Thermal residual solutions of carbon fiber reinforced polymer composites by 3D printing

Thermal residual phenomena occurrs in carbon fiber reinforced polymer (CFRP) composite laminates by 3D printing due to the material mismatch among layers and the gradient cooling during printing, and affects the forming quality. Instead of the simple assumption of synchronous cooling, the concept of gradient cooling was introduced to characterize real manufacturing processes. The analytical solutions of thermal residual deformations and stresses of cross-ply composite plates and beams were established. To characterize time-dependent forming and cooling processes during 3D printing, a through-thickness cooling gradient was considered in each layer forming turn. The thermal residual responses in each turn were deduced. The total thermal residual deformations and stresses were obtained in an accumulative way. Four gradient cooling models were summarized to cover various 3D printing techniques. The accuracy and reliability of the present solutions are proved in the example of CFRP composite by 3D printing. It is illustrated that the assumption of synchronous cooling would lead to big errors. Thermal residual level is proportional to the cooling gradient. The effects of ply-up patterns on thermal residual responses are discussed. This work provides reliable methods to optimize structures and techniques and decrease thermal residual level of CFRP composites in 3D printing. © 2019, Editorial Office of Acta Materiae Compositae Sinica. All right reserved.