials in Technology and Biology - Characteristics, Properties, and Parameter Identification}, series = {Bioengineering in Cell and Tissue Research / Artmann, Gerhard M. ; Chien, Shu (Eds.)}, journal = {Bioengineering in Cell and Tissue Research / Artmann, Gerhard M. ; Chien, Shu (Eds.)}, publisher = {Springer}, address = {Berlin}, isbn = {978-3-540-75408-4}, pages = {253 -- 315}, year = {2008}, language = {en} } @article{StaatHeitzer2002, author = {Staat, Manfred and Heitzer, M.}, title = {Limit and Shakedown Analysis with Uncertain Data}, series = {Stochastic optimization techniques : numerical methods and technical applications / Marti, K. [ed]}, journal = {Stochastic optimization techniques : numerical methods and technical applications / Marti, K. [ed]}, publisher = {Springer}, address = {Heidelberg}, isbn = {3-540-42889-5}, pages = {241 -- 254}, year = {2002}, language = {en} } @article{StaatHeitzer2003, author = {Staat, Manfred and Heitzer, M.}, title = {Probabilistic 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.}, journal = {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}, pages = {217 -- 268}, year = {2003}, language = {en} } @article{StaatHeitzerLangetal.2005, author = {Staat, Manfred and Heitzer, M. and Lang, H. and Wirtz, K.}, title = {Direct Finite Element Route for Design-by-Analysis of Pressure Components}, series = {International Journal of Pressure Vessels and Piping. 82 (2005), H. 1}, journal = {International Journal of Pressure Vessels and Piping. 82 (2005), H. 1}, isbn = {0308-0161}, pages = {61 -- 67}, year = {2005}, language = {en} } @article{StaatHeitzerReinersetal.2003, author = {Staat, Manfred and Heitzer, M. and Reiners, H. and Schubert, F.}, title = {Shakedown and ratchetting under tension-torsion loadings: analysis and experiments}, series = {Nuclear Engineering and Design. 225 (2003), H. 1}, journal = {Nuclear Engineering and Design. 225 (2003), H. 1}, isbn = {0029-5493}, pages = {11 -- 26}, year = {2003}, language = {en} } @article{StaatSchwartzLangetal.2003, author = {Staat, Manfred and Schwartz, M. and Lang, H. and Wirtz, K. and Heitzer, M.}, title = {Design by Analysis of Pressure Components by non-linear Optimization}, series = {The 10th International Conference on Pressure Vessel Technology, July 7-10, 2003, Vienna, Austria, Proceedings ICPVT-10 / Zeman, J. L. [ed]}, journal = {The 10th International Conference on Pressure Vessel Technology, July 7-10, 2003, Vienna, Austria, Proceedings ICPVT-10 / Zeman, J. L. [ed]}, publisher = {{\"O}GS, {\"O}sterreichische Gesellschaft f{\"u}r Schweißtechnik}, address = {Wien}, isbn = {3950152814}, pages = {59 -- 65}, year = {2003}, language = {en} } @article{StaatSponagelNguyen2010, author = {Staat, Manfred and Sponagel, Stefan and Nguyen, Nhu Huynh}, title = {Experiment and material model for soft tissue materials}, series = {Constitutive models for rubber VI : proceedings of the sixth European Conference on Constitutive Models for Rubber, Dresden, Germany, 7 - 10 September 2009 / eds. Gert Heinrich ...}, journal = {Constitutive models for rubber VI : proceedings of the sixth European Conference on Constitutive Models for Rubber, Dresden, Germany, 7 - 10 September 2009 / eds. Gert Heinrich ...}, publisher = {CRC Press}, address = {Boca Raton [u.a.]}, isbn = {978-0-415-56327-7}, pages = {465 -- 470}, year = {2010}, language = {en} } @article{StaatTranKreissig2008, author = {Staat, Manfred and Tran, Thanh Ngoc and Kreißig, R.}, title = {Load bearing capacity of thin shell structures made of elastoplastic material by direct methods}, series = {Technische Mechanik. 28 (2008), H. 3-4}, journal = {Technische Mechanik. 28 (2008), H. 3-4}, pages = {299 -- 309}, year = {2008}, language = {en} } @article{StaatTrenzLohmannetal.2012, author = {Staat, Manfred and Trenz, Eva and Lohmann, Philipp and Frotscher, Ralf and Klinge, Uwe and Tabaza, Ruth and Kirschner-Hermanns, Ruth}, title = {New measurements to compare soft tissue anchoring systems in pelvic floor surgery}, series = {Journal of Biomedical Materials Research Part B: Applied Biomaterials}, volume = {100B}, journal = {Journal of Biomedical Materials Research Part B: Applied Biomaterials}, number = {4}, publisher = {Wiley}, address = {Hoboken, NJ}, issn = {1552-4981}, doi = {10.1002/jbm.b.32654}, pages = {924 -- 933}, year = {2012}, abstract = {Suburethral slings as well as different meshes are widely used treating stress urinary incontinence and prolaps in women. With the development of MiniSlings and special meshes using less alloplastic material anchorage systems become more important to keep devices in place and to put some tension especially on the MiniSlings. To date, there are many different systems of MiniSlings of different companies on the market which differ in the structure of the used meshes and anchors. A new objective measurement method to compare different properties of MiniSling systems (mesh and anchor) is presented in this article. Ballistic gelatine acts as soft tissue surrogate. Significant differences in parameters like pull-out strength of anchors or shrinkage of meshes under loading conditions have been determined. The form and size of the anchors as well as the structural stability of the meshes are decisive for a proper integration. The tested anchorings sytems showed markedly different mechanical function at their respective load bearing capacity. As the stable fixation of the device in tissue is a prerequisite for a permanet reinforcement, the proposed test system permits further optimisation of anchor and mesh devices to improve the success of the surgical treatment}, 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{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{StaatVu2007, author = {Staat, Manfred and Vu, Duc-Khoi}, title = {Limit analysis of flaws in pressurized pipes and cylindrical vessels. Part I: Axial defects}, series = {Engineering Fracture Mechanics. 74 (2007), H. 3}, journal = {Engineering Fracture Mechanics. 74 (2007), H. 3}, isbn = {0013-7944}, pages = {431 -- 450}, year = {2007}, language = {en} } @article{StaatVu2006, author = {Staat, Manfred and Vu, Khoi Duc}, title = {Limit loads of circumferentially flawed pipes and cylindrical vessels under internal pressure}, series = {International Journal of Pressure Vessels and Piping. 83 (2006), H. 3}, journal = {International Journal of Pressure Vessels and Piping. 83 (2006), H. 3}, isbn = {0308-0161}, pages = {188 -- 196}, year = {2006}, language = {en} } @article{StadlerDigelArtmannetal.2008, author = {Stadler, A. M. and Digel, Ilya and Artmann, Gerhard and Embs, Jan P. and Zaccai, Joe and B{\"u}ldt, Georg}, title = {Hemoglobin Dynamics in Red Blood Cells: Correlation to Body Temperature}, series = {Biophysical Journal. 95 (2008), H. 11}, journal = {Biophysical Journal. 95 (2008), H. 11}, isbn = {1542-0086}, pages = {5449 -- 5461}, year = {2008}, language = {en} }