<?xml version="1.0" encoding="utf-8"?>
<export-example>
  <doc>
    <id>14433</id>
    <completedYear/>
    <publishedYear>2015</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>19</pageFirst>
    <pageLast>31</pageLast>
    <pageNumber/>
    <edition/>
    <issue>129-130</issue>
    <volume/>
    <type>articler</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2015-07-07</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Simplified Theory of Plastic Zones for cyclic loading and multilinear hardening</title>
    <abstract language="eng">The Simplified Theory of Plastic Zones (STPZ) is a direct method based on Zarka's method, primarily developed to estimate post-shakedown quantities of structures under cyclic loading, avoiding incremental analyses through a load histogram. In a different paper the STPZ has previously been shown to provide excellent estimates of the elastic–plastic strain ranges in the state of plastic shakedown as required for fatigue analyses. In the present paper, it is described how the STPZ can be used to predict the strains accumulated through a number of loading cycles due to a ratcheting mechanism, until either elastic or plastic shakedown is achieved, so that strain limits can be satisfied. Thus, a consistent means of estimating both, strain ranges and accumulated strains is provided for structural integrity assessment as required by pressure vessel codes. The computational costs involved typically consist of few linear elastic analyses and some local calculations. Multilinear kinematic hardening and temperature dependent yield stresses are accounted for. The quality of the results and the computational burden involved are demonstrated through four examples.</abstract>
    <parentTitle language="eng">International Journal of Pressure Vessels and Piping</parentTitle>
    <identifier type="doi">10.1016/j.ijpvp.2015.03.002</identifier>
    <identifier type="url">http://www.sciencedirect.com/science/article/pii/S0308016115000289</identifier>
    <identifier type="issn">0308-0161</identifier>
    <enrichment key="BTU">an der BTU erstellt / created at BTU</enrichment>
    <author>
      <firstName>Hartwig</firstName>
      <lastName>Hübel</lastName>
    </author>
    <submitter>
      <firstName>Hartwig</firstName>
      <lastName>Hübel</lastName>
    </submitter>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Simplified Theory of Plastic Zones</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Shakedown</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Ratcheting</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>cyclic loading</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>progressive deformation</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>elastic-plastic strain range</value>
    </subject>
    <collection role="old_institute" number="08005">Prof. Baustatik, Stahlbau, FEM</collection>
    <collection role="institutes" number="6386">FG Baustatik, Stahlbau, FEM</collection>
  </doc>
  <doc>
    <id>14434</id>
    <completedYear/>
    <publishedYear>2014</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>10</pageFirst>
    <pageLast>19</pageLast>
    <pageNumber/>
    <edition/>
    <issue>116</issue>
    <volume/>
    <type>articler</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2015-07-07</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Performance study of the simplified theory of plastic zones and the Twice-Yield method for the fatigue check</title>
    <abstract language="eng">As elastic–plastic fatigue analyses are still time consuming the simplified elastic–plastic analysis (e.g. ASME Section III, NB 3228.5, the French RCC-M code, paragraphs B 3234.3, B 3234.5 and B3234.6 and the German KTA rule 3201.2, paragraph 7.8.4) is often applied. Besides linearly elastic analyses and factorial plasticity correction (Ke factors) direct methods are an option. In fact, calculation effort and accuracy of results are growing in the following graded scheme: a) linearly elastic analysis along with Ke correction, b) direct methods for the determination of stabilized elastic–plastic strain ranges and c) incremental elastic–plastic methods for the determination of stabilized elastic–plastic strain ranges.&#13;
&#13;
The paper concentrates on option b) by substantiating the practical applicability of the simplified theory of plastic zones STPZ (based on Zarka's method) and – for comparison – the established Twice-Yield method. The Twice-Yield method is explicitly addressed in ASME Code, Section VIII, Div. 2. Application relevant aspects are particularly addressed. Furthermore, the applicability of the STPZ for arbitrary load time histories in connection with an appropriate cycle counting method is discussed.&#13;
&#13;
