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A Mechanism-Based Thermomechanical Fatigue Life Assessment Method for High Temperature Engine Components with Gradient Effect Approximation

  • High temperature components in internal combustion engines and exhaust systems must withstand severe mechanical and thermal cyclic loads throughout their lifetime. The combination of thermal transients and mechanical load cycling results in a complex evolution of damage, leading to thermomechanical fatigue (TMF) of the material. Analytical tools are increasingly employed by designers and engineersHigh temperature components in internal combustion engines and exhaust systems must withstand severe mechanical and thermal cyclic loads throughout their lifetime. The combination of thermal transients and mechanical load cycling results in a complex evolution of damage, leading to thermomechanical fatigue (TMF) of the material. Analytical tools are increasingly employed by designers and engineers for component durability assessment well before any hardware testing. The DTMF model for TMF life prediction, which assumes that micro-crack growth is the dominant damage mechanism, is capable of providing reliable predictions for a wide range of high-temperature components and materials in internal combustion engines. Thus far, the DTMF model has employed a local approach where surface stresses, strains, and temperatures are used to compute damage for estimating the number of cycles for a small initial defect or micro-crack to reach a critical length. In the presence of significant gradients of stresses, strains, and temperatures, the use of surface field values could lead to very conservative estimates of TMF life when compared with reported lives from hardware testing. As an approximation of gradient effects, a non-local approach of the DTMF model is applied. This approach considers through-thickness fields where the micro-crack growth law is integrated through the thickness considering these variable fields. With the help of software tools, this method is automated and applied to components with complex geometries and fields. It is shown, for the TMF life prediction of a turbocharger housing, that the gradient correction using the non-local approach leads to more realistic life predictions and can distinguish between surface cracks that may arrest or propagate through the thickness and lead to component failure.show moreshow less

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Author:Radwan Hazime, Thomas SeifertORCiDGND, Cherng-Chi Chang, Abdallah Kassir, Asok Sethy
Year of Publication:2019
Page Number:9
Language:English
GND Keyword:Materialermüdung; Plastizität
Tag:thermomechanische Ermüdung
DDC classes:600 Technik, Medizin, angewandte Wissenschaften
Parent Title (English):SAE Technical Papers
Issue:2019-01-0536
First Page:1
Last Page:9
Document Type:Article (reviewed)
Institutes:Bibliografie
Open Access:Zugriffsbeschränkt
Release Date:2019/12/07
Licence (German):License LogoEs gilt das UrhG
URL:https://www.sae.org/publications/technical-papers/content/2019-01-0536/
DOI:https://doi.org/10.4271/2019-01-0536