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Modeling of weight and vibration reduction using high performance LASD

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This presentation demonstrates how to use Optistruct to predict the vibration levels of a floor pan and how to model Liquid Applied Sound Deadeners to reduce the vibrations with a minimum weight addition.

Speakers

Jean-Paul Allal, R&D Project Leader, PPG Automotive Adhesives and Sealants

Published in: Engineering
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Modeling of weight and vibration reduction using high performance LASD

  1. 1. Modeling of weight and vibration reduction using high performance LASD in the automotive industry Jean-Paul ALLAL R&D Engineering Project Leader September 2015
  2. 2. Aug-15 PPG Automotive Adhesives & Sealants • Key facts :  > 600 employees  Worldwide presence  Complete paint-shop & body-shop portfolio  Fundamental research with resin synthesis capability 2 PPG REVOCOAT – Modeling of automotive weight and vibration reduction using high performance LASD 1982 1984 1992 2000 2002 2004 2008 2011 2015 1982 PPG acquired Hughes Products (NA-Adrian) 1983 1984 PPG acquired Industrie Vernici Italiane (IVI) from FIAT Group 1983 PPG acquired Cipisa which was then renamed to PPI Iberica 2002 PPG acquired Grow Chemical 2008 PPG acquired Dow sealants in NA April 2015 PPG acquired Revocoat 1992 PPG started a JV with a Korean A&S start-up and initiated A&S activities Ferndale, Adrian, Michigan R&D Synthesis : Pittsburgh, Pa Pinhais, Brazil Wuhan, China Pondicherry, India Kolomna, Russia Bursa, Turkey St Just, France : HQ & Center of Excellence Camarma, Valladolid, Spain Ahmedabad ,India Quattordio Italy Partnership with Asahi Rubber, Japan & Bokwang Corporation, Korea Busan, Korea
  3. 3. Aug-15 PPG Adhesives & Sealants : Portfolio 3 PPG REVOCOAT – Modeling of automotive weight and vibration reduction using high performance LASD Body-shop : Adhesives Body-shop : Antiflutters LASD and BPR UBC & Paint shop sealers Body-shop : Parts
  4. 4. Aug-15 Technical trends at OEM’s 4 PPG REVOCOAT – Modeling of automotive weight and vibration reduction using high performance LASD  Reduction of curing conditions  Compact paint-shop, multifunctional materials  Platform strategy • Bonding vs. welding • Lighter materials • Substrate :  Thin layer as HSS  Alu, Mg  Composites  Reduction fogging & emissions Mass reduction at targeted performances Cost optimization Clean & greenAcoustical comfort  Engines  NVH treatment
  5. 5. Aug-15 WEIGHT SAVINGS in AUTOMOTIVE • Strategies : Redesign, downsizing, lighter or more efficient materials 5 PPG REVOCOAT – Modeling of automotive weight and vibration reduction using high performance LASD Weight saving to consumption real cars data : 100 Kg  0.5 L/100 km
  6. 6. Aug-15 PPG ENGINEERING SUPPORT 6 Engineering support Testing Material testing Oberst Drop Tower Tensile/compre ssion DMA … Static Oil canning Deformation Noise Door slam test Static / driving car noise Vibration Scanning head Laser accelerometers Modeling Static linear non linear Thermal deformation Modeling of read through Stress calculations Modal response Frequency response Random excitation Measured excitation Dynamic Linear Non linear (CRASH) 0 0,02 0,04 0,06 0,08 0,1 0,12 0,14 0,16 30 50 70 90 110 130 150 170 190 210 230 250 Mobility(mm/s/N) Frequency (Hz) 0,E+00 1,E-02 2,E-02 3,E-02 4,E-02 5,E-02 6,E-02 7,E-02 AVT DRT CTR DRT TUNNEL AVT GAU CTR GAU PIED ARRASSISE TRAIN ARR COFFRE GAMELL E MOYENN E RESP_DAMPER 70-250Hz RESP_NUE 70- 250Hz The engineering main target is to provide expertise to show the best usage of our materials. We have 2 methodologies : Testing and Modeling PPG REVOCOAT – Modeling of automotive weight and vibration reduction using high performance LASD PPG Modeling : NVH but also Crash, Thermal, … using Optistruct &/or Radioss
  7. 7. Aug-15 Damping products will convert to heat a part of the strain energy of the panels and reduce the mobility (or the vibration levels) and the acoustical emission. Vibrations • Sources • Amplitudes Structure • decoupling • Transfer path Panels • Loud speakers • Modal shapes Noise • Acoustical level • Perceived quality What are we speaking about ? 7 PPG REVOCOAT – Modeling of automotive weight and vibration reduction using high performance LASD A car body is made of a rigid frame and of panels.
