Home

LS-DYNA Thermal Analysis User Guide - LS

1. 22 1 15 16 20 19 13 1 17 18 22 21 14 1 18 19 23 22 15 1 19 20 24 23 16 1 21 22 26 2 3 17 1 22 23 27 26 18 1 23 24 28 27 DEFINE NODE SET FOR BOUNDARY CONDITIONS SET_NODE_LIST_GENERATE 1 25 28 SET_NODE_LIST_GENERATE 2 1 28 TEMPERATURE INITIAL CONDITON INITIAL TEMPERATURE SET 2 20 5 MECHANICAL BOUNDARY CONDITIONS BOUNDARY_PRESCRIBED_MOTION_SET 1 2 2 1 1 DEFINE_CURVE 1 0 0 2 0099 end 19 LS DYNA Thermal Analysis User Guide 20
2. CONTROL THERMAL SOLVER 1 0 i CONTROL_TIMESTEP 20 CONTROL THERMAL TIMESTEP 0 1 id CONTROL TERMINATION s DATABASE BINARY D3PLOT 01 5 PART DEFINITIONS 5 PART EID SECID MID TMID slab 1 1 1 1 5 5 SECTION PROPERTIES SECTION SOLID SECID ELFORM 1 1 MECHANICAL MATERIAL PROPERTIES 5 ELASTIC PLASTIC THERMAL 1 qu 0 10 20 30 40 50 1 e 10 1 e 10 1 e 1 0 1 e 10 1 e 1 0 1 e 1 0 s Ne 39 25 0 e 06 20 e 07 40 e 07 60 e 07 80 e 07 100 e 07 1 e 20 1 e 20 1 e 2 0 1 e 2 0 1 e 2 0 1 e 2 0 0 0 0 0 0 THERMAL MATERIAL PROPERTIES MAT THERMAL ISOTROPIC 1 T 0 L T 1 5 5 NODE DEFINTIONS NODE Cor EUER COO IP EC FESO Ore poe QO Jj OT MS Co PO S poppe gu m m r s c N ls O CI Jj 10 LS DYNA Thermal Analysis User Guide EMENT DEFINITIONS Eo 4240 I Hi ELEMENT SOLID 1 1 1 2 3 4 THERMAL BOUNDARY CONDITIONS 1 07 INITIAL TEMPERATURE NODE 1 10 2 10 3 10 4 10 5 6 7 8 10 10 Tos 10 11 LS DYNA Thermal Analysis User Guide Problem 4 Welding 3D Thermal Stress With Slide Surfaces This problem models a hot block sliding along a colder block This is a way to model welding The hot block is set at a fixed temperature to model a heat source e g torch e beam
3. or laser The velocity of the moving hot block and contact resistance between the blocks determines the energy transfer to the work piece BLOCK Line Li A KUT LUCK Line Li A K T i Um mam p n u Toa k H a k BE u a Boog h b E dl fee i Ea kl l RS H i ope be 4114 arri hi 333 aa j j j k b b Peet 1113 1311 A l Pe li J k E ln j ji l li Shown are the node numbers defining The hot block on the right is sliding up the elements for this problem A the 4 element block on the left Shown thermal mechanical slide surface is are temperature contours defined between the 1 block on the right and the 4 blocks on the left Note the following model parameters defined in the input file that follows 1 The problem is specified as a coupled structural thermal analysis in the CONTROL SOULTION section 2 The mechanical mass scaled time step is set to 0 0001 seconds CONTROL_TIMESTEP and the thermal time step is set to 0 001 seconds CONTROL_THERMAL_TIMESTEP Explicit time integration is used for the structural calculations and implicit time integration is used for the thermal calculations Implicit time integration is unconditionally stable and therefore a larger thermal time step can be taken CONTROL_THERMAL_TIMESTEP 3 A thermal mechanical slide surface between the blocks is used to define thermal resistance pa
4. A execution line The following problems demonstrate using LS DYNA for heat transfer and coupled thermal stress 1 Steady State Heat Transfer steady state heat transfer in a slab using shell elements 2 Transient Heat Transfer transient heat transfer in a rod using 8 node brick elements 3 Thermal Stress unconstrained expansion of a block due to heating The following problems demonstrate using LS DYNA for manufacturing problems where modeling coupled fluid thermal and mechanical effects are important 4 Welding demonstrates the use of a thermal