Note, that the STPZ is applicable both for the determination of (fatigue relevant) elastic–plastic strain ranges and (ratcheting relevant) locally accumulated strains. This paper concentrates on the performance of the method in terms of the determination of elastic–plastic strain ranges and fatigue usage factors. The additional performance in terms of locally accumulated strains and ratcheting will be discussed in a future publication.</abstract>
    <parentTitle language="eng">International Journal of Pressure Vessels and Piping</parentTitle>
    <identifier type="doi">doi:10.1016/j.ijpvp.2014.01.003</identifier>
    <identifier type="url">http://www.sciencedirect.com/science/article/pii/S0308016114000143</identifier>
    <identifier type="issn">0308-0161</identifier>
    <enrichment key="BTU">an der BTU erstellt / created at BTU</enrichment>
    <author>
      <firstName>Hartwig</firstName>
      <lastName>Hübel</lastName>
    </author>
    <submitter>
      <firstName>Hartwig</firstName>
      <lastName>Hübel</lastName>
    </submitter>
    <author>
      <firstName>Adrian</firstName>
      <lastName>Willuweit</lastName>
    </author>
    <author>
      <firstName>Jürgen</firstName>
      <lastName>Rudolph</lastName>
    </author>
    <author>
      <firstName>Rainer</firstName>
      <lastName>Ziegler</lastName>
    </author>
    <author>
      <firstName>Hermann</firstName>
      <lastName>Lang</lastName>
    </author>
    <author>
      <firstName>Klemens</firstName>
      <lastName>Rother</lastName>
    </author>
    <author>
      <firstName>Simon</firstName>
      <lastName>Deller</lastName>
    </author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Simplified Theory of Plastic Zones</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Simplified elastic-plastic fatigue analyses</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Zarka's method</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Thermal cyclic loading</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>elastic-plastic strain range</value>
    </subject>
    <collection role="old_institute" number="08005">Prof. Baustatik, Stahlbau, FEM</collection>
    <collection role="institutes" number="6386">FG Baustatik, Stahlbau, FEM</collection>
  </doc>
  <doc>
    <id>14435</id>
    <completedYear/>
    <publishedYear>2003</publishedYear>
    <thesisYearAccepted/>
    <language>deu</language>
    <pageFirst>844</pageFirst>
    <pageLast>852</pageLast>
    <pageNumber/>
    <edition/>
    <issue>12</issue>
    <volume>72</volume>
    <type>articler</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2015-07-07</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="deu">Bemerkungen zur Ausnutzung plastischer Querschnitts- und Systemreserven</title>
    <abstract language="deu">Plastische Tragreserven werden im Stahlbau häufig planmäßig in Anspruch genommen und zumindest auf der Bewertungsseite (Verfahren Elastisch - Plastisch der DIN 18800) oder zusätzlich auch auf der Ermittlungsseite der Beanspruchungen (Verfahren Plastisch - Plastisch) quantitativ berücksichtigt. In diesen Nachweisverfahren lauern jedoch einige Gefahren, die nicht immer leicht zu erkennen sind. Einige davon werden in diesem Beitrag angesprochen.</abstract>
    <parentTitle language="deu">Stahlbau</parentTitle>
    <identifier type="doi">10.1002/stab.200303010</identifier>
    <enrichment key="BTU">an der BTU erstellt / created at BTU</enrichment>
    <author>
      <firstName>Hartwig</firstName>
      <lastName>Hübel</lastName>
    </author>
    <submitter>
      <firstName>Hartwig</firstName>
      <lastName>Hübel</lastName>
    </submitter>
    <subject>
      <language>deu</language>
      <type>uncontrolled</type>
      <value>Ratcheting</value>
    </subject>
    <subject>
      <language>deu</language>
      <type>uncontrolled</type>
      <value>progressive Deformation</value>
    </subject>
    <subject>
      <language>deu</language>
      <type>uncontrolled</type>
      <value>plastische Tragreserven</value>
    </subject>
    <collection role="old_institute" number="08005">Prof. Baustatik, Stahlbau, FEM</collection>
    <collection role="institutes" number="6386">FG Baustatik, Stahlbau, FEM</collection>
  </doc>
  <doc>
    <id>16095</id>
    <completedYear/>
    <publishedYear>1998</publishedYear>
    <thesisYearAccepted/>
    <language>deu</language>
    <pageFirst>492</pageFirst>
    <pageLast>502</pageLast>
    <pageNumber/>
    <edition/>
    <issue>11</issue>
    <volume>73</volume>
    <type>articler</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2016-05-09</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="deu">Vereinfachte Fließzonentheorie</title>
