### Abstract

This study examines the judder behavior of a centrifugal clutch from the start of hot spots in the conformal contact, then the repeated developments of thermoelastic instability, and finally the formation of cyclic undulations in the vibrations, friction coefficient and torque. This behavior is proved to be consistent with the testing results. Using the Taguchi method, 18 kinds of frictional lining specimens were prepared in order to investigate their performance in judder resistance and establish a relationship between judder behavior and the T_{s}/T_{d} (T_{s}: static torque; T_{d}: dynamic torque) and dμ/dV_{x} (μ: friction coefficient; V_{x}: relative sliding velocity of frictional lining and clutch drum) parameters. These specimens are also provided to examine the effects and profitability with regard to the centrifugal clutch, and find the relative importance of the various control factors. Theoretical models for the friction coefficient (μ), the critical sliding velocity (V_{c}) with clutch judder, and the contact pressure ratio p^{∗}/p¯ (p∗: pressure undulation w.r.t. p¯; p¯: mean contact pressure) and temperature corresponding to judder behavior are developed. The parameters of the contact pressure ratio and temperature are shown to be helpful to explain the occurrence of judder. The frictional torque and the rotational speeds of the driveline, clutch, and clutch drum as functions of engagement time for 100 clutch cycles are obtained experimentally to evaluate dμ/dV_{x} and T_{s}/T_{d}. A sharp rise in the maximum p^{∗}/p¯ occurred when the relative sliding velocity reached the critical velocity, V_{c}. An increase in the maximum p^{∗}/p¯ generally led to an increase of the (initially negative) dμ/dV_{x} value, and thus the severity of judder. The fluctuation intensity of dμ/dV_{x} becomes a governing factor of the growth of dμ/dV_{x} itself in the engagement process. The mean values of dμ/dV_{x} and T_{s}/T_{d} for the clutching tests with 100 cycles can be roughly divided into three groups dependent on the fluctuation intensities of these two parameters, for each of which there is a linear relationship.

Original language | English |
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Pages (from-to) | 811-828 |

Number of pages | 18 |

Journal | Mechanical Systems and Signal Processing |

Volume | 66-67 |

DOIs | |

Publication status | Published - 2016 Jan 1 |

### All Science Journal Classification (ASJC) codes

- Control and Systems Engineering
- Signal Processing
- Civil and Structural Engineering
- Aerospace Engineering
- Mechanical Engineering
- Computer Science Applications

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## Cite this

*Mechanical Systems and Signal Processing*,

*66-67*, 811-828. https://doi.org/10.1016/j.ymssp.2015.06.010