TY - JOUR A1 - Grelle, Tobias A1 - Wolff, Dietmar A1 - Jaunich, Matthias T1 - Leakage behaviour of elastomer seals under dynamic unloading conditions at low temperatures JF - Polymer Testing N2 - In technical applications, static seals are sometimes also subjected to dynamic loadings. Therefore, the leakage behaviour under dynamic conditions has to be evaluated as well. For this purpose, FKM elastomer seals have been tested by using newly designed equipment that allows for rapid partial release of the seal and simultaneous leakage rate measurement at a wide range of test temperatures. Furthermore, material characterisation was done by using Dynamic Mechanical Analysis, Differential Scanning Calorimetry and Compression Set. It was shown that, under static conditions, the leakage rate increased significantly during cooling at temperatures around 18 K lower than the glass transition range. On reheating, the seal’s functionality was restored in the high temperature region of the glass rubber transition. In the subsequent dynamic release tests, that comprised a reduction of the seal compression within 1 s from 25 % to 23 %, increased leakage rates were observed in the high temperature region of the glass transition range. It was shown that the temperature that is critical for increased leakage is significantly lower under static conditions compared to dynamic conditions. The obtained leakage rates for static tests and dynamic release tests at different temperatures were analysed with reference to results of the material characterisation. KW - Sealing material KW - Rubber KW - Partial release KW - Low temperature behaviour KW - Leakage rate PY - 2017 DO - https://doi.org/10.1016/j.polymertesting.2016.12.018 SN - 0142-9418 SN - 1873-2348 VL - 58 SP - 219 EP - 226 PB - Elsevier Ltd. CY - Oxford, UK AN - OPUS4-38911 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Grelle, Tobias A1 - Wolff, Dietmar A1 - Probst, Ulrich A1 - Jaunich, Matthias A1 - Völzke, Holger T1 - Investigation programme for evaluation and prediction of the long-term behaviour of Helicoflex® metal seals T2 - 48th Annual Meeting on Nuclear Technology (AMNT 2017) Proceedings N2 - In Germany, for the transport and storage of spent nuclear fuel, casks with double closure lid systems are used, which are equipped with Helicoflex® metal seals. The original interim storage period for these casks was planned to be 40 years. However, recent political developments indicate that a storage time of more than 80 years might be necessary. Therefore, the current storage licenses have to be renewed in due course, which requires extended knowledge of the long-term behaviour of all cask components. At the Bundesanstalt für Materialforschung und -prüfung (BAM), metal seals have been investigated after ageing at temperatures between room temperature and 150 °C for up to 7 years. At regular intervals the seals have been tested for leakage rate as well as for their mechanical behaviour. From these tests pronounced influence of ageing could be shown which results in the decrease of the seal force and the useable resilience. The main reason attributed to these performance changes is the increasing permanent deformation of the outer layer of the seal due to creep. So far, an explicit analytical description of the long-term behaviour that could be used for predictions exceeding the tested ageing times and temperatures was not suitable. In addition to the component tests that were already conducted, a comprehensive investigation programme has been started to describe the mechanical behaviour of the individual seal components. The individual seal components are tested regarding different material characteristics including creep, deformation and microstructural properties. The comparability of the material characterization is ensured by comparing the basic raw material of the specimen with the actual component material. Furthermore, detailed investigations of the time and temperature dependent deformation behaviour are realized by ageing seal segments at multiple temperatures for different periods of time and employing standardized tests. By analysing the acquired data in combination with the ongoing long-term component tests a dataset for analytical prediction of the long-term behaviour of the seals is intended for an extended period of time under a certain temperature regime. T2 - 48th Annual Meeting on Nuclear Technology (AMNT 2017) CY - Berlin, Germany DA - 16.05.2017 KW - Metal seal KW - Creep KW - Long-term behavior PY - 2017 SP - 1 EP - 7 AN - OPUS4-43418 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Grelle, Tobias A1 - Wolff, Dietmar A1 - Probst, Ulrich A1 - Jaunich, Matthias A1 - Völzke, Holger T1 - Material