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Numerical simulation and experimental studies of mandrel effect on flow-compaction behavior of CFRP hat-shaped structure during curing process

Li S., Zhan L., Chang T.

Archives of Civil and Mechanical Engineering

2018

Vol. 18, no. 4

1386--1400

CFRP hat-shaped structure is a typical stiffened structure used in aerospace field. In this work, aimed to provide a theoretical basis for manufacturing CFRP hat-shaped structure, the multi physical field coupling model considering influence of mandrel was established. Effect of mandrel on resin flow and fiber compaction during curing process was studied by simulation and experiment. Results showed that temperature and curing degree affected by mandrel can be negligible in hat-shaped structure, and the distribution of temperature and curing degree was relatively homogeneous. However, the behavior of resin flow and fiber compaction during curing process was not uniform. There was a larger gradient among resin flow, pressure, fiber volume fraction and laminate thickness. Presetting a suitable hole in mandrel can effectively improve the uniformity of resin flow and fiber compaction. By simulation analysis and optimization, the acceptable aperture of 11.5–12.5 mm was obtained. Finally, the model and simulation developed in this study was validated by experiment. The reliability coefficient of 93.4–99.6% was obtained, which indicated a good agreement between simulation and experiment.

Mild Method to Synthesize TATB by Amination of 1,3,5-Trialkoxy-2,4,6-Trinitrobenzene under Phase Transfer Catalysis Conditions

Chang T., Li B., Chen L., Ge L., Lu M.

Central European Journal of Energetic Materials

2017

Vol. 14, no. 1

47--59

Nucleophilic amination, as a vital step in the synthesis of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) using 1,3,5-trialkoxy-2,4,6-trinitrobenzene (TORTNB) and aqueous ammonia as the starting materials and catalyzed by phase transfer catalysis (PTCs) under mild conditions is described. Various phase transfer catalysts, such as crown ethers, tertiary amines, quaternary ammonium salts, poly ethers and cyclodextrin, and various experimental parameters, such as no. of equivalents of PTC, mole ratio of ammonium hydroxide to the starting material, reaction time, reaction temperature and cycle times of the organic phase were investigated. The crown ethers, especially 18-crown-6, show good catalytic activity and re-usability for the amination of 1,3,5-triethoxy-2,4,6-trinitrobenzene giving a yield of 96.52%. This makes for a safe process and suitable for scale-up, because the reactions are carried out under atmospheric conditions. The material synthesised by the new system was characterized by DSC, SEM and LPS.