Acoustic optimization of an engine oil pan concerning the equivalent radiated sound power function


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Acoustic optimization of an engine oil pan concerning the equivalent radiated sound power function

  1. 1. Author: Eduardo Porto1EATC 2013 Turin, Italy 24.04.2013“Acoustic optimization of an engine oil pan concerning theequivalent radiated sound power function”Author: Eduardo PortoPhone: +49 5362 17 226Email: eduardo.porto@semcon.comCompany: Semcon Wolfsburg GmbHWolfsburg, Germany
  2. 2. Author: Eduardo Porto• Founded in 1968 in Germany• Operations on 45 locations and 3 000 employees• Turnover € 295 M (2012)• A global partner in engineering services and product information• Competencies in several industries2Semcon Group in shortAutomotive Manufacturing industries Energy Telecom Life Science
  3. 3. Author: Eduardo Porto3EATC 2013 Turin, Italy 24.04.2013Introduction So far, the optimization calculations have been mostly applied to problems involvingcompliance, frequency and/or stress responses; Now with HyperWorks 12 a new class of optimization problems can be solved,concerning the task of minimizing the sound radiated power. A new type of response, the so called ERP (abbreviation for Equivalent RadiatedPower), is now officially available in OptiStruct 12 as objective function.
  4. 4. Author: Eduardo Porto4EATC 2013 Turin, Italy 24.04.2013Problem Definition• Aim: To reduce the structure-borne sound radiation related to the oil pan bottom part.Figure 2. Engine model exploded view.Engine head coverEngine headCylinder blockGear unit housingEngine front coverMain bearing capOil pan top partOil pan bottom part(t = 3 mm)Figure 1. Simplified engine model.• Oil pan bottom part modeled withCTRIA3/CQUAD4 elements; theother parts with PENTA6/HEXA10.• Oil pan bottom part material is steel;the other parts are of aluminum.• Average element size: 6 mm• Total number of nodes: 75 749• Total number of elements: 53 840• Part connections modeled with RBE2elements.
  5. 5. Author: Eduardo Porto5EATC 2013 Turin, Italy 24.04.2013Problem DefinitionPlot 1. Excitation force in the frequency domain.f (Hz)Fz (kN)30004001 Harmonic Excitation Load:• Engine model is not constrained.• The Fz forces are simultaneously applied.• Overall structural damping: 4%FzFzFzSection A-AAAFigure 3. Excitation loads of amplitude Fz.• 1st. eigenfrequency of the model: 653 Hz
  6. 6. Author: Eduardo PortoFigure 6. Air model in the vicinity of the oil pan: 350 x 330 x 150 mm.6EATC 2013 Turin, Italy 24.04.2013Analyses and Optimization Methods ERP Analysis [1]: Optimization Techniques [1]:𝐸𝑅𝑃 = 𝐸𝑅𝑃𝐿𝐹 ∗12𝐸𝑅𝑃𝐶 ∗ 𝐸𝑅𝑃𝑅𝐻𝑂 ∗ 𝐴𝑖 ∗ 𝑣𝑖2𝑛𝑔𝑟𝑖𝑑𝑖where:ERPLF = radiation loss factor; ERPC = speed of sound;ERPRHO = fluid density; A = radiating surface area;v = sound particle velocity; ngrid = number of nodes; i = node ID. Exterior Acoustic Analysis [2]:Radiating surfaceFigure 4. Radiating surface.Design spaceNon-Design spaceFigure 5. Design and non-design space.o Bead (Topography)o Free-Sizeo TopologyNo air modeling required!• For validation of the ERP• For analyses and re-analyses
  7. 7. Author: Eduardo Porto7EATC 2013 Turin, Italy 24.04.2013Structural OptimizationSubjected to:h = 3 mmw = 10 mm = 60°whDesignelementsFigure 7. Bead parameters.w = bead min. widthh = bead height = draw angleBead Optimization Free-Size Optimization Topology OptimizationMinMax ERP MinMax ERP MinMax ERPSubjected to:No volume restriction!TShell cross-sectionT0Figure 8. Free-size element parametersT = max. shell thicknessT 0 = min. shell thicknessT = 3 mmT0 = 6 mmSubjected to:No volume restriction!TShell cross-sectionT0CoreDesignable regionsFigure 9. Topology element parametersT = max. shell thicknessT 0 = min. shell thicknessT = 3 mmT0 = 6 mm
  8. 8. Author: Eduardo Porto8EATC 2013 Turin, Italy 24.04.2013Plot 2. Oil pan bottom part radiated sound power.1st. Eigenmode at 653 HzAcoustic pressure in the airAir density = 1.204E-12 ton/mm3Sound speed = 3.43E5 mm/sResult Discussions