investigation and long-term sealing behavior of Helicoflex® metal seals used in containers for spent nuclear fuel T2 - Waste Management Symposia 2017 Proceedings N2 - In Germany spent nuclear fuel is stored and transported in casks that possess bolted lid systems equipped with double jacket metal seals of Helicoflex® type in order to enable safe enclosure of the radioactive inventory. A dry interim storage period of 40 years was planned and the casks are licensed for that time span. However, due to political reasons and delayed disposal projects this time span is expected to increase significantly. It is therefore necessary to evaluate the long-term sealing behavior of the casks exceeding 40 years of operating time. In this paper, we discuss our approach to investigate the aging behavior of such metal seals, and to predict the long-term sealing behavior. Accelerated aging component tests with seals are performed at temperatures up to 150°C to investigate the course of seal force, useable resilience and leakage rate. Even though these tests have already shown a significant decrease in seal force and useable resilience after aging times of less than 1 year, for most seals the leakage rate stayed better than the specified value. However, observation of the leakage rate has to be continued to determine the aging effect on the seal properties. As a main influence on the seal long-term behavior the increasing permanent deformation of the outer jacket has been recognized. It is made of aluminum or silver which means that the temperatures that are relevant for the aforementioned application in casks lead to creep deformation. For further investigation of seal behavior a comprehensive research program concerning the material characteristics and aging behavior of the individual seal components, with an emphasis on the outer jacket material, has been launched. The aim is to get a better understanding of the time and temperature dependent creep mechanisms and deformation. The examinations are separated into tests on seal segments and tests on standardized specimen. In order to be able to study the aging process, seal segments are compressed in flanges and stored at temperatures ranging from room temperature to 150°C. After defined time intervals the segments are analyzed by using standardized tests including structure investigation and creep tests. The results are compared with the behavior of the specimen basic raw material. This is done to ensure comparability of the thin jacket material and additional sheet material used for standardized tests. Thus, the prediction of component changes after different aging times at different temperatures can be made. As a result forecasts on the long term seal behavior are intended. T2 - Waste Management Symposia CY - Phoenix, AZ, USA DA - 05.03.2017 KW - Metal seal KW - Creep KW - Long-term behavior PY - 2017 SN - 978-0-9828171-6-2 SP - Article 17135, 1 EP - 8 AN - OPUS4-40611 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias A1 - Kömmling, Anja A1 - Wolff, Dietmar T1 - Characterisation of degradation and determination of end-of-lifetime criterion for O-ring seals N2 - The ageing of polymers, including elastomers, is an undesirable but inevitable process leading to a limited lifetime of rubber products such as seals. Independent of the application, as e.g. automotive, piping or container applications, a long lifetime or at least a timely exchange of a seal before occurence of critical failure is desired. In order to investigate the degradation of material properties and to determine the lifetime of elastomers used as seals, an ageing programme was started with hydrogenated acrylonitrile butadiene rubber (HNBR), ethylene propylene diene rubber (EPDM) and fluorocarbon rubber (FKM) [1-3]. Both O-ring seals (uncompressed and compressed by 25 %) with a cord diameter of 10 mm as well as sheets with a thickness of 2 mm were aged at 75 °C, 100 °C, 125 °C and 150 °C for up to two years. The changes of material properties during ageing were characterised for each material using the sheets by means of e.g. dynamic-mechanical analysis and tensile tests, while sealing properties such as compression stress relaxation (CSR), compression set (CS) and leakage rate were determined on O-rings. The experimental results indicate that while material properties, CSR and CS show considerable degradation effects, the static leakage rate stays constant or even decreases before failure occurs quite suddenly at advanced degradation levels. This reveals that static leakage rate has only limited sensitivity for the degradation of the seal material. Our approach to determine a suitable end of lifetime criterion, which involves a partial decompression of