| Knuckle is the most important part of automobile. It not only is the key part ofsteering system, but also the connection to frame and wheels. It will cause serious accidentwhile knuckle is broken. Hence, the research about Structural strength and fatigue life ofknuckle is important.After the research situation of suspension dynamics modeling and simulation,structural optimization, and fatigue life was introduced. Then the structural strength andmodal were analyzed. Knuckle was optimized by topology optimization techniques andthen was reconstructed. Finally, the fatigue life of the optimized knuckle was estimated. Inthis dissertation, main research works were focused on the following four aspects:(1) Dynamic modeling and simulation of the double wishbone suspension. Thedynamic model of double wishbone suspension was built on the base of actual geometrymodel and hard point. As a motivation for dynamic simulation of front double wishbonesuspension, the grounding force of tire was calculated under1g braking condition and3.5gbumping condition and0.95g cornering condition respectively. Then the load of each nodeof control arm was extracted.(2) Finite element analysis of knuckle. The finite element model of knuckle wasestablished based on the geometry model. The detail of the process was represented. Afterthe analysis of the strength and natural frequency of knuckle, we can conclude that thestress of knuckle is less than allowable stress.(3) Structure optimization of the knuckle. Lighten the weight of knuckle is the mainobjective of optimization. With the topology optimization technology, the layout of thematerial of knuckle was built. The knuckle was redesigned according to the information ofthe layout of material. After the optimization, the strength and the natural frequency wereverified. (4) Fatigue life estimation of knuckle. The finite life design method for nominal stresswas applied to estimate the fatigue life of knuckle. It comes to the conclusion that thefatigue life of knuckle is more than1million cycles in three limit working condtion. At last,the fatigue life of knuckle is estimated.Through the research work mentioned above, the optimization design and fatigue liferesearch of knuckle have been completed. The methods and process of the research toknuckle have reference value on other important parts of mechanical products in the future. |
