The effects of local variations in mechanical behaviour – Numerical investigation of a ductile iron component

Abstract

The effects of incorporating local mechanical behaviour into a structural analysis of a cast ductile iron component are investigated. A recently presented simulation strategy, the closed chain of simulations for cast components, is applied to incorporate local behaviour predicted by a casting process simulation into a Finite Element Method (FEM) structural analysis, and the effects of the strategy on predicted component behaviour and simulation time are evaluated. The results are compared to using a homogeneous material description. A material reduction method is investigated, and the effects of material reduction and number of linearization points are evaluated.The results show that local mechanical behaviour may significantly affect the predicted behaviour of the component, and a homogeneous material description fails to express the stress-strain distribution caused by the local variations in mechanical behaviour in the component. The material reduction method is able to accurately describe this effect while only slightly increasing the simulation time. It is proposed that local variations in mechanical behaviour are important to consider in structural analyses of the mechanical behaviour of ductile iron components.

Characterisation and investigation of local variations in mechanical behaviour in cast aluminium using gradient solidification, Digital Image Correlation and finite element simulation

“…one material definition for every element of the FEM mesh. This software has previously been applied to create element individual material definitions for cast components based on casting process simulation results [16,18,37]. In this work, characterisation models relating the coarseness of the microstructure and the local mechanical behaviour were established using the tensile testing results.…”

“…The simulation strategy includes characterisation models developed for cast iron [17] and sand cast aluminium alloys [2,3], whereas models for High Pressure Die Cast (HPDC) aluminium alloys have not been previously established. A numerical investigation of a ductile iron component using the proposed simulation strategy has shown that the predicted behaviour of the component when subjected to load is significantly affected by local variations in mechanical behaviour, which cause a redistribution of stresses and strains that it is impossible for a model in a homogenous material to predict [18]. However, this effect has only been predicted numerically, not confirmed experimentally.…”

Closed Chain Simulations of a Cast Aluminium Component - Incorporating Casting Process Simulation and Local Material Characterization into Stress-strain Simulations

“…This is an important difference from the results reported in in the previous study of a ductile iron component. 21,22) The Young's modulus in cast iron is related to the chemical composition of the alloy and the morphology of the graphite precipitates. 24) In ductile iron variations in solidification conditions cause variations in graphite morphology, thus a variation in Young's modulus is obtained throughout a ductile iron component.…”

“…In previous work the simulation strategy has been applied to a ductile iron component. 21,22) The strategy has however not been previously applied to a cast aluminium component.…”

Influence of specimen size and sheet thickness on the material behavior of AZ31B under uniaxial tension

“…Another chance of reducing the part weight is the maximum utilization of the material's performance by an exact characterization of the material behavior. Therefore, the knowledge of local mechanical properties enables an accurate validation of processand part design to extend the process limits [1]. Especially, the variation of local material behavior of a part can be characterized for the validation of a numerical simulations [2].…”