the seal during the leakage test, is presented and discussed. T2 - RubberCon 2017 CY - Prague, Czech Republic DA - 23.05.2017 KW - Rubber seal KW - Ageing KW - Leakage PY - 2017 AN - OPUS4-40381 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias A1 - Hagenow, Peter A1 - Kasparek, Eva Maria A1 - Kömmling, Anja A1 - Noack, Volker A1 - Völzke, Holger A1 - Wolff, Dietmar T1 - Requirements for the use of elastomer seals in casks for final disposal of low and intermediate level waste N2 - Elastomer seals are widely used as barrier seals in containers for low and intermediate level radioactive waste and in some countries for spent fuel transportation casks. Depending on the area of use, the rubber materials have to demonstrate proper sealing performance with regard to mechanical, thermal and environmental conditions as well as irradiation during the entire operation period. In Germany the low and intermediate level radioactive waste is planned to be disposed in the Konrad repository in standardized containers. Many of these containers use an elastomer seal between lid and container body. Depending on the radiactive inventory and a possible containment of the waste in inner barrels and/or concrete structures, such containers may require a specific leak tightness. In such cases, specified leakage rates are shall not be exceeded by the the seals to keep potential activity releases from the inventories well below defined limits. Generally, all waste containers have to fulfill the waste acceptance criteria for the Konrad repository as defined by the reports BfS SE-IB-29/08 and SE-IB-30/08. From these criteria several requirements for seal performance are derived. The seals have to: - ensure full functionality until final container disposal, - maintain its function in case of a thermal or mechanical accident, - ensure encapsulation also at -20 °C. This combination of requirements is challenging especially as a seal exchange, which is typical for many other applications, is hardly possible and thus a sound understanding of how to perform safety evaluation of containers is required. Therefore BAM has initiated investigations on elastomer seal behaviour. This work focuses on low temperature behaviour and sealing performance concerning static conditions as well as partial loss of compression and ageing of elastomer seals. Concerning ageing, property changes caused by long-term thermooxidative conditions as well as gamma irradiation are investigated. This contribution presents an overview and explanation of the aims of the ongoing research and gives an update of the most relevant results. T2 - 13th International Symposium "Conditioning of Radioactive Operational & Decomissioning Wastes" CY - Dresden, Germany DA - 22.03.2017 KW - Disposal KW - Konrad repository KW - Seal KW - Ageing PY - 2017 AN - OPUS4-39868 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias A1 - Grelle, Tobias A1 - Goral, Milan A1 - Wolff, Dietmar T1 - Investigations on the low temperature performance of rubber seals N2 - For many sealing applications rubbers are applied due to their special material properties and easy use. In many applications as e.g. in aviation, traffic or process technology the material can be exposed to low temperatures during operation. Therefore, it is important to know the material behaviour at those low temperatures to determine the temperature range that allows a safe operation of the seal. In this work, we focus on the behaviour of elastomer seals at low temperatures with regard to potential decrease of leak-tightness or catastrophic seal failure of O-ring rubber seals. This is required as material properties of rubbers are strongly temperature dependent but their temperature application range is not always clearly defined. Based on previous investigations which considered the physical material properties and the seal behaviour under purely static conditions we widen the focus on the sealing performance after a fast partial relief of compressed seals and additional materials. For the investigations, different typical rubber seal materials were used as e.g. fluorocarbon (FKM), ethylene propylene diene (EPDM) and hydrogenated acrylonitrile-butadiene (HNBR) rubber. The correlation of the physical material properties with seal performance is studied. This includes as well purely static sealing applications as the Performance during/after fast partial relief of seals at low temperatures. T2 - Technomer 2017 CY - Chemnitz, Germany DA - 09.11.2017 KW - Seal KW - Rubber KW - Low temperature KW - Recovery PY - 2017 AN - OPUS4-42839 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jaunich, Matthias T1 - Editorial: Shape memory polymers JF - Polymer Testing N2 - In this editorial