Winter 2008 - Engineering Dynamics Corporation
Contents
1. WINTER 2008 ENGINEERING DYNAMICS CORPORATION Technical Newsletter Available on line in the EDC website Library at www edccorp com HVE amp HVE 2D Version 6 00 Available Soon HVE and HVE 2D Version 6 00 are in the final stage of development and will be available soon Here is a brief overview of some of the enhancements users will find in Version 6 00 DyMESH Version 2 0 DyMESH has been significantly improved in the following areas e Maulti vehicle Collision Simulation e Vehicle vs Environment Rollover Simulation Contact Algorithm and Deformation Force and Acceleration vs Time History e Restitution Modeling Early testing also shows event run times of validation cases have been reduced by as much as 40 percent More details about the improvements to DyMESH are presented in the Technical Session of this newsletter Advanced Mesh Options Dialog DyMESH users will now be able to optimize their simulation runs using the Advanced Mesh Options dialog In this dialog the user drags an adjustable cylinder to select the region of the vehicle mesh requiring detailed tessellation These actions reduce calculation run times and also improve results for pole impact collisions or other simulations where highly detailed vehicle meshes are required IPC Redesign The Inter Process Communication IPC has been further redesigned to utilize shared memory for communication between HVE and all HVE compatible2. EOS 4 WINTER 2008 Technical Newsletter with another vehicle or environment We had seen conditions where the mesh deformed significantly on one vehicle while there was not as much deformation as we would expect on the other vehicle of similar Stiffness Our research showed this was occurring because one vehicle s mesh became concave shaped The source of the condition was traced to the fact that in DyMESH Version 1 only the slave vehicle vertices deform during a single timestep The contact algorithm was Changed to deform vertices on both the master and Slave vehicle simultaneously As a result crush depth is also simulated more accurately Another significant improvement is that DyMESH Version 2 does not require that the mesh be water tight This reduces the burden on the mesh builder especially for environment meshes a back side is not required The radio button on the Vehicle Mesh dialog Water tight Yes No Dont Know has thus been removed as it is no longer required Force and Acceleration vs Time History The new contact algorithm has solved several problems For example depending on which vehicle was the slave vehicle the calculated force which is based on the vertex displacement of the slave vehicle is predicted more accurately This has an obvious effect on acceleration as well Thus the overall collision dynamics are improved Restitution DyMESH uses the Relaxation Length value default 0 10
3. gt Force and Acceleration vs Time History gt Restitution Each of these areas is addressed below Multi vehicle Collision Simulation Although many users discovered that DyMESH appeared to work for events involving three or more vehicles EDC had not performed a rigorous investigation and did not officially endorse its use for such applications Part of the development of DYMESH E HVE Untitled Untitled Fie Edit View Mode Set up 3 DEdit Options Help a i K SIMON Untitled Event ji Ch a ae SD lt A GOgs T q Version 2 involved a thorough investigation of the code as it applies to multi vehicle simulation Limitations were found complicated issues involving the number of vertices on each vehicle mesh and the order of collisions and removed DyMESH Version 2 supports multi vehicle simulation Figure 2 shows a four vehicle simulation involving simultaneous contact between all four vehicles This condition is handled by the new code Vehicle vs Environment Simulation DyMESH Version 1 did not simulate collision forces between a vehicle and the environment This precluded its use for rollover simulation Some users got around this restriction by placing a vehicle with an environment emulating mesh into the ground This is no longer required DyWESH Version 2 includes direct interaction between vehicle s and the environment surface This enhancement allows for direct simulation of rollover c
