Large engine vibration analysis using a modular modelling approach

Transcription

1 Large engine vibration analysis using a modular modelling approach Dr.-Ing. Jochen Neher Mechanics, Engine Structure 16th, October, 2018 Dr. Alexander Rieß Mechanics, Power Train Marko Basic AVL-AST d.o.o. Croatia

2 Large engine vs. car engine J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

3 Agenda short 1 Motivation 2 Established vibration analysis disciplines 3 Virtual Engine approach 4 Modular modelling 5 Reorganised interaction 6 Next steps J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

4 1 Motivation J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

5 Structural Requirements Operational Safety Comfort Aspects Vibration analysis is essential for both requirements J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

6 2 Established vibration analysis disciplines J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

7 p [bar] Torsional Vibration Calculation (1D) 1D Torsional Vibration Calculation(TVC): Transient and Steady state Conceptual design crankshaft, crank star, firing order sequence Vibration damper and flywheel selection to minimize torsional stress Vibration analysis of ship propulsion according to classification societies 200 p e cyl, p max cyl, ε, gas pressure curve [ ] Transient Load Cases: stochastic misfiring, power fluctuations, grid events J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

8 Cranktrain Simulation J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

9 Crankcase Vibration Simulation Scope Conceptual design for crankcase, oilpan, foundation frame, charging unit Basis for strength analysis of main and attached components Efficient for complete engine series Shell model approach Shell free cut at cranktrain z y x J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

10 Engine Mounting Simulation Engine-plant integration Comfort requirement Special load cases (earthquake, shock) Standard: Rigid body approach Single stage mounting 2 stage mounting F z M z M y F y M x F x J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

11 Airborne Noise Simulation Comfort requirement Component optimization Automated FEM Workflow f K J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

12 Vibration Assessment Mounting Design Design Modification Decision v = v * f FEM v = Y * F F = c * x Structure Borne Noise SBN Engine Comfort requirement Mounting Stiffness Excitation Force F Forced excitation (low frequency approach) Combination of analytics, simulation, measurements Model Unitary Excitation Admittance Y SBN Frame Mounting Stiffness Foundation Stiffness SBN Foundation Compliance Limit F 0 v 0 m 2 F1 c 2 v 2 m 1 c 1 2DOF Check Modifications Z F F3 v 3 J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

13 Limitations Established vibration analysis disciplines focus on specific problems Interaction of engine components simplified strongly (e.g. crankshaft-crankcase) efficient, flexible Combination of vibration analysis disciplines relevant e.g. for 2-stage-mounted engines Structure Borne Noise New engine technologies different engine behavior (e.g. 7 th eo 12V) Different expert tools - obstacle for knowledge exchange between engineers J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

14 3 Virtual Engine approach J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

15 Virtual Engine (AVL Excite) J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

16 Project with AVL Croatia 2018 Implementation Pilot, MAN Rollout, MAN Workflow 2015 Pilot, AVL Workflow Inspiration J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

17 Virtual Engine - workflow Structural matrices Nodes: >6,000,000 Elms: >5,000,000 J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

18 Virtual Engine example: Axial bearing - setup EXCITE model - Update MAN disciplines HD (squeeze effect only) Initial EXCITE model Standard spring/damper J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

19 Virtual Engine example: Axial bearing - results Initial Update Updated AVL significantly improved correlation of simulation and measurement J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

20 Virtual Engine example: Axial bearing - results Initial Velocity RMS Horizontal Complete speed range Velocity RMS Horizontal Update Nominal speed Magnitude Velocity - Horizontal Improved vibration behavior of crankcase due to updated axial thrust bearing J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

21 Virtual Engine example: Axial bearing - Bearing behavior with significant impact on crankcase vibration - Cranktrain EHD (established MAN discipline) showed detailed bearing behavior - Implementation in Excite, simplified - Good result Benefit: - Identified design sensitivity - In cranktrain MBS and crankcase FEM (MAN disciplines), this effect is not visible - Virtual engine + experience => benefit J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

