Durability Load Cases - Free of Papers from LS
Contents
1. Figure 1 Graphical definition of a load case The input data can be raw geometry parts or it can be completed sub models sub assemblies The output data can be a single solver deck output file or an output composed of several includes files The modeling steps are all the actions that are needed to prepare the output Such actions are the applications of joints contacts boundary conditions positioning of dummies and test devices control keywords etc 2 35 Automotive 1 11 International LS DYNA Users Conference Difficulties in Building a Load Case This process as easy as it is to define 1s a very complex and error prone process to materialize This is because It is a process that greatly depends on the engineer s technical expertise It is difficult to gather all the data needed for the load case It needs to follow written guidelines It is difficult to control minor parameter changes It is difficult to repeat it It is not a streamlined operation Ford Werke in cooperation with BETA CAE Systems SA has proceeded in developing a template driven durability process to address the above issues BETA CAE Systems SA using the technologies of the Task Manager has delivered multiple load case templates for various loading conditions The Task Manager templates have been delivered and they currently are in testing phase before they enter production work Some of the tasks that were developed as part of the pr2. in analysis parameters are easily applied while modifications of crucial areas components are seamlessly imported 2 The process becomes repeatable and robust Actions needed to build a model are followed in sequence considering their inter dependencies 3 The template process aims to reduce the overall CAE turnaround time 4 Association with ANSA DM assists data collection and organization and promotes the use of library items 5 Model quality becomes inherent in the process and does not depend on user experience expertise References 1 ANSA version 13 0 1 User s Guide BETA CAE Systems S A July 2009 2 Makropoulou I Kolokythas Y Rorris L LS DYNA Impact Model Build Up Process Automation with ANSA Data Manager and Task Manager 10th International LS DYNA User s Conference Detroit USA June 2008 3 Seitanis s Giannakidis M Definition and Parameterization of a Task Manager Process Workflow Applied on the Generation of an ABAQUS Loadcase 2nd International ANSA and ETA Congress Halkidiki Greece 2007 4 LS DYNA Keywords User s Manual Version 971 R4 Livermore Software Technology Corporation Livermore 2009 2 46
3. 11 International LS DYNA Users Conference Automotive 1 LS DYNA Durability Load Cases An Automated Template Driven Process Using the ANSA Task Manager Yianni Kolokythas Dietmar Fels Matthias Weinert BETA CAE Systems SA Thessaloniki Greece Ford Werke GmbH Cologne Germany Abstract Process organization and standardization are essential in a CAE turnaround cycle In an era where the vehicle development time is getting reduced and the number of load case analysis is getting increased the need for automatic standard processes is increasing Ford Werke GmbH and BETA CAE Systems SA are cooperating to develop streamlined automatic processes using the ANSA Task Manager The goal of these template driven processes are to create realistic repeatable and robust durability simulation models The ANSA Task Manager supervises the generation of the simulation models while ANSA Data Management in the background facilitates the components management ensuring that the engineering teams will always work with the most up to date data The simulation model set up becomes a repeatable and user independent procedure safeguarding the model quality and fidelity Introduction Definition of a Loadcase A load case build up process is a series of modeling actions in order to model an engineering testing protocol or a loading condition This process requires input data and the modeling steps that will create the desired output data
4. A output is created without destroying the working model This output file is solved in DYNA and afterwards the task with the assistance of ETA read the new deformed coordinates of the cushion nodes Figure 12 A dummy de penetration LS DYNA input file 1s created from the main file 2 45 Automotive 1 11 International LS DYNA Users Conference Conclusions The data organization and process standardization are necessary for the load cases creation in Ford Werke This can be achieved with the use of ANSA Task Manager in combination with ANSA Data Management With the aid of ANSA Task Manager Ford can safeguard the model quality and promote knowledge transfer capturing the best proven practices for the analysis model build up as a sequence of modeling actions ANSA Data Management assures the organization of all data storing them in a structured form under a common location enabling their easy retrieval by the Task Manager During the execution of pre defined Tasks ANSA Task Manager makes sure that all task items are properly executed considering at the same time possible dependencies between them The validity of model entities definitions is checked prior to the output with the aid of various built in check algorithms The model quality 1s safeguarded and the build up of durability simulation models becomes fast and efficient Summarizing the effort of creating a template process has the following advantages 1 Changes
