Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - AddMan (Innovative Re-Design and Validation of Complex Airframe Structural Components Formed by Additive Manufacturing for Weight and Cost Reduction)

Teaser

The overall aim of the AddMan project is to enable aerospace industry to redesign and manufacture optimal system components for reduced weight and costs while meeting the prevailing stress and fatigue requirements and regulations by:• Characterization of AM manufactured...

Summary

The overall aim of the AddMan project is to enable aerospace industry to redesign and manufacture optimal system components for reduced weight and costs while meeting the prevailing stress and fatigue requirements and regulations by:
• Characterization of AM manufactured parts to determine the effect of geometry, microstructure, surface roughness and residual stresses on material behaviour to enable optimization of fatigue performance by cost effective surface post processing,
• Extension of existing Topology Optimization (TO) techniques for AM specific material characteristics and complex geometries for optimal performance and structural strength,
• Development of Computer Aided Engineering (CAE) methods for metal AM including connection to TO and flexible parametric CAD models to enable holistic product optimization, and
• Demonstration of the applicability of the developed methods and tools by designing and manufacturing airframe titanium components by using AM technology, where the validation will be carried out through component like specimen testing.
The European aerospace industry leaders have committed to create recourse efficient transport that is safe, respects environment and supports industrial leadership in EU through various innovations as set out in Clean Sky 2 work programmes. Thus, the implementation of these challenges depends on AddMan as we are targeting innovative technologies to support development of more efficient fuselages and airframes to reduce material waste and use, weight, costs, energy use and CO2 compared to the state-of-the-art.

Work performed

The work in AddMan has been divided into five work packages (WPs). WP1 is in charge of the project management, dissemination and exploitation. A series of the management and dissemination activities were put into place.

WP2 is focusing on material properties and post processing. WP2 results during this period include significant development of the various post processing methods and their parameters to improve fatigue life, initial design of specimens and test matrix, manufacturing of EBM and SLM builds and specimens for the experimental and characterization work, and launch of the test programmes.

WP3 is responsible for extension of today’s TO techniques to comprise AM specific material characteristics and complex geometries to fully utilize use of TO for designing AM structures. The essential issues that we have identified are anisotropic material properties, residual stresses, fatigue behaviour, manufacturing constraints and design of grid-like structures. In Period 1, extensions regarding transversally anisotropic material properties and their build process rotation, which are relevant for AM material that is weaker in the build direction, have been implemented. Further, additional extensions related to AM overhang filter and so-called boundary extension to achieve an efficient optimal structure fulfilling all the given requirements have been established. Methods for stress constraints that are computationally efficient have been developed as well as a new TO method that includes fatigue constraints. The WP3 team has also ensured that both TO and finite element analysis software used in the project (i.e. Trinitas) are able to communicate with the CAD software through standard file formats and vice versa, Figure 1.

The main goal of WP4 is to create a best practice guideline for design for AM (DfAM) aiming at a fully automated design process. The WP4 work was initiated with an in-depth examination of the key process variables through the AM entire process chain (pre-, in- and post) to understand demands for metal AM design and describe the manufacturing flow from concept to end-use part. In parallel, the WP4 team has gone through over 1500 different publications in the area of DfAM, design automation for AM, optimisation for AM and relevance of AM for the aeronautic industry to develop an automated process that transfers from TO to CAD geometries. Then, a more automated framework allowing a faster product development process has been proposed as seen in Figure 2. In order to achieve design automation in the DfAM process, the iterative work after the creation of the initial design is automated. In the next step, the proposed automated DfAM framework was implemented and evaluated by using a case study where it has been shown that with a weight increase of only 3%, compared to the TO shape, a design with 45% less support material could be achieved, hence reducing both the material usage as well as the labour needed to remove the support material.

The main goal of WP5 is to integrate the elements designed in WP2, WP3 and WP4 to design and experimentally validate a real-life door component to demonstrate the applicability of the developed methods and tools. In addition, the benefits of using the AddMan tools will be assessed. The first period of the activity in WP5 was devoted to the collecting and analysis of the results from a survey that captures the end-user requirements in order to provide input to WP2, WP3 and WP4. The defined set of requirements covered component size, geometrical features, bulk and surface properties, geometric dimensioning and tolerancing (GD&T) requirements and factors influencing cost models.

Final results

One of the major factors that considerable influence fatigue behaviour of AM components is surface finish because high level of roughness associated to AM as-build parts leads to increased number of crack initiation sites resulting in premature failure. Therefore, the five post processing techniques developed in AddMan address the need to improve the surface of AM parts in order to increase their mechanical performance. New TO formulations and methods that include AM specific features such as anisotropic material properties, build direction, stress and fatigue constraints have been developed and implemented in the project. In order to use the TO formulations developed in AddMan for general industrial problems, the FEA/TO research software used in AddMan, has been expanded to enable it to communicate with the Catia software and vice versa through standard file formats. A novel automated design process implemented as a Knowledge Based Engineering (KBE) framework has been proposed and validated on a first test case. In the KBE environment it is possible to optimize the component considering mechanical aspects such as stress and weight, and to balance these characteristics against AM properties as well as the amount of support structure needed and post-processing methods and costs.

The economic impact of the project is expected in a substantial time savings by shortening the design and production of AM parts which will, in turn, lead to reduction of time to market while increasing competitiveness of EU aerospace industry. Other impacts include cut down of material use and waste, reduced weight of AM parts due to optimised shape as well reduced manufacturing costs through less use of material, dies and tools. Each of the described technologies and impacts directly contribute to energy savings that indirectly lead to environmental benefit in terms of reduced CO2 emissions. Thus, the AddMan developed AM technologies shown economic and environmental potential beyond airplane components, e.g. automotive industry.

Website & more info

More info: http://www.solidmechanics.iei.liu.se/Projects/AddMan/index.html.