    <abstract language="deu">Es wird eine vereinfachte Fließzonentheorie vorgestellt, mit der das plastische Verhalten eines Tragwerks berechnet werden kann. Sie lässt sich nicht nur auf Stabwerke, sondern auch auf Flächentragwerke unter beliebiger Belastung anwenden. Das zugrunde gelegte Werkstoffgesetz ist bilinear, wodurch Verfestigung erfasst werden kann. Die Theorie beruht auf dem Konzept transformierter interner Variabler nach Zarka, mit dem das plastische Problem in ein geeignet formuliertes elastisches Problem überführt wird. Damit fällt oft nur eine weitere elastizitätstheoretische Berechnung an mit modifizierten elastischen Werkstoffparametern und mit (in Form von Anfangsdehnungen) modifizierter Belastung. Das Ergebnis kann gegebenenfalls iterativ verbessert werden, bis das "exakte" Ergebnis erreicht ist. Mehrere Beispiele erläutern die Methode.</abstract>
    <parentTitle language="deu">Bauingenieur</parentTitle>
    <identifier type="issn">0005-6650</identifier>
    <enrichment key="BTU">nicht an der BTU erstellt / not created at BTU</enrichment>
    <author>
      <firstName>Hartwig</firstName>
      <lastName>Hübel</lastName>
    </author>
    <submitter>
      <firstName>Hartwig</firstName>
      <lastName>Hübel</lastName>
    </submitter>
    <subject>
      <language>deu</language>
      <type>uncontrolled</type>
      <value>Vereinfachte Fließzonentheorie</value>
    </subject>
    <subject>
      <language>deu</language>
      <type>uncontrolled</type>
      <value>Fließgelenktheorie</value>
    </subject>
    <subject>
      <language>deu</language>
      <type>uncontrolled</type>
      <value>Shakedown</value>
    </subject>
    <subject>
      <language>deu</language>
      <type>uncontrolled</type>
      <value>Dehnungsakkumulation</value>
    </subject>
    <subject>
      <language>deu</language>
      <type>uncontrolled</type>
      <value>Dehnschwingbreite</value>
    </subject>
    <collection role="institutes" number="6386">FG Baustatik, Stahlbau, FEM</collection>
  </doc>
  <doc>
    <id>16098</id>
    <completedYear/>
    <publishedYear>1997</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>343</pageFirst>
    <pageLast>352</pageLast>
    <pageNumber/>
    <edition/>
    <issue>3</issue>
    <volume>174</volume>
    <type>articler</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation>Gesellschaft fur Anlagen und Reaktorsicherheit (GRS) mbH</contributingCorporation>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2016-05-09</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Determination of more realistic Ke,r-factors for simplified elastic–plastic analysis</title>
    <abstract language="eng">According to the relevant KTA-Rules, e.g. KTA 3201.2, strain correction factors — Ke-factors — have to be used in the fatigue analysis of pressurised components if the strain intensity ranges are determined by elastic analyses, and if in this case the range of primary plus secondary stress intensity exceeds a certain limit. This limit is three times the design stress intensity value, Sm, and thus approximately corresponds to twice the value of the 0.2% strain limit. The relations given in the above-mentioned rules to determine the Ke-factors for considering plastification have proved to be very conservative in many cases compared with the strain intensity ranges that were determined by complete elastic–plastic analyses. In order to improve the validity of the fatigue analysis, the topic of `Performance of fundamental work to prepare concrete proposals for realistic Ke,r-factors (strain correction factors) to consider plastification at large strain amplitudes' was one of the subjects of the BMU project SR 2063. In summary, the result was that the proposed realistic Ke,r-factors present a real alternative to the Ke-factors of the regulations; the latter serve a mostly conservative registration of the observed elastic–plastic strain but cannot be explained in terms of physics and are not formulated in a manner adequately specific of any material. The exemplary verification calculations that have been performed so far show, furthermore, that the proposed realistic Ke,r-factors can be easily determined and also deliver sufficiently conservative results. This new method therefore has great potential which, however, still has to continue to be verified by further calculations before it can be included in the KTA-Rules.</abstract>
    <parentTitle language="eng">Nuclear Engineering and Design</parentTitle>
    <identifier type="issn">0029-5493</identifier>
    <enrichment key="BTU">nicht an der BTU erstellt / not created at BTU</enrichment>
    <author>
      <firstName>Klaus W.</firstName>
      <lastName>Bieniussa</lastName>
    </author>
    <submitter>
      <firstName>Hartwig</firstName>
      <lastName>Hübel</lastName>
    </submitter>
    <author>
      <firstName>Hans</firstName>
