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Granström, Jan
Publications (5 of 5) Show all publications
Golling, S., Frómeta, D., Casellas, D., Granström, J., Jonsén, P. & Oldenburg, M. (2017). Determination of the essential work of fracture at high strain rates. In: Mats Oldenburg, Braham Prakash, Kurt Steinhoff (Ed.), 6th International Conference Hot Sheet Metal Forming of High-Performance Steel CHS2: June 4-7 2017, Atlanta, Georgia, USA : proceedings. Paper presented at 6th International Conference Hot Sheet Metal Forming of High-Performance Steel CHS2, Atlanta, Georgia, 4-7 June 2017 (pp. 261-269). Warrendale, PA: Association for Iron & Steel Technology, AIST
Open this publication in new window or tab >>Determination of the essential work of fracture at high strain rates
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2017 (English)In: 6th International Conference Hot Sheet Metal Forming of High-Performance Steel CHS2: June 4-7 2017, Atlanta, Georgia, USA : proceedings / [ed] Mats Oldenburg, Braham Prakash, Kurt Steinhoff, Warrendale, PA: Association for Iron & Steel Technology, AIST , 2017, p. 261-269Conference paper, Published paper (Refereed)
Abstract [en]

During the last decades, the use of ultra-high strength steel (UHSS) has increased as its favorable ratio between strength and mass allows the design of lighter body-in-white while maintaining passenger safety. Modeling impact loads of components made of UHS steel requires reliable descriptions of the material deformation and fracture behavior.

Traditional stress or strain based fracture criteria are used in finite element modeling. A different approach in modeling fracture in components uses the fracture energy as a model parameter.

Fracture toughness is difficult to measure in thin sheets; a method termed Essential Work of Fracture (EWF) provides the possibility to determine the fracture toughness in sheet metal. With knowledge of the fracture toughness the understanding of fracture behavior and crack propagation in ultra-high strength steel can be increased. The obtained EWF is related to the fracture energy and can be used in numerical models as a material parameter.

In the present work results from preliminary testing are shown and a discussion on cross-head speed and strain rate in the critical specimen cross section is given. The use of digital image correlation provides information about the displacement field in the vicinity of the notch and hence about the strain- and strain rate distribution. Furthermore, the difficulties in reliable measurement of force and elongation in high speed tensile testing machines are elucidated. Issues encountered during the development of the high-speed DENT specimen are not limited to the specific geometry presented in this paper.

The present work aims at the development of a test specimen to obtain the Essential Work of Fracture (EWF) at high test speed. This work contributes to the overall goal to model fracture behavior and crack propagation, dependent on the strain rate. For the investigation, a high-speed tensile testing machine equipped with an in-house developed load cell and an optical elongation measurement system was used with a high-speed camera to obtain data for digital image correlation.

Place, publisher, year, edition, pages
Warrendale, PA: Association for Iron & Steel Technology, AIST, 2017
Series
CHS2-series ; 6
National Category
Other Mechanical Engineering Applied Mechanics
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-64050 (URN)978-1-935117-66-7 (ISBN)
Conference
6th International Conference Hot Sheet Metal Forming of High-Performance Steel CHS2, Atlanta, Georgia, 4-7 June 2017
Available from: 2017-06-15 Created: 2017-06-15 Last updated: 2017-11-24Bibliographically approved
Sundqvist, J., Kaplan, A., Granström, J., Sundin, K.-G., Keskitalo, M., Mäntyjärvi, K. & Ren, X. (2015). Identifying residual stresses in laser welds by fatigue crack growth acceleration measurement (ed.). Paper presented at . Journal of laser applications, 27(4), Article ID 42002.
Open this publication in new window or tab >>Identifying residual stresses in laser welds by fatigue crack growth acceleration measurement
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2015 (English)In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 27, no 4, article id 42002Article in journal (Refereed) Published
Abstract [en]

During laser welding, residual stresses are thermally induced. They can have strong impact on the fatigue behavior and fatigue life. A standardized measurement method for the fatigue crack growth rate was expanded to identify residual stress along the cracking path. The second derivative of the measured crack opening and in turn the crack acceleration corresponded well with distinct acceleration maxima and minima and accordingly with tensile and compressive stress, as was basically proven by numerical simulation. The method is simple and extendable. It provides valuable information, as was demonstrated for various situations.

