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Technical Paper

Innovative Automatic Meshing Method for ComplexMesh Patterns for Integrated CAD / CAE Analysis

With strict government requirements for automobile fuel economy and global climate warming concerns, powertrain design becomes ever more challenging and complicated. New technologies come out daily, and each component, small or large, is scrutinized for weight, cost, performance, etc. To meet these ever demanding requirements, Computer Aided Engineering (CAE) becomes very critical in the product development process. It not only saves tremendous developing time and cost, but also helps discover new and innovative ideas very quickly. Digital product development process is an industrial norm nowadays. Parts are modeled in 3D in a Computer Aided Design (CAD) system, and then they are passed to and modeled in a Finite Elements Analysis (FEA) software package for analysis. If the analysis results do not meet the requirements, engineers either modify the FEA models or 3D CAD geometry for re-analysis.
Technical Paper

Cylinder Head Design Process to Improve High Cycle Fatigue Performance

Cylinder head design is a highly challenging task for modern engines, especially for the proliferation of boosted, gasoline direct injection engines (branded EcoBoost® engines by Ford Motor Company). The high power density of these engines results in higher cylinder firing pressures and higher operating temperatures throughout the engine. In addition to the high operating stresses, cylinder heads are normally heat treated to optimize their mechanical properties; residual stresses are generated during heat treatment, which can be detrimental for high-cycle fatigue performance. In this paper, a complete cylinder head high cycle fatigue CAE analysis procedure is demonstrated. First, the heat treatment process is simulated. The transient temperature histories during the quenching process are used to calculate the distribution of the residual stresses, followed by machining simulation, which results in a redistribution of stress.
Technical Paper

Field Risk Assessment Based on Cylinder Head Design Process to Improve High Cycle Fatigue Performance

In a separate SAE paper (Cylinder Head Design Process to Improve High Cycle Fatigue Performance), cylinder head high cycle fatigue (HCF) analysis approach and damage calculation method were developed and presented. In this paper, the HCF damage calculation method is used for risk assessment related to customer drive cycles. Cylinder head HCF damage is generated by repeated stress alternation under different engine operation conditions. The cylinder head high cycle fatigue CAE process can be used as a transfer function to translate engine operating conditions to cylinder head damage/life. There are many inputs, noises, and design parameters that contribute to the cylinder head HCF damage CAE transfer function such as cylinder pressure, component temperature, valve seat press fit, and cylinder head manufacturing method. Material properties and the variation in material properties are also important considerations in the CAE transfer function.
Technical Paper

A Finite Element Method for Camshaft Cap Durability Analysis

In this study, a finite element analysis method is developed for simulating a camshaft cap punching bench test. Stiffness results of simulated camshaft cap component are correlated with test data and used to validate the model accuracy in terms of material and boundary conditions. Next, the method is used for verification of cap design and durability performance improvement. In order to improve the computational efficiency of the finite element analysis, the punch is replaced by equivalent trigonometric distributed loads. The sensitivity of the finite element predicted strains for different trigonometric pressure distribution functions is also investigated and compared to strain gage measured values. A number of equivalent stress criteria are also used for fatigue safety factor calculations.
Journal Article

Effect of Valvetrain Components Misalignment on Valve and Guide Interactions in Automotive Engines

Strict requirements for fuel economy and emissions are the main drivers for recent automotive engine downsizing and an increase of boosting technologies. For high power density engines, among other design challenges, valve and guide interactions are very important. Undesirable contact interactions may lead to poor fuel economy, engine noise, valve stem to valve guide seizure, and in a severe case, engine failure. In this paper, the valve stem and valve guide contact behavior is investigated using computational models for the camshaft drive in push and pull directions under several misalignment conditions for an engine with roller finger follower (RFF) valvetrain and overhead cam configuration. An engine assembly analysis with the appropriate assembly and thermal boundary conditions are first carried out using the finite element solver ABAQUS.