Aiming at the problem of the fatigue life prediction of rubber under the influence of temperature, the effects of thermal ageing and fatigue damage on the fatigue life of rubber under the influence of temperature are analysed and a fatigue life prediction model is established by selecting strain energy as a fatigue damage parameter based on the uniaxial tensile data of dumbbell rubber specimens at different temperatures. Firstly, the strain energy of rubber specimens at different temperatures is obtained by the Yeoh model, and the relationship between it and rubber fatigue life at different temperatures is fitted by the least-square method. Secondly, the function formula of temperature and model parameters is obtained by the least-square polynomial fitting. Finally, another group of rubber specimens is tested at different temperatures and the fatigue characteristics are predicted by using the proposed prediction model under the influence of temperature, and the results are compared with the measured results. The results show that the predicted value of the model is consistent with the measured value and the average relative error is less than 22.26%, which indicates that the model can predict the fatigue life of this kind of rubber specimen at different temperatures. What's more, the model proposed in this study has a high practical value in engineering practice of rubber fatigue life prediction at different temperatures.

Fused deposition modeling (FDM) has been one of the most widely used rapid prototyping (RP) technologies leading to the increase in market attention. Obviously it is desirable to print 3D objects; however, existing FDM printers are restricted to printing only monochrome objects because of the entry-level nozzle structure, and literature on the topic is also sparse. In this paper, the CAD model of the nozzle is established first by UG (Unigraphics NX) software to show the structure of fused deposition modeling 3D printer nozzle for color mixing. Second, the flow channel model of the nozzle is extracted and simplified. Then, the CAD and finite element model are established by UG and ICEM CFD software, respectively, to prepare for the simulation. The flow field is simulated by Fluent software. The nozzle’s suitable temperature at different extrusion speeds is obtained, and the reason for the blockage at the intersection of the heating block is revealed. Finally, test verification of the nozzle is performed, which can produce mixed-color artifacts stably.

To improve the accuracy of the Fused Deposition Modeling (FDM) color 3D printer in printing color pieces, the vibration characteristics were studied. Firstly, the models of the FDM color 3D printer were qualitatively simplified by mechanics theory to provide theoretical support for dynamic characteristics of the structure, and the finite element modal analysis was performed by the ANSYS (It is an engineering simulation and 3D design software) Workbench to obtain the natural frequency and mode shape displacement of the FDM color 3D printer. Then, the power spectrum of the vibration signal of the previous FDM color 3D printer was measured through frequency domain analysis, and the resonance positions of the 3D printer were obtained by comparing the finite element analysis with experimental analysis. Finally, the design of the color 3D printer was optimized based on the analysis. The results indicate that the optimized scheme can effectively improve the resonance characteristics of the device and reduce the overall modal displacement. The actual experiment of the 3D printer demonstrates that the accuracy of the optimized device has been improved, which has crucial reference significance for the development of the FDM color 3D printer.