4. create my own vehicle A You can start with the appropriate class of generic vehicle for more details see EDC Publication 19 Updating the Vehicle Class Categories in the Technical Reference Library on the EDC website and then edit the data parameters to match the specifics for your vehicle You may be able to determine values from physical measurements or from the manufacturer of your case vehicle That procedure will take care of the data required for the appropriate behavior of the vehicle in your reconstruction or simulations If you also require a geometry file 3 D model of the vehicle one option is to build your own model using a total station or photogrammetry program to take measurements of the actual vehicle then use a CAD program to build a surfaced 3 D model of the vehicle in DXF or VRML format Another option may be to find and edit an existing model available from Internet sites like www digimation com www 3dcadbrowser com or www turbosquid com More details about the process of how EDC builds complete vehicles data and geometry for the EDVDB vehicle database and also how to build your own vehicles are available in the Building a Vehicle for HVE amp HVE 2D workshop at the 2008 HVE Forum Q What s the easiest way to use an aerial photograph or scaled drawing image as an environment for my reconstructions or simulations A Build a scaled surface in the 3 D Editor and then apply the image as a Mater
5. physics programs This redesign eliminates the use of sockets thereby avoiding any conflicts with firewall settings or other Internet security programs Vehicle Mesh Tessellation in EDSMAC EDSMAC users will now have the option to apply tessellation to the mesh of a generic vehicle which will improve the visualization of the damage profiles of vehicles involved in collision simulations Off Steer DOF Normal f Append f Manual User Adjusted f Adjust Tow Yehicl Inter Yehicle Connection E a as f Adjust Trailer f Adjust Both Equally Cancel Close up view of EDSMAC4 Calculation Options dialog showing the new Steer Degree of Freedom DOF options and also the new Inter Vehicle Connection options AutoConnect Tow and Towed Vehicles EDSMAC4 EDVTS and EDVDS now provide an option for automatic matching of the connection heights between tow and towed vehicles The user can choose between settings of Manual User Adjusted Adjust Tow Vehicle Adjust Trailer or Adjust Both Equally using the Calculation Options dialog for the event EDSMAC4 Steer Degree of Freedom EDSMAC4 now supports the Steer Degree of Freedom Model as discussed in the Technical Session of the Summer 2007 Newsletter A great application of this feature is in the situation where a vehicle is spinning and or sliding after a collision and the driver is disabled and not providing steering input In this situation the vehicle is essentially
6. or 10 percent in the Vehicle Mesh dialog to determine how much vertex displacement is restored during contact A value of O means that there is no vertex restoration and thus no restitution force The mesh concavity issue described earlier see Contact Algorithm and Deformation prevented restitution from working properly The result was essentially zero restitution The new contact algorithm results in the expected restitution behavior These improvements and additional information about the theory and application of DyMESH will be discussed in great detail in the DyMESH 3 D Collision Model workshop at the 2008 HVE Forum Using the Buttons on the Right Side of the Viewer The buttons down the right side of the viewer can help HVE and HVE 2D users work efficiently in their reconstructions or simulations Here s a brief description of each button i Select Pick Button be Selects Object Pick mode The cursor shape will change to an arrow In this mode the user is selecting objects or icons e g vehicles wheels library objects displayed in the viewer is Manipulate View Button Selects Manipulate mode The cursor shape will change to a hand icon In this mode the user is moving the camera in space A Help This menu provides help about the viewer Home Button Returns the camera to its home position initial position if not set using the Set Home button Set Home Button Resets the home position to the curre
7. self steering based upon its steering system geometry and the current post impact Slip angle at each tire The Steer DOF Model can simulate the post collision steer angle history providing an obvious improvement in the crash reconstruction EDSMAC4 Damage Reporting EDSMAC4 now has improved post processor logic for matching the CDC PDOF Delta V and Peak Acceleration to a Damage Range These results are presented in the Damage Data report in Playback EOO Technical Newsletter WINTER 2008 DyMESH Options SIMON Untitled Event Technical Session This Technical Session provides a high level overview w Use DyMESH Version No 2 00 of the changes incorporated into DyMESH We have M Include Environment gained much experience with DyMESH since its Force To x y Plane introduction in March 2004 We had invested years literally to develop a 3 D collision simulation code that Ares dutetr o was Stable and robust And though we were largely z successful while evaluating hundreds of events supplied by DYMESH users we found conditions where DyMESH needed improvement As a result of nearly a R year of redevelopment we are releasing DYMESH a Version 2 Set Box Size fin 2000 Relaxation Length The first thing you will notice is that the DYMESH dialog Timesteps see Figure 1 has been greatly simplified The simplification has been the result of two things First several of the original DYMESH options relat
