Cranktrain Design Analysis
Cranktrain and Block Dynamics, Bearings, Crankshaft Durability
GT-SUITE offers a comprehensive toolbox for the design analysis of IC engine cranktrains and crankshafts, including kinematic and rigid or flexible-body dynamic analysis. These are applied to address issues of crankshaft and block vibrations, balance, design and optimization of torsional dampers, block mounting systems and bearings, and crankshaft durability. Details of types of analysis are as follows:
- Cranktrain rigid dynamics: kinematics, forces, torques, working stresses
- Time and frequency domain analysis of torsional vibrations, including non-linear (i.e. viscous or rubber damper) effects
- Unbalanced (shaking) forces and moments on block, balance shafts
- 3-D dynamics of engine block and mounting system
- Crankshaft bending vibrations (quasi-static or dynamic)
- Crankshaft fillet stresses and fatigue analysis
- Journal bearing oil film (hydrodynamic) analysis
In GT-SUITE, models involving the above may also be integrated with models of a Valvetrain, Timing Drive (gear, chain or belt) in order to account for and study interactions, especially for transient applications. A cranktrain model can also be combined with an engine Performance (combustion, gas dynamics, turbocharger) model, e.g. to explore interactions between combustion variability, cylinder-to-cylinder variations and crankshaft torsional dynamics.
Cranktrains are dynamically modeled as collection of rigid and/or flexible bodies (crankshaft, connecting rods, pistons, balance shafts, engine block etc.) typically connected by revolute joints or journal bearings. The crankshaft model can be rigid, torsional or fully (3-D) elastic and can be coupled to journal bearing oil film hydrodynamic HD models in all three cases, with predictions of orbits, bearing loads, min. oil film thicknesses, friction, oil flow and peak oil pressures. Time or frequency-domain torsional models may include all connected systems (torsional damper, driveline, gears, camshafts etc.) and even multiple engines geared together to drive a single (e.g. marine) drivetrain. Frequency-dependent non-linear stiffness and damping information (e.g for rubber dampers) can be consistently used for either frequency or time-domain analysis.
For dynamic or quasi-steady 3-D flexible-body analysis of the crankshaft, GT-SUITE employs 3-D Beam finite elements. To ensure that the beam element model produces a representative response, the stiffness is calibrated based on measurements or from a 3D FEA static analysis of a single crank throw. On the output side, an comprehensive automated “unit load stress recombination” methodology is provided, for post-processing results of the dynamic analysis in GT-SUITE, along with results of unit load case 3D FEA static analysis. This calculation can be applied to predict peak equivalent fully reversing (EFR) stress in key stress concentration regions such as fillets and oil holes, and (through the application of standard fatigue analysis and statistical techniques) estimation of the probability of crankshaft failure.
The basic GT-SUITE cranktrain analysis functionality can be applied to any type of conventional cranktrain configuration (I, V, W etc.). Single and double (or split) throw configurations, 2- or 4-stroke engines, pin, throw and crank offsets are all handled. Object-oriented modeling allows representation of any cylinder-to-cylinder variations in geometry and combustion pressure. The underlying GT-SUITE library (general-purpose Multi-Body Dynamics -MBD) is also available to users at no additional cost and extends the reach of GT-SUITE Cranktrain analysis to non-conventional and alternative cranktrains and power transmission mechanisms.
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| Gamma Technologies, Inc. 601 Oakmont Lane, Suite 220 Westmont, IL 60559 USA |
Tel. Fax. (630) 325-5849 Email: CAE@gtisoft.com Web: www.gtisoft.com |
APPLICATIONS
Engine Performance
Test Pressure Analysis
Exhaust Aftertreatment
Acoustics
SiL, HiL, real-time
Vehicle, driveline
Hybrid Vehicles
Cooling Systems
AC and Rankine
Lubrication and bearings
Fuel Injection
Valvetrain, camshaft
Cranktrain, crankshaft
Chain, gear, belt drive