Energy-Efficient Approaches to the Manufacturing of Polymer Composite Structures

Abstract

This paper investigates approaches to improving the energy efficiency of the manufacturing process of thermosetting polymer composites through optimization of curing parameters. It is shown that the isothermal dwell stage is the longest and most energy-intensive phase of the technological cycle, while curing schedules commonly used in industrial practice and often based on averaged datasheet properties of the resin are not always rational when the part geometry, composite lay-up structure, and heat transfer conditions are taken into account.

Within the study, two principal approaches to determining optimal technological parameters are analysed: the experimental approach and the online method. The experimental approach involves selecting curing schedules based on a series of tests for a specific structure, which ensures compliance with the required material properties but is associated with significant time and energy costs. The online method is based on continuous monitoring of parameters characterising the degree of completion of chemical reactions in the resin and enables adaptive adjustment of temperature–time profiles during the forming process without the need for additional experiments.

To analyse the curing process, well-established physical and mathematical models of heat transfer and polymerisation kinetics are employed, allowing prediction of the spatial–temporal distributions of temperature and degree of cure within the composite laminate. Particular attention is paid to the investigation of the stress–strain state formed as a result of the combined effects of thermal, shrinkage, and relaxation processes. It is demonstrated that the level of residual stresses can be reduced by ensuring a uniform temperature field, applying double-sided heating, optimising tooling design, and exploiting the relaxation properties of the material.

As a result of curing schedule optimisation for a given composite laminate configuration, the duration of the isothermal dwell was reduced by a factor of 1.7, leading to a decrease in energy consumption of the forming process from 40 to 23 kWh without deterioration of processing conditions or product quality. The obtained results are methodological in nature and can be applied in the development of energy-efficient manufacturing technologies for polymer composite structures and in the creation of computer-integrated process control systems.