Construction equipment off highway vehicles are heavy industry vehicles that run on diesel engines. To meet the emission norms, these engines have the Exhaust After Treatment System (EATS) which includes two primary subassemblies, i.e., a Diesel Oxidation Catalyst (DOC) subassembly to reduce the HC and CO emissions and a Selective catalytic Reduction (SCR) subassembly to reduce NOx emissions. Because of the excessive vibrations in the engine and continuous heavy-duty usage of the Construction equipment, any failures in the EATS system leading to escape of exhaust gas is a statuary non-compliance. Hence, understanding the effect of engine vibrations and proposing a cost-effective solution is paramount in designing the EATS system including the SCR assembly.
A field-testing failure of an SCR assembly has been taken in consideration for this study. Several use-cases were simulated for the baseline design using real world acceleration data and Frequency Response Function (FRF) Analysis was performed to capture the failure mode in virtual simulation. To build confidence in the design and CAE analysis, physical testing was performed, and frequency correlation was achieved along with capturing the failure mode in lab setup. Additionally, assembly strains were observed during lab testing and solution was provided for the same to increase the design robustness. Based on the results of the CAE analysis, design modification was performed to meet the CAE Acceptance criteria. The modified design was analyzed in CAE and Physical Testing and based on the confidence; it was implemented in physical vehicle.
Learnings from the virtual and physical testing have been captured, implemented in other similar designs and DVP enhancement has been done for future design validation.