      <lastName>Reck</lastName>
    </author>
    <author>
      <firstName>Hartwig</firstName>
      <lastName>Hübel</lastName>
    </author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>strain correction factor</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>KTA</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Ke-factor</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>fatigue analysis</value>
    </subject>
    <collection role="institutes" number="6386">FG Baustatik, Stahlbau, FEM</collection>
  </doc>
  <doc>
    <id>16109</id>
    <completedYear/>
    <publishedYear>1996</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>55</pageFirst>
    <pageLast>65</pageLast>
    <pageNumber/>
    <edition/>
    <issue>1</issue>
    <volume>162</volume>
    <type>articler</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2016-05-10</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Basic Conditions for Material and Structural Ratcheting</title>
    <abstract language="eng">This paper is intended to provide an overview of different aspects of ratcheting under cyclic loading below the creep range. It distinguishes between material ratcheting and structural ratcheting, each being characterized by several different phenomena which appear in different configurations of materials, states of stress, structural geometries and loadings. The systematic compilation of these phenomena presented in the paper may help to improve understanding between material researches, developers of inelastic methods of analysis, structural analysts and design code committees. Above all, a certain degree of knowledge about the different mechanisms of ratchetting is important for a structural analyst to be able to choose an appropriate analytical method for assessing the ratcheting phenomena involved in a specific design problem.</abstract>
    <parentTitle language="eng">Nuclear Engineering and Design</parentTitle>
    <identifier type="doi">10.1016/0029-5493(95)01136-6</identifier>
    <identifier type="url">http://www.sciencedirect.com/science/article/pii/0029549395011366</identifier>
    <identifier type="issn">0029-5493</identifier>
    <enrichment key="BTU">nicht an der BTU erstellt / not created at BTU</enrichment>
    <author>
      <firstName>Hartwig</firstName>
      <lastName>Hübel</lastName>
    </author>
    <submitter>
      <firstName>Hartwig</firstName>
      <lastName>Hübel</lastName>
    </submitter>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Shakedown</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Material Ratcheting</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Structural Ratcheting</value>
    </subject>
    <collection role="institutes" number="6386">FG Baustatik, Stahlbau, FEM</collection>
  </doc>
  <doc>
    <id>19874</id>
    <completedYear/>
    <publishedYear>2017</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>139</pageFirst>
    <pageLast>152</pageLast>
    <pageNumber/>
    <edition/>
    <issue>2</issue>
    <volume>9</volume>
    <type>articler</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2017-04-13</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Ratcheting caused by moving loads</title>
    <abstract language="eng">Progressive deformation (ratcheting) can occur as a response to variable loads as soon as the elastic limit is exceeded. If this is the case, strains and displacements accumulate in the event of cyclic loading in each load cycle. Widely known as triggers for ratcheting and already being considered in some design codes are configurations, in which a structure is subjected to at least two different types of load, namely a constant load (the primary load) and a superimposed cyclic load. In this paper, another mechanism that generates ratcheting is introduced. It can be attributed solely to the effect of a single load. In the simplest case, this can be explained by the successive activation of (an infinite number of) plastic hinges if a load of constant magnitude is moved in space. The increments of strains and displacements can decrease or increase from cycle to cycle, when the material is hardening, or if elastic foundation is present, or if the equilibrium condition is formulated for the deformed system (second-order theory) or if “large” rotations are taken into account (third-order theory).</abstract>
    <parentTitle language="eng">International Journal of Advanced Structural Engineering</parentTitle>
    <identifier type="url">http://link.springer.com/article/10.1007/s40091-017-0154-0/fulltext.html</identifier>
    <identifier type="issn">2008-6695</identifier>
    <identifier type="issn">2008-3556</identifier>
    <enrichment key="BTU">an der BTU erstellt / created at BTU</enrichment>
    <author>
