Modeling of jamming phenomenon in fixture design application: an analytical, numerical, and experimental study

Jamming may occur during the loading of the workpiece in the fixture and cause an improper locating process or damage to the workpiece, fixture, and loading system. Consideration of the jamming phenomenon is a necessary task in the planning of the workpiece loading strategy. In the present paper, the minimum norm principle is used to present an analytical model for predicting the jamming occurrence conditions through calculating reaction forces at the contact points. The implementation of this model results in an optimization problem that is solved using the augmented Lagrange multiplier method. The proposed model is applied to two well-known jamming problems, namely the peg-in-hole and block and palm configurations. Numerical analysis is also conducted in Adams software to verify the theoretical predictions. Finally, the experimental setups are fabricated for these configurations to validate the theoretical predictions and numerical results. The results show that the maximum errors between the theoretical predictions and experimental results are 14.4% and 3.8% for the jamming-out angle in the peg-in-hole study and jamming-in travel in the block and palm problem, respectively. Moreover, the worst-case error of 6.9% is obtained for the theoretical prediction of the jamming-in travel of block compared to the numerical result. Agreement between the theoretical, numerical, and experimental results proves the capabilities of the suggested model in the accurate prediction of the jamming occurrence conditions and its potentials for use in the three-dimensional jamming-prone fixturing systems.