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Åhlin, Hans
Publications (2 of 2) Show all publications
Yi, C., Johansson, D., Schunnesson, H. & Åhlin, H. (2019). Numerical study of the impact of joints on rock fragmentation by blasting. In: : . Paper presented at EFEE 10th World Conference on Explosives and Blasting.
Open this publication in new window or tab >>Numerical study of the impact of joints on rock fragmentation by blasting
2019 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Rock masses consist essentially of intact rock and discontinuities such as joints. Blasting is mostly used method for the rock excavation. To investigate the effects of joints on the fragmentation by blasting, three models with different joint patterns and one model without joint were created in the LS-DYNA code. In these models, a bonded particle model was used to represent the rock to be blasted, a finite element model was adopted to model the remaining rock mass and a particle blast model was employed to describe the detonation of explosives. To validate the contact model for joints, the fragmentation pattern and the individual particle motion from two single borehole shot models with and without joints were compared. The numerical results indicated that the existence of joints has a significant effect on fragmentation and vibration. The models with joints produced finer fragmentation compared to the model without joints in the paper. 

Keywords
blasting, joints, fragmentation
National Category
Geotechnical Engineering
Identifiers
urn:nbn:se:ltu:diva-76089 (URN)978-0-9550290-6-6 (ISBN)
Conference
EFEE 10th World Conference on Explosives and Blasting
Available from: 2019-09-23 Created: 2019-09-23 Last updated: 2019-12-17
Odenberger, E.-L., Pérez Caro, L., Åhlin, H. & Oldenburg, M. (2018). Thermo-mechanical Material Characterization and Stretch-bend Forming of AA6016. Paper presented at International Deep Drawing Research Group 37th Annual Conference 3–7 June 2018, University of Waterloo, Waterloo, Ontario, Canada. IOP Conference Series: Materials Science and Engineering, 418, Article ID 012022.
Open this publication in new window or tab >>Thermo-mechanical Material Characterization and Stretch-bend Forming of AA6016
2018 (English)In: IOP Conference Series: Materials Science and Engineering, ISSN 1757-8981, E-ISSN 1757-899X, Vol. 418, article id 012022Article in journal (Refereed) Published
Abstract [en]

Lightweight design has become increasingly in focus for the manufacturing industry. Global environmental challenges, goals and legislations imply that lighter and sustainable products are imperative to remain competitive. One example is stamped products made of aluminum alloys which are of interest to the automotive industry, where lightweight designs are essential. In order to increase formability and to produce more complex geometries in stamped aluminum components there is a need to develop hot forming techniques. The Finite Element Method (FEM) has enabled important advances in the study and design of competitive manufacturing procedures for metal parts. Predicting the final geometry of a component is a complex task, especially if the forming procedure occurs at elevated temperatures. This work presents selected results from thermo-mechanical material testing procedures, FE-analyses and forming validation tests in AA6016 material. The material tests are used to determine the thermo-mechanical anisotropic properties, strain rate sensitivity and formability (Forming Limit Curves, FLC) at temperatures up to 490°C. Stretch-bending tests are performed to compare predicted results with experimental observations such as punch force, strain levels, thinning, forming temperatures, springback and failure. It was found that the heat-treatment and forming at elevated temperatures substantially increased formability and that measured responses could in general be predicted if care was taken to model the initial blank temperatures, heat transfer and thermo-mechanical material properties. The room temperature case confirms the importance of considering anisotropy.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2018
National Category
Applied Mechanics Other Civil Engineering
Research subject
Solid Mechanics; Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-71364 (URN)10.1088/1757-899X/418/1/012022 (DOI)2-s2.0-85054260019 (Scopus ID)
Conference
International Deep Drawing Research Group 37th Annual Conference 3–7 June 2018, University of Waterloo, Waterloo, Ontario, Canada
Note

Konferensartikel i tidskrift;2018-10-30 (svasva)

Available from: 2018-10-30 Created: 2018-10-30 Last updated: 2019-01-11Bibliographically approved
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