  8. 8. Aug-15 Energy absorption Very high damping (η) or tg(δ) different θ°C Young’s modulus / stiffness Substrate & material Thickness Material deformation strain What are damping coatings ? 8 PPG REVOCOAT – Modeling of automotive weight and vibration reduction using high performance LASD Common industrial products : - Parts (mastic pads or constrain layers) most of the time manually fitted - Pumpable products applied with robots
  9. 9. Aug-15 Characterization & Oberst method The main characteristic of dampers is measured with DMA that provide values of η (or of tg(δ)) & of product Young’s modulus with no sensitivity to adhesion phenomenon’s or more frequently in the automotive industry with Oberst method (DIN 53440 – ISO 6721-3 – D45 1809 - … ) 9 PPG REVOCOAT – Modeling of automotive weight and vibration reduction using high performance LASD Vibration response of a steel bar •Thickness 1mm •Coated with product -3dB (δF/F) method •Modes 2, 3, … •about 100Hz, 300Hz, … Linear Interpolation •Oberst result @200Hz (for most OEMs) Results in % •For a given surface weight & for each θ °C Frequency (Hz)
  10. 10. Aug-15 Characterization & Oberst method • The Oberst value is dependant of the material and of the substrate (material & thickness) and is an interpolated value @200Hz. • The damping material is frequency dependant (this is masked in a single Oberst value) and in the calculations it should be used as such. As a consequence there is a calculation time penalty (It increases a lot and for a full car optimization it comes difficult). • For aluminum substrates results are quite different than for steel (because of higher frequencies). It is also common sense that on such substrates the natural frequencies of the panels are more important so analysis have to be made more carefully on higher frequency range. 10 PPG REVOCOAT – Modeling of automotive weight and vibration reduction using high performance LASD
  11. 11. Aug-15 Modeling techniques are the same for all the chemical basis except for the constraint layers because of the 3rd layer : the aluminum foil. (1st is the panel material and 2nd is the damping coating). Technology Mastic Pads Constrain Butyl/alu EPOXY RUBBER PVC Acrylic EPOXY Rubber Density (wet/dry) 1,4 à 2 magnetic or adhesive 1,6 (the paste) 1,6 1,6 1,3 1,3 1,5 ,9 1,6 1,6 Surface weight for 14% damping @200Hz 4 kg/m² 1,8kg/m² 3 kg/m² 3 kg/m² 4 kg/m² 1,8 kg/m² dry 2,3 kg/m² wet 3 kg/m² 3 kg/m² Maxi oberst damping / surface weight 30% - 10kg/m² >30 - 4kg/m² 19% - 4kg/m² 19% - 4kg/m² 16% - 6,5kg/m² >30%: 4kg/m² sec ou 5,1kg/m² cru 25% - 6,5kg/m² 25% - 6,5kg/m² VOC / Fogging / Toxproof Low No No No Yes No No Low Sealing capability No ??? Yes Yes Yes No Yes Yes Underbody protection No No No No Yes (ep>1mm) No Yes (ep>2mm) No Print through risk 2/5 1/5 3/5 3/5 2/5 1/5 3/5 3/5 Paint ShopBody ShopAll Shops Damping products may have different chemical basis. Technology comparison 11 PPG REVOCOAT – Modeling of automotive weight and vibration reduction using high performance LASD
  12. 12. Aug-15 Example of real application in an automotive plant. 12 PPG REVOCOAT – Modeling of automotive weight and vibration reduction using high performance LASD VIDEO 
  13. 13. Aug-15 Example of automotive floor optimization 13 PPG REVOCOAT – Modeling of automotive weight and vibration reduction using high performance LASD • This study is made on a -non real- floor pan to avoid confidentiality issues. • AS an example, this presentation will focus on the floor pan only. It is always more efficient to do this study including the floor pan, the firewall, the doors, the roof, … • Frequency range of optimization depends on mesh quality & size. In this example it’s up to 250Hz. • Damping coatings absorb the strain energy of the panels, thus the first modes (flexion/torsion) of the car body are not interesting. We will focus on panel vibrations reduction. • We decided to explain step by step the methodology knowing that in HYPERMESH the NVH Process manager does all the pre-processing automatically. • We don’t use automatic optimization since it doesn’t allow to understand the physics.
