FEA Newsletter October 2001 - Free of Papers from LS
Contents
1. I would like to take this opportunity to thank everyone for helping us publish a monthly publication for the past year A special thanks to Desktop Engineering Magazine a Helmers Publishing Inc publication www deskeng com for allowing FEA Information News to reproduce their articles relating to FEA Information Participants In coming issues we will have articles in reference to our engineering websites High Performance Computing Servers www hpcservers com has information online and is scheduled to be fully operational February 2002 e Meshless Methods www meshlessmethods com will be operational February 2002 e Fluid Structure Interaction www fluid structureinteraction com has information online and is scheduled to be fully operational February 2002 Future articles in the news will correlate with our numerous engineering applications websites such as e Heat Transfer Analysis www heattransferanalysis com Implicit FEA www implicitfea com Linux for PC www linuxforpc com Marsha Victory President FEA Information Inc 20 Courses and Events will be limited to 1 page For further information contact event course sponsor Events Conferences 2001 Oct 30 31 LS DYNA Users Conference sponsored by Japanese Research Institute JRI to be held Japan at the Sheraton Grande Tokyo Bay Hotel LMS 2001 Conference for Physical and Virtual Prototyping to be held at Hotel New York Nov2. ETA FEA Information Inc World Wide Participant Introduction The Japan Research Institute Limited Courses amp Events Web Site Summary Monthly Product Showcase DO NOT OPEN e mail from feainformation com FEA Information Inc ONLY uses vic Istc com feainfo Istc com Smoothed Particle Hydrodynamics Part I of II O Copyright Dr Jean Luc Lacome 2001 INTRODUCTION Smoothed Particle Hydrodynamics SPH is an N body integration scheme developed by Lucy Gingold and Monaghan 1977 The method was developed to avoid the limitations of mesh tangling encountered in extreme deformation problems by the conventional finite element method The uniqueness of SPH is the absence of background grids Therefore partial differential equations such as conservation laws are transformed into integral equations The kernel estimate then provides approximation functions to estimate field variables at discrete points This paper is devoted to the presentation of this method The first part will introduce the foundational theories of this method In part II we will present the development of this new feature in LS DYNA and the coupling method for SPH and the finite element method I Definitions The particle approximation of a function is II fG FOWE yhdy Where W is the kernel function The Kernel function W is defined as 1 h x W x h 0 x Where d is the number of spatial dimensions and h is called smoothing length
3. STRAIN RAT DEPENDENT PLASTICIT CONTACT NCDES TO SURF Ae 20 1 MAT IGID CONTACT ONE WAY SURACE TO SURFACE TITLE 21 1 MAT DRTHOTROPIC THERMAL CONTACT RIGID NODES TO RIGID BODY TITLE 22 1 MAT CDMPOSITE DAMAGE 23 1MAT TEMPERATURE DEPENDENT DRTHOTF SEA MRSS moe EIS eres ne UMS 241 MAT PIECEWISE LINEAR PLASTICITY CONTACT RIGID BODY TWO WAY TO RIGID BODY TITLE 251 MAT GEDLDGICAL CAP MODEL CONTACT SINGLE EDGE TITLE 26 1 MAT HONEYCOMB 27 1 MAT MOONEY RIVLIN RUBBER CONTACT SINGLE SURFACE TITLE 28 1 MAT_RESULTANT_PLASTICITY CONTACT_SLIDING_ONLY_TITLE 231 MAT FORCE LIMITED CONTACT SLIDING ONLY PENALTY TITLE 301 MAT CLOSED FORM SHELL PLASTICITY p etico 31 1 MAT_FRAZER_NASH_RUBBER_MODEL CONTEST irsz e Sinds UIE 32 1 MAT LAMINATED GLASS CONTACT TIEBREAK NODES TO SURFACE TITLE 33 1 MAT_BARLAT_ANISOTROPIC_PLASTICITY Sea ERED NDE CONTACT_TIEBREAK_SURFACE_TO_SURFACE_TITLE 34 T MAT FABRIC CONTACT TIED NODES TO SURFACE TITLE 35 1 MAT PLASTIC GREEN NAGHDI RATE xl CONTACT TIED SHELL EDGE TO SURFACE TITLE CONTACT TIED SURFACE TO SURFACE TITLE CONTACT TIED SURFACE TO SURFACE FAILURE TITLE _ toe Fig 2 Structural Material Keyword list Fig 3 3D Contact Keyword List Productivity is improved by easy command access through function keys and model handling is enhanced with mouse and keyboard combinations Model handling is also better due to the introduction of mouse drag zoom The menus are reo
4. and plastic materials the contact stiffness given by the two methods can differ by one or more orders of magnitude The primary disadvantage of choosing the soft constraint method is its dependence on the global time step Occasionally the global time step must be scaled down using the TSSFAC parameter in CONTROL_TIMESTEP to avoid numerical instabilities in the contact behavior This results in an increased run time for the entire simulation As an alternative to reducing the global time step the soft constraint scale factor SOFSCL in the CONTACT definition can be reduced from the default value of 0 1 to 0 04 0 07 If the standard penalty based approach in used in a global contact definition the soft constraint approach can be used locally to handle dissimilar materials in contact The following are examples where contact behavior may benefit from use of the soft constraint method e Airbag to Steering Wheel e Airbag to Occupant e Front Tire to SIL e Spare tire to neighboring components e Foam to structural components Using a combination of both contact stiffness methods may promote good contact behavior without having to reduce the global time step 7 4 Definition of Slave Set There are several ways to define the slave set for the global contact definition These include all parts this is the default a set of included parts a set of excluded parts or a set of segments The default which includes all parts can sometimes result in
