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The quality of woven carbon fiber fabric/polycarbonate thermoplastic composites after thermoforming and demolding was investigated using finite element simulation and the Taguchi orthogonal array. The simulation utilized a discrete approach with a micro-mechanical model to describe the deformation of woven carbon fabric, combined with a resin model. This simulation was validated with bias extension tests at five temperatures. The thermoforming process parameters considered were blank temperature, mold temperature, and blank holding pressure, with three levels for each factor. Optimal values for the fiber-enclosed angle, spring-back angle, mold shape fitness, and the strain of the U-shaped workpiece were desired. The results indicated that the comparison of the stress-displacement curve of bias extension tests verified the application of the discrete finite element method. Results from the Taguchi array indicated that blank holding pressure was the dominant parameter, with the optimal value being 1.18 kPa. Blank temperature was the second most significant factor, effective in the range of 160 °C to 230 °C, while mold temperature had a minor effect. Furthermore, the four quality values are dependent and have a similar trend. The best combination was identified as a blank holding press of 1.18 kPa, a blank temperature of 230 °C, and a mold temperature of 190 °C. [ABSTRACT FROM AUTHOR]

The spring-in behavior of woven carbon fiber/polycarbonate thermoplastic composite is investigated by both the experiment and simulation ways. These thermoplastic composite plates are thermoformed into V-shaped structures, and the final bending angle is measured after demolding. In the finite element simulation to describe the thermoforming and spring-in behavior of the composite, the discrete approach is adopted to simulate the behavior of woven carbon fabric and combined with a resin model. The results from both the experiment and the simulation indicate the spring-in behavior of this thermoplastic composite. For [(±45)]6 blanks, the spring-in angle is around 2.60° for a 60-degree V-shape and around 1.72° for a 90-degree V-shape. For [(0/90)]6 blanks, the spring-in angle is around 2.38° and 1.19° for 60-degree and 90-degree V-shapes, respectively. The [(±45)]6 blank always has a slightly higher spring-in angle than the [(0/90)]6 blank, even though the difference is small. The finite element results show 6% to 12% differences with the experimental values if the spring-in angle is used, and the error is less than 0.6% when the bending angle is compared. By using the present finite element analysis, the results indicate that the stacking sequence could have an evident effect on the spring-in angle, and symmetric laminates have less spring-in effect as compared to their unsymmetric counterparts. [ABSTRACT FROM AUTHOR]

The mixing situation of Fe or Co atoms implanting onto Cu(001) substrate is investigated with regard to substrate temperature and deposition rate by molecular dynamics. The tight-binding-second-momentum-approach many-body potential is used to model the atomic interaction. The results indicate that the morphology of the layer is under epitaxial growth as the substrate temperature is 700 or 1000 K, while it is not epitaxial at the substrate temperature of 300 or 450 K. The quality of epitaxial film is better when the substrate temperature is increased. The intermixing at the deposited layers becomes clear as the substrate temperature increases. It also indicates that there are more Co atoms penetrating into the substrate than the Fe atoms, regardless of the substrate temperature. Hence, one could say that the interface mixing of Co and Cu atoms is better than that of Fe and Cu atoms. When the deposition rate is raised from 5 to 10 atoms/ps, there is no increase in the interface mixing at both systems except for that at low substrate temperature. Furthermore, the first peak of the radial distribution function becomes lower and wider for both the Fe–Cu and Co–Cu systems as the substrate temperature is increasing from 300 to 1000 K. [ABSTRACT FROM AUTHOR]