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Automotive drive shafts are made of two constant velocity joints coupled by an intermediate shaft. In general, the joint close to the gearbox is a plunging tripod joint, the movement of which serves suspension. The joint close to the wheel is a fixed ball type joint, which allows the steering movement. The article is devoted to secondary torque generated by the ball joint during torque transmission. This study is based on an ADAMS model in rigid bodies with local deformation at contact (Hertz theory) and on industrial test bench measurements. After geometrical representation of ball joint kinematics and before the secondary torque calculation, the ADAMS model is validated through the calculation of internal efforts, which are compared with the models and measurements already presented in the literature. Concerning the secondary torque study, measurements with an industrial test bench at the NTN TE Test Department and the ADAMS model show that the R6 component of the secondary torque (orthogonal to the joint plane) is found to be negligible with respect to the transmitted torque (<2 N m for 300 N m input torque). The results of the ADAMS model also show that the steering component of the secondary torque (in the joint plane and orthogonal to the wheel axis) does not only depend on the joint angle but also on the friction and sign of the transmitted power. [ABSTRACT FROM AUTHOR]

The present paper deals with a virtual model devoted to isokinetics and isometrics assessment of a human muscular group in the common joints, knee, ankle, hip, shoulder, cervical spine, etc. This virtual model with an analytical analysis followed by a numerical simulation is able to predict measurement errors of the joint torque due to offset of rotation centers between the body segment and the ergometer arm. As soon as offset is present, errors increase due to the influence of inertial effects, gravity effects, stiffness due to the limb strapping on the ergometer arm or Coulomb friction between limb and ergometer. The analytical model is written in terms of Lagrange formalism and the numerical model uses ADAMS software adapted to multi-body dynamics simulations. Results of models show a maximal relative error of 11%, for a 10% relative offset between the rotation centers. Inertial contributions are found to be negligible but gravity effects must be discussed in regard to the measured torque. Stiffness or friction effects may also increase the torque error; in particular when offset occurs, it is shown that errors due to friction have to be considered for all torque level while only stiffness effects have to be considered for torque less than 25Nm. This study also emphasizes the influence of the angular range of motion at a given angular position.