5. h x x x x 1 h x x A is the a th component of the A vector II Discrete form of conservative equations We are looking for the solution of the equation L 0 divF x t 9 S where R is the unknown F with Be 1 d represents the conservation law and L is the transport operator defined by L 9 L o ae 9 e The strong formulation approximation For the strong form solution the equation is kept at its initial formulation The discrete form of this equation implies the definition of the operator of derivation D defined by D gt D x V x 6G V1 x The particle approximation of this operator is D x w 6 x xA where A is defined previously Finally the discrete form of the strong formulation is written d pz Ww OX w D F x t 0 w S x However this discrete form is not conservative therefore the strong formulation approximation is not acceptable for the numerical computation Thus we are compelled to use the weak form e The weak formulation approximation In the weak form formulation the adjoint of the L operator is used o 96 Ld L 2L 0 v v gt ar t V ox The discrete form of this operator corresponds to the discrete formulation of the adjoint of D D x w 9 x A x A A discrete adjoint operator for the partial derivative is also necessary and is taken to be the th component of the o
6. obvious instabilities at the beginning of a simulation unless great care is taken in setting up the model to avoid such things as initial penetrations and nonphysical intersections of parts The option to ignore penetrations on the CONTROL CONTACT keyword set IGNORE equal to 1 is recommended if care is not taken to eliminate initial penetrations Many models run perfectly with just one 15 interface definition others however will not run until changes are made to the input usually by excluding parts or by modifying the finite element mesh to more accurately reflect the physical model To reiterate the following methods can be used for defining the global contact definition e All parts default e Included parts by SET PART e Excluded parts by SET PART Non Excluded parts will be considered for contact e Segments by SET SEGMENT In addition to the above slave sets a three dimensional box defined using DEFINE BOX may be used to restrict the contact to the parts or segments that lie within the box at the start of the calculation This will reduce the extent of the contact definition leading to a reduction in contact associated cpu time 7 5 Friction When using one global contact that includes several components of the vehicle a uniform friction coefficient possibly zero may be acceptable for initial analyses However the use of PART CONTACT keyword to specify friction coefficients on a part by part basis is recommended when fri
7. which varies in time and in space and xis the location of the particle Usually W x h is a centrally peaked function The common smoothing kernel 0 used by the SPH community is the cubic B spline I utdu for O u sl 4 amp u Cx 10 0 for 1 lt u lt 2 0 else Where C is a constant of normalization that depends on the number of spatial dimensions The SPH method is based on the quadrature formula for moving particles x t ie I N ls where x t is the location of particle i which moves along the velocity field v The particle approximation of a function can now be defined by N II f x 2 Y w f x W x xh j l m Where w is the weight of the particle j The weight of a particle varies proportionally to the Pj divergence of the flow The SPH formalism implies the use of a derivative operator So we need to define a particle approximation for this operator Before giving the definition of this approximation we define the gradient of a function as Vf x Vf x FV Where 1 is the unit function Starting from this relation we can define the particle approximation of the gradient of a function II Vf x Y re pA E f A jd Fj 1 4 7 x x where A Fan 8 E We can also define the particle approximation of the partial derivative Mn x 9 x I G Pw f x A x ox ra 1 4 Uxx where A is the operator defined by A x x g
8. 13 14 P f Pinna Disneyland Paris Paris France If you have any questions contact Kirsten Cabergs via e mail kirsten cabergs Ims be or phone 32 16 384 200 ANSYS Users Conference amp Exhibition 2002 Pittsburgh Hilton Pittsburgh PA For April 22 24 information visit ANSYS Inc May 19 21 2002 USA th International LS DYNA User s Conference at the Hyatt egency Hotel amp Conference Center Fairlane Town Center Dearborn MI 48126 Hyatt Regency Hotel amp Conference Center Due to the amount of travel classes conferences being rescheduled I have listed the websites of our FEA Information Participants for you to visit for up to date information Headquarters Company website USA Livermore Software Technology www lstc com USA Engineering Technology Associates www eta com UK OASYS Ltd www arup com dyna Japan The Japan Research Institute Ltd WWW jri co jp USA ANSYS Inc WWW ansys com USA Hewlett Packard www hp com USA SGI WWW sgi com USA MSC Software www mscsoftware com Japan Fujitsu Ltd www fujitsu com USA EASi Engineering WWW easiusa com Belgium LMS International www lImsintl com Sweden Engineering Research AB www erab se USA DYNAMAX www dynamax inc com Korea THEME Engineering www lsdyna co kr Korea Korean Simulation Technologies www kostech co kr Australia Leading Engineering Analysis Providers www leapaust com au Canada M
9. AL contact should be used sparingly and only where conditions dictate its use One advantage of the AUTOMATIC SINGLE SURFACE contact starting with LS DYNA version 950d is in its more rigorous treatment of interior sharp corners within the finite element mesh and in the handling of triangular contact segments consequently the AUTOMATIC SINGLE SURFACE contact is usually superior for parts meshed from triangular and tetrahedron elements In future version of LS DYNA the AUTOMATIC GENERAL option will also include these improvements 7 3 Standard Penalty Based or Soft Constraint Stiffness Method When several parts of dissimilar mesh sizes and or dissimilar material properties are included into one global slave set for AUTOMATIC SINGLE SURFACE the soft constraint stiffness method SOFT 1 is recommended The soft constraint method seeks to maximize contact stiffness while also maintaining stable contact behavior The interacting nodal masses and the global time step are used in formulating the contact stiffness The segment based contact method invoked by setting SOFT 2 calculates contact stiffness much like the soft constraint method but otherwise is quite different Segment based contact can often be quite effective where other methods fail at treating contact at sharp corners of parts In contrast to a soft constraint approach the standard penalty based contact stiffness SOFT 0 is based on material elastic constants and element dimensions In foam