mechanical slide surface 5 Metal Forming demonstrates modeling of the conversion of plastic work to heat LS DYNA Thermal Analysis User Guide Problem 1 Steady State Heat Transfer in a Slab Using Shell Elements This problem demonstrates using LS DYNA to solve a steady state 2 dimensional heat transfer problem with temperature boundary conditions The figure below defines the geometry mesh and boundary conditions y 1 2 4 6 boundary conditions T 0 at nodes 1 2 T 2 at nodes 5 6 answer T 1 at nodes 3 4 ll co 6 y 0 1 x 0 x The analytical solution for the temperature distribution in a slab of thickness with prescribed temperatures T at x 0 and T at x is The answer to this problem is T 1 at x 1 Note the following model parameters defined in the input file that follows 1 The input is defined
5. ELL 1 15 0 001 0 001 0 001 0 001 0 MECHANICAL MATERIAL PROPERTIES MAT PIECEWISE LINEAR PLASTICITY 1 7830 210 e 09 28 0 0 0 0 0 000E 00 1 000E 02 2 000E 02 5 000E 02 1 000E 01 2 000E 01 4 000E 01 1 000E 00 2 500E 08 2 800E 08 3 000E 08 3 500E 08 4 200E 08 5 000E 08 5 200E 08 5 400E 08 THERMAL MATERIAL PROPERTIES MAT THERMAL ISOTROPIC 1 7830 460 46 NODE DEFINTIONS NODE 1 0 0 4 TS 2 003 0 2 Teg 3 006 0 2 7 4 009 0 2 7 5 0 003 1 Ws 6 003 003 0 7 4 006 003 0 7 8 009 003 0 ds 9 0 006 1 Tu 10 003 006 0 7 11 006 006 0 7 12 009 006 0 hes 13 0 009 dz dus 14 003 009 0 7 ko 006 009 Qe dos 16 009 009 0 17 0 012 dis 12 18 003 012 0 T 19 006 012 0 7 20 009 012 0 7 21 0 015 1 Bs 22 003 015 0 7 23 006 015 0 7 24 009 015 0 T 25 0 018 1 T 26 003 018 d 27 006 018 7 28 009 018 15 Tes 5 5 5 ELEMEN T SH ELL 1 1 1 2 6 5 2 1 2 8 7 6 3 1 3 4 8 7 4 1 5 6 10 9 5 1 6 7 11 10 6 1 7 8 12 11 7 1 9 10 14 13 8 1 10 11 15 14 9 1 11 12 16 15 10 1 13 14 18 17 11 1 14 15 19 18 oo LS DYNA Thermal Analysis User Guide
6. IC 1 Tx 1 d 5 NODE DEFINTIONS NODE 1 Ox z z 2 T 0 3 Tx 0 4 0 T 0 5 0 0 25 6 1 0 7 Ta 8 05 1 s 9 0 T 10 1 0 T4 11 L iL 12 0 5 5 ELEMENT DEFINITIONS LS DYNA Thermal Analysis User Guide ELEMENT SOLID 1 1 1 2 3 4 3 6 7 8 2 1 5 6 7 8 9 10 11 12 THERMAL BOUNDARY CONDITIONS 9 BOUNDARY_TEMPERATURE_NODE 9 0 Le 10 0 ile 11 0 i 12 0 T LS DYNA Thermal Analysis User Guide Problem 3 3D Thermal Stress This problem demonstrates using LS DYNA to solve for the unconstrained expansion of a block due to heating The model consists of one 8 node brick element at an initial temperature of 10C The brick material is given a volumetric thermal generation rate The rise in temperature can be calculated by equating the thermal generation rate to an increase in internal energy qVt mcAT Where volumetric heat generation rate q 10 W m volume V lm mass 1 1 1 kg heat capacity c 1J kgC time for heat generation t 3 sec The block increases in temperature by 30 C The final block temperature is 10C 30C 40C A tangent coefficient of thermal expansion is defined by A 2 0e 07 T The thermal expansion can be calculated by 40 Al 2 0e 07 1 06 07 T 1 5e 04 10 Note the following model parameters defined in the input file that follows 1 The prob
