Translated Abstract
The principle of automated dry fiber placement technology is to prepare the dry fiber preform by means of automated placement equipment, and then to obtain the composite component by liquid forming. The molding technology has a high degree of automation, which can adapt to large curvature and complex surface composite component manufacturing. The components are of high surface quality, high precision, good mechanical properties, high efficiency and low cost. The technology of automated dry fiber placement has become a hot spot and trend in the research of composite material automated placement equipment. In this thesis, the structural design and placement process of the automated dry fiber placement system was studied, which provided a reference for the development of the fiber placement equipment and the determination of the parameters.
First and foremost, the functional requirements and structural design of the two modules for the delivery system and the placement head of the automated dry fiber placement equipment were analyzed. The experiment platform of the single tow automated dry fiber placement was carried out, and the control program was developed. The filament stretching method was used to extend the fiber tow, and the carbon fiber could be widened to 14.3mm. In this thesis, the penetration of the resin film under the condition of heating and pressure was studied, and the hot pressing fusion process of 0.3MPa and 60°C was determined. The paper put forward and designed the clamping type of low damage refeeding mechanism. Integrated design by clamping and shearing mechanism, the whole shearing process was completed in 0.1s, and the action was fast and reliable. The placement system realized the tension 0~8N, the control precision was ±1N, the pressing force 100N~250N and laying speed range 0~250mm/s.
Furthermore, the effects of tension on the automated dry fiber placement process layer quality have been analyzed. The tension control system platform based on the GOOGOL motion control card and its expansion module was built. The effect of tension on the precision of the refeeding and shearing was analyzed, which affected the layer initial boundary precision and termination boundary precision. Through the method of error compensation, when the control of the tow tension was in the range of 2N~6N, the layer boundary precision could reach the design requirement of ±1.0mm. The effect of tension on the compactness of the paving layer was analyzed, thus affecting the pore distribution of dry preform and molding components. The RTM process and resin filling process of preform were simulated by PAM-TRM software. When the tow tension was 5N, the porosity of the preform was 22.6%. After simulation, the porosity of the component was 6.27%, which was only 0.6% difference from the actual value. It showed that the simulation results are reliable.
Finally, the composite laminate samples test and characterization methods were determined and laminated samples was prepared. The interlaminar shear strength and the pore were used as the evaluation indexes. The effects of the process parameters such as the tow tension, compression force and laying speed on the interlaminar properties of laminates were studied and the appropriate range of parameters was determined. Based on single factor experiment, L9(33) orthogonal experimental table was developed, through the orthogonal analysis, the process parameters and factors on the optimal placement were determined: the tow tension was 4N, pressure 200N, laying speed 100mm/s, the sample uniform pore distribution porosity 5.48%. The interlaminar shear strength reached the maximum value of 72.1MPa and the fiber volume fraction was 60.2%.
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