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100 results on '"Dzugan, Jan"'

18. Damage tolerant design of additively manufactured metallic components subjected to cyclic loading: State of the art and challenges

Author

Zerbst, Uwe, Bruno, Giovanni, Buffière, Jean-Yves, Wegener, Thomas, Niendorf, Thomas, Wu, Tao, Zhang, Xiang, Kashaev, Nikolai, Meneghetti, Giovanni, Hrabe, Nik, Madia, Mauro, Werner, Tiago, Hilgenberg, Kai, Koukolíková, Martina, Procházka, Radek, Džugan, Jan, Möller, Benjamin, Beretta, Stefano, Evans, Alexander, Wagener, Rainer, and Schnabel, Kai

Published
2021
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41. New approach for determination of strain rate sensitivity of mild steel dc01 under stack compression and uniaxial tensile test

Author

Farahnak, Pedram, Urbanek, Miroslav, Rund, Martin, Dzugan, Jan, Gerke, Stefen, and Brünig, Michael

Subjects
Finite element method, Plasticity -- Mathematical models, Plasticitat, Elements finits, Mètode dels, Matemàtiques i estadística::Anàlisi numèrica::Mètodes en elements finits [Àrees temàtiques de la UPC], Material Characterization, Forming Process, Strain Rate Sensitivity, Tensile Test, Stack Compression Test, Plasticitat -- Models matemàtics
Abstract

Deformation under uniaxial tensile loading with using Digital Image Correlations (DIC) is the easiest way to analyze the material behavior in sheet metal forming. In order to determine the plastic parameters such as hardening, anisotropy and strain rate sensitivity at higher strain level, equi-biaxial stress state is prerequisite. As reported in the literature, Bulge tests are frequently used for this purpose, but in this work, stack compression test is used as an alternative. In this experiment, deformation in the middle layer where the friction effect is the lowest was monitored using two pairs of DIC systems in rolling and transversal directions. Uniaxial tensile tests as well as stack compression tests were performed on mild ferritic steel DC01 at different strain rates, from 0.001 𝑠𝑠−1 to 10 𝑠𝑠−1. Strain rate sensitivity parameter was investigated at different level of strains for both experiments and strain rate sensitivity profiles were obtained. Results show a decrease of material strain rate sensitivity with increasing the true strain.

Published
2019

42. Fracture Toughness Determination with the Use of Miniaturized Specimens

Author

Dzugan, Jan

Subjects
Science / Mechanics / Solids
Abstract

Fracture mechanics has been used for decades nowadays, and methods have been well established in the community especially for standard-sized specimens. As it was mainly developed for large structure assessment against the brittle failure, standardized specimens are of large size at present. However, in many cases, these standard specimens are not possible to apply due to size requirements of the available experimental material or the size of the component considered. These can be cases of residual service life assessment of in-service components, local properties determination (e.g., across weld), anisotropy determination and assessment of mechanical properties of newly developed materials under laboratory conditions (e.g., SPD processed materials, etc.). Therefore, development of new methods using significantly smaller specimens has to be carried out, and procedures using smaller-sized specimens together with their validity limits and relation to standardly obtained results have to be provided in order to provide solution for wide applications.

Published
2018

46. Uncoupled material model of ductile fracture with directional plasticity

Author

Spaniel, Miroslav, Mares, Tomás, Kuzelka, Jiri, Sêbek, Frantisek, Dzugan, Jan, Spaniel, Miroslav, Mares, Tomás, Kuzelka, Jiri, Sêbek, Frantisek, and Dzugan, Jan

Abstract

Proposed paper deals with the application of plastic response with directional distortional hardening (DDH) in uncoupled ductile fracture model and comparison of the results with the same ductile fracture model based on isotropic J2 plasticity. The results of simulations have proven not negligible role of model of plasticity and the response of the model with DDH plasticity is closer to reality then the one of the model with isotropic plasticity.

Published
2017

50. Crack lengths calculation by unloading compliance technique for Charpy size specimens

Author

Dzugan, Jan and Dzugan, Jan

Abstract

The problems with the crack length determination by the unloading compliance method are well known for Charpy size specimens. The final crack lengths calculated for bent specimens do not fulfil ASTM 1820 accuracy requirements. Therefore some investigations have been performed to resolve this problem. In those studies it was considered that measured compliance should be corrected for various factors, but satisfying results were not attained. In the presented work the problem was attacked from the other side, the measured specimen compliance was taken as a correct value and what had to be adjusted was the calculation procedure. On the basis of experimentally obtained compliances of bent specimens and optically measured crack lengths the investigation was carried out. Finally, a calculation procedure enabling accurate crack length calculation up to 5mm of plastic deflection was developed. Applying the new procedure, out of investigated 238 measured crack lengths, more than 80% of the values fulfilled the ASTM 1820 accuracy requirements, while presently used procedure provided only about 30% of valid results. The newly proposed procedure can be also prospectively used in modified form for the specimens of different than Charpy size.

Published
2010

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