  14. 14. Aug-15 0 50 100 150 200 250 300 350 400 450 500 0 100 200 300 400 500 600 700 800 900 Modefrequency(Hz) Mode # Numberof modes / frequency The first stage of a damping optimization (after validation of the mesh quality) is to perform a modal analysis of the car body. - Define the EIGRL card (in this example up to 250 Hz) - Define the LOAD STEP : Normal modes - Define the GLOBAL OUTPUT REQUEST : VELOCITY and ESE (Element Strain Energy) Because of the small number of nodes of this mesh, the standard LANCZOS method doesn’t create any calculation size or speed issue for OPTISTRUCT. If the mesh is huge, the AMSES card (Automatic Multi-Level Sub-Structuring Eigensolver Solution) may be activated and the EIGRL card changed to EIGRA. The results are vey close and calculation size & speed is much smaller. Number of nodes: 181 887 Number of elements: 184 150 Number of rigid elements: 3 350 Number of rigid element constraints: 23 850 Number of degrees of freedom: 1 084 674 Number of non-0 stiffness terms: 27 242 403 Number of ELAS1 elements: 19 902 Number of HEXA elements: 453 Number of QUAD4 elements: 155 744 Number of TRIA3 elements: 8 051 MODAL ANALYSIS 14 PPG REVOCOAT – Modeling of automotive weight and vibration reduction using high performance LASD
  15. 15. Aug-15 1. Boundary conditions In the frequency response calculation (modal response) the excitation points have to be carefully chosen. They have to be as close as possible to real excitation forces but also have to be on parts rigid enough to transfer the excitation to all the body with small resonance effects. 2. Loads and control cards a) A set (1) is defined with the nodes to be monitored A Punch and a H3D files are generated with the speeds of the nodes defined in the set. b) This run (Freq. Resp. Modal) has these cards: i. EIGRL (1): Modal analysis up to 500Hz (has to be at least 2x the higher frequency response). ii. FREQ1 (2): calculation of responses from 5 to 250Hz with steps of 0.5Hz (490 steps) iii. Loading RLOAD2 (5) is made with a Force (4) of 1N on a node (5027) and is « multiplied » by the curve Tabled1 (3). This permits –if needed- to have frequency dependant excitations. c) A Damping value of 1% is given to all the steel material cards. This value comes to 2% for aluminum. It represents the material + the structural damping. OUTPUT,PUNCH,FL OUTPUT,H3D,FL VELOCITY = 1 SET 1 = 19975, … SUBCASE 1 LABEL REPONSE FREQ ANALYSIS MFREQ MPC = 1 METHOD(STRUCTURE) = 1 FREQUENCY = 2 DLOAD = 5 FREQ1 2 5.0 0.5 490 RLOAD2 5 4 3 0 EIGRL 1 500.0 MASS TABLED1 3 LINEAR LINEAR + 0.0 1.0 1000.0 1.0ENDT FORCE 4 5027 01.0 0.0 0.0 1.000 TABLED1FORCE FREQUENCY RESPONSE : Models Pre-processing 15 PPG REVOCOAT – Modeling of automotive weight and vibration reduction using high performance LASD
  16. 16. Aug-15 3. Definition of the control points a) The control points (nodes) are uniformly selected on every panel to be dampened. b) We must have a points density high enough to get an average mobility of each panel. c) In this example we selected 99 points grouped in 10 zones. d) The Post-treatment may be done in Hypergraph to get the average amplitude for each area of the floor pan and in total e) We may also use the ERP (Equivalent Radiated Power) that provide for each selected panel similar results ( is the area associated to each node and the normal speed of the node) and it may be minimized using an automatic optimization.* f) The ERP in very useful when for post-process we use the NVH Process utility to look at the modal participation of each panel or grid. g) The PEAKOUT parameter has not been used in this “small” model but is very useful when model is huge and there are a lot of modes and storage space is limited. FREQUENCY RESPONSE : Models Pre-processing 16 PPG REVOCOAT – Modeling of automotive weight and vibration reduction using high performance LASD