the focus lies on the testing of shape memory materials. KW - Shape memory polymer KW - Testing PY - 2017 DO - https://doi.org/10.1016/j.polymertesting.2017.08.019 SN - 0142-9418 VL - 62 SP - A1 PB - Elsevier CY - Oxford AN - OPUS4-41714 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias A1 - Kömmling, Anja A1 - Wolff, Dietmar T1 - Ageing behaviour of elastomer seals N2 - The current results of the ongoing ageing investigations performed at BAM 3.4 are presented. T2 - ElastoMER 2017 CY - Merseburg, Germany DA - 27.09.2017 KW - Ageing KW - Seal KW - Degradation PY - 2017 AN - OPUS4-42476 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias A1 - Kömmling, Anja A1 - Wolff, Dietmar T1 - O-ring seals: Material degradation, seal performance and determination of end-of-lifetime criterion N2 - Ageing of O-ring seals to evaluate the probable lifetime is an important task for long term applications. In this contribution the material degradation of O-ring seals is studied and a suitable end-of-lifetime criterion is determined under consideration of the application conditions. T2 - VDI Fachtagung Dichtungstechnik CY - Schweinfurt, Germany DA - 27.06.2017 KW - O ring KW - Ageing KW - Lifetime criterion PY - 2017 AN - OPUS4-40957 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias A1 - Grelle, Tobias A1 - Goral, Milan A1 - Wolff, Dietmar ED - Gehde, M. ED - Wagenknecht, U. ED - Bloß, P. T1 - Further investigations on the low temperature performance of rubber seals T2 - Technomer 2017 N2 - For many sealing applications low temperature performance is required. The overall understanding of the relevant influences on low temperature performance of rubber seals are summarized and the currently running investigations described. The correlation of the physical material properties with seal performance is studied. This includes as well purely static sealing applications as the performance during/after fast partial relief of seals at low temperatures. T2 - Technomer 2017 CY - Chemnitz, Germany DA - 09.11.2017 KW - Seal KW - Low temperature KW - Rubber KW - Recovery PY - 2017 SN - 978-3-939382-13-3 VL - 2017 SP - 40 EP - 40 AN - OPUS4-42845 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaunich, Matthias A1 - Hagenow, Peter A1 - Kasparek, Eva Maria A1 - Kömmling, Anja A1 - Noack, Volker A1 - Völzke, Holger A1 - Wolff, Dietmar T1 - Requirements for the use of elastomer seals in casks for final disposal of low and intermediate level waste T2 - KONTEC 2017 N2 - Elastomer seals are widely used as barrier seals in containers for low and intermediate level radioactive waste and in some countries for spent fuel transportation casks. Depending on the area of use, the rubber materials have to demonstrate proper sealing performance with regard to mechanical, thermal and environmental conditions as well as irradiation during the entire operation period. In Germany the low and intermediate level radioactive waste is planned to be disposed in the Konrad repository in standardized containers. Many of these containers use an elastomer seal between lid and container body. Depending on the radiactive inventory and a possible containment of the waste in inner barrels and/or concrete structures, such containers may require a specific leak tightness. In such cases, specified leakage rates are shall not be exceeded by the the seals to keep potential activity releases from the inventories well below defined limits. Generally, all waste containers have to fulfill the waste acceptance criteria for the Konrad repository as defined by the reports BfS SE-IB-29/08 and SE-IB-30/08. From these criteria several requirements for seal performance are derived. The seals have to: - ensure full functionality until final container disposal, - maintain its function in case of a thermal or mechanical accident, - ensure encapsulation also at -20 °C. This combination of requirements is challenging especially as a seal exchange, which is typical for many other applications, is hardly possible and thus a sound understanding of how to perform safety evaluation of containers is required. Therefore BAM has initiated investigations on elastomer seal behaviour. This work focuses on low temperature behaviour and sealing performance concerning static conditions as well as partial loss of compression and ageing of elastomer seals. Concerning ageing, property changes caused by long-term thermooxidative conditions as well as gamma irradiation are investigated. This contribution presents an overview and explanation of the aims of the ongoing research and gives an update of the most relevant results. T2 - 13th Internationales Symposium "Konditionierung radioaktiver Betriebs- und Stillegungsabfälle CY - Dresden, Germany