The front door sash of the car is selected as the research object, and the design of the original gate position causes the warpage displacement of the front door sash to be large. Based on the CAE principle, using Molde×3D mold flow software analysis, it was found that the cause of the large amount of warpage deformation was flow imbalance. Then, according to the principle of flow balance, the design of the gate position was changed. The results of the mold flow analysis showed that the warpage displacement decreased from 18.5 mm to 14.1 mm, and the overall optimization was 24%. And the comparison found that the molding pressure was reduced from 224 MPa to 171 MPa (single cavity), and the clamping force was reduced from 2003 Ton to 1474 Ton (single cavity).
This work focuses on the pull-in phenomena of electrically actuated size-dependent microbeam laminated with the light-activated shape memory polymer, which can realise the Young's modulus variation under the light exposure. Based on the modified couple stress theory, a size-dependent microbeam model is developed. The dynamic governing equation of the microbeam is derived according to the Hamilton principle and solved by the Galerkin method and Runge-Kutta method numerically. The reliability and accuracy of the present method are validated experimentally. The static and dynamic pull-in behaviours of the microbeam are studied when the microbeam is under a purely direct current voltage and alternating current voltage, respectively. Influences of the size effect and dynamic Young's modulus on pull-in behaviour of the microbeam are discussed comprehensively. This research may be helpful and useful in electrostatically actuated microstructure applications and provide a theoretical foundation for designers and engineers.
In this research, nonlinear dynamics and characteristics of a micro–plate system under electrostatic forces on both sides are studied. A novel model, which takes micro-scale effect and damage effect into account, is established on the basis of the Talreja’s tensor valued internal state damage model and modified couple stress theory. According to Hamilton principle, the dynamic governing equations of the size-dependent micro–plate are derived by variational method and solved via Galerkin method and the fourth order Runge-Kutta method. The effects of damage variable and material length scale parameter on bifurcation and chaos of the micro–plate system are presented with numerical simulations using the bifurcation diagram, Poincare map. Results provide a theoretical basis for the design of dynamic stability of electrically actuated micro- structures.
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