National Category
Manufacturing, Surface and Joining Technology Applied Mechanics
Research subject
Manufacturing Systems Engineering; Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-10852 (URN)10.2351/1.4923472 (DOI)000362569000002 ()2-s2.0-84936882579 (Scopus ID)9bb76bdd-9c0b-4c71-8a47-fc833d81bb4e (Local ID)9bb76bdd-9c0b-4c71-8a47-fc833d81bb4e (Archive number)9bb76bdd-9c0b-4c71-8a47-fc833d81bb4e (OAI)
Note
Validerad; 2015; Nivå 2; 20151102 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Sundin, K.-G., Granström, J. & Oldenburg, M. (2013). Experimental investigation of plastic and fracture behaviour of 22MnB5 at hot stamping conditions (ed.). In: (Ed.), Mats Oldenburg; Braham Prakash; Kurt Steinhoff (Ed.), 4th International Conference Hot Sheet Metal Forming of High-performance Steel CHS: June 9-12, Luleå, Sweden : Proceedings. Paper presented at International Conference on Hot Sheet Metal Forming of High-Performance Steel : 09/06/2013 - 12/06/2013 (pp. 557-564). Auerbach: Verlag Wissenschaftliche Scripten
Open this publication in new window or tab >>Experimental investigation of plastic and fracture behaviour of 22MnB5 at hot stamping conditions
2013 (English)In: 4th International Conference Hot Sheet Metal Forming of High-performance Steel CHS: June 9-12, Luleå, Sweden : Proceedings / [ed] Mats Oldenburg; Braham Prakash; Kurt Steinhoff, Auerbach: Verlag Wissenschaftliche Scripten , 2013, p. 557-564Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Auerbach: Verlag Wissenschaftliche Scripten, 2013
National Category
Applied Mechanics
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-40068 (URN)f0bef510-5ee5-4322-9615-237d947efa7b (Local ID)9783942267823 (ISBN)f0bef510-5ee5-4322-9615-237d947efa7b (Archive number)f0bef510-5ee5-4322-9615-237d947efa7b (OAI)
Conference
International Conference on Hot Sheet Metal Forming of High-Performance Steel : 09/06/2013 - 12/06/2013
Note
Godkänd; 2013; 20130612 (ysko)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2017-11-25Bibliographically approved
Sundqvist, J., Eriksson, I., Kaplan, A., Keskitalo, M., Mäntyjärvi, K., Granström, J. & Sundin, K.-G. (2013). Measuring the influence of laser welding on fatigue crack propagation in high strength steel (ed.). In: (Ed.), (Ed.), ICALEO, 32nd International Congress on Applications of Lasers & Electro-Optics: October 6-10, 2013, Hyatt Regency Miami, Miami, FL USA. Orlando, Fl.: Laser institute of America
Open this publication in new window or tab >>Measuring the influence of laser welding on fatigue crack propagation in high strength steel
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2013 (English)In: ICALEO, 32nd International Congress on Applications of Lasers & Electro-Optics: October 6-10, 2013, Hyatt Regency Miami, Miami, FL USA, Orlando, Fl.: Laser institute of America , 2013Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Orlando, Fl.: Laser institute of America, 2013
National Category
Manufacturing, Surface and Joining Technology Applied Mechanics
Research subject
Manufacturing Systems Engineering; Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-32582 (URN)71e189df-916a-46ad-b3dd-d218b42014d4 (Local ID)978-0-912035-98-7 (ISBN)71e189df-916a-46ad-b3dd-d218b42014d4 (Archive number)71e189df-916a-46ad-b3dd-d218b42014d4 (OAI)
Note
Godkänd; 2013; 20151117 (jessun)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Gren, P., Tatar, K., Granström, J., Molin, N.-E. & Jansson, E. (2006). Laser vibrometry measurements of vibration and sound fields of a bowed violin (ed.). Paper presented at . Measurement science and technology, 17(4), 635-644
Open this publication in new window or tab >>Laser vibrometry measurements of vibration and sound fields of a bowed violin
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2006 (English)In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 17, no 4, p. 635-644Article in journal (Refereed) Published
Abstract [en]

Laser vibrometry measurements on a bowed violin are performed. A rotating disc apparatus, acting as a violin bow, is developed. It produces a continuous, long, repeatable, multi-frequency sound from the instrument that imitates the real bow-string interaction for a 'very long bow'. What mainly differs is that the back and forward motion of the real bow is replaced by the rotating motion with constant velocity of the disc and constant bowing force (bowing pressure). This procedure is repeatable. It is long lasting and allows laser vibrometry techniques to be used, which measure forced vibrations by bowing at all excited frequencies simultaneously. A chain of interacting parts of the played violin is studied: the string, the bridge and the plates as well as the emitted sound field. A description of the mechanics and the sound production of the bowed violin is given, i.e. the production chain from the bowed string to the produced tone

National Category
Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-4368 (URN)10.1088/0957-0233/17/4/005 (DOI)000237497600007 ()2-s2.0-33645242120 (Scopus ID)24fdda20-6f73-11db-962b-000ea68e967b (Local ID)24fdda20-6f73-11db-962b-000ea68e967b (Archive number)24fdda20-6f73-11db-962b-000ea68e967b (OAI)
Note
Validerad; 2006; 20060925 (cira)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
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