10. Contact Upcoming issue Part 4 Airbag Contact Edge to Edge Contact and Rigid Body Contact 7 0 Modeling Guidelines For Full Vehicle Contact Crash analysis involving a full vehicle incorporates contact interactions between all free surfaces This is quite expensive since 20 30 percent of the total calculation CPU time is used by the contact treatment One of the challenging aspects of contact modeling in crash analysis is the handling of interactions between structural metallic parts and non structural components typically made from foam and plastic This is especially important when occupants are included in the model Another challenge is handling contact at corners or edges of geometrically complex parts Guidelines should be followed to achieve stability in contact as well as reasonable contact behavior Some of the modeling practices based on experience are discussed below 7 14 Global or Local Contact Historically many individual contact definitions were used for the treatment of contact The development and implementation of a robust single surface type of contact has changed the way engineers model the contact today From the standpoints of simplicity in preprocessing numerical robustness and computational efficiency it is now usually advantageous to forsake the use of numerous contact definitions in favor of ONE single surface type contact that includes all parts which may interact during the crash event We often casually refer to th
11. DYNA model We borrowed from the UNIX version to design the new GUI We feel that the new design has made the GUI even more organized and intuitive The fact that the new GUI resembles the UNIX version allows for a smooth transition to the new PC version 17 CI x CONTACI AIRBAG SINGLE SURFACE TTE CONTACT AUTOMATIC GENERAL TITLE 1 2 MAT ELASTIC FLUID CONTACT AUTOMATIC NODES TO SURFACE TITLE ZI MATT ORTHO TROPIC ELASTIC CONTACT AUTOMATIC ONE WAY SURFACE TO SURFACE TITLE SE Haare KNEE CONTACT_AUTOMATIC_SINGLE_SURFACE_TITLE A1 MAT ELASTI PLASTIC THERMAL CONTACT AUTOMATIC SURFACE TO SURFACE TITLE MAT SOIL AND FDAM CONTACT CONSTRAINT NODES TO SURFACE TITLE L MAT VISEDELASTIC CONTACT CONSTRAINT SURFACE TO SURFACE TITLE 1 MAT_BLATZ KO_RUBBER SURFACE TO 2 1 MAT HIGH EXPLOSIVE BURN CONTACT DRAWBEAD TITLE S1 MAT NULL CONTACT ERODING NODES TO SURFACE TITLE ii MATI ELASTIC PLASTIC HYDRO ial eat a 11 1 MAT STEINBERG CONTACT_ERODING_SURFACE_TO_SURFACE_TITLE 12 1 MAT ISOTROPIC ELASTIC_PLASTIC Seo EL Rees states EEn Cir MTS 131 MAT ISDTROPIC ELASTIC FAILURE CONTACT FORCE TRANSDUCER PENALTY TITLE 141 MAT SOIL AND FOAM FAILURE CONTACT FORMING NODES TO SURFACE TITLE 15 1 MAT JOHNSON COOK CONTACT_FORMING_ONE_WAY_SURFACE_TO_SURFACE_TITLE 16 1 MAT_PSEUDO_TENSOR d ONE WAY TO 17 1 MAT_ORIENTED_CRACK CONTACT FORMING SURFACE TO SURFACE TITLE 18 17MAT POWER LAW PLASTICITY 19 1 MAT
12. FEA Information International News For The Worldwide Engineering Community The Japan Research Institute Limited EAN Ay Xd u LMS INTERNATIONAL Empowering Engineering Innovation MSC SOFTWARE SIMULATING REALITY 1 t Anniversary Issue October 2001 FEA Information Inc www feainformation com Featured Articles FEA Information International News Managing Editor Trent Eggleston Feature Editor Marsha Victory Technical Writer David Benson Art Director Wayne Mindle The contents of FEA Information International News is deemed to be accurate and complete However FEA Information Company doesn t guarantee or warrant accuracy or completeness of the material contained in this publication All trademarks are the property of their respective owners FEA Information International News 1s published for FEA Information Inc 2001 FEA Information Inc International News All rights reserved Not to be reproduced in hardcopy or electronic format without permission of FEA Information Inc Pg 03 07 12 14 17 19 20 21 22 Featured Articles Smoothed Particle Hydronamics Part I of II Jean Luc Lacome LSTC Editing LS DYNA Input Files using Oasys PRIMER Version 8 1 History amp Future of Computing FAQ Part 3 of 3 Paul Bemis ANSYS Contact Modeling in LS DYNA part 3 of 4 Suri Bala LSTC Eta FEMB27 PC Armando Esteves
13. Mhz the e CAE com server is delivering solutions nearly 3x faster for static analysis in the range of 100K DOF using one CPU Additionally when operating ANSYS in parallel mode on e CAE com the time to solution will decline proportionately as processors are applied to the solution For pricing and further information contact Paul Bemis paul bemis ansys com the author of this series article and the manager of The ANSYS Inc e CAE com ASP Program that provides e A mechanism for running ANSYS simulations and or LS DYNA simulations on large parallel compute servers at a remote data center site using the internet e A system that has been developed to allow engineers the ability to run remote simulations with specific controls on job execution parameters e A solution that uses state of the art security and systems infrastructure technology from providers including Sun Hewlett Packard Silicon Graphics Cisco and others e A service that is ideal for engineers and companies requiring occasional surge capacity for time critical simulations or periodic simulations of large models Key e CAE com seccurity features e HTTP or HTTPS Secure access e Strict account amp file controls e Full data communication encryption e Secure Socket Layer SSL e Continuous monitoring on all operations 13 Contact Modeling in LS DYNA O Copyright LSTC Suri Bala 2001 Part 3 Modeling Guidelines For Full Vehicle
