Product design reliability with consideration of material property changes during service

Abstract

A method of computationally determining material property changes for a cast aluminum alloy component. Accuracy of the determination is achieved by taking into consideration material property changes over the projected service life of the component. In one form, the method includes accepting time-dependent temperature data and using that data in conjunction with one or more constitutive relationships to quantify the impact of various temperature regimes or conditions on the properties of heat-treatable components and alloys. Finite element nodal analyses may be used as part of the method to map the calculated material properties on a nodal basis, while a viscoplastic model may be used to determine precipitation hardening and softening effects as a way to simulate the time and temperature dependencies of the material. The combined approach may be used to determine the material properties over the expected service life of a cast component made from such material.

Description

technical field [0001] The present invention relates generally to changes in material properties during the service life of a cast part, and in particular to improved product design reliability and durability analysis accuracy by accounting for changes in material properties over the expected service life of a cast part. Background technique [0002] The most common Al-Si-based alloys used to make cast automotive engine blocks and cylinder heads are heat-treatable variants, including Alloy 319 (nominal composition by weight: 6.5% Si, 0.5% Fe, 0.3 % Mn, 3.5% Cu, 0.4% Mg, 1.0% Zn, 0.15% Ti and the balance Al) and alloy 356 (nominal composition by weight: 7.0% Si, 0.1% Fe, 0.01% Mn, 0.05% Cu, 0.3% Mg, 0.05% Zn, 0.15% Ti and the balance Al). Aluminum alloys like 319 and 356 are usually heat treated to a T6 or T7 temper prior to use by subjecting them to three main stages: (1) solution treatment at a relatively high temperature below the melting point of the alloy, often for Mo...

AI Technical Summary

Problems solved by technology

Current methods of durability analysis and life prediction (such as fatigue analysis or related life prediction) for cast components often resort to making simplifying assumptions—such as constant material properties—that cannot actually represent these changes that occur over time. Material properties change; analyzes based on such assumptions suffer from inaccuracies as parts age

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