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_2flow theory and J_2deformation theory. The deformation developments for the specimens of interest are visualized using a contour plot method denoted qplot.
In the case of dynamic buckling of plates, the visualized results using the qplot method are compared with that obtained using a direct geometrical method, denoted geoplot. 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_2flow
theory. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/record/544395
 author
 Nilsson, Kristina ^{LU}
 supervisor

 Solveig Melin ^{LU}
 opponent

 Professor Olsson, Peter, Mekanik, Chalmers tekniska högskola, Göteborg
 organization
 publishing date
 2005
 type
 Thesis
 publication status
 published
 subject
 keywords
 numerical simulation, nonlinear, wave propagation, multiple necking, necking, buckling, fracture, Mechanical engineering, Maskinteknik, finite elements, cohesive elements, dynamic, J2flow theory, J2deformation theory, viscoplastic, background inertia
 publisher
 Division of Mechanics, Lund University
 defense location
 Room M:B of the Mbuilding at Lund Institute of Technology, Lund University, Lund, Sweden
 defense date
 20050317 10:15
 external identifiers

 other:ISRN: LUTFD2/TFME05/2005SE(194)
 ISBN
 9162864270
 language
 English
 LU publication?
 yes
 id
 54634dc94d6b4c0e983dd84dad172592 (old id 544395)
 date added to LUP
 20071013 12:52:18
 date last changed
 20160919 08:45:11
@phdthesis{54634dc94d6b4c0e983dd84dad172592, 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_2flow theory and J_2deformation theory. The deformation developments for the specimens of interest are visualized using a contour plot method denoted qplot.<br/><br> <br/><br> In the case of dynamic buckling of plates, the visualized results using the qplot method are compared with that obtained using a direct geometrical method, denoted geoplot. 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_2flow<br/><br> <br/><br> theory.}, author = {Nilsson, Kristina}, isbn = {9162864270}, keyword = {numerical simulation,nonlinear,wave propagation,multiple necking,necking,buckling,fracture,Mechanical engineering,Maskinteknik,finite elements,cohesive elements,dynamic,J2flow theory,J2deformation 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}, }