22 Virtual Engine example: Unbalance mass - setup Crankshaft modified by adding mass on flywheel bolt node: EXCITE with unbalance: m=50kg (0.17% of total mass) RBE2 element with added CONM2 mass J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

23 Virtual Engine example: Unbalance mass - results 1st Engine Order 1st Engine Order 1st Engine Order 1.5th Engine Order Significant influence on engine motion. Lower influence on crankshaft motion. J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

24 Virtual Engine example: Unbalance mass - results Operation deflection shape Strain directly from EXCITE EXCITE w/o unbalance EXCITE with unbalance Nominal speed 1st engine order Significant influence on motion Low influence on strain J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

25 Virtual Engine example: Unbalance mass - TVC: Not relevant. No bending. Inertia not effected significantly - Crankcase FEM: Mounting not considered in detail, difference just at 1 frequency - Mounting calculation: Only rigid body modes considered (mostly(!), this is sufficient) - Measurement: Balancing is expensive, difficult to distinguish between elastic and rigid modes! - Virtual Engine shows influence in detail, also at higher frequencies - ODS enables overall engine behaviour evaluation; frequency (order) analysis being particularly beneficial J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

26 Experience at MAN Launch phase still ongoing at MAN, close collaboration with AVL Software improvements implemented by AVL (functions, interfaces) Virtual engine is a platform for different vibration disciplines improved exchange supports a better understanding of the engine behavior virtual engine benefits from established disciplines (efficient modelling, experience, validation) established disciplines benefits from virtual engine (interaction) will not replace established disciplines in the near future at MAN validation with measurements not always satisfying, overall engine simulation remains a challenge sometimes replaces testing Currently, time to model is too long action required modular modelling J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

27 4 Modular modelling J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

28 Crankcase intersection modelling for 6-10L Base +1cyl J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

29 Crankcase intersection modelling for 6-10L Engine Assembly Engine Section CS Engine Section Mid Engine Section CCS Power Unit without liner ANSYS ACT assembly conversion to mass point right inertia properties, position in cog of assembly, only attaching location need J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

30 Alignment of models for different disciplines Crankcase Ansys macro 30V skeleton 10L crankcase vibration model 10L skeleton J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

31 Crankshaft intersection modelling for 6-10L 3D crankshaft Generator e.g. 10L crankshaft Parametrized CAD J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

32 Alignment of models for different disciplines Crankshaft with identical meshes for different MBS solver Cranktrain simulation Nodes Elements Virtual Engine J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

33 Parameterized AVL Excite model (by AVL) AVL Excite, engine template Definition of approx. 300 parameters Values defined via case table Excel with Makros case table input Parameters Gas pressure curve Calculation of bearing stiffness parameters Automated checks Case Set Name "Case Set 1" Joint Type of MB Config of Engine Home Input data Cylinder pressure Stiffness Threshold NONL Excite parameter specification Run Checker Reset Cell Color Export casetable Param. Name for Excite Unit Crank Train Globals General Data Engine Speed Engine_Speed rpm Engine Speed Initial Engine_Speed_Init rpm Number of Cylnders Num_Cyl "" Bore Bore mm Stroke Stroke mm 8 1 Technical Help Protect This Sheet Unprotect This Sheet Maintenance J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

34 5 Reorganised interaction J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

35 Coupling Alternator Engine Frame Ship Foundation CAD J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

36 6 Next steps J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

37 Next steps Proceed with AVL Excite launch, collaboration with AVL Workflow validation for component (crankcase) optimization in FEM (frequency domain) FEM excitation analytical vs. FEM excitation with AVL Excite results Structure Borne Noise interaction engine ship underwater noise evaluation of necessary modelling depth for ship excitation J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

38 Disclaimer All data provided in this document is non-binding. This data serves informational purposes only and is especially not guaranteed in any way. Depending on the subsequent specific individual projects, the relevant data may be subject to changes and will be assessed and determined individually for each project. This will depend on the particular characteristics of each individual project, especially specific site and operational conditions. J. Neher, A. Rieß, M. Basic Large Engine Vibration Analysis

39 Thank you very much! Dr.-Ing. Jochen Neher Head of Mechanics, Engine Structure th, October, 2018