14. an TEL 81 3 3288 4700 Bi Osaka Head Office 5 8 Shinmachi 1 chome Nisi ku Osaka 550 0013 TEL 81 6 6534 5111 Branch Offices Sapporo Nagoya Fukuoka New York Singapore Representative Office Hong Kong Computer Centers Tokyo Higashi Nihon Gokokuji Yotsubashi Kinyu kyodo rac or Eg EM a Analysis Software D JSTAMP WORKS JSTAMP WORKS J A sheet metal forming simulation system sheet metal forming simulation system EET 19 FEA Information Web Sites Monthly Summary September articles are archived on the News Page at www feainformation com Articles from September on FEA Information website Sept 03 New Site High Performance Computing Servers www hpcservers com Software PostGL 1 0 from Engineering Technology Associates Software OASYS T HIS from OASYS Ltd Software LMS Roadrunner from LMS Int l Sept 10 Hardware hp 9000 unix servers from Hewlett Packard Software EASI SEAL from EASi Engineering Distributor Engineering Research AB ERAB located in Sweden Sept 17 Product LifeBook notebook series from Fujitsu Ltd Software LS POST free post processor from Livermore Software Technology Corp Distributor THEME Engineering Inc located in Korea Sept 24 Software MSC Linux version August 2001 from MSC Software Software JOH Nike 2D 3D from The Japan Research Institute Distributor Metal Forming Analysis Corp MFAC located in Canada
15. ation based on three nodes in each model and then mapping the thickness and plastic strain data from the forming model to the crash model A typical result is shown in Figure 6 Advanced Checking Functions PRIMER has always had the capability to check and clean up a model before saving it for analysis For the Version 8 1 release even more checks have been added and a number of these now have an Autofix option Beyond these several new functions have also been added to visually inspect the model and ensure that the analysis runs right the first time Find Attached is one of the new visual checking capabilities This feature allows Control the contour levels the user to build the model entity by entity ipee to ensure that the connections are intended i PRIMER s ability to visualize all LS DYNA MI features gives it a unique capability to visualize the model construction Contact Penetration checking is another new addition Once a contact surface has been defined a check can be made PRIMER reports the number of penetrating nodes as well as any shells which actually cross each other The maximum penetration is stated Only draw the and contour plots of the depth of penetration penetrations not the rest are available as shown in Figure 7 When of the contact surface the number of penetrations is high L individual nodes can be selected for Figure7 Contour plot of contact penetration checking At present the opti
16. ce With the advent of the LS DYNA template we can also provide the default values as defined in the User s Manual and perform an input validation check according to the expected value range and numerical format The introduction of the LS DYNA Template generates a graphical entity named LS DYNA Data Table Collector Fig 1 Eme Pc oyna rabie 8 PART Part m vari E3 Description M Vae PD e PARTID o to SECID mn PART SECTIONID J 0 J gt MD T 0 jJ EOSID UO EON OF STATED 0 J gt HGD m HOURGLASS S oo GAV mmn GRAVITY LOAD INITIALIZATIO 0 BDPOPT ADAPTIVITY FLAG 0 Jal l MID THERMAL MATERIALID 0 gt PART v id E Fig 1 LS DYNA Data Table Collector The LS DYNA Data Collector is a graphical and intuitive version of the command descriptions in the LS DYNA User s Manual It graphically provides the keyword command the number of cards associated with it the variable name on each card a brief description and a value field for data input and default value if any It provides the user with an electronic version of the LS DYNA User s Manual embedded in the pre processor interface Sample windows with the extensive list of Material Keywords Fig 2 and the available Contact Keyword selection Fig 3 are shown on the next page Redesign of the eta FEMB27 PC started by determining the best way to handle the large amount of data necessary to build an LS
17. crash models PRIMER now offers the option not to read included models when the main model is imported and offers three alternative ways of handling the included models when writing the main file Finally a new HTML help facility has been added for with all the details of the original online PDF manual but with powerful search and jump functions this is in addition to the text help menus in the previous version There is now a MANUAL button on every help window which links directly to the relevant page of the HTML manual Here you will find detailed explanation with diagrams and screen captures to demonstrate the use of the function of interest Full search and navigation functions allow the user to quickly find related information 11 Part 3 of 3 FAQ on Web Based Distributed Simulation Copyright Paul Bemis 2001 ANSYS Inc Web Based Distributed Simulation ANSYS has been a pioneer in the area of delivering complete engineering solution systems for over 30 years Over the past ten years these solutions have focused primarily on the Engineering Workstation and Personal Computer model of computing due to their outstanding cost effectivity and market demand However the trend towards highly complex real world engineering simulation often exceeds the capacity of these personal systems As web based computing becomes more popular and cost effective the opportunity to use remote computational servers to augment the desktop systems becomes p