8. ar time of year for visiting San Diego so don t wait until the last minute to make your reservations if you want to stay at the 2008 HVE Forum hotel EQO 6 WINTER 2008 Technical Newsletter Recommendations for Windows Vista Installations If you are not the sole Administrative User on a computer using any version of Windows Vista we strongly recommend that you install HVE or HVE 2D into a location other than the default Program Files folder that has been used for Windows XP installations One of Vista s security features could make it very difficult to locate the case files and simulation movie files you create while using HVE Here s a description of the security feature and how it affects users Vista strongly protects the Program Files folder against unauthorized writing or creating of files The user of an application that needs to write into any folder within the Program Files location must have administrative privileges for the program to function as expected However Vista will allow a user without administrative privileges to run the application using a feature called File and Registry Virtualization This feature redirects the writes and subsequent reads to a user virtual store located within the user s profile This feature tricks the application into thinking they are still running with full administrative privileges but simply redirects the reads and writes elsewhere For example in HVE the cas
9. ce Course Registration You may register for a course by contacting EDC Customer Service at 503 644 4500 or by email to training edccorp com You can also visit the Training pages on our website and download a course registration form All courses are eligible for Continuing Education Units and ACTAR credits See you at our next course Related Training Courses Northwestern University Center for Public Safety NUCPS is no longer actively scheduling the COMPTAR and MATAR courses which used EDCRASH and EDSMAC The material previously covered in these courses is covered in the EDC Reconstruction and EDC Simulations courses If you are interested in hosting one of these courses at your location please contact EDC Customer Service at 503 644 4500 Engineering Dynamics Corporation 8625 SW Cascade Blvd Suite 200 Beaverton Oregon 9 008 USA Phone 503 644 4500 FAX 503 526 0905 Email info edccorp com Website www edccorp com EDVAP EDCRASH EDSMAC EDSMAC4 EDCAD EDSVS EDVTS EDHIS EDVSM EDVDS EDGEN EDVDB HVE HVE 2D HVE Brake Designer and GetSurfacelnfo are trademarks of Engineering Dynamics Corporation All Rights Reserved SIMON and DyMESH Patent number 6 195 625 are registered trademarks of Engineering Dynamics Corporation All Rights Reserved GATB GBF DiscoverHVE com and PhotolntoHVE are trademarks of Collision Engineering Associates Inc EQO 8
10. cle parameters and then work through real world cases using a variety of analytical approaches and techniques At the 2008 HVE Forum you have choices from a large selection of workshops the HVE White Paper session Users Groups and interactive social hours for everyone As in previous years the Advanced HVE workshops are filling up quickly with users eager to learn a tremendous amount of detailed information about how to apply their software to real world crash analyses Workshop schedules descriptions registration forms and details about the hotel and special room rates are available to download on the 2008 HVE Forum pages of the website Visit www edccorp com or call EDC Customer Service at 503 644 4500 and sign up today About the 2008 HVE Forum Hotel The Holiday Inn San Diego On The Bay offers a convenient hotel location and San Diego waterfront destination Just a complimentary shuttle ride from San Diego International Airport and footsteps to the Downtown Gaslamp Quarter This San Diego lodging is popular for its proximity to fine restaurants theaters museums shops and sporting venues A special room rate of 165 00 per night has been arranged for your stay during the 2008 HVE Forum To receive this special rate you must use the Group Booking Code HVE when making your reservation This special rate will only be available until January 18 2008 or while rooms are available in the block February is a very popul
