Crankshaft Durability of Rover K-Series Engine: Comparison of ENGDYN Analysis with Dynamic Measurements


Filed Under (BMW) by admin on 17-11-2010

The Rover K-Series engine has now been in production for over 10 years, initially of 1.4 L capacity. Since then 1.1L, 1.6L, 1.8L and 1.8L VVC (Variable Valve Control) have been introduced with an accumulative build of two million engines since 1989. The 1.8L engine is also built under official licence for Lotus and Caterham, and also in the MGF motorsport series. The K-Series is an attractive buy due to its reduced cost and low weight, which is a necessity for sport cars. This report aims to validate Ricardo ENGDYN software with respect to Rover K-Series 1.8 Litre VVC crankshaft durability. The software will be used to output the behaviour of the crankshaft under as realistic conditions as possible. The oil film thickness and bearing load characteristics of the crankshaft through the running range of the engine will be compared to results obtained from in-house software. The torsional and bending vibration output from ENGDYN will then be compared with results obtained from dynamic measurements. Finally, the crank stress and durability results from ENGDYN will be compared to strain gauge measurements at comparative points on the crankshaft. ENGDYN is a computer program used for analysing the dynamics of the engine, and in particular the crankshaft and its interaction with the cylinder block. In this analysis the software will be used to predict the time-domain response of the 3-dimensional vibration of the crankshaft coupled to the block by way of a non-linear oil film. When this loading and motion has been calculated the software can perform a fast Fourier transform to break down the time-domain response into its corresponding frequencies. This allows the results to be post-processed in the frequency domain. 2 Method of Analysis 2.1 Engine Specifications Configuration: in-line 4 Fuel: Gasoline Cylinder bore: 80 mm Piston stroke: 89.3 mm Swept volume: 1.8L Crankpin Peak Power: 107 KW @ 7000 rpm Peak Torque: 174 N/m @ 4500 rpm Engine running range: 750-7200 rpm 2.2 Component Modelling 2.2.1 Crankshaft To perform the analysis within ENGDYN two crankshaft models were created. These included a complete stiffness representation of the crank (excluding the crank nose hub and the flywheel), and a detailed model of the crank from main bearing 4 to main bearing 5, with mesh density increased around the fillets. ENGDYN can however perform crank analysis of any portion of the crank as long as the model incorporates at least two main journal bearings. Features such as bolt holes and oil drilling were omitted on both models, which were meshed using solid tetrahedral elements