18. ction is expected to play a significant role Friction coefficients specified in PART CONTACT will override friction coefficients specifed elsewhere if and only if FS in CONTACT is set to 1 0 Please note that the dynamic friction coefficient FD will have no effect unless a nonzero decay coefficient DC is provided 7 6 Contact Thickness To reduce the number of initial penetrations the contact thickness can changed from the default element thickness by using the global SST and MST parameters in CONTACT The OPTT parameter in PART CONTACT can be used to override SST and MST on a part by part basis The user is cautioned against setting the contact thickness to an extremely small value as this practice will often cause contact failure In fact for treating contact of very thin shells e g less than 1 mm it may be necessary to increase the contact thickness to prevent contact failure If a contact surface is comprised of tapered shell elements then a uniform contact thickness should always be specified The contact assumes that the segment thickness is constant which can result in thickness discontinuities between adjacent segments As a node moves between segments of differing thickness the interface force will either suddenly drop or increase as a result of the discontinuous change in the penetration distance This can result in negative contact interface energies 16 eta FEMB27 PC Finite Element Model Builder version 27 for PC O Copy
19. e during mesh creation Now with the release of PRIMER 8 1 the user can take 8 full advantage of mesh independent Spotweld file spotwelds as almost all of the hard work in creating the required nodes beams materials n and tied contact surfaces has been eliminated fA Individual spotwelds can be quickly created by the user After defining which panels are to be joined the user only needs to select one node and all the rest is automatic A second node is projected onto the mating flange and a beam created between them for a weld through three or more layers PRIMER will create a chain of beams The beam material and section properties and the tied contact interface required to stick the projected node to the flange are all easily defined Even more powerful however is the ability to read a spotweld CAD file This file which need only contain the x y z coordinates of each weld can be read from a spreadsheet format As with the BOM the user must define which column defines which data Including the panel part IDs for the weld can also be useful as it can avoid errors later An example is shown in Figure 4 All possible spotwelds are created in the model by pressing Apply once the file is read and the columns are defined A typical result is shown in Figure 5 Any spotwelds that cannot be made are reported to the user for individual editing Individual welds can be isolated and shown this may revea
20. el is up to date After reading the spreadsheet the user must define the meaning of each data column e g Part ID number material name gauge etc PRIMER then checks the model against the spreadsheet and reports any errors including parts in the BOM that are not in the model and vice versa Materials Database Once the BOM has been read the materials for each matching part are renamed accordingly This name can be used to extract the required material properties and values from an existing material database created by the individual user or system manager The database is in LS DYNA Keyword format As long as some part of the model material name matches the database a match will occur e g a material name CR4 Treatment C will match one named CR4 in the database After applying all matched materials are highlighted the user may then modify the selection and choose values from the database for unmatched materials Multiple databases can be created and selected within PRIMER Spotweld Definition One of the most time consuming tasks in constructing a vehicle model is the definition of the thousands of spotwelds connecting the body in white panels Up until recently it was necessary for spotweld elements to join nodes in the panel flanges directly forcing the model to have carefully matched mesh densities on all mating flanges LS DYNA from Version 950 has offered mesh independent spotwelds with the potential to save a great deal of tim
21. etal Forming Analysis Corp www mfac com France Dynalis www dynalis fr India GissEta www gisseta com Russia Strela Russia www ls dynarussia com 21 FEA Information Showcase 7th International LS DYNA Users Conference May 19 21 2002 Dearborn Michigan USA Second Call for Papers Abstract Deadline December 19 2001 Notification of Acceptance January 19 2002 Final Paper Deadline March 19 2002 Specification for Paper Submission Abstract Length Approximately 300 words please include figures if possible Paper Length Maximum of 3000 words single spaced on 8 1 2 x 11 paper Papers must be in MS Word format with imbedded graphics Please mail fax or email your abstracts to Ms Pat Kulzer Livermore Software Technology Corp 7374 Las Positas Road Livermore CA 94550 Tel 925 245 4546 Fax 925 449 2507 Email papers Istc com The Japan Research Institute Limited www jri co jp pro eng jmag e jmg index html eta FEMB27 PC JMAG Studio AE K No more text editing FEMB27 PC Finite Element A magnetic field analysis program Modei Builder is a complete pre post processing package designed from the ground up for LS DYNA This example shows how JMAG can be used for compatibility FEMB PC s new graphical interface the analysis of an eddy current brake for railcars supports all LS DYNA keyword cards through version 950 New Features Compiete LS DYNA Compatibility amp New Graphic Use
22. fferings Does e cae com supply clear reports with detailed application access and usage statistics Yes the reporting capabilities of e cae com are quite extensive Users can access reports online that include parameters such as number of file transfers number of CPU hours number of logins and other data of interest Customer site administrators have more reporting features including the above statistics for multiple users and or multiple sites within the customers company How does e cae com manage the ANSYS version or release migration Yes e cae com completely manages application migration for the customer This includes the rapid same day introduction of new ANSYS releases and patches as well as the operation of older versions of ANSYS for users requiring revision compatibility with installed base application revisions What happens when a job that has been submitted hangs or crashes ANSYS has developed a customer support process that will determine the reason for the problem and appropriate resolution In cases where it is determined to be an issue with the ANSYS program a proportionate amount of CPU time will be credited to the customer account Performance How fast is e CAE com compared to my local computer The answer to this will largely depend on the configuration of the local computer as well as the size and type of simulation being run However in test comparisons between the e CAE com service and a local PC operating at 800