  17. 17. Aug-15 FRT RIGHT FRT LEFT TUNNEL CTR RGHT CTR LEFT MIDDLE SEAT AREA REARMEMBER BOOT SPARE WHEEL Exampleofpostprocessingperpanel FREQUENCY RESPONSE : panel post processing 17 PPG REVOCOAT – Modeling of automotive weight and vibration reduction using high performance LASD 0,0001 0,001 0,01 0,1 1 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Averagemobility(mm/S/N) Frequency (Hz) FLOOR PAN ANALYSIS - AVERAGE PANEL MOBILITY FRTRIGHT CTR RIGHT
  18. 18. Aug-15 0,001 0,01 0,1 1 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Averagemobility(mm/s/N) Frequency (Hz) FLOOR PAN - AVERAGEMOBILITY Globalpost-processing/strainenergylocations FREQUENCY RESPONSE : Global Post processing 18 PPG REVOCOAT – Modeling of automotive weight and vibration reduction using high performance LASD
  19. 19. Aug-15 0,001 0,01 0,1 1 10 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Averagemobility(mm/s/N) Frequency (Hz) FLOOR PAN - AVERAGE MOBILITY FOR EACH AREA AVERAGE FRT RIGHT CTR RIGHT TUNNEL FRT LEFT CTR LEFT MIDDLE SEAT AREA REAR MEMBER BOOT SPARE WHEEL Globalpost-processing/strainenergylocations FREQUENCY RESPONSE : Global Post processing 19 PPG REVOCOAT – Modeling of automotive weight and vibration reduction using high performance LASD
  20. 20. Aug-15 Globalpost-processing/strainenergylocations FREQUENCY RESPONSE : Global Post processing 20 PPG REVOCOAT – Modeling of automotive weight and vibration reduction using high performance LASD
  21. 21. Aug-15 For the models in OPTISTRUCT, the material card for the composite steel/Damper is PCOMP where we will fill the field GE that represents the damping of this component. This has not to be done in the material card. As already mentioned, the materials are frequency dependant so we may also use the MATF1 card and tables (TABLED1) for Young’s modulus and Damping if needed. For this study, we will use as example an acrylic material and only one damper thickness. Here is a HYPERMESH screen copy with the useful parameters: Damper measured Oberst Damper on 0,62mm steel Damper on 0,67 steel Steel thickness mm 1,00 0,62 0, Damper thickness mm 3,12 3,12 3, Steel Young's modulus MPa 208000 208000 2080 Damper Young's modulus MPa 250 250 2 Damper density 0,80 0,80 0, Dampermaterial Damping η 0,91 0,91 0, Damper surface weight kg/m² 2,50 2,50 2, Composite Loss Factor GE 20,70% 74,02% 74,0 FREQUENCY RESPONSE : MATERIAL CARDS 21 PPG REVOCOAT – Modeling of automotive weight and vibration reduction using high performance LASD 32 32,5 33 33,5 34 34,5 35 35,5 36 110 115 120 125 130 135 140 145 150 155 VALIDATION CARTE MATERIAU - OBERST RESPONSE SP400 X= 113 Hz Y=32,24 dB X= 152,8 Hz Y=32,24 dB Model results : Freq: 121,8 Hz Damp : 30,2% Test results : Freq: 126,7 Hz Damp : 30,5% difference : Freq: 4,9 Hz --> 3,9% Damp : 0,3% --> 0,1% X= 131,8 Hz Y=35,24 dB Mode 1 Damping measurement
  22. 22. Aug-15 The definition of the damping product mapping is made with these considerations : Vibration levels / mobilities of each panel and information from strain energy pictures The damper material is always more efficient on thin panels, so we avoid to put on welded panels junctions with double thickness (this is easily achieved with robotic application). Keep an homogeneous treatment and instead of too high thickness it’s sometimes better to increase the treatment surface. Check the result and optimize the mapping till the target (performance & product mass) is not reached. PRODUCT MAPPING 22 PPG REVOCOAT – Modeling of automotive weight and vibration reduction using high performance LASD