      <firstName>Hartwig</firstName>
      <lastName>Hübel</lastName>
    </author>
    <submitter>
      <firstName>Hartwig</firstName>
      <lastName>Hübel</lastName>
    </submitter>
    <author>
      <firstName>Bastian</firstName>
      <lastName>Vollrath</lastName>
    </author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Ratcheting</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Progressive deformation</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Shakedown</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Traveling load</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Moving temperature front</value>
    </subject>
    <collection role="institutes" number="6386">FG Baustatik, Stahlbau, FEM</collection>
  </doc>
  <doc>
    <id>23689</id>
    <completedYear/>
    <publishedYear>2019</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>92</pageFirst>
    <pageLast>103</pageLast>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume>171</volume>
    <type>articler</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2019-03-04</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Simplified determination of accumulated strains to satisfy design code requirements</title>
    <abstract language="eng">In case of cyclic loading, strain may accumulate due to a ratcheting mechanism until the state of shakedown is possibly achieved. Design Codes frequently require strain limits to be satisfied at the end of the specified lifetime of the structure. In addition, the strain range is required for performing fatigue analyses in case of plastic shakedown. However, little guidance is usually provided by Design Codes on how the accumulated strains and strain ranges are to be calculated, and some of the guidelines implemented in Design Codes are not well founded and may therefore be misleading. This is, for example, true for the ASME B&amp;PV Code, Section III. Of course, strains and strain ranges can be determined by means of incremental elastic-plastic analyses, which require to go step-by-step through many cycles of a given load histogram until the state of shakedown is reached. This is rather costly in terms of engineering time and numerical effort. As an alternative, simplified methods can be adopted, e.g. the Simplified Theory of Plastic Zones (STPZ) as used in the present paper. Being a direct method, effects from load history are disregarded. The theory is described shortly and illustrated by some examples. It is shown that the Simplified Theory of Plastic Zones is well suited to provide reasonable estimates of strains accumulated in the state of elastic and plastic shakedown at the cost of few linear elastic analyses.</abstract>
    <parentTitle language="eng">International Journal of Pressure Vessels and Piping</parentTitle>
    <identifier type="doi">10.1016/j.ijpvp.2019.01.014</identifier>
    <identifier type="url">https://www.sciencedirect.com/science/article/pii/S0308016118304617</identifier>
    <identifier type="issn">0308-0161</identifier>
    <enrichment key="BTU">an der BTU erstellt / created at BTU</enrichment>
    <enrichment key="opus.doi.autoCreate">false</enrichment>
    <enrichment key="opus.urn.autoCreate">false</enrichment>
    <author>
      <firstName>Hartwig</firstName>
      <lastName>Hübel</lastName>
    </author>
    <submitter>
      <firstName>Hartwig</firstName>
      <lastName>Hübel</lastName>
    </submitter>
    <author>
      <firstName>Bastian</firstName>
      <lastName>Vollrath</lastName>
    </author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Simplified elastic-plastic analysis</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Simplified theory of plastic zones (STPZ)</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Zarka's method</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Shakedown</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Ratcheting</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Cyclic loading</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Accumulated strains</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Strain range</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Residual stress</value>
    </subject>
    <collection role="institutes" number="6386">FG Baustatik, Stahlbau, FEM</collection>
  </doc>
  <doc>
    <id>23794</id>
    <completedYear/>
    <publishedYear>2019</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>031206-1</pageFirst>
    <pageLast>031206-10</pageLast>
    <pageNumber/>
    <edition/>
    <issue>3</issue>
    <volume>141</volume>
    <type>articler</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2019-03-25</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Limited Versus Unlimited Strain Accumulation Due to Ratcheting Mechanisms</title>