23. g Massi The Purpose of PRIMER The standard approach Dai ri E to using PRIMER is illustrated in Figure 1 A general purpose pre processor is used to create the Finite Element mesh from CAD data Primer imports the mesh where all of the many LS DYNA specific features can be added In addition to editing these features PRIMER aids the user by Figure 1 The Purpose of PRIMER visualizing them and providing detailed cross referencing from feature to feature Both by using the edit menus and by using Find Attached Modify mesh Change some other data Further data can be combined with the model from other sources such as the Bill of Materials buckby Materials Database and Spotweld file The required editing ihe fil mass can be applied to the model using the Massing ly some ef the users can function Other models can be combined at this make mistakes point One of the original reasons that PRIMER was developed was to assist in merging Occupant models handling the issues related to positioning contact definition and seatbelt fitting Finally the model can be checked with over 1500 separate checks carried out as well as new functions to check contact penetration mass scaling requirements PRIMER provides checks of material and section properties using contour plotting Data added data can he understoed by the pre processor Figure 2 Typical model modification process While all this is very useful when preparing a new
24. is single contact approach as a global contact approach This however does not mean that one should always avoid local contact definitions Frequently there exist certain areas of the vehicle that require special contact considerations where the global contact definition is observed to fail In such instances the user is encouraged to define local contact interfaces with non default parameters that would best suit the contact condition 7 2 AUTOMATIC SINGLE SURFACE or AUTOMATIC GENERAL Though both contact algorithms belong to the single surface contact type several key parameters distinguish these two contact types Table 7 1 highlights the important differences Parameters RC AUTOMATIC GENERAL PENMAX 0 4 100 BSORT frequency Every 10 cycles SEARCH DEPTH 2 3 Shell Exterior Edge Treatment No Yes Beam to Beam Contact No Yes Table 7 1 Difference Between AUTOMATIC SINGLE SURFACE 13 and AUTOMATIC GENERAL 26 14 Of the two single surface contact types listed in Table 7 1 AUTOMATIC GENERAL is computationally more expensive owing to its additional capabilities and its more frequent and thorough contact search The AUTOMATIC SINGLE SURFACE contact option is recommended for global contact To treat special contact conditions where shell edge to edge or beam to beam contact is anticipated the additional use of the AUTOMATIC GENERAL contact in localized regions is recommended AUTOMATIC GENER
25. l that the wrong panels were selected Other reasons why the welds could not be made can also be displayed Most often these will relate to the maximum or minimum length defined for a spotweld the minimum pitch the angle to the panel or the maximum number of panels that can be model from the joined with a single weld Finally Find com forming model Connected and Find Unconnected functions x can be used to check that all relevant panels have been successfully spotwelded Mass Assign Another new useful function for LS DYNA users is Mass Assign Often parts in a model are represented by approximate geometry or a solid body might just be represented by an exterior shell Figure 6 Result of mapping forming data element mesh PRIMER offers the ability to smear Thickness and plastic strain is mapped onto the crash mass over these parts to obtain the required total mass and centre of gravity Effects of Forming An area gaining more and more interest is how the forming process affects the performance of the manufactured component Research has shown that strain hardening and thickness changes can have a significant influence on the crash response of a vehicle so functions have been added to PRIMER to help users include these effects Data from a separate forming simulation must be mapped onto the crash model but often the forming model will have a different mesh density and a different orientation PRIMER tackles this by defining an orient
26. list data such as load curves joints complex material models and so on can be lost when an existing analysis is taken back into them for modification or when models are merged In addition there are several specialist functions peculiar to particular types of analysis such as occupant positioning which are not provided satisfactorily by general purpose pre processors Oasys PRIMER has been designed to solve these problems Primer is capable of reading processing and writing out the entire LS DYNA keyword input deck with no exceptions or omissions no information is lost during processing It will also read and write several other common formats Input decks may be visualized directly and any number of input models may be merged intelligently into a single output model with the additional ability to translate rotate reflect and scale models parts or individual components in the process PRIMER provides several specialist occupant modeling features It will manipulate occupant dummy models intelligently providing easy interactive positioning of whole models and their constituent parts it will fold airbags it will fit seatbelts This positioning folding and fitting Reference Bill of Materials information is appended to the end of the output ied ae PER EIDE EE RAE Vor Re TET deck and can be reread back in directly for further eee DEUS manipulation if required e g seals Automatically connect spotweld file engine etc Model checkin