11. e files are usually placed in C Program Files HVE supportFiles case If the user does not have administrative privileges then HVE will not write to this folder and the write will get redirected to C Users username AppData Local VirtualStore ProgramFiles HVE supportFiles case with the username being the currently logged on user ID However in HVE all file browsers will appear to be looking in C Program Files HVE supportFiles case but when outside of HVE a file browser will not show your new files in that location Users can look for the new files in the VirtualStore directory which is hidden by default To make your file browser find these redirected files simply press the Compatibility Files button on Windows Explorer or any Explorer Shell Window Note that the Compatibility Files button will only appear when there is a virtual version of a file related to the current directory Once pressed the user will be taken to the virtual store location to view all redirected files Note This column has been summarized from an article on the My Digital Life website at www mydigitallife info Readers are encouraged to visit their website for more information HVE and HVE 2D F A Q This section contains answers to frequently asked questions submitted to EDC Technical Support staff by HVE and HVE 2D users Q I have a case that requires a commercial vehicle that is not available in the EDVDB vehicle database How can
12. ed to the tree e en sale fi 0200 contact algorithm were made available in the dialog simply because we did not have the experience to know which options might be helpful to our users After __ Cancel several years we now have that experience Unnecessary options have been removed Figure 1 New simplified DyMESH Options dialog HVE Untitled Untitled File Edit View Mode Set up 3 DEdit Options Help E SIMON Untitled Event ey p gt gt I 1 5000 0 0010 0 0200 0 2200 11 EJ Key Results Isuzu Hom Select Variable 12625 41 11944 38 Variable Fz imp Ib 707 50 takde EAGAR LA 13666 58 5781 97 Fz imp lb 3793 92 Fa ra A S aea E Key Results Acura 3 2 Key Results Dodge Neo Select Variable Variable 5228 86 2558 31 i 10831 89 i TTE Famo _ 773 60 S Fz mp 3433 32 Rotx Roty Mnn Zoom gt 8 4 Dolly Figure 2 DYMESH simulation of a hypothetical 4 car collision simulating simultaneous collision forces between four vehicles Key Results windows show collision force on each vehicle EOS 2 WINTER 2008 Technical Newsletter second the new contact algorithm see discussion below removes the need for many of the original options The technical enhancements to DyMESH fall into the following areas gt Multi vehicles Simulation gt Vehicle vs Environment Simulation gt Super tessellation gt Contact Algorithm and Deformation
13. he vicinity of impact needed to be tessellated using a very small dimension say 2 to 3 inches gt HVE Untitled Untitled File Edit view Mode Set up 3 DEdit Options Help E a K SIMON Untitled Event ia SE o Rotx Roty MTT TTT However when an entire vehicle is tessellated to 2 inches the number of vertices reaches an astronomical value say a half a million Simulation time and computer memory requirements make such a simulation totally impractical thus pole simulations were not done DyMESH Version 2 takes advantage of HVE s Advanced Mesh Options dialog which allows the user to select a small section of the vehicle mesh and tessellate it to a very small size without changing the remainder of the mesh Thus it is now possible to choose a 2 inch tessellation just in the vicinity of impact on the mesh Pole impacts are now quick and easy as shown in Figure 4 Contact Algorithm and Deformation Technically speaking the most important internal change to DyMESH has been a significant revision of the contact algorithm The contact algorithm is the part of DyMESH that determines how much and in what direction the mesh moves on one vehicle during impact 5 0000 0 0010 0 0200 1 9000 95 h Se gt Beles gt Lr Select Variable Zoom 4 gt 21 6 Dolly Figure 4 DyYMESH simulation of a 35 mph collision involving a van and a highway overpass support Peak acceleration was 39 g
14. ial Texture Follow the steps in your Users Manual section for the 3 D Editor for exact details Another option is to join www DiscoverHVE com and use their PhotolIntoHVE utility program to create the Surface and apply your image In just a few minutes you will have an environment model that s ready to drive on Visit the Support section of www edccorp com for the latest Downloads and answers to F A Q s 7 EQO Technical Newsletter WINTER 2008 EDC Training Courses EDC Reconstruction amp EDC Simulations EDC offers an excellent training course on the use of the EDC reconstruction program EDCRASH Both new and long time users of EDCRASH agree that the EDC Reconstruction course is extremely beneficial and challenging EDC also offers an excellent training course on the use of EDC simulation programs such as EDSMAC EDSMAC4 EDSVS and EDVITS The EDC Simulations course offers the fastest way to learn what you really need to know how to efficiently use the program and get the right results These one week courses are designed to fully investigate the program s inner workings Lectures are full of helpful hints gained from years of experience During the course students will use the programs e g EDCRASH EDSMAC4 in either the HVE or HVE 2D simulation environment to complete several workshops highlighting the capabilities of the programs HVE Forum The HVE Forum is an excellent opportunity for HVE and HVE 2D
