Friction of plasticity: Application of the dynamic friction model

There have not been any suitable friction models to properly solve plasticity problems yet. Most recently, a new dynamic friction model merging the definition expression of the viscosity with the Amontons-Coulomb friction model suggested by the author has been successfully applied in axisymmetric upsetting to predict the contact stresses. In this paper, the dynamic friction model is further used for resolving the problem of plane-strain compression. With element-equilibrium approach, contact stresses in plane-strain compression have been derived. The mathematical expressions of these contact stresses are verified by the previous experimental data with various ratios of instant length to instant height of workpiece and different lubrications. The curves obtained from the dynamic friction model agree with these experimental results very well, not only for contribution of the normal pressure, mean normal pressure, but also for contribution of the friction stress. Comparisons of results of the dynamic friction model, the Amontons-Coulomb friction model, and the constant friction model with the experimental data are also made. It is seen that the predictions by the dynamic friction model show much better solutions to the practical plasticity problems. It is believed that the dynamic friction model could extensively be used to plasticity problems of solids.

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