27. model for analysis there are more reasons why PRIMER should be used when modifying a model for second and subsequent runs The typical process to modify an existing model is shown in Figure 2 Most pre processors lose data on reading the LS DYNA model because not all features are supported Although it is sometimes possible to re stitch this lost data back in after the model is written again one of the great benefits of the Keyword format of course mistakes can be made and a lot of time can be wasted The procedure with PRIMER is improved as shown in Figure 3 Mesh modifications are made in the pre processor as before The model to be modified is read in by PRIMER along with the new or modified mesh PRIMER s powerful model merging is then used to combine the two with full checking to avoid clashes Any further changes can then be made in PRIMER before writing the LS DYNA model ready for a new analysis Figure 3 Model modification process with PRIMER New Modelling Features in Version 8 1 Bill of Materials It can be difficult to ensure that a crash model is up to date with the latest product release material properties and gauge can change for existing parts and parts can be added or deleted This information is summarized in the Bill of Materials BOM which is usually maintained as a spreadsheet PRIMER is now able to read this spreadsheet By matching names between BOM and model PRIMER can be used to ensure that the mod
28. ons to fix penetrations within PRIMER are limited although null beam elements can be created to help find the problem areas in a meshing pre processor The new contouring capability allows a number of other model characteristics to be checked in PRIMER 8 1 Values that can currently be displayed include shell thickness material properties such as yield stress and element timestep and percentage added mass for mass scaling requirements if a minimum timestep is defined Vector plots are also now possible For example initial velocity can be plotted to check that all entities have the required velocity value and direction and any errors due to PART_INERTIA definitions can be corrected 10 Improvements to General Functionality A new header bar has been added to the top of the graphics window giving rapid access to commonly used functions such as the draw commands hidden line shaded image etc and the blanking menu Some of the new features such as vector plots of velocity or contour plots of timestep or mass scaling can also be accessed from here In addition new options have been added to modify the appearance of the graphics display and a bitmap output option has been added More options for handling the INCLUDE keyword have been added in the latest release More often modellers are using INCLUDE to assemble large models from a library of smaller sub models this provides a flexible way to manage a complex family of vehicle
29. perator N D x w K JA x x w x A x x j l Clearly the final form of the discrete equation is conservative Hence all the conservative equations encountered in the SPH method will be solved using this weak form It has been proved that this approximation is PO which means that we have a good particle approximation for constant functions and that error estimate between any function and its particle approximation is known III Applications to conservative equations With the definitions explained above the conservative equations can now be written in their discrete form e Momentum conservation equation The momentum equation is 2 d x 1 where a B are the space indices v is the velocity and o is the stress tensor The particle approximation of the weak form of this equation is N c ot Y Od E E j x aL e Energy conservation equation The energy equation is where E is the internal energy P is the pressure and p is the density The particle approximation of the weak form of this equation is dE Bw Pu m pr 440 v x A i jd Editing LS DYNA Input Files using Oasys PRIMER Version 8 1 Copyright Oasys 2001 PRIMER is a pre processor dedicated to editing LS DYNA input files While there are many pre processors available for mesh building and general modeling their support for non linear input data is often incomplete specia
30. puters Our goal has been to achieve the same features and ease of use in eta FEMB27 PC that have been the hallmark of our workstation version 18 With our 1 anniversary issue of FEA Information News we are pleased to Showcase one of our participating companies The Japan Research Institute Limited President Masahiko Koido Message from the President From Dreams to Reality through Knowledge Engineering www jri co jp excerpt from the website The Japan Research Institute Limited Information technology IT is at the heart of a broad process that is radically transforming industry and society not only in Japan but on a worldwide scale To survive this age of rapid change requires sound business management based on a clear vision of the future and well thought out strategies for information utilization Since its establishment The Japan Research Institute Limited JRI has kept pace with its clients and their changing needs by basing our operations on the underlying principle of creating new value for clients That is by identifying problems hindering companies and offering concrete practical proposals for solving those problems JRI generates new arenas of value for its clients to explore At JRI these efforts toward comprehensive problem solving are understood as knowledge engineering a concept which forms the foundation of all our activities Offices Head Office 16 Ichiban cho Chiyoda ku Tokyo 102 0082 Jap
