Simulation of dynamic instabilities during high rate deformation of ductile bars and plates
(2005)- Abstract
- In this thesis, some of the phenomena occurring in plates and cylindrical bars subjected to dynamic loading are investigated. Numerical simulations using a dynamic finite element code are performed for a number of different sized specimens with various initial surface imperfections. Typically imposed loading velocities are in the range 10m/s<v_0<50m/s. The specimens are either subjected to tensile or to compressive loading.
Effects of inertia are examined by introducing an artificial volume load, representing the hydrostatic pressure that follows a homogeneous deformation of a cylindrical bar where no necking is accounted for. The influence of elastic unloading is studied by comparing the necking patterns obtained... (More) - In this thesis, some of the phenomena occurring in plates and cylindrical bars subjected to dynamic loading are investigated. Numerical simulations using a dynamic finite element code are performed for a number of different sized specimens with various initial surface imperfections. Typically imposed loading velocities are in the range 10m/s<v_0<50m/s. The specimens are either subjected to tensile or to compressive loading.
Effects of inertia are examined by introducing an artificial volume load, representing the hydrostatic pressure that follows a homogeneous deformation of a cylindrical bar where no necking is accounted for. The influence of elastic unloading is studied by comparing the necking patterns obtained for cylindrical bars, using two different material models,
J_2-flow theory and J_2-deformation theory. The deformation developments for the specimens of interest are visualized using a contour plot method denoted q-plot.
In the case of dynamic buckling of plates, the visualized results using the q-plot method are compared with that obtained using a direct geometrical method, denoted geo-plot. Ductile fracture is simulated by using cohesive elements, included in the original finite element mesh after a prescribed state of deformation is reached. Fracture is controlled by
the cohesive law, whereas the constitutive relation for the bulk material is chosen as J_2-flow
theory. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/544395
- author
- Nilsson, Kristina LU
- supervisor
- opponent
-
- Professor Olsson, Peter, Mekanik, Chalmers tekniska högskola, Göteborg
- organization
- publishing date
- 2005
- type
- Thesis
- publication status
- published
- subject
- keywords
- numerical simulation, non-linear, wave propagation, multiple necking, necking, buckling, fracture, Mechanical engineering, Maskinteknik, finite elements, cohesive elements, dynamic, J2-flow theory, J2-deformation theory, viscoplastic, background inertia
- publisher
- Division of Mechanics, Lund University
- defense location
- Room M:B of the M-building at Lund Institute of Technology, Lund University, Lund, Sweden
- defense date
- 2005-03-17 10:15:00
- external identifiers
-
- other:ISRN: LUTFD2/TFME--05/2005--SE(1-94)
- ISBN
- 91-628-6427-0
- language
- English
- LU publication?
- yes
- id
- 54634dc9-4d6b-4c0e-983d-d84dad172592 (old id 544395)
- date added to LUP
- 2016-04-04 11:38:31
- date last changed
- 2018-11-21 21:06:11
@phdthesis{54634dc9-4d6b-4c0e-983d-d84dad172592,
abstract = {{In this thesis, some of the phenomena occurring in plates and cylindrical bars subjected to dynamic loading are investigated. Numerical simulations using a dynamic finite element code are performed for a number of different sized specimens with various initial surface imperfections. Typically imposed loading velocities are in the range 10m/s<v_0<50m/s. The specimens are either subjected to tensile or to compressive loading.<br/><br>
<br/><br>
Effects of inertia are examined by introducing an artificial volume load, representing the hydrostatic pressure that follows a homogeneous deformation of a cylindrical bar where no necking is accounted for. The influence of elastic unloading is studied by comparing the necking patterns obtained for cylindrical bars, using two different material models,<br/><br>
<br/><br>
J_2-flow theory and J_2-deformation theory. The deformation developments for the specimens of interest are visualized using a contour plot method denoted q-plot.<br/><br>
<br/><br>
In the case of dynamic buckling of plates, the visualized results using the q-plot method are compared with that obtained using a direct geometrical method, denoted geo-plot. Ductile fracture is simulated by using cohesive elements, included in the original finite element mesh after a prescribed state of deformation is reached. Fracture is controlled by<br/><br>
<br/><br>
the cohesive law, whereas the constitutive relation for the bulk material is chosen as J_2-flow<br/><br>
<br/><br>
theory.}},
author = {{Nilsson, Kristina}},
isbn = {{91-628-6427-0}},
keywords = {{numerical simulation; non-linear; wave propagation; multiple necking; necking; buckling; fracture; Mechanical engineering; Maskinteknik; finite elements; cohesive elements; dynamic; J2-flow theory; J2-deformation theory; viscoplastic; background inertia}},
language = {{eng}},
publisher = {{Division of Mechanics, Lund University}},
school = {{Lund University}},
title = {{Simulation of dynamic instabilities during high rate deformation of ductile bars and plates}},
year = {{2005}},
}