7. LL 1 1 1 3 4 2 2 1 3 5 6 4 THERMAL BOUNDARY CONDITIONS BOUNDARY_TEMPERATURE_NODE 1 0 On 2 0 0 5 0 2 6 0 2 LS DYNA Thermal Analysis User Guide Problem 2 Transient Heat Transfer in a Rod Using 8 Node Brick Elements This problem demonstrates using LS DYNA to solve a transient 3 dimensional heat transfer problem with temperature boundary conditions The figure below defines the problem X boundary conditions x 0 insulated surface at nodes 1 2 3 4 x 1 T 1 at nodes 9 10 11 12 x material properties ke1 Trhoe1 tim c 1 answer at x 0 5 nodes 5 6 7 8 temperatur analytical solution 0 0 2822 0 2643 0 1 The analytical solution to this problem is n 1 Y a x zz De Frnt Fane cos n 1 2 With the Fourier number defined as F ot L and the thermal diffusivity defined as o k pc Parameters for this problem are thermal conductivity density heat capacity temperature initial condition temperature boundary condition k 1W mC 1 kg m c 1 J kg C Te 0 Tac l atx 1 Note the following model parameters defined in the input file that follows 1 Transient thermal problems are solved using implicit time integration Therefore there is no stability condition on the thermal time step Much larger time steps can be used for the thermal solution as opposed to the mechanical solution which uses explicit time integration Time step siz
8. LS DYNA Thermal Analysis User Guide August 1999 Copyright 1999 LIVERMORE SOFTWARE TECHNOLOGY CORPORATION All Rights Reserved Mailing Address Livermore Software Technology Corporation 2876 Waverley Way Livermore California 94550 1740 Support Address Livermore Software Technology Corporation 7374 Las Positas Road Livermore California 94550 TEL 925 449 2500 FAX 925 449 2507 EMAIL sales Istc com Copyright 1999 by Livermore Software Technology Corporation All Rights Reserved LS DYNA Thermal Analysis User Guide Introduction LS DYNA can solve steady state and transient heat transfer problems on 2 dimensional plane parts cylindrical symmetric parts axisymmetric and 3 dimensional parts Heat transfer can be coupled with other features in LS DYNA to provide modeling capabilities for thermal stress and thermal fluid coupling This document presents several very simple examples in using LS DYNA for heat transfer coupled thermal stress and coupled fluid thermal problems The input files presented below use the KEy worpD structure for clarity The structured LS DYNA input file requires that thermal control parameters be defined on control cards 27 30 followed by thermal material definition cards and thermal boundary condition cards LS DYNA distinguishes between a structural thermal or coupled structure thermal analysis by the CONTROL_SOLUTION keyword or by specifying thermal or couple on the LS DYN
9. e is set in CONTROL TH ERMAL TIM ESTE P 2 Transient thermal problems are solved using a generalized trapezoidal time integration algorithm Two special cases are the Crank Nicholson method o 0 5 and the fully implicit method o 1 0 which are defined in CONTROL_TH method is second order accurate in time it can introduce oscillations in the solution These oscillations can cause nonlinear problems to diverge Therefore we suggest using the fully implicit method for nonlinear problems ERMAL_TIMESTEP Although the Crank Nicholson LS DYNA Thermal Analysis User Guide 3 Insulated boundary conditions such as exist in this problem for the surface at x 0 are the default and don t need to be specified in the input file LS DYNA Input File KEYWORD 5 5 1 2 3 4 5 6 3 8 5 CONTROL DEFINITIONS TITLE transient conduction in a slab CONTROL_SOLUTION il CONTROL_THERMAL SOLVER 1 0 9 CONTROL THERMAL TIMESTEP 0 i Od CONTROL TERMINATION 1 DATABASE TPRINT 02 DATABASE BINARY D3PLOT 01 5 5 PART DEFINITIONS PART PID SECID MID TMID slab 1 1 1 5 5 SECTION PROPERTIES 5 SECTION SOLID SECID ELFORM 1 T 5 THERMAL MATERIAL PROPERTIES MAT THERMAL ISOTROP
