Constraint Force Analysis On Mul-Pair Dowel Bars Space RCCR Mechanism

At present, the force law of a constraint mechanism has been solved such as space RCCR mechanism by making all the parts flexible or adding denaturing compatibility equation,but the result can’t normally reflect the motion law of the mechanism.The force law is studied theoretically on the multiple-pair and uniform dowel bars space RCCR mechanism in this thesis. In COSMOSMotion plug-in in Solid Works, the ‘rigid body + bushing’ 3D entity model is established by adding local bushing.Based on the Darren Bell principle,the force of the mechanism is divided into static part and dynamic part and the results are obtained by the combination of the simulation experiment and theoretical analysis.The force law is obtained on the multiple-pair and uniform dowel bars space RCCR mechanism by summing up two part results in rigid conditions,Ignoring the effects of mechanism gravity, friction and damping coefficient etc.To solve the stress rule of the mechanism, the following several aspects have mainly been researched.(1)In COSMOSMotion plug-in in Solid Works, the model of n-pair and uniform dowel bars space RCCR mechanism was established(n=3,4,5,6).And then simulation experiment was done. The data of simulation was dealed with the Matlab software and the result of the static part was obtained by summarizing.(2)The constraint force of the rotating pair was analyzed in theory and theoretical expressions of constraint force was obtained. To stablish the model of 3-pair and uniform dowel bars space RCCR mechanism,experimental data are in reasonable agreement with this theory which validate the rightness and feasibility of the theory.(3)Combinning results of the static part and results of the dynamic part, the universal law of equation of rotating pair about mul-pair and uniform dowel bars space RCCR mechanism is obtained during normal operation in rigid conditions.To stablish the model of 120° and 3-pair and uniform dowel bars space RCCR mechanism,experimental data are in reasonable agreement with this theory which validate the rightness and feasibility of the theory.(4)The constraint force of rotating pair Ak as known condition,calculating the constraint force of other kinematic pairs one by one and comparing with the simulation results.Through the research of the above,finally the general equation of the constraint force in the rotating pairs about the mul-pair and uniform dowel bars space RCCR mechanism is obtained.And that, the constraint force in the X, Y direction of rotating pair is only related to the input angular velocity and has nothing to do with the external torque.They can not transfer torque. All the constraint force in the Z direction can only transfer torque,and has nothing to do with the input angle.