31. que user and password ID Advanced security features are used extensively throughout the site and data within e cae com is protected using unique naming conventions Under this method there is no ability for one customer to view another customers data unless explicitly permitted How can I be sure the e cae com solution will work with my current corporate firewall Provided the customer can see the internet e cae com will be operative There is no incremental work required from the customers IT organization The e cae com solution will use either port 80 or 443 depending whether the customer is operating in secure SSL or utilizing an open connection What precautions are in place to prevent an attack of the e cae com site Continuous traffic monitoring is in place on a 7x24x365 basis providing the highest degree of pro active protection available today Procedures used leverage state of the art technologies and methods to provide extensive security capability Will e cae com provide a virtual private network VPN Yes please ask ANSYS Inc reseller or partner for pricing VPN s are available for an added level of security in most geographies worldwide 12 Support How does the support model work Support for ANSYS users is provided in the same model as today ANSYS customers typically purchase through an ANSYS Support Distributor in their local region This same organization is responsible for the support of the e cae com o
32. r interface Improved Mode Handling Controls CAD Capabilities Robust IGES amp VDA translator Load Curve Manipulation Presentation Ready JPG AVI VRML OpenGL Supported Windows 98 N T4 2000 Mowement direction o o o o o o o o o Armature cod eta FEMB IS A FULL FEATURE FULL FUNCTION GENERAL PURPOSE PRE POST PACKAGE FOR USE WITH LS DYNA Product names referenced herein are trademarks of their respective owners 22
33. ractical The ANSYS e Sim strategy is focused on delivering engineering simulation solutions that can be deployed on web based infrastructures for optimal cost effectivity and efficiency in product design environments The primary benefit of this strategy is by creating ANSYS products that are web enabled the deployment of these solutions can be done on LANS WANS Intranets Extranets or the worldwide web Furthermore they can be deployed either within one company or across the supply chain that services a company The following FAQ covers Security Support and Performance Security Generally how secure is the e cae com infrastructure All communications between the users system and e cae com utilize state of the art Secure Socket Layer SSL technology Communication is encrypted and secure User names and passwords are randomly generated and unique All operations are continuously monitored for possible misuse The technology used on e cae com provides the highest level of security in the market today For those users who require excellent security private VPN or leased lines can be provided as well as dedicated computational systems The hosting provider for e cae com is Genuity Inc www genuity com and a tour of the Genuity facility can be arranged for customers who desire to see the security infrastructure first hand What kinds of security does e cae com use to protect customers data All customer data is protected using a scheme of uni
34. rganized in a logical way File CAD Model Properties and the tools icon menus are pre emptive The simple interface eliminates the steep learning curve normally associated with a full featured program eta FEMB27 PC has extensive CAD capabilities which cover the line and surface definition needs of most power users Also more robust IGES and VDA input translators are now available A powerful new feature is the ability to generate curves or load curves directly from a new graphic plot handler Curves can be input or inserted read from a table in various ways and are immediately associated with the loading case eta FEMB27 PC contributes to model data discussion by providing direct export of model images to JPEG format which can be easily inserted into documents presentations or posted on the Internet eta FEMB27 PC allows direct export of the LS DYNA model to virtual reality VRML format allowing anyone to manipulate the 3D model using an internet capable browser Eta FEMB27 PC Compete LS DYNA Solution Package Although FEMB has historically been perceived as only a pre processor eta FEMB27 PC is in reality a complete LS DYNA solution package that includes e FEMB pre processor e PostGL post processor d3plot e eta Graph plot post processor ASCII and binary Cost Effective Solution ETA foresaw the current trend and began several years ago to make the transition from Unix platforms to more cost effective personal com
35. right 2001 Armando Esteves ETA eta FEMB27 PC is the newly released version of ETA s pre post processor for LS DYNA for personal computers using Windows 98 NT4 2000 More than a regular upgrade eta FEMB27 PC was redesigned from the ground up based on the Unix version of eta FEMB which is 10096 compatible with LS DYNA Complete LS DYNA Interface The major goal in the development of eta FEMB27 PC was to fully support LS DYNA in a non text editing environment To reach this goal the following requirements were defined e support all LS DYNA cards and keywords graphical and numerical set default values as in the LS DYNA User s Manual and input validation check total graphical interface remain user friendly and intuitive maintain efficiency and high performance remain the most cost effective solution available to users During development of eta FEMB27 for unix workstations ETA designed an LS DYNA Template which allows our developers to easily keep pace with the evolution of LS DYNA and the release of new keyword commands A simple addition to our text based template enables almost immediate compatibility with new or enhanced features of LS DYNA In eta FEMB PC Version 26 LS DYNA capabilities were hardcoded into the software making it difficultto keep up with solver development To respond effectively to user needs it was essential to port the LS DYNA Template to eta FEMB PC This was the primary motivation for a completely new interfa
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