10. er Guide 5 0 0 L 7 6 sid 0 aL 7 7 0 vl 7 8 s 7 9 0 0 7 10 s 0 gt 2 7 11 0 2 7 12 22 7 13 0 0 3 7 14 1 0 3 E 15 0 3 7 16 3 7 17 0 lt 0 4 7 18 1 0 4 cf 19 0 4 7 20 4 7 21 el 0 0 4 22 2 0 0 4 23 0 4 24 2 0 4 25 1 0 ga 4 2 0 22 0 oul 4 27 1 4 28 2 1 4 9 5 5 9 ELEMENT SOLID 1 1 1 2 4 3 5 6 8 7 2 3 6 8 7 9 10 12 11 3 1 9 10 12 11 23 14 16 15 4 1 13 14 16 L5 17 18 20 19 5 m 21 22 24 23 25 26 28 27 DEFINE NODE SET FOR BOUNDARY CONDITIONS SET_NODE_LIST_GENERATE 1 21 28 S MECHANICAL BOUNDARY CONDITIONS BOUNDARY_PRESCRIBED_MOTION_SET 1 3 2 1 DEFINE CURVE 1 0 0 01 4 5 5 THERMAL BOUNDARY CONDITIONS BOUNDARY_TEMPERATURE_SET 1 0 l THERMAL MECHANICAL CONTACT DEFINTION SET SEGMENT 1 21 25 27 23 SET SEGMENT 2 2 6 8 4 6 10 T2 8 10 14 16 12 14 18 20 16 I CONTACT SURFACE TO SURFACE THERMAL 14 LS DYNA Thermal Analysis User Guide 1 0 0 1 e 06 1 e 02 1 e 02 END 15 LS DYNA Thermal Analysis User Guide Problem 5 Metal Forming Compression of a Cylinder With Conversion of Plastic Work to Heat This problem models the m
11. etal forming process known as upsetting The upsetting process is defined as the axial compression of an axisymmetric body between two perfectly rough insulated plates The material used is low carbon steel The initial temperature is 20C the initial height is 0 036m and the initial radius is 0 009m There is no heat transfer to the environment The total imposed reduction is Ah h 44 over 1 6 seconds i e displacement boundary condition 0 0792m Only a quarter of the problem is modeled because of symmetry The problem geometry and results are shown in the following figure The temperature change of the body is from conversion of mechanical work into heat through plastic deformation UPSET OF A CYLINDRICAL PART time 1 60000E 00 contours of temperature displacement boundary condition contour values Al 8 333E 01 min 6 154E 01 at node 25 9 167E 01 max 1 401E 02 at node 1 1 000E 02 1 083E 02 1 167E 02 undeformed geometry deformed geometry 16 LS DYNA Thermal Analysis User Guide Note the following model parameters defined in the input file that follows 1 A mechanical mass scaled time step dt 1 e 04 is used CONTROL_TIMESTEP 2 A thermal time step dt 0 1 is used which is 1000 times larger than the mechanical time step CONTROL_THERMAL_TIMESTEP Heat transfer takes place on a longer time scale than the mechanical deformation Volumetric adiabatic heating is from con
12. lem is specified as a coupled structural thermal analysis in the CONTROL SOULTION section 2 Any LS DYNA material model can be used It is not necessary to use the temperature dependent constitutive models 4 21 23 and 60 However only these 4 models account for the thermal coefficient of expansion LS DYNA uses a tangent coefficient of thermal expansion which is defined as the slope of the thermal strain versus temperature curve for the material This should not be confused with the secant coefficient of thermal expansion which is the change in thermal strain between the current temperature and a reference temperature 3 The mechanical mass scaled time step is set to 0 01 seconds CONTROL TIMESTEP and the thermal time step is set to 0 1 seconds CONTROL_THERMAL_TIMESTEP Explicit time integration is used for the structural calculations and implicit time integration is used for the thermal calculations Implicit time integration is unconditionally stable and therefore a larger thermal time step can be taken CONTROL_THERMAL_TIMESTEP LS DYNA Thermal Analysis User Guide LS DYNA Input File KEYWORD 9 1 2 3 4 5 6 7 8 CONTROL DEFINITIONS ME thermal expansion of a block CONTROL SOLUTION 2
