The Barrel Institutions Gap Model And Parameter Identification Study

Joint clearance has significant influence on system dynamic response especially for the high speed, overload and high precision mechanism. Development of clearance dynamics in theoretical modeling, simulation and experiment will bring intensive practical engineering value. Under the background of a National Defense Project, this dissertation is concerned with sliding contact dynamics for system with clearance by combination of theoretical modeling, experimental testing and parameter identification, including moving rigid body-cantilever beam and cylindrical section of the barrel-cradle bush.Nonlinear spring damper of two-state method was used to build clearance contact model. Based on Contact Elastic/Plastic Mechanics Theory, a more accurate surface-to-surface contact model of revolute joint with small clearance that can take clearance size, material property into consideration was derived. The nonlinear relationship between static contact force and contact deformation was obtained, which was compared with that from traditional Hertz model.Coupled transverse vibration equations of cantilever beam with clearance subjected to a moving rigid body were formulated by discreting Euler beam based on Assumption Mode Method. And numeric computation code was developed. The influences of clearance, velocity and contact force parameters on dynamics response were analyzed. Under the platform of ADAMS, the flexible body-to-rigid body contact model was used to simulate the interaction between cylindrical barrel and cradle bush. Parameters of Impact contact force function were obtained by least square fitting. The multibody dynamics model of barrel recoil system was established. The influence of different assembly clearance on the performance of contact/impact and muzzle disturbance was then investigated via numerical calculation.The test bed for measuring joint clearance was constructed. And dynamic clearance tests were carried out under different working conditions. Via dynamic clearance curve, the interior contact/impact discipline, as well as process of elements'separation and contact can be recognized indirectly. The accuracy of theoretical modeling and calculation was verified by comparison between experimental data and simulated result.Based on theoretical calculation and clearance experiment, the error function was defined. Genetic algorithm is utilized to identify the nonlinear spring damper coefficients of plane-to-plane contact between moving mass and cantilever beam. Also the assembly clearance and continuous contact force parameters between barrel and cradle bush were identified by using DOE optimization method in ADAMS/Insight module. The calculated clearance curve retrieved from computation in light of the identified parameters was more consistent with experimental result.