Simulation Research On In-situ Forming Process Of Thermosetting Resin Matrix Fiber Winding Composites

Themosetting resin matrix fiber winding composite has been more and more widely used due to its outstanding structure performance. With the development of new energy and aerospace engineering, the requirement to the forming quality and mechanical property of composite products becomes strict. The key to the quality and performance of composite products is the forming technology.The traditional forming method is called the External Curing, which means the composite wound on the mandrel should be placed into the oven to be heated to cure. In this way, the efficiency is low, and the forming quality cannot be guaranteed.In this paper, a new technology, the In-Situ Forming Process, is proposed. The advantages of the new process: The In-Situ Winding-Curing technology makes the composite cured directly on the mandrel while winding by inserting high pressure steam to the mandrel. The significant advantages of this process includes: continuous winding and curing improves the forming efficiency and reduces the costs; curing from inside out is beneficial to resin flow, fiber infiltration, and the discharge of excess resin, bubbles, and gas, and decreasing the peak temperature and residual stress; improving the radial elastic modulus,and decreasing the slackening of external fiber; is able to realize accurate temperature control so as to decreasing residual stress.Based on the application of thermosetting resin matrix fiber winding composite, the basic theory and internal law of In-situ Forming Process is researched. Main work of this dissertation is shown as below.1. The method of In-situ Forming Process is proposed, and the overall schemeis confirmed, which is to explore the inside mechanism of In-situ Forming Process, and to reveal the changing law of the parameters during curing process via simulation, and then to propose the method of mandrel structure optimization based on the analysis of the influence to the curing process of the mandrel.2. The internal heat transfer and curing mechanism of the curing process of Insitu Forming Process is expounded. The thermal analysis and curing model is established. The 3-D finite element simulation is conducted based on the composite flywheel. The changing law of temperature and degree of curing of the thermosetting resin matrix composite of the three phases of beginning, during and ending is revealed. The comparison of the two sets of simulation with and without the die mould is conducted, and the influence of the heat transfer of the die mould to the temperature and degree of curing during different phases of the curing reaction is analyzed.3. The stress and strain mechanism of the curing process of In-situ Forming Process is expounded. The physical parameter predicting model is established,and the thermal expansion, the elastic modulus, and the shear modulus of the composite during the curing process are predicted. The structural analysis model is established, and the 3-D finite element structural simulation is conducted based on the thermal analysis. The deformation law of the resin matrix composite is revealed. The comparison of the two sets of simulation with and without the consideration of die mould is conducted, and the influence of the die mould to the deformation of composite is analyzed.4. The influence of the temperature uniformity on the composite curing and the steam heat transfer mechanism inside the mandrel are expounded. The steam flow and heat transfer models are established, and the heat transfer process of the mandrel is simulated. A method to optimize the temperature distribution with deflector is proposed. The temperature uniformity of mandrel with different deflector angels are evaluated via simulation, and the angels are selected to improve the temperature uniformity.