In this paper, influences of the shapes of spring leaves in a progressive multi-leaf spring were investigated using the semi-analytic models based on the Euler beam theory. The results from calculations using the semi-analytic models were verified with numerical simulation using a commercial FEM package ABAQUS. The following are drawn from this investigation: 1) The trends in shiftting of the contact point locations change with the shapes of spring leaves. A progressive multi-leaf spring with the spring leaves of a certain shape can have a quantum jump of contact point locations while the one with the leaves of a different shape does not. 2) As expected, the change in the shapes of spring leaves causes change in the transition load of the stiffness of a progressive multi-leaf spring. If there is a quantum jump of the contakt point locations, the stiffness shifted abruptly from its lower value to its higher one depending on the distance between the two contact points. 3) A noise which was absent, can be generated if the shape of spring leaves changes. It was suggested while ivestigating the shifting patterns of constant locations using the model based on the Euler beam theory that the noise might be generatd by a small collision between the main and the help spring leaves when the contact point between them is shifted to a location at a finite distance. The load condition was identified to be a dynamic loading around a static load where the contact point jump occurs. Generation of such noise was confirmed by the experiments with a real progressive multi-leaf spring. 4) It was shown experimentally that the noise can be successfully eliminated if the progressive multi-leaf spring is designed and fabricated so as to satisfy the shape condition that eliminates quantum jumps of the contact point between the main and the help spring leaves. 5) The semi-analytic model based on Euler Beam theory can predict the contact point locations in an acceptable accuracy between the main and the help spring leaves as well as the varying stiffness of a progressive multi-leaf spring. Therefore, the influence of leaf shape can be predicted more efficiently with the Euler beam model. In this paper, it is shown that a progressive multi-leaf spring designed properly can reveals unexpected problems due to geometrical error introduced during its fabrication processes. Hence, the geometrical errors in the shapes of spring leaf should be controlled carefully when the fabrication process is designed.
Influences of leaf shapes on performance of progressive multi-leaf springs
Einfluss der Blattform auf das Verhalten von progressiven Federpaketen
International Journal of Vehicle Design ; 34 , 1 ; 65-83
2003
19 Seiten, 13 Bilder, 12 Quellen
Article (Journal)
English
Influences of leaf shapes on performance of progressive multi-leaf springs
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