About five years ago, the riding comfort was set after conducting various types of tuning tests. These required considerable man powers and large scale improvement was impossible in wide frequency range.
To get large scale improvement and reduce these man powers, an optimum design was needed in the initial stage of development.
First, the simulation model of whole vehicle was made to analyze the frequency responce on cab floor and human body when an excited force was added to the front tire.
Next, 25 parameters which effected the riding comfort were allocated to L36(211 × 313) type orthogonal array and then 72 simulation analyses were conducted.
Of the 25 parameters, 8 were finally selected to be the most effective, after comparing the results with many factorial effect charts.
It was confirmed that the test results were well matched with the simulation and all acceleration levels at resonance points fell down over 50%.