Ductile iron optimization approach for mechanically and thermally loaded components

Jarkko Laine,J Vaara,A Leppänen,T Frondelius,J Orkas,K Jalava

doi:10.1007/s40962-020-00529-9

Jarkko Laine, J Vaara + Show 4 more

Open Access

https://doi.org/10.1007/s40962-020-00529-9

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Abstract

The mechanical and thermal properties of ferritic–pearlitic ductile irons vary widely according to their silicon and pearlite contents. Thus, different combinations of silicon and pearlite affect components’ lifetime under mechanical and thermal stress. An excellent example of the usage of such irons is combustion engine cylinder heads. They experience transient thermal loading (heating and cooling) during starting and stopping in addition to mechanical loading (combustion) during engine operation. An optimization approach and calculation models for the estimation of the optimal ductile iron composition are presented in this study. The approach allows selection of the most suitable base composition for subsequent analyses, such as casting simulation and final accurate finite element modelling and fatigue calculations.

Highlights

Factors such as reliability and durability are the primary targets for the structural analysis of components
This study aims to develop a methodology that can be used for selection of an optimized ductile iron composition for a thermally and mechanically loaded component
The results of this study indicate that thermal conductivity plays a significant role in thermo-mechanically loaded component lifetimes

Summary

Introduction

Factors such as reliability and durability are the primary targets for the structural analysis of components. Current design processes take account of integral boundary conditions, such as component geometry, and optimize them in order to achieve the set objectives.[1,2,3]. Large combustion engines contain many components that operate under combined thermal and mechanical loads. Cylinder heads are one of the most loaded of these, experiencing static, thermal and dynamic loads during operation. Maximum combustion pressures of modern large engines are well over 200 bar (20 MPa). Such pre-tension is used, for example, to ensure cylinder head sealing tightness during combustion.[4]

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