13. rameters CONTACT_SURFACE_TO_SURFACE_THERMAL 12 LS DYNA Thermal Analysis User Guide 4 The cold block has an initial temperature of 0 at time 0 The hot block has a temperature boundary condition of 10 degrees and a displacement boundary condition to move it along the cold block 5 Any LS DYNA material model can be used It is not necessary to use the temperature dependent constitutive models 4 21 23 and 60 However only these 4 models account for the thermal coefficient of expansion LS DYNA Input File KEYWORD 1 2 3 4 5 6 7 8 5 5 CONTROL DEFINITIONS TITLE block sliding up a rod CONTROL_SOLUTION 2 CONTROL_THERMAL SOLVER 1 0 1 CONTROL_TIMESTEP 0001 CONTROL_THERMAL TIMESTEP 0 E 001 CONTROL_TERMINATION 007 DATABASE BINARY D3PLOT 001 PART DEFINITIONS PART PID SECID MID TMID slab 1 1 1 1 SECTION PROPERTIES 5 SECTION_SOLID 1 1 MECHANICAL MATERIAL PROPERTIES 5 ELASTIC t 7830 3 e 07 33 THERMAL MATERIAL PROPERTIES MAT THERMAL ISOTROPIC 1 7830 460 46 NODE DEFINITIONS 5 NODE A 0 0 0 7 2 1 0 0 7 3 0 i 0 7 4 1 z li 0 7 13 LS DYNA Thermal Analysis Us
14. using shell elements with a shell formulation of 12 for a plane geometry note use shell formulation 14 for an axisymmetric geometry 2 Direct and iterative solvers are available to solve the system of equations for the heat transfer calculations The solver to be used is specified in CONTROL THERMAL SOLVER This problem uses the direct solver ACTCOL which is a Gauss type profile solver The diagonal scaled preconditioned conjugate gradient solver DSCG uses much less memory and is faster on most problems than the direct solvers LS DYNA Input File KEYWORD 1 2 3 4 5 6 7 8 CONTROL DEFINITIONS WUD x TITLE Steady state conduction in a slab CONTROL SOLUTION 1 CONTROL_THERMAL SOLVER 0 0 1 CONTROL TERMINATION L DATABASE_TPRINT LS DYNA Thermal Analysis User Guide DATABASE_BINARY_D3PLOT T5 PART DEFINITIONS PART 5 EID SECID MID TMID slab 1 1 1 SECTION PROPERTIES SECTION SHELL SECID ELFORM 1 12 0 001 0 001 0 001 0 001 5 5 THERMAL MATERIAL PROPERTIES MAT THERMAL ISOTROPIC 1 1 1 I4 5 5 NODE DEFINTIONS NODE 1 0 0 2 0 Ta 3 w 4 T4 Tx 5 25 0 6 2 m ELEMENT DEFINITIONS ELEMENT SHE
15. version of mechanical work into heat through plastic deformation 100 of the mechanical work is converted to heat by setting the conversion factor to 1 in the MAT_THERMAL_SOLVER input section 3 The hourglass control is set to 4 CONTROL HOURGLASS This helps control but does not eliminate hourglassing on this very corse mesh 4 Shell formulation 15 is used SECTION_SHELL This 2D axisymmetric shell formulation with volume weighting works better than shell formulation 14 with area weighting for this problem 5 Any LS DYNA material model can be used It is not necessary to use the temperature dependent constitutive models 4 21 23 and 60 However only these 4 models account for the thermal coefficient of expansion LS DYNA Input File KEYWORD 1 2 3 4 5 6 7 8 CONTROL DEFINITIONS UU x TITLE upset of a cylindrical part CONTROL_SOLUTION 2 CONTROL_TIMESTEP 0 0 0 0 1 e 04 CONTROL THERMAL SOLVER 1 0 1 CONTROL_THERMAL TIMESTEP 0 de ran CONTROL_TERMINATION 1 6 CONTROL_HOURGLASS 4 DATABASE TPRINT np DATABASE BINARY D3PLOT np 5 PART DEFINITIONS 5 cylinder 1 1 1 1 17 LS DYNA Thermal Analysis User Guide SECTION PROPERTIES SECTION SH

LS-DYNA Thermal Analysis User Guide - LS

Contents

Download Pdf Manuals

Related Search

Related Contents