Investigation on Cylinder Bore Deformation under Static Condition Based on Fourier Decomposition 2017-01-0366

Due to the mechanical forces under static conditions, the engine cylinders cross section will not be a round circle any more once they are installed. The deformation of an engine cylinder causes increasing lubricating oil consumption and abnormal wear, resulting in worse fuel economy and emissions. However, prediction of deformation on a liner has not been made because of the complication of conditions and structure. In this study, a V6-type engine body model was built and meshed with Hypermesh suit software. Then, cylinder deformation under static condition has been simulated and analyzed. First of all, experimental work was done to verify the engine model. Basically, few parameters like pre-tightened force, structure and distribution of bolts have been investigated to figure out how the cylinder bore deformation behaves via finite element analysis. Also, a simple Matlab program was developed to process the data. Specifically, Fourier decomposition has been used to find out the typical style of cylinder deformation. The results show that under static condition, the level of pre-tightened force is one of the most important factors. Furthermore, longer length of the bolt reduces the cylinder distortion due to changing the depth distribution of forces, and symmetrically distributed bolts lead to the lowest bore deformation. The Fourier program results indicate that the most typical cylinder deformation styles are the 2nd-order and the 4th-order. Among all of those deformation styles, the 2nd-order dominates and orders higher than 8 do not contribute too much to the total deformation. Based on this study, optimizing the static conditions will be helpful to protect the cylinder from distorting and wearing.