Many car components that are redesigned to reduce their weight become more prone to fatigue failure. Therefore, it is critical to detect potential issues and identify effective design changes during the virtual development phase before prototyping has started.
We asked Gergana Dimitrova, Senior Technical Specialist with SIMULIA who developed this workflow, to provide answers to some common questions.
Q. Why does this workflow need to be analyzed?
A. The Transportation and Mobility industry is under pressure to constantly reduce the weight of new generation vehicles, in order to meet fuel consumption regulations. To achieve this, each component of the vehicle is scrutinized and redesigned, either to be manufactured with alternative lighter materials or to use as little material as possible. 
Therefore, downsizing often pushes designs to their limits and their durability may be compromised. In this situation, it is critical for the industry to employ technologies allowing early estimation of designs feasibility with respect to their expected life span and also effective ways to improve designs if they do not fulfill the requirements.
Q. Describe the workflow.
A.The steering knuckle is a part of the ground vehicle suspension where the wheel, steering, chassis and suspension come together. With this interfacing function, loads due to steering, acceleration, braking and road roughness are transferred to the knuckle in various directions and magnitude. These loads are measured or simulated and realistically represent the common vehicle’s usage during driving. In order to estimate correctly the expected life of the knuckle under these complex loading conditions and improve the design of the knuckle, a three step process is carried out. First, static analysis is performed to extract the basic stress state of the knuckle when loaded. Then fatigue analysis, which takes into account the full loading history, is used to assess the life span (mileage) of the knuckle. Fatigue analysis identifies not only the number of safe operation miles but also the location where cracks would first develop. Finally, free shape optimization was applied to fine tune the design geometry so that the durability of the knuckle is increased.
Q. Which SIMULIA solutions did you use?
A. Abaqus is used for the stress analysis, fe-safe for the fatigue analysis and Tosca Structure for the shape optimization.
Q. What were the advantages of using simulation?
A. Simulation helps accurately assess the life span of the component without actually passing it through physical tests thus saving time and costs from prototyping potentially weak designs. Further, targeted fatigue-based optimization helps to quickly find an improved design showing maximum performance gain with minimum design changes, reducing inefficient trial and error procedures and re-designing iterations.