  23. 23. Aug-15 The patterns are defined as per former slides and result mapping is: Covered surface = 0.69m² - product mass = 1.722 kg PRODUCT MAPPING 23 PPG REVOCOAT – Modeling of automotive weight and vibration reduction using high performance LASD
  24. 24. Aug-15 0,E+00 1,E-02 2,E-02 3,E-02 4,E-02 5,E-02 6,E-02 7,E-02 FRT RIGHT CTR RIGHT TUNNEL FRT LEFT CTR LEFT MIDDLE SEAT AREA REAR MEMBER BOOT SPARE WHEEL AVERAG E 0,E+00 1,E-02 2,E-02 3,E-02 4,E-02 5,E-02 6,E-02 7,E-02 FRT RIGHT CTR RIGHT TUNNEL FRT LEFT CTR LEFT MIDDLE SEAT AREA REAR MEMBER BOOT SPARE WHEEL AVERAG E RESP_DAMPER 70-250Hz RESP_BARE 70- 250Hz 5dB OPTIMIZED LAYOUT RESULTS 24 PPG REVOCOAT – Modeling of automotive weight and vibration reduction using high performance LASD -50 -45 -40 -35 -30 -25 -20 -15 -10 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Averagemobility(mm/s/N) Frequency (Hz) FLOOR PAN - AVERAGE MOBILITY NAKED FLOOR DAMPENED FLOOR 5dB 0,E+00 1,E-02 2,E-02 3,E-02 4,E-02 5,E-02 6,E-02 7,E-02 FRT RIGHT CTR RIGHT TUNNEL FRT LEFT CTR LEFT MIDDLE SEAT AREAREAR MEMBER BOOT SPAREWHEEL AVERAGE Averageresponse(mm/s/N) Panel average response 70-250Hz RESP_BARE 70-250Hz RESP_DAMPER 70-250Hz
  25. 25. Aug-15 Mastic Pads PVC Acrylic Epoxy Rubber Mass (kg) 3,822 3,727 1,720 2,867 2,962 Reduction (%) 0,0% 2,5% 55,0% 25,0% 22,5% 0,0% 10,0% 20,0% 30,0% 40,0% 50,0% 60,0% 0,000 0,500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 Massreduction(%).BasisisMasticPads Productmass(kg) Product mass for 40% vibration decrease The floor pan vibration level is reduced from 4.4 mm/s/N to 2.7 mm/s/N so a reduction of 40% with 1.72kg of damping product. We conducted same study with other generic products and for the same vibration level got : FUNCTIONAL SUMMARY 25 PPG REVOCOAT – Modeling of automotive weight and vibration reduction using high performance LASD
  26. 26. Aug-15 All the meshes were generated in HyperMesh, the runs were submitted with OPTISTRUCT and for Post processing we used : HyperMesh (POST), HyperView, HyperGraph and Microsoft Excel. This is only a BIW model, same methodology may be used for trimmed car or other models. For a trimmed car, number of DOF is huge so required memory and calculation time are also huge. The use of the AMSES method permits a time reduction up to 90%. For such a mesh, the number of modes comes to be incredibly high so the relevant strain energy maps are hard to select and to visualize and the PEAKOUT option is very useful. Also the NVH utility in Post process help to visualize the panels or grids modal participation. I would recommend in this case to perform the study in two steps, first doing the optimization using a simplified mesh (only the BIW) and second as a validation using the optimized patterns from the first on the trimmed body mesh. As already mentioned, the use of the ERP calculation is useful to get direct results with smaller result files. It also reduces the post processing time (no need to perform in the post process an average of all the nodes) and may be used for optimization purpose. CONCLUSION 26 PPG REVOCOAT – Modeling of automotive weight and vibration reduction using high performance LASD
  27. 27. THANK YOU FOR YOUR ATTENTION QUESTIONS ? Jean-Paul ALLAL Email: allal@ppg.com

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