Experimental and Finite Element Studies on Free Vibration of Automotive Steering Knuckle

The main aim of this research is to determine the best material for manufacturing of steering knuckle in order to reduce the weight using aluminum alloy and Metal Matrix Composite (MMC). To achieve this purpose, the Modal test has been performed to study vibrational behavior of steering knuckle. CAD Model has been prepared by using coordinate measuring machine (CMM). Finally, the Finite Element Analysis (FEA) has been performed to evaluate natural frequencies and mode shapes of knuckle. The results of the Finite Element Model (FEM) have been compared with experimental data to validate the simulation. Three groups of materials (iron, aluminum alloy and metal matrix composite with different fiber volume ratio) have been investigated to determine the best material for manufacturing. DIN 1.7035, unreinforced alumina and MMC-Al 15% Ti-C have been reported as the best materials in each groups. The MMC material has higher vibrational rigidity and by using it, about 63.65 percent weight reduction is possible. FEM results for different models including Coordinate-Measuring Machine (CMM) and smooth model have been compared with test data. The CMM model is closer to reality and it contains all details such as barcode, data and surface defects. It is obvious that meshing of smooth surface is easier than CMM model, but some details will be ignored which could affect the results. However, it has been shown that use of CMM model creates about 5.21% errors related to test data in comparison  with 2.58% when the smooth model is used.