The design of the fork-pin compression-fit joints of front motorbike suspensions is uncertain mainly because of the poor knowledge about the starting friction coefficient µll and about the mean coupling pressure p. The axial releasing force Fll=µll∙p∙A, which is the fundamental design parameter, depends on the mentioned two factors, usually unknown, and on the coupling surface dimension, usually known. For these reasons, we decided to develop a generalized methodology which may be able to calculate the parameters (µll and p) of fork-pin joints like those reported in Figure 1 and produced by Paioli Meccanica S.p.A.. In a previous work [Croccolo, 2002], the mathematical model useful to calculate the starting friction coefficient µll has been defined as a function of the production and assembly specifications which are the resting time, the presence of humidity, and the presence of protecting oil. Instead, the definition of the coupling pressure is more difficult because it requires the help of numerical (FEM) analyses. In fact, cause to the not axial symmetric geometry of the fork, the tensile state on the coupling surfaces does not result constant as shown by the different contours of the images of the Figure 2 and therefore it is not possible to apply the high thickness pipe theory. Furthermore, the FEM analysis needs to use many contact elements which increase the computational time and which often do not provide any solution. On the other hand, the pin has, normally, a perfect axial symmetric geometry which is simple to study with the theoretical formulas. Therefore, we decided to separate the strain contribution of the pin and of the fork going on improving the methodology presented in [Croccolo, 2002] and [Croccolo, 2003] which allows to continue in applying the theoretical formulas appropriately corrected. The mathematical models of µll and p are, therefore, implemented in a program which is useful to quickly perform the design and the verification of the joint without using the FEM analyses.
D. Croccolo, R. Cuppini, N. Vincenzi (2006). The design and the optimization of the fork-pin compression joints in front motorbike suspensions. TEHNICKI DIZAJN - ZBORNIK : Bibliografija uz svaki rad - Kazalo.
The design and the optimization of the fork-pin compression joints in front motorbike suspensions
CROCCOLO, DARIO;CUPPINI, ROSSANO;VINCENZI, NICOLÒ
2006
Abstract
The design of the fork-pin compression-fit joints of front motorbike suspensions is uncertain mainly because of the poor knowledge about the starting friction coefficient µll and about the mean coupling pressure p. The axial releasing force Fll=µll∙p∙A, which is the fundamental design parameter, depends on the mentioned two factors, usually unknown, and on the coupling surface dimension, usually known. For these reasons, we decided to develop a generalized methodology which may be able to calculate the parameters (µll and p) of fork-pin joints like those reported in Figure 1 and produced by Paioli Meccanica S.p.A.. In a previous work [Croccolo, 2002], the mathematical model useful to calculate the starting friction coefficient µll has been defined as a function of the production and assembly specifications which are the resting time, the presence of humidity, and the presence of protecting oil. Instead, the definition of the coupling pressure is more difficult because it requires the help of numerical (FEM) analyses. In fact, cause to the not axial symmetric geometry of the fork, the tensile state on the coupling surfaces does not result constant as shown by the different contours of the images of the Figure 2 and therefore it is not possible to apply the high thickness pipe theory. Furthermore, the FEM analysis needs to use many contact elements which increase the computational time and which often do not provide any solution. On the other hand, the pin has, normally, a perfect axial symmetric geometry which is simple to study with the theoretical formulas. Therefore, we decided to separate the strain contribution of the pin and of the fork going on improving the methodology presented in [Croccolo, 2002] and [Croccolo, 2003] which allows to continue in applying the theoretical formulas appropriately corrected. The mathematical models of µll and p are, therefore, implemented in a program which is useful to quickly perform the design and the verification of the joint without using the FEM analyses.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
