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With the increasing research into selective laser sintering of composite powders, a modified numerical model was introduced to provide appropriate process predictions for the production of different functional composites. This numerical method included an effective volumetric heat source model and an integrated testing procedure, in which the differences of polyamide/carbon fiber (PA/CF) and PA/NaCl composite powders in thermo-physical and optical properties were studied. The unknown variables in the numerical model were all determined by experiments. The simulated temperature distributions of different powder beds exhibited a big difference in the melting depth. Entirely different processing parameters were planned for the two composites according to their simulation results. In the following experiments, highly porous PA derived from PA/NaCl composites had a maximum porosity of 59%. Compared with pure PA, CF reinforced PA showed a dramatic increase of the flexural strength and modulus by a factor of 100% and 380%, respectively. Therefore, the design objectives of two PA composites were both well accomplished. In addition, the experimental investigation became more efficient due to the process prediction. The accuracy of the model was validated by the microstructures of PA/CF and PA/NaCl, which meant this method could be used to provide appropriate process planning for more composites. [ABSTRACT FROM AUTHOR]

Multifunctional heat flux manipulation plays an essential role on the industrial processes. A well-designed spatial distribution of thermal conductivity enables a variety of thermal functions, including thermal cloaks and rotators. Despite the promising potential of metamaterials in achieving multifunctional heat transfer in complex nonconformal geometries, significant challenges remain due to limitations in design methods. In this work, a novel approach based on conformal discretization was proposed to address these major challenges, in which the thermal conductivity tensors of discrete functional cells were diagonalized with the local thermal conductivity tensors as inputs. To verify the effectiveness of the conformal discretization, a nonconformal thermal rotating cloak was designed and manufactured. Both simulations and experiments confirmed the effectiveness of this approach in obtaining multifunctional thermal metamaterial with remarkable thermal cloaking and rotating capabilities. Moreover, the nonconformal thermal rotating cloak still maintained thermal functionality well under the condition of omnidirectional heat flow. This work provides a feasible approach to realize multifunctional thermal manipulation in arbitrarily transformed regions, and thus shows significant application potential in the fields of aerospace engineering and civil engineering. [ABSTRACT FROM AUTHOR]