5. Conditions y O W Lert Dumy y Ol he BCs SPCs at the Fixing Locations M sy Apply Position H ae Bc SPCs at Fixing Locations you my Positioner C g Read Acceleration Pulse Curve m W Save Position k C BA BCs Prescibed motion gt B sosh sert E ae Bc Prescribed Motion at model cut b EA Shoulder Belt H las BC Prescribed Motion at Fixed Locat err LSDyna Control gt E Bho Dury Contacts _ ai srovity gt L he Model Checks Fixes p BA Middle Dumpy gf Analysis Details gt L Be Right Dummy Output C gt Be Contacts ge create Initial Foom Reference Geometry C Dummy Seat Depenetration Pre C Durmry Seot Depenetration Post p m Model Checks Fixes Figure 10 The load case related group of tasks Cutting the Model The Cutting Plane reduces the size of the model and only the needed portion of the model is kept On the free edges of the result of the cutting plane SPCs and prescribed motions are applied depending on the need of the specific load case The cut plane is predefined in the Task and the CAE expert can predefine its cutting position Figure 11 Plane cutting with creation of SPCs on the boundaries 2 43 Automotive 1 11 International LS DYNA Users Conference Creation of New Entities SPCs and Loadings During the creation of a load case there is a need to create new entities These new entities are created using the GEB General Entity Builders group of ent
6. Data Manager The ANSA Data Manager In order for the Task Manager to be able to retrieve all the required information it needs to cooperate with another ANSA tool called ANSA Data Manager The ANSA DM is a structured and centralized data management system It assures that all engineering data which is used for the creation of the model is stored securely and is organized in a way that can be easily retrieved by all CAE engineers working on various CAE disciplines A task should be built by the CAE expert and saved in the ANSA DM thus making it available for usage by the whole CAE team 2 38 11 International LS DYNA Users Conference Automotive 1 Model Assembly The Model Assembly part of the Task Manager is where the assembly Tasks take place Such Tasks are the sub model merging application of connections and connectors etc v 0 Cormon Model o Bf Read Params 0O EF Read Connectors XML pD gf Merge Models C EF Read Hard Points oD MH Edit Hard Points C BF Write Hard Points ie Q mA Sub Models p o oY BIW Connections v l Gh Model Assembly b O Gh Connectors Sliprings Ie o GR Connectors Rear Seat BiW je O he Connectors Left Front Seat BiW j C Re Connectors Right Front Seat BiW D TR Connectors Brackets BiW pL b O Connectors Retractors BiW Ie O Connectors Striker BiW Figure 5 The Model Assembly group of Tasks Model Merging The model assembly is achieved with the assis
7. Properties By User Thickness Penetrations Load Curves E gf axes H By End Time Figure 12 Various checks that are performed before model output WU Ce Oe mgr a 2 44 11 International LS DYNA Users Conference Automotive 1 Other Various Tasks Solver Controls The Solver Controls are set up once for each load case by the CAE analysis expert and are safeguarded in the Task Contact Interface Cards The contact interface cards along with their parameters are set up once during the Task build up During the Task execution Task Manager automatically fills the contact sets and there is no need for user intervention in the contact definition The Role of Scripting The role of scripting 1s to supplement the hardcoded ANSA Task Manager functionality for functions that are very specific and specialized to a load case Such cases where scripting has heavily been used is the positioning of test blocks previously stated and in tasks where calculation is needed to be made An example is the calculation of the angular velocity of the lift gate slam load case Another example of specialized tools that were built using ANSA s scripting language 1s a tool that does dummy seat de penetration using the LS DYNA solver When a dummy is positioned at the H Point there is an initial penetration of the dummy with the cushions of the seat Ford s procedures require that this de penetration should be performed through the solver A DYN
8. e the blocks need to be positioned a procedure was set up where the user does some manual work with the assistance of the Task Figure 9 Initial and final state of the blocks in the ECE 14 loadcase The figure above shows the case of the ECE 14 FMVSS 210 where one upper and one lower block are read in With the assistance of script functions the blocks are positioned and the additional two pairs are created automatically In the case of middle blocks an option to edit their position is given due to the higher H Point of the middle passenger All the positioning steps are saved in a session file This gives the user the ability to position the blocks automatically the second time the task needs to be executed when there is a design change in one of the sub assemblies Similar procedure was developed for the ISOFIX test block positioning Building the Load Case The Assembly Tasks are followed by the Load Case creation Tasks The roles of these Tasks are to create loading and boundary conditions of the load case Such items include the cutting of the model the creation of contacts creation of SPCs and prescribed motions etc The most important aspects of the Load Case Task are outlined below 2 42 11 International LS DYNA Users Conference Automotive 1 y L Be Lspyna Common Model v C BR Lsdyna Load Case g Position Cut Plane b C B Manual Items b l ge cut Model y L he FE Model pO M GEB GN SeatBelts Elements v Ol GR Boundary
9. ities These entities work similarly to the connectors These entities can be retrieved from the ANSA DM with their properties parameterized and with GEBs they can be applied in the needed location and orientation Template in ANSA DM ELEMENT_SEATBELT_SLIPRING ELEMENT _BEAM_ELFORM_2 Parameters beam inertias and cross sectional area slipring dynamic friction coefficient Load Case All load cases that require seatbelts Slipring SELEMENT_SEATBELT_RETRACTOR ELEMENT_SEATBELT_SENSOR ELEMENT_ BEAM_ELFORM_2 Parameters Sensor trigger time beam cross sectional area and inertias Load Case All load cases that require seatbelts Table 2 Parameterized templates for GEBs retrieved from the ANSA DM library The GEBs are also used to apply boundary conditions such as SPCs loadings and velocities The entities again can be either retrieved from the ANSA DM or they can be options of the GEB card itself Such boundary conditions used by GEBs that are saved in the DM are the INITIAL_VELOCITY_GENERATION and BOUNDARY_PRESCRIBED_MOTION Model Checks The model is checked prior to the output with respect to load case specific entities definition There are multiple checks that can be performed for the various aspects of the model E Bk Model Checks Fixes gf Joints gf Rigic Bodies Dependency ls Contacts ls Undefined Materials gf Tables gf Multipte Initial Velocities gf Mosstess Nodes gf uncer ine
