An innovative methodology for the thermo-mechanical simulation of the laser transmission welding (LTW) process for thermoplastic components is presented. The work consists of two parts. In the first part, a finite element (FE) thermal model is developed, for the prediction of the transient spatial temperature history developing during the LTW process. Experimental measurements have been used for the calibration of the developed thermal model. Through this thermal model, a parametric study on the main welding parameters is performed, in order to investigate their effect on the maximum temperature. Using the parametric study results, the optimal combination of the welding parameters is derived taking into account the welding cost. In the second part, the optimized set is used in a model developed for the thermo-mechanical simulation of the LTW process and the calculation of the thermal stresses, strains, and distortions of the welded parts. The benefit of the proposed methodology is that it offers the capability of optimizing the LTW process, and also provides a reliable estimation of the developed temperature, as well as the thermal stress and strain fields reducing the experimental effort.
An innovative methodology for the thermomechanical simulation of the infrared heating diaphragm forming (DF) process is proposed. In the first section of the paper, the heat transfer mechanisms between the infrared (IR) heating lamps and the thermoplastic plate are simulated, and the effect of the various preheating parameters on the heating time and temperature distribution is investigated. In the second section, the mechanical deformation of the thermoplastic component is simulated to enable prediction of heat losses due to the plate contact with the mold. Based on the developed simulation methodology, the main process parameterse.g., the number, location, and power of IR lamps for optimal preheating; the heat losses during plate deformation; and the minimum required mold temperature throughout the forming phase -are derived for five different thicknesses. The optimization results show that the forming parameters considered influence the heating of the plate in a complex and interactive way; in addition, it is found that with increasing plate thickness, the heating time required to reach the desired temperature also increases.
In the present work the carbon footprint and the financial viability of different materials, manufacturing scenarios, as well as recycling scenarios, associated with the production of aeronautical structural components are assessed. The materials considered were carbon fiber reinforced epoxy and carbon fiber reinforced PEEK (polyetheretherketone). The manufacturing techniques compared were the autoclave, resin transfer molding (RTM) and cold diaphragm forming (CDF). The recycling scenarios included mechanical recycling and pyrolysis. For this purpose, Life Cycle Analysis (LCA) and Life Cycle Costing (LCC) models were developed and implemented for the case of a helicopter’s canopy production. The results of the study pointed out that producing the canopy by using carbon fiber reinforced thermosetting composites and involving RTM as the manufacturing process is the optimal route both in terms of environmental and financial efficiency. The environmental and financial efficiency of the scenarios including thermoplastic composites as the material of choice is impaired from both the high embodied energy and raw material cost of PEEK. The scenarios investigated do not account for potential benefits arising from the recyclability and the improved reusability of thermoplastic matrices as compared to thermosetting ones. This underlines the need for a holistic aircraft structural optimization approach including not only performance and weight but also cost and environmental criteria.
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