DA - 22.03.2017 KW - Disposal KW - Konrad repository KW - Seal PY - 2017 SP - 595 EP - 601 AN - OPUS4-39870 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Jaunich, Matthias A1 - Kömmling, Anja A1 - Wolff, Dietmar ED - Grellmann, W. ED - Langer, B. T1 - Investigations of elastomeric seals – Low temperature performance and aging behavior T2 - Deformation and Fracture Behaviour of Polymer Materials N2 - Due to their simple and reliable application, elastomers are used for many tasks. Many fields of application like transport, aviation and process technology, entail low temperatures where proper functionality of the employed seals has to be ensured. Therefore, understanding the low temperature behavior of elastomeric seals is important for safe seal operation to restrict the temperature application range. For all areas of application, the question of seal lifetime is also important for replacement or maintenance intervals. The lifetime is especially important in applications that allow no seal replacement. Since the seal can determine the lifetime of storage in such cases, reliable lifetime estimation is necessary for these applications, and requires an extensive knowledge of the specific aging behavior. KW - Seal KW - Rubber KW - Ageing KW - Replacement PY - 2017 SN - 978-3-319-41877-3 SN - 978-3-319-41879-7 DO - https://doi.org/10.1007/978-3-319-41879-7_30 SN - 0933-033X SN - 2196-2812 VL - 247 SP - 431 EP - 443 PB - Springer Verlag AN - OPUS4-41167 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kömmling, Anja A1 - Chatzigiannakis, E. A1 - Beckmann, Jörg A1 - Wachtendorf, Volker A1 - von der Ehe, Kerstin A1 - Braun, Ulrike A1 - Jaunich, Matthias A1 - Schade, U. A1 - Wolff, Dietmar T1 - Discoloration Effects of High-Dose gamma-Irradiation and Long-Term Thermal Aging of (U) HMW-PE JF - International Journal of Polymer Science N2 - Two polyethylene types with ultra-high (UHMWPE) and high molecular weight (HMW-PE) used as neutron radiation shielding materials in casks for radioactive waste were irradiated with doses up to 600 kGy using a 60Co gammasource. Subsequently, thermal aging at 125∘C was applied for up to one year. Degradation effects in the materials were characterized using colorimetry, UV-Visspectroscopy, IR spectroscopy, and DSC. Both materials exhibited a yellowing upon irradiation.The discoloration of UHMW-PE disappeared again after thermal aging.Therefore, the yellowing is assumed to originate fromannealable color centers in the formof free radicals that are trapped in the crystalline regions of the polymer and recombine at elevated temperatures. For the antioxidantcontaining HMWPE, yellowing was observed after both irradiation and thermal aging. The color change was correlated mainly to decomposition products of the antioxidant in addition to trapped radicals as in UHMW-PE. Additionally, black spots appeared after thermal aging of HMW-PE. KW - Irradiation KW - UHMWPE KW - Colour center KW - Yellowness index PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-423992 DO - https://doi.org/10.1155/2017/1362491 SN - 1687-9422 VL - 2017 IS - Article ID 1362491 SP - 1 EP - 10 PB - Hindawi AN - OPUS4-42399 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Pourmand, P. A1 - Wolff, Dietmar A1 - Gedde, U.W. T1 - Influence of ageing on sealability of elastomeric O-rings JF - Macromolecular Symposia N2 - At BAM, which is the federal institute for materials research and testing in Germany, it is one of our tasks to evaluate the safety of casks designed for transport and/or storage of radioactive material. This includes the assessment of the service lifetime of elastomeric seals that are part of the container lid system with regard to the requirements for long-term safety (40 years and more) of the containers. Therefore, we started an accelerated ageing programme with selected rubbers often used for seals (HNBR, EPDM and FKM) which are aged at four different temperatures (75 °C, 100 °C, 125 °C and 150 °C) up to 1.5 years. In order to assess sealability, O-rings are aged in compression by 25 % (corresponding to the compression during service) between plates as well as in flanges that allow leakage rate measurements. For comparison, uncompressed O-rings are aged as well. Further methods characterising seal performance are compression stress relaxation (CSR) reflecting the loss of sealing force of a compressed seal over time, and compression set (CS) which represents the recovery behaviour of a seal after release from compression. Additionally, hardness is measured for information about the change of mechanical properties. The experimental results indicate that while hardness, CSR and CS show considerable degradation effects, the leakage rate stays relatively constant or even decreases until shrinkage combined with the loss of resilience of the aged seal leads to leakage. This demonstrates that static leakage rate, which is the only available direct seal performance criterion, has only limited sensitivity towards the degradation of the seal material. CS data is extrapolated using time-temperature shifts and Arrhenius graphs. An exemplary CS of 50 % would be reached after approx. 