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Abstract
This article numerically investigates the effects of flexibility at different locations on a mechanism on the wear at a clearance joint as well as the dynamic performance of a multibody mechanical system. A numerical approach is proposed for the modeling and prediction of wear at a revolute clearance joint in a flexible multibody mechanical system by integrating the procedures of wear prediction with multibody dynamics. Using this approach, a planar slider–crank mechanism including a clearance joint is used as an illustrative case. The effects of the flexibilities of a connecting rod and crankshaft on the clearance joint wear are compared. From the main results obtained, it can be concluded that the differently located flexibilities of the mechanism have different effects on the clearance joint wear and dynamic performance of the system. The flexibility of a connecting rod has a positive influence on reducing the impact and wear at the revolute clearance joint. Moreover, the higher the value of the connecting rod flexibility, the more positive the influence will be. However, the influence of the flexibility of a crankshaft on the impacts and wear at a clearance joint is very complex. It is not always as positive as that of the connecting rod but has much to do with the operating speed of the mechanical system. Even when the system has a high operating speed, the flexibility of the crankshaft will cause greater impacts and hence aggravate the wear at the joint.
Nomenclature
| = | Nodal coordinates of all flexible bodies | |
| ce | = | Restitution coefficient |
| = | Nodal coordinates of the beam element | |
| = | Weighted reaction force vector | |
| = | Elastic forces | |
| Fn | = | Normal force in the contact interface |
| Ft | = | Tangential force in the contact interface |
| h | = | Wear depth |
| K | = | Generalized stiffness |
| k | = | Dimensioned wear coefficient |
| = | Mass matrix | |
| nt | = | Number of integration results |
| nw | = | Number of wear results |
| p | = | Contact pressure |
| = | Element generalized nodal forces | |
| = | Generalized coordinate of the system | |
| = | Displacement field of the element | |
| S | = | Shape function |
| = | Weighted incremental sliding distance | |
| = | Nodal coordinates of all rigid bodies | |
| δ | = | Penetration |
| = | Vector of Lagrange multipliers | |
| = | Vector of system constraint equations | |
| = | Jacobian matrix |
Superscripts and Subscripts
| β | = | Node of the FEM on the contact surface |
| f | = | Flexible bodies |
| r | = | Rigid bodies |