    <abstract language="eng">After distinguishing material ratcheting and structural ratcheting, different phenomena related to structural ratcheting are gathered. Ratcheting of elastic–plastic structures observed with stationary position of loads is distinguished from ratcheting with moving loads. Both categories are illustrated by examples. The effect of evolution laws for the internal variables describing kinematic hardening on the accumulation of strain due to a ratcheting mechanism, and whether the ratcheting mechanism ceases with the number of cycles so that the accumulated strains are limited, is discussed. Some conditions are shown, under which the Chaboche model can lead to shakedown. Scenarios where shakedown is guaranteed at every load level, or where it may or may not occur at a specific load level, or where it definitely cannot occur at any load level, are distinguished. Correspondingly, the usefulness of shakedown analyses, which are searching for maximum load factors assuring shakedown, or direct (or simplified) methods to obtain postshakedown quantities by avoiding incremental cyclic analyses is discussed.</abstract>
    <parentTitle language="eng">Journal of Pressure Vessel Technology</parentTitle>
    <identifier type="doi">10.1115/1.4042853</identifier>
    <identifier type="url">http://pressurevesseltech.asmedigitalcollection.asme.org/article.aspx?articleid=2725462</identifier>
    <enrichment key="BTU">an der BTU erstellt / created at BTU</enrichment>
    <enrichment key="Artikelnummer">PVT-18-1148</enrichment>
    <author>
      <firstName>Hartwig</firstName>
      <lastName>Hübel</lastName>
    </author>
    <submitter>
      <firstName>Hartwig</firstName>
      <lastName>Hübel</lastName>
    </submitter>
    <author>
      <firstName>Bastian</firstName>
      <lastName>Vollrath</lastName>
    </author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Ratcheting</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>moving loads</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>cyclic loads</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>strain accumulation</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>hardening</value>
    </subject>
    <collection role="institutes" number="6386">FG Baustatik, Stahlbau, FEM</collection>
  </doc>
  <doc>
    <id>27013</id>
    <completedYear/>
    <publishedYear>2021</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst/>
    <pageLast/>
    <pageNumber>12</pageNumber>
    <edition/>
    <issue>2</issue>
    <volume>143</volume>
    <type>articler</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2021-02-16</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Plastic Limit Analysis Using the Simplified Theory of Plastic Zones</title>
    <abstract language="eng">The simplified theory of plastic zones (STPZ) was mainly developed to determine strain ranges and accumulated strains in the state of shakedown at cyclic loading between prescribed levels of loading. Kinematic hardening is an indispensable feature of the STPZ. The plastic limit load, however, is defined for monotonic loading and elastic–plastic material behavior without hardening. Simply assigning a zero value or a numerically very low value of the tangent modulus when applying the STPZ is generally not possible due to arising numerical instabilities. It is, therefore, not immediately obvious how the STPZ can be used to determine the maximum load level that can be applied to a structure without developing a kinematic mechanism. This paper describes the theory and the analysis steps required and provides some illustrative examples. Typically, between one and three linear elastic analyses and some local calculations are required to provide either the exact value or at least a reasonable estimate of a range of the plastic limit load, as well as of the associated stress and strain fields and displacements that are not provided by classical limit analysis.</abstract>
    <parentTitle language="eng">Journal of pressure vessel technology</parentTitle>
    <identifier type="doi">10.1115/1.4049643</identifier>
    <identifier type="issn">1528-8978</identifier>
    <enrichment key="BTU">an der BTU erstellt / created at BTU</enrichment>
    <enrichment key="opus.source">publish</enrichment>
    <enrichment key="Artikelnummer">021303</enrichment>
    <enrichment key="Fprofil">4 Künstliche Intelligenz und Sensorik / Artificial Intelligence and Sensor Technology</enrichment>
    <author>
      <firstName>Hartwig</firstName>
      <lastName>Hübel</lastName>
    </author>
    <submitter>
      <firstName>Hartwig</firstName>
      <lastName>Hübel</lastName>
    </submitter>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>limit load</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>simplified theory of plastic zones</value>