1.2, 17 and 29 years at 60 °C for HNBR, EPDM and FKM respectively. T2 - PolymerTec 2016 CY - Merseburg, Germany DA - 15.06.2016 KW - Compression KW - Leakage KW - Degradation KW - Rubber KW - Lifetime PY - 2017 DO - https://doi.org/10.1002/masy.201600157 SN - 1022-1360 SN - 1521-3900 VL - 373 IS - 1 SP - UNSP 1600157, 1 EP - 10 PB - WILEY-V C H VERLAG GMBH CY - Weinheim AN - OPUS4-40958 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Wolff, Dietmar T1 - Characterisation of degradation and determination of end-of-lifetime criterion for O-ring seals T2 - RubberCon 2017 N2 - The ageing of polymers, including elastomers, is an undesirable but inevitable process leading to a limited lifetime of rubber products such as seals. Independent of the application, as e.g. in automotive, piping or container applications, a long lifetime or at least a timely exchange of a seal before occurrence of critical failure is desired. In order to investigate the degradation of material properties and to determine the lifetime of elastomers used as seals, an ageing programme was started with hydrogenated acrylonitrile butadiene rubber (HNBR), ethylene propylene diene rubber (EPDM) and fluorocarbon rubber (FKM) [1-3]. Both O-ring seals (uncompressed and compressed by 25 %) with a cord diameter of 10 mm as well as sheets with a thickness of 2 mm were aged at 75 °C, 100 °C, 125 °C and 150 °C for up to two years. The changes of material properties during ageing were characterised for each material using samples from the sheets by means of e.g. Dynamic Mechanical Analysis and tensile tests, while sealing properties such as leakage rate were determined on O-rings. The experimental results indicate that while material properties show considerable degradation effects, the static leakage rate stays constant or even decreases before failure occurs quite suddenly at advanced degradation levels. This reveals that static leakage rate has only limited sensitivity for the degradation of the seal material. Our approach to determine a suitable end of lifetime criterion, which involves a partial decompression of the seal during the leakage test, is presented and discussed. T2 - RubberCon 2017 CY - Prague, Czech Republic DA - 23.05.2017 KW - Life time prediction KW - Ageing KW - Rubber seal KW - Leakage PY - 2017 SN - 978-80-906662-0-7 SP - 65 EP - 72 AN - OPUS4-40391 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Subramani Bhagavatheswaran, E. A1 - Wießner, S. A1 - Jaunich, Matthias A1 - Wolff, Dietmar T1 - Einfluss der Alterung auf dichtungsrelevante Eigenschaften von FKM-, VMQ- und EPDM-Elastomeren T2 - Technomer 2017 N2 - Da Elastomere in vielfältigen Dichtungsanwendungen eingesetzt werden und dabei teilweise großen Einfluss auf die Funktionsfähigkeit und Sicherheit haben, ist der Einfluss der Alterung auf dichtungsrelevante Eigenschaften relevant. Eine strukturierte Untersuchung des Einflusses von verschiedenen Mischungsrezepturen auf die Bauteileigenschaften, das Alterungsverhalten und die Funktion wird vorgestellt. T2 - Technomer 2017 CY - Chemnitz, Germany DA - 09.11.2017 KW - Dichtung KW - Alterung KW - Struktur-Eigenschaftsbeziehung KW - Elastomer PY - 2017 SN - 978-3-939382-13-3 VL - 2017 SP - 41 EP - 41 AN - OPUS4-42844 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Subramani Bhagavatheswaran, E. A1 - Wießner, S. A1 - Jaunich, Matthias A1 - Wolff, Dietmar T1 - Aging study and electrical resistance based stress-monitoring of rubber seals T2 - 192nd Technical meeting of the ACS Rubber Division N2 - Elastomer seals are widely used as barrier seals in containers for low and intermediate level radioactive waste. In addition, they are also used in waste fuel storage and transportation casks as auxiliary seals. Depending on the area of use, the rubber materials have to demonstrate proper sealing performance with respect to mechanical, thermal and environmental conditions as well as irradiation during the entire operation period. A fundamental understanding of the structure property relationship and their changes during aging can help to evaluate the long-term sealing performance. In the present study, specific materials are investigated to study the structure-property and seal performance-correlation. Fluoro-elastomer (FKM), silicone rubber (VMQ) and ethylene propylene diene rubber (EPDM) were chosen as base rubbers. Comparable mechanical properties for these seals, especially in terms of a comparable compression behavior were achieved by careful control of base rubber formulation, i.e., by opting for the right filler and its concentration, amount of crosslinking chemicals, and with the assistance of process oils. Moreover, with the same rubber, similar mechanical properties were achieved by varying the filler concentration and crosslinking degree, which shall enable to correlate the particular influence on the structure property dependency of the seals in detail. The materials are investigated under pristine and aged conditions to evaluate the influence of aging, e.g. on the stress relaxation or recovery behavior. These values appear to be suitable parameters to judge the expected sealing performance. Due to the electrically conducting nature of some fillers used to reinforce rubbers (such as carbon blacks, carbon nanotubes (CNTs), Graphene, etc.) it is possible to obtain current information about mechanical and visco-elastic properties by monitoring the electrical conductivity or resistivity. A simple relation that relates electrical resistance with mechanical stress was derived and the stress values were theoretically predicted from the electrical resistance values, which showed good correlation with experimental results. T2 - 192nd Technical meeting of the ACS Rubber Division CY - Cleveland, OH, USA DA - 09.10.2017 KW - Seal KW - Rubber KW - Degradation KW - Structure-property relationship KW - Ageing PY - 2017 VL - 2017 SP - 1 EP - 25 AN - OPUS4-42849 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weber, Mike A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Wolff, Dietmar A1 - Zencker, Uwe A1 - Völzke, Holger A1 - Schulze, Dietmar A1 - Probst, Ulrich T1 - Testing and Numerical Simulation of Elastomers - From Specimen Tests to Simulation of Seal Behavior under Assembly Conditions T2 - Proceedings-CD, ASME 2017 Pressure Vessels & Piping Conference (PVP2017) N2 - Due to delays in the siting procedure to establish a deep geological repository for spent nuclear fuel and high level radioactive waste as well as in construction of the already licensed Konrad repository for low and intermediate level radioactive waste, extended periods of interim storage become more relevant in Germany. BAM is involved in most of the cask licensing procedures and especially responsible for the evaluation of cask-related long-term safety issues. The long-term performance of elastomer seals for lid systems of transport and storage casks, whether used as auxiliary seals in spent fuel casks or as primary seals for low and intermediate level waste packages, is an important issue in this context. The polymeric structure of these seals causes a complex mechanical behavior with time-dependent sealing force reduction. The results of a comprehensive purpose-designed test program consisting of basic compression and tension tests as well as relaxation tests on unaged specimens of representative types of elastomers (fluorocarbon rubber (FKM) and ethylene propylene diene rubber (EPDM)) at different temperatures and strain rates are presented. They were used to identify the constitutive behavior and to obtain parameters for finite element material models provided by the computer code ABAQUS®. After estimating the influence of uncertainties such as Poisson’s ratio and friction coefficient by sensitivity analyses, the chosen parameters had to prove their suitability for the finite element simulation of the specimen tests themselves. Based on this preliminary work the simulation of a specific laboratory test configuration containing a typical elastomer seal with circular cross section is presented. The chosen finite element material model and the implemented parameters had to show that they are able to represent not only the specimen behavior under predominantly uniaxial load but also the more complex stress states in real components. Deviations between the measured and calculated results are pointed out and discussed. For the consideration of long-term effects in the simulation of elastomer behavior, test results of aged specimens are needed. First information about a new test program, started recently and planned to provide these data, are given. T2 - ASME 2017 Pressure Vessels & Piping Conference (PVP2017) CY - Waikoloa, Hawaii, USA DA - 16.07.2017 KW - Time dependent effects KW - Low temperature behavior KW - Elastomeric seals KW - Aging KW - Simulation KW - Testing PY - 2017 SN - 978-0-7918-5802-8 VL - 7 SP - Article UNSP V007T07A035, 1 EP - 8 AN - OPUS4-41841 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -