Concept
Automotive suspension design is an aspect of automotive engineering, concerned with designing the suspension for cars and trucks. Suspension design for other vehicles is similar, though the process may not be as well established. The process entails Selecting appropriate vehicle level targets Selecting a system architecture Choosing the location of the 'hard points', or theoretical centres of each ball joint or bushing Selecting the rates of the bushings Analysing the loads in the suspension Designing the spring rates Designing shock absorber characteristics Designing the structure of each component so that it is strong, stiff, light, and cheap Analysing the vehicle dynamics of the resulting design Since the 1990s the use of multibody simulation and finite element software has made this series of tasks more straightforward. A partial list would include: Maximum steady state lateral acceleration (in understeer mode) Roll stiffness (degrees per g of lateral acceleration) Ride frequencies Lateral load transfer percentage distribution front to rear Roll moment distribution front to rear Ride heights at various states of load Understeer gradient Turning circle Ackermann Jounce travel Rebound travel Once the overall vehicle targets have been identified they can be used to set targets for the two suspensions. For instance, the overall understeer target can be broken down into contributions from each end using a Bundorf analysis. Typically a vehicle designer is operating within a set of constraints. The suspension architecture selected for each end of the vehicle will have to obey those constraints. For both ends of the car this would include the type of spring, location of the spring, and location of the shock absorbers. For the front suspension the following need to be considered The type of suspension (MacPherson strut or double wishbone suspension) Type of steering actuator (rack and pinion or recirculating ball) Location of the steering actuator in front of, or behind, the wheel centre For the rear suspension there are many more possible suspension types, in practice.