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27 results on '"Krexner, Gerhard"'

4. Contributors

Author

Cser, László, primary, Hess, Dennis W., additional, Kalelkar, Sandeep, additional, Kohli, Rajiv, additional, Krexner, Gerhard, additional, Levitin, Galit, additional, Lyon, Brad, additional, Markó, Márton, additional, Postlewaite, Jay, additional, Prabu, S. Lakshmana, additional, Reinhardt, Karen, additional, Suriyaprakash, T.N.K., additional, and Thirumurugan, R., additional

Published
2013
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8. Influence of thermal ageing on the mechanical properties of an additively manufactured photopolymer used in soft tooling applications

Author

Billington , D., Leach, R. K., Phillips , D., Riemer , O., Savio, E., Mischkot, Michael, Krexner, Gerhard, Soprunyuk, Viktor, Schranz, Wilfried, Pedersen, David Bue, Tosello, Guido, Billington , D., Leach, R. K., Phillips , D., Riemer , O., Savio, E., Mischkot, Michael, Krexner, Gerhard, Soprunyuk, Viktor, Schranz, Wilfried, Pedersen, David Bue, and Tosello, Guido

Abstract

In recent years, direct rapid soft tooling based on inserts manufactured additively by light reactive photopolymer curing has become a solid alternative to classic tooling based on subtractive machining of metals for prototyping and pilot production of polymer parts by injection moulding. Reported numbers of injection-moulded parts per insert are in the low to medium three-digit range. This, however, is based on using additive manufacturing for the production of both mould halves. It was found that combining a soft tooling insert on one mould half and a metal insert on the other half can increase insert lifetime to more than 10 000 parts in acrylonitrile butadiene styrene (ABS) with a negligible influence of insert wear on the dimensional stability of the injection-moulded parts. Photopolymers are known for their very low heat conductivity compared to metals and their sensitivity to elevated temperatures leading to degradation and negative effects on their mechanical properties. Considering heat transfer laws, it can be assumed that most thermal energy brought into the cavity during the plastic injection is conducted away through the steel half of the mould, thus leading to a significant reduction of the thermal ageing of the photopolymer insert. This research supports the quantification of the influence of thermal ageing on insert lifetime by performing experiments with photopolymer samples aged thermally after exposure to different elevated temperature levels for different time spans.

Published
2018

21. Neutron Physics with Photorefractive Materials.

Author

Rhodes, William T., Günter, Peter, Huignard, Jean-Pierre, Fally, Martin, Pruner, Christian, Rupp, Romano A., and Krexner, Gerhard

Abstract

When the subject of photorefractive effects began with the discovery of lightinduced refractive-index inhomogeneities in lithium niobate [1], neutron optics had already been established for more than 20 years [2, 3]. Both of the fields have evolved independently of each other into important branches of science and industry. In 1990 those dynamic areas were linked by an experiment in which cold neutronswere diffracted from a grating created by a spatially inhomogeneous illumination of doped polymethylmethacrylate (PMMA). A typical holographic two-wave mixing setup was used to record a refractive-index pattern, a grating, in PMMA that was reconstructed not only with light, as usual, but also with neutrons [4]. Evidently, the illumination induced refractive-index changes for both light and neutrons! In analogy to light optics this phenomenon is called the photo-neutron-refractive effect. [ABSTRACT FROM AUTHOR]

Published
2007
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27. Contributors

Author

Cser, László, Hess, Dennis W., Kalelkar, Sandeep, Kohli, Rajiv, Krexner, Gerhard, Levitin, Galit, Lyon, Brad, Markó, Márton, Postlewaite, Jay, Prabu, S. Lakshmana, Reinhardt, Karen, Suriyaprakash, T.N.K., and Thirumurugan, R.

Published
2012
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