Exhaust manifold is one of the key components of engine exhaust system. Exhaust manifold simulations are time consuming as they require modelling of complex thermal loading and multiple non-linearities like friction and plasticity. This proves to be a big constraint for using Multidisciplinary design optimization (MDO) for exhaust manifolds as it involves running large number of models specified by a Design of Experiments (DOE). Also, during the initial phase of design development it seems reasonable to compromise accuracy of simulations at the cost of speed if we get correct feedback on design direction. Hence, main objective of the current work was to develop simplified analysis process for Thermomechanical Fatigue (TMF) and Modal analysis. This approach was then used for optimization of exhaust manifold at concept stage using MDO process. This did provide better direction for exhaust manifold design during concept stage.&nbsp; 
At concept stage, due to lack of availability of accurate thermal Boundary Conditions (BCs) and with a goal to simplify modeling, use of historical engines thermal boundary conditions was made instead of accurate thermal BCs from test cell. Similarly, other aspects such as ‘level of component assembly required’, ‘mechanical loading’ and ‘outputs to be monitored for making design decision’ were also investigated to come up with simplified approach. &nbsp;Proposed approach was quick compared to conventional one. This approach was implemented on few Heavy Duty &amp; Mid-Range engine programs to check repeatability. It was observed that proposed analysis approach provides correct design direction with significantly reduced computational time up to 80%. Incorporating simplified approach for the MDO process has made it more practical and feasible for implementation during concept design cycle in early stage of engine development program. 
&nbsp;Keywords: Exhaust manifold, Multidisciplinary design optimization (MDO), Thermomechanical fatigue (TMF).

Development of Simplified Analysis Process for Multidisciplinary Design Optimization (MDO) of Exhaust Manifold During Concept Stage

Paper Proceedings: https://asmedigitalcollection.asme.org/ICEF/ICEF2021/volume/85512

ASME 2021 Internal Combustion Engine Division Fall Technical Conference (ICEF2021)

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