This thesis deals with an efficient path planning for the residual stress and distortion optimized manufacturing of structures in aerospace industry using Wire Arc Additive Manufacturing (WAAM). The basis of this work is an additively manufactured, representative prototype, for which efficient path planning is to be realized. The main goal of this thesis is to build and develop an automated path planning program for additive manufacturing of thin-walled structures. The developed path planning program basically consists of three modules, the optimization module, the calculation module and the path generator. The latter outputs the selected paths in a format which is compatible with the simulation program. The optimization module provides the path variations (sequence of paths) for the calculation module. Due to the large number of possible variations, a step-by-step reduction plan was developed which significantly reduces the number of possible variants. The calculation module calculates a normalized energy input for each path variation. The results of the energy input from the calculation module are returned to the optimization module and subsequently evaluated, using a previously defined cost function for assessment. The scattering parameters span, variance and standard deviation are considered as cost functions. The minimization of these parameters is intended to represent a normalized energy distribution as uniform as possible during the construction of the representative prototype. A conventionally designed and manufactured component was modeled using simufact welding structural simulation software. The simulation model was compared with the experimental data and subsequently serves as a reference for evaluating the simulation results from the parameter variations in the course of the path planning optimization. The comparison of the experimental data with the simulation shows a good agreement. The evaluation of the simulations with the optimized path planning shows that the average distortion of the base plate can be reduced by about 14 % over all simulation results and that the span of the normalized energy input can be reduced by 30 % under optimization to the cost function. Similarly, the residual stresses of the base plate could be reduced by 12 % on average over all optimized simulations, and by 21 % under optimization to the cost function variance. All investigated cost functions are suitable for the evaluation of the normalized energy distribution. The developed program allows time-efficient path planning of additively manufactured structures, reducing residual stresses and warpage compared to the conventionally designed component.
|Translated title of the contribution||Numerical parameter study for optimized and modular weld path planning of a representative additively manufactured Ti-6Al-4V structure.|
|Award date||1 Jul 2022|
|Publication status||Published - 2022|
Bibliographical noteembargoed until 12-05-2027
- additv manufacturing
- path planning