10. oject are Restrain Integrity Sled Test Seatbelt Static Strength ECE R 14 FMVSS 210 Figure 2 Some of the load case developed to Task Manger Templates 2 36 11 International LS DYNA Users Conference Automotive 1 The ANSA Task Manager Task Manager Definition The ANSA Task Manager is a tool within ANSA that allows the creation and execution of template driven processes A Task is a hierarchical process comprising a series of distinct modelling actions that have to be followed in order to set up a discipline specific model Essentially as shown in image below the Task Manager replaces the manual modelling steps with automated actions Tasks Model Sub assemblies ANSA Task Manager Ready to run LS DYNA model Figure 3 Graphical definition of the Task Manager The Task Manager has replaced the manual modeling steps 2 37 Automotive 1 11 International LS DYNA Users Conference The Task Manager is divided into two major categories These are the model assembly and the load case build up In addition to modeling actions the Task Manager s goal is to carry all the pre determined parameters such as Connector and Boundary Condition properties seatbelt materials and properties Dummy Positions etc Ford Modeling Guidelines Ford Test Devices ANSA Task Manager Ford Materials and Properties Ford Connectors Joints Entities Contacts Figure 4 Information contained in the Task Manager and ANSA
11. sting Connectors and adds new connectors when needed The information is shared through an XML file with the rest of the team It can either be used in the same load case or in a different type of a load case that has the same connectors connector locations Dummies and Test Blocks Positioning The durability load cases presented in this paper require demanding positioning functionality in order to position the dummies and the test blocks Handling the Dummies The hardcoded functionality of dummy positioning is used to read and position the dummy The dummies are read from the DM and the tasks guide the user to rotate and translate the dummy to the correct position While the dummy is in the correct position the position can be recorded This recorded position can be saved in the task and anytime the task is re executed the user selects from the list of the available saved positions This capability reduces the amount of work and makes the task repeatable since it would be very difficult otherwise to position the dummy with the exact same rotations and translations the second time around Figure 8 Dummy Positioning in Restrain Integrity Loadcase 2 41 Automotive 1 11 International LS DYNA Users Conference Handling the Test Blocks The positioning of the test block is a complex procedure were special tools were developed with ANSA s scripting language Due to the fact that there are no pre defined start and end points for wher
12. tance of the Task Manager The sub models of the load case BiW Seats etc are read into ANSA These sub models are already meshed and all their internal connections joints and contacts are already applied Figure 6 Merging of all sub models into ANSA 2 39 Automotive 1 11 International LS DYNA Users Conference Connecting the Model A major task is the connection of the sub assemblies These connections are realized with the ANSA entities called Connectors The Connector Entities are applied during the execution of the Model assembly group of items Some characteristic features of the connector entities realization are The Connector Entities are defined using mesh density independent patterns for the identification of the connected entities Thus a connector can be applied on a hole circular feature or a certain number of nodes or elements in a pre defined search domain Connector Entities that connect a rigid with a deformable component with rigid interface automatically detect the case and create CONTRAINED_EXTRA_NODE instead of CONSTRAINED_NODAL_RIGID_BODY entities Connector Entities that connect rigid components together with rigid interface automatically detect the case and create CONSTRAINED RIGID BODY entities The Connector Entities can use the built in representations 1 e revolute and spherical joints or custom made ones retrieved as templates from ANSA DM libraries LS DYNA deck card values of
13. the library items can also be parameterized so that they can be editable during the set up of the connector Template in ANSA DM ELEMENT _BEAM_ELFORM_ 1 Parameters diameter length and orientation according to application CONSTRAINED_JOINT_SPHERICAL Parameters Value of added mass on both ends CONSTRAINED_JOINT_ REVOLUTE Parameters Value of added mass on both ends orientation according to application Table 1 Parameterized templates for connectors retrieved from the ANSA DM library The figure below shows an example of a connector entity realization Figure 7 The liftgate hinges connectors are applied and revolute joints are created 2 40 11 International LS DYNA Users Conference Automotive 1 Managing the Connector Information The Connector locations and properties could change from one Task into the other In addition the number of connectors may change based on the design changes of the sub assemblies As an example a seat in one model may connect to the BiW in four locations and in another model a seat may connect to six locations Many of the load cases such as the Seatbelt restrain integrity Belt Static Strength ISOFIX etc share the same connector information To avoid multiple users to have to do the same work of setting up essentially the same connectors a procedure was developed to output and share this information through XML files One user sets up the new locations and properties of the exi
Download Pdf Manuals
Related Search