    </subject>
    <collection role="institutes" number="6309">FG Statik und Dynamik</collection>
  </doc>
  <doc>
    <id>27325</id>
    <completedYear/>
    <publishedYear>2021</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst/>
    <pageLast/>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume>192</volume>
    <type>articler</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2021-04-20</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Effect of stress stiffness on elastic-plastic strain range</title>
    <abstract language="eng">Many pressure vessel and piping components have to withstand high internal pressures and are therefore thick-walled so that geometric effects such as stress stiffening need not be accounted for. However, thin-walled or moderately thick structures may be sensitive to these effects. Design Codes such as the ASME Boiler and Pressure Vessel Code usually provide little guidance on when they are to be accounted for. In the opinion of the authors, this effect deserves more attention. Therefore, the purpose of this paper is to illuminate the effect of stress stiffening by investigating some examples, with particular attention to elastic-plastic strain ranges and the plastic strain range enhancement factor Ke used for fatigue analyses.</abstract>
    <parentTitle language="eng">International Journal of Pressure Vessels and Piping</parentTitle>
    <identifier type="issn">0308-0161</identifier>
    <identifier type="url">https://www.sciencedirect.com/science/article/pii/S0308016121001174?via%3Dihub</identifier>
    <identifier type="doi">10.1016/j.ijpvp.2021.104421</identifier>
    <enrichment key="BTU">an der BTU erstellt / created at BTU</enrichment>
    <enrichment key="Artikelnummer">104421</enrichment>
    <enrichment key="opus.source">publish</enrichment>
    <enrichment key="opus.doi.autoCreate">false</enrichment>
    <enrichment key="opus.urn.autoCreate">false</enrichment>
    <enrichment key="Fprofil">4 Künstliche Intelligenz und Sensorik / Artificial Intelligence and Sensor Technology</enrichment>
    <author>
      <firstName>Hartwig</firstName>
      <lastName>Hübel</lastName>
    </author>
    <submitter>
      <firstName>Hartwig</firstName>
      <lastName>Hübel</lastName>
    </submitter>
    <author>
      <firstName>Bastian</firstName>
      <lastName>Vollrath</lastName>
    </author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Ke</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Elbow</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Strain range</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Stress stiffening</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Plasticity</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Twice Yield</value>
    </subject>
    <collection role="institutes" number="6309">FG Statik und Dynamik</collection>
  </doc>
  <doc>
    <id>28785</id>
    <completedYear/>
    <publishedYear>2022</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst/>
    <pageLast/>
    <pageNumber>15</pageNumber>
    <edition/>
    <issue/>
    <volume>95</volume>
    <type>articler</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2022-04-21</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Simplified Theory of Plastic Zones in the state of elastic shakedown with stress stiffening</title>
    <abstract language="eng">Cyclic loading may cause elastic-plastic strains to accumulate if a ratcheting mechanism is present. After a number of cycles, strain accumulation may cease so that a state of either elastic or plastic shakedown is reached. Determination of strains and other quantities in the state of shakedown (post-shakedown quantities) by means of incremental analyses is costly. Direct methods such as the Simplified Theory of Plastic Zones (STPZ) aim at providing estimates of the post-shakedown quantities, bypassing cycle-by-cycle analyses. If geometric effects such as stress stiffening play a role, determination of accumulated strains even becomes more complicated. The STPZ has been further developed in order to account for the combination of plasticity and stress stiffening with respect to elastic shakedown. The theory is described and illustrated using examples such as a pipe bend subjected to cyclic in-plane bending. The implications of cyclic as opposed to constant stress stiffness are discussed. The effect of stress stiffening on ratcheting interaction diagrams (RID), separating regions of elastic and plastic shakedown in the space of loading parameters, is discussed.</abstract>
    <parentTitle language="eng">European Journal of Mechanics - A/Solids</parentTitle>
    <identifier type="doi">10.1016/j.euromechsol.2022.104613</identifier>