  9. 9. Author: Eduardo Porto9EATC 2013 Turin, Italy 24.04.2013Plot 3. Acoustic radiated power versus ERP.Result DiscussionsAcoustic Radiated Power(Exterior acoustic analysis)Fluid-structure interactionconsideredEquivalent Radiated Power(Frequency response analysis)Radiation loss factor = 1.0
  10. 10. Author: Eduardo PortoFigure 10. Bead optimization results.10EATC 2013 Turin, Italy 24.04.2013Result DiscussionsOptimal solutionInterpretation of theoptimal solutionBead Optimization∆ = -25%
  11. 11. Author: Eduardo PortoFigure 11. Free-Size optimization results.11EATC 2013 Turin, Italy 24.04.2013Result DiscussionsOptimal solutionInterpretation of theoptimal solutionFree-Size Optimization∆ = -18%
  12. 12. Author: Eduardo PortoFigure 12. Topology optimization results.12EATC 2013 Turin, Italy 24.04.2013Result DiscussionsOptimal solutionInterpretation of theoptimal solutionTopology Optimization∆ = -21%
  13. 13. Author: Eduardo PortoFigure 13. Conventional approach result.13EATC 2013 Turin, Italy 24.04.2013Result DiscussionsConventional bead patternConventional Approach∆ = -3%
  14. 14. Author: Eduardo Porto14EATC 2013 Turin, Italy 24.04.2013Result DiscussionsBead Optimization Free-Size Optimization Topology OptimizationBaseline ConventionalMax. Value:169.7 PaMin. Value:21.2 PaMax. Value:157.1 PaMin. Value:19.6 PaMax. Value:168.5 PaMin. Value:21.1 PaMax. Value:164.7 PaMin. Value:20.6 PaMax. Value:176.7 PaMin. Value:22.1 PaFigure 14. Acoustic pressure results at the critical excitation frequency.
  15. 15. Author: Eduardo Porto15EATC 2013 Turin, Italy 24.04.2013Result SummaryModel Bead PatternPre-processingConvergenceCurveIterationNumberCPU-Time *Post-processingAcousticRadiatedPowerMax.AcousticPressureBaseline - - - - -BeadFree-SizeTopologyConventional - - - - -* JOB-Machine: 8 CPU Intel(R) Xeon(R) @3.30GHz, 32162 MB RAM.Table 1. Result summary.NodifficultiesNodifficultiesNodifficultiesMonotonicMonotonicNon-monotonic12916New FE-meshrequiredNew FE-meshrequiredNew FE-meshrequired00:16:1300:34:3700:41:46122.1 mW@810Hz(-25%)133.1 mW@810Hz(-18%)128.6 mW@783Hz(-21%)157.8 mW@796Hz(-3%)162.0 mW@653Hz157.1 mW@810Hz168.5 mW@810Hz164.7 mW@783Hz176.7 mW@796Hz169.7 mW@653Hz
  16. 16. Author: Eduardo Porto16EATC 2013 Turin, Italy 24.04.2013Methodology OverviewRe-analyses(exterior acoustic analyses)FE-ModellOptimal resultsinterpretationStructural Optimization(Goal: MinMax ERP-Function)ERP-Analysis(no FSI)Bead OptimizationFree-Size OptimizationTopology OptimierungKonventionelles ModellBasisExterior acousticanalysis(with FSI)
  17. 17. Author: Eduardo Porto17EATC 2013 Turin, Italy 24.04.2013Conclusions & Significance of the Work The acoustic optimization task is successfully performed without requiring the fluid-structure interaction modeling. The structural optimizers show exactly where the beads have to be implemented onthe radiating component in order to reduce the acoustic radiated power efficiently. The three optimal proposals are clearly more efficient than the conventional design(acoustic sound power reduction: 18-25% vs. 3%). Three different optimization techniques can be applied to the optimal bead patterngeneration on a radiating surface in the detailed project phase. The methodology here demonstrated can also be applied to problems concerningradiating casting parts (thin shells on the radiating surface). The presented methodology has been already applied successfully to real powertrainproblems.
  18. 18. Author: Eduardo Porto18EATC 2013 Turin, Italy 24.04.2013Acknowledgments To Altair`s support team in Germany, especially to Mr. Jürgen Kranzeder (Altair’stechnical manager in Böblingen), for the excellent technical support on theoptimization topics as well as for the very good client relationship.
  19. 19. Author: Eduardo Porto19EATC 2013 Turin, Italy 24.04.2013Q&AThank you!