Abstracts Category : Other

Add abstract

Want to add your dissertation abstract to this database? It only takes a minute!

Search abstract

Search for abstracts by subject, author or institution

Share this abstract

Fracture prediction of stretched shear cut edges in sheets made of Dual-Phase steel

by Johannes Falk

Institution: , Department of Mechanical Engineering
Year: 2017
Keywords: Strain; DP steel; Dual-phase steel; Autoform; Aramis; Fracture strain; Advanced High Strength Steels; AHSS; Fracture prediction
Posted: 02/01/2018
Record ID: 2183272
Full text PDF: http://urn.kb.se/resolve?urn=urn:nbn:se:bth-13956


Abstract

Dual-Phase (DP) steels, part of the group of Advanced High Strength Steels (AHSS), are used by car manufactures due to its large strength to weight ratio. The high strength of the DP steel does have a negative impact on the formability during sheet metal forming and stretch forming, e.g. fractures often appear in shear cut edges during forming of blanks made of DP steel. The main objective with this thesis is to develop a new punch for Volvo Cars that concentrates the strain to the sheared edges of a test specimen made from different types of DP steel. This is done to be able to measure and obtain maximum fracture strain during stretch forming tests in a press. The newly developed test method is called CTEST (Concentrated Trim Edge Strain Test). The tests are performed with DP steel specimens with three different qualities of the shear cut edges; fine cut, medium cut and worn cut. DP steels tested are DP600GI, DP600UC and DP800GI from three different suppliers. 10 different types of DP steels are tested in this study with different thickness. Thickness of specimens tested are 1 mm, 1.1 mm, 1.5 mm and 2 mm and all specimens tested have a lengthwise (RD) rolling direction. The quality of the sheared cut edge has a great impact to the formability and maximum fracture strain of the specimen. A specimen with a fine cut endures higher fracture strain than medium cut and a worn cut for all types of DP steel with different thickness. A 1 mm thick specimen endures a lower fracture strain than 1.5 mm and 2 mm specimen for all cut qualities. Further, the impact of the orientation of the burr zone of a shear cut edge is studied. With the burr zone facing upwards from the CTEST punch the formability of the specimens is decreased compared to a burr zone facing downwards, especially for a worn cut specimen with micro cracks and imperfections in the edge surface. ARAMIS Digital Image Correlation (DIC) system is used to analyze the specimen edges during press experiments. The ARAMIS results unveil that several small fractures appear in the sheared edges of a specimen just before the specimens split into two pieces. This phenomenon was seen for specimen with worn and medium shear cut qualities. Finite Element (FE) simulations of the CTEST is performed in AutoForm to determine maximum values of the true strain for the three different cut qualities. The simulation in AutoForm does show a slightly higher value of the force and press depth than the value from the press test before maximum fracture strain in reached. The small fractures seen in ARAMIS just before the specimen split into two pieces cannot be seen in the simulation in AutoForm.

Add abstract

Want to add your dissertation abstract to this database? It only takes a minute!

Search abstract

Search for abstracts by subject, author or institution

Share this abstract

Featured Books

Book cover thumbnail image
Electric Cooperative Managers' Strategies to Enhan...
by White, Michael Edward
   
Book cover thumbnail image
Bullied! Coping with Workplace Bullying
by Gattis, Vanessa M.
   
Book cover thumbnail image
The Filipina-South Floridian International Interne... Agency, Culture, and Paradox
by Haley, Pamela S.
   
Book cover thumbnail image
Solution or Stalemate? Peace Process in Turkey, 2009-2013
by Yurtbay, Baturay
   
Book cover thumbnail image
Performance, Managerial Skill, and Factor Exposure...
by Avci, S. Burcu
   
Book cover thumbnail image
The Deritualization of Death Toward a Practical Theology of Caregiving for the ...
by Gibson, Charles Lynn
   
Book cover thumbnail image
Emotional Intelligence and Leadership Styles Exploring the Relationship between Emotional Intel...
by Olagundoye, Eniola O.
   
Book cover thumbnail image
Commodification of Sexual Labor Contribution of Internet Communities to Prostituti...
by Young, Jeffrey R.
   
Book cover thumbnail image
The Census of Warm Debris Disks in the Solar Neigh...
by Patel, Rahul I.
   
Book cover thumbnail image
Risk Factors and Business Models Understanding the Five Forces of Entrepreneurial R...
by Miles, D. Anthony