    <identifier type="issn">0997-7538</identifier>
    <enrichment key="BTU">an der BTU erstellt / created at BTU</enrichment>
    <enrichment key="opus.source">publish</enrichment>
    <enrichment key="Artikelnummer">104613</enrichment>
    <enrichment key="opus.doi.autoCreate">false</enrichment>
    <enrichment key="opus.urn.autoCreate">false</enrichment>
    <enrichment key="Fprofil">4 Künstliche Intelligenz und Sensorik / Artificial Intelligence and Sensor Technology</enrichment>
    <author>
      <firstName>Hartwig</firstName>
      <lastName>Hübel</lastName>
    </author>
    <submitter>
      <firstName>Hartwig</firstName>
      <lastName>Hübel</lastName>
    </submitter>
    <author>
      <firstName>Bastian</firstName>
      <lastName>Vollrath</lastName>
    </author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Cyclic strain accumulation</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Shakedown</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Ratcheting</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Post-shakedown quantities</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Stress stiffening</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Geometric effects</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Second order effects</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Progressive buckling</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Zarka's method</value>
    </subject>
    <collection role="institutes" number="6309">FG Statik und Dynamik</collection>
  </doc>
  <doc>
    <id>29052</id>
    <completedYear/>
    <publishedYear>2022</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>1</pageFirst>
    <pageLast>11</pageLast>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume>199</volume>
    <type>articler</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2022-06-30</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Ratcheting and strain ranges in the shakedown state with stress stiffening using the Simplified Theory of Plastic Zones</title>
    <abstract language="eng">The behavior of elastic-plastic structures under cyclic loading can be determined by incremental elastic-plastic analyses where a given load histogram is analysed cycle-by-cycle until shakedown is achieved. Many cycles may be required for this, if a ratchet mechanism is causing plastic strains to accumulate in each cycle until either elastic or plastic shakedown is achieved. The complexity of the elastic-plastic response of a structure is further increased if geometric effects are present. It may be very costly to get the accumulated strains and strain ranges in the state of shakedown by incremental analyses so that simplified or direct methods have been developed as an alternative. The Simplified Theory of Plastic Zones (STPZ) has proven itself for estimating the required quantities in the state of elastic and plastic shakedown within the framework of the 1st order theory, i.e., if the equilibrium conditions are satisfied for the undeformed structure. It is shown in this paper, how the STPZ can be expanded to capture 2nd order effects introduced by the equilibrium of the deformed structure. Some examples are used to demonstrate its applicability and the quality of the results, but also its limitations with respect to determining the accumulated strains and elastic-plastic strain ranges.</abstract>
    <parentTitle language="eng">International Journal of Pressure Vessels and Piping</parentTitle>
    <identifier type="issn">0308-0161</identifier>
    <identifier type="doi">10.1016/j.ijpvp.2022.104727</identifier>
    <enrichment key="BTU">an der BTU erstellt / created at BTU</enrichment>
    <enrichment key="Artikelnummer">104727</enrichment>
    <enrichment key="opus.source">publish</enrichment>
    <enrichment key="Fprofil">4 Künstliche Intelligenz und Sensorik / Artificial Intelligence and Sensor Technology</enrichment>
    <author>
      <firstName>Hartwig</firstName>
      <lastName>Hübel</lastName>
    </author>
    <submitter>
      <firstName>Hartwig</firstName>
      <lastName>Hübel</lastName>
    </submitter>
    <author>
      <firstName>Bastian</firstName>
      <lastName>Vollrath</lastName>
    </author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Simplified theory of plastic zones</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Cyclic strain accumulation</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Shakedown</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Ratcheting</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Post-shakedown quantities</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Stress stiffening</value>
    </subject>
    <collection role="institutes" number="6309">FG Statik und Dynamik</collection>
  </doc>
</export-example>
