Virtual Aluminum Castings: An Industrial Application of ICME

JOM, Nov 2006 by Allison, John, Li, Mei, Wolverton, C, Su, XuMing

The automotive product design and manufacturing community is continually besieged by Herculean engineering, timing, and cost challenges. Nowhere is this more evident than in the development of designs and manufacturing processes for cast aluminum engine blocks and cylinder heads. Increasing engine performance requirements coupled with stringent weight and packaging constraints are pushing aluminum alloys to the limits of their capabilities. To provide high-quality blocks and heads at the lowest possible cost, manufacturing process engineers are required to find increasingly innovative ways to cast and heat treat components. Additionally, to remain competitive, products and manufacturing methods must be developed and implemented in record time. To bridge the gaps between program needs and engineering reality, the use of robust computational models in up-front analysis will take on an increasingly important role. This article describes just such a computational approach, the Virtual Aluminum Castings methodology, which was developed and implemented at Ford Motor Company and demonstrates the feasibility and benefits of integrated computational materials engineering.

(ProQuest Information and Learning: ... denotes formulae omitted.)

INTRODUCTION

Virtual Aluminum Castings (VAC) is a revolutionary computer-aided engineering (CAE) process that tightly couples manufacturing and design analysis into a holistic system to enable up-front analysis. It demonstrates the capability and benefits of the integrated computational materials engineering (ICME) paradigm discussed in this special edition of JOM. Virtual Aluminum Castings is a suite of integrated computational tools that enables the rapid development of durable, cost-effective cast aluminum puwertrain components. It is based on advanced material models that bridge the many key dimensional scales from the atomistic level to the component level. Using VAC, virtual components are now designed, cast, heat treated, and tested for durability on a workstation long before components are fabricated. The development of VAC is the culmination of years of comprehensive research on cast aluminum. It has been accomplished by a combination of theoretical, experimental, and computational technologies and has involved the development of it deep. fundamental understanding of dozens of separate phenomena. This theorelical and empirical knowledge has been captured in a computationally eflicient software package within VAC.

Virtual Aluminum Castings is the rare technological innovation that can be used to simultaneously reduce cost. improve quality, save time, and reduce weight. It is not asset intensive and uses existing CAE infrastructure so it costs relatively little to implement. Virtual Aluminum Castings has been successfully implemented within the Ford powertrain design, manufacturing, and CAH communities. significantly reducing product development lime and saving Ford millions of dollars.

VIRTUAL ALUMINUM CASTINGS: USING THE ICME METHODOLOGY

The central objective of VAC is to significantly reduce the time reijuired to develop and optimize new cast aluminum components and casting/heat-treatment processes. This objective is accomplished bv developing and validating a computational capability with four interdependent parts (Figure 1): the accurate simulation of the thermal history of an aluminum component through casting and heat treatment, the prediction of the microstructure that evolves during these manufacturing processes at all locations in a casting (i.e., the local microstructure). the prediction of critical local mechanical properties which result from these local microstructures, and coupling predicted local properties and new damage and residual stress models with unite element analysis (FEA) methods to predict the durability of engine components. Commercial casting simulation software, specifically MagmaSoft(TM) and ProCast(TM) and FEA software, specifically AHAQUS(TM), provide the basic framework for development of these computational capabilities. This methodologv provides Ford with the capability to quickly engineer low-cost, durable aluminum castings.

The development of VAC required activities in several key areas, specifically:

* Use of advanced materials models to integrate analytical tools for simulating the casting and heattreatment processes with analvsis of component durability

* Linkage of fundamental models for microstructural evolution with fundamental models for propertv prediction

* Integration of fundamental knowledge of phenomena occurring at a wide variety of length scales into complete and coherent models

* Validation of the integrated models

* Incorporation of these software tools into a simultaneous manufacturing and product engineering process, stressing computational efficiency and having the right information available at the right time

Not coincidentally, these areas also comprise the key areas of the ICME methodology described elsewhere.1 Figure 2 shows the key processing, microstructure, and property knowledge nodes required for cast aluminum alloys. In developing the VAC tools, the focus was as much on linking the models that describe these individual knowledge nodes as it was on the development of the individual models themselves. The interactions between these knowledge areas and. in particular, the needlooptimize multiple properties as well as cost constraints demonstrate the complexity of this problem and thus the need to conduct this optimization in an integrated modeling environment.