15. nt camera position eee View All Button Brings the entire scene into view Be careful In the Environment and Event Modes the entire scene includes the light Source used for the sun position which is a long long way away from the environment model Bmw s L F Seek Button Allows the user to select a new center of rotation for the camera When clicked in Manipulate mode the cursor changes to a crosshair The next left mouse click selects the object underneath the cursor as the new center of rotation When the button is released the camera moves to its new position hia i Projection Button Aa selects the type of camera used by the viewer It toggles between the two available camera types perspective a view of a three i dimensional image that portrays height width J and depth and orthographic a projection on a plane using lines perpendicular to the plane 5 EOS Technical Newsletter WINTER 2008 2008 HVE Forum February 18 22 2008 San Diego CA Join your colleagues at the 2008 HVE Forum and learn how to Hang Ten using your HVE or HVE 2D software The 2008 HVE Forum offers workshops of interest to every user of HVE and HVE 2D For example you might choose to study the background theory and application for your physics programs Or you might choose to learn how to build a vehicle from scratch build a 3 dimensional scene using Survey data run test simulations to adjust vehi
16. rashes wherein the vehicle body interacts EJ 5 0000 0 0010 0 0200 1 1600 58 Select Variable Variable 75 88 71 94 2 91 241 51 11 95 7 09 55 36 4 09 10418 04 14424 87 4175 09 8086 60 18460 56 44803 95 zl Mz fimp ft lb Rotx Roty MOm h eleal AL Zoom 4 gt 270 Dolly Figure 3 DYMESH simulation of a hypothetical rollover showing vehicle body vs environment interaction Key Results window shows impact forces and moments 3 EQO Technical Newsletter WINTER 2008 with the ground Collisions between vehicles and rigid barriers such as bridge abutments and other fixed objects may also be simulated directly Figure 3 shows a rollover collision simulation Figure 4 shows a simulation between a vehicle and a highway overpass support Simulating rollovers using S MON DyMESH provides another important improvement in rollover simulation The issue of an excessive wheel force launching the vehicle during a rollover this is caused when the tire plane becomes nearly parallel to the road plane and the tire radius calculation yields an abnormally large tire deflection can be eliminated Simply use SIMON S Radial Spring Tire terrain Model option Super tessellation DyMESH simulation of narrow object impact e g a telephone pole or a tree was not previously practical Although DyMESH would theoretically work the vehicle mesh in t
17. users to jump to a new level of ability By participating in workshops attendees brush up on their present skills learn new techniques and learn how to use the latest advancements in the software The HVE Forum also presents a great opportunity to meet other users and expand your network of resources Engineering Dynamics Corporation Training Course Schedule EDC Simulations Los Angeles CA January 2009 Miami FL 2 2 November 2009 EDC Reconstruction Los Angeles CA January 7 11 2008 Miami FL November 10 14 2008 Theoretical amp Applied Vehicle Dynamics VB De opie ee eb ee TBA 2008 2008 HVE FORUM san Diego CA February 18 22 2008 Vehicle Dynamics Theoretical and Applied Vehicle Dynamics extends the theory of the basic SAE course and includes direct applications using several vehicle simulation programs e g SIMON EDVSM within the HVE simulation environment as well as a Solid theoretical background for such simulations The course is focused towards vehicle design engineers and safety researchers with an interest in a greater understanding of vehicle dynamics and automotive chassis systems development Hands on Training Intensive hands on training on how to use your HVE or HVE 2D system software physics programs and databases is available Contact EDC Customer service for more information about bringing this two day on site course to your offi
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