European and Chinese Platform for Stacked Aero-Structure Drilling Process and Equipment

Project Information

ECSASDPE

Grant agreement ID: 734272

DOI

10.3030/734272

Project closed

EC signature date 15 November 2016

Start date 1 January 2017

End date 30 June 2022

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 1 615 500,00

EU contribution

€ 859 500,00

Coordinated by

UNIVERSITY OF WARWICK
United Kingdom

Periodic Reporting for period 2 - ECSASDPE (European and Chinese Platform for Stacked Aero-Structure Drilling Process and Equipment)

Reporting period: 2019-01-01 to 2022-06-30

Summary of the context and overall objectives of the project

Weight reduction and cost savings have driven composites research towards a number of recent high profile achievements. The increased use of anisotropic AL/CFRP/Ti stacks in aircraft structures has in turn created enormous challenges for the industry due to the difficulties that arise from drilling these heterogeneous stack materials. The project ECSASDPE focuses on the staff exchange and the development of key enabling techniques and equipment for the orbital drilling process of stacked AL/CFRP/Ti. The objectives of the project are given as follows:
• Establish a long-term research cooperation platform through the ECSASDPE joint programme by exchange of researchers for short periods during the project. As the research work is fully supported by partners’ existing projects and their own resources, in such a case, a long-term research cooperation platform ECSASDPE will be firmly established, and will be in function even after the project period.
• Exchange ideas and technology concepts for further development of novel machining processes and innovative productive equipment for effectively and automatically producing satisfactory holes on AL/CFRP/Ti stacks. All the consortium partners have been actively working on international, national and regional research projects in robotics and automation, composite material machining, surface integrity for many years. The advanced knowledge and expertise will contribute to the development of new technologies on ECSASDPE.
• Strengthen research partnerships through staff exchanges and networking activities between European research organisations and Chinese institutions. Partners can learn from each other the new science and technology developments of orbital drilling technique and equipment technologies and benchmark them against their own developments. Each partner will have at least one publication on average each year. The consortium targets at least 3 patent applications during the project period.
• Take a synergistic approach to the research areas and explore novel methodologies and applications for potential major scientific and technological breakthroughs by optimal combination of the different backgrounds and disciplines from the partners.
The ultimate goal of ECSASDPE is to set up a long-term international and inter-sector collaboration consortium through research and innovation staff exchanges between 8 world-recognised institutions in the cutting-edge research area of high value manufacturing with promising applications in scientific and engineering sectors. The synergistic methodologies achieved by ECSASDPE will serve as the building blocks of the stacked composite material machining mechanism, equipment design, process monitor and control, and machining quality metrology and characterisation and scale up application, and thus enhance the leading position of the consortium for the scientific and technological progresses in high value manufacturing. This project is divided into six inter-related work packages: (1) Setup of knowledge base and road mapping; (2) Fundamentals of drilling process; (3) Key techniques for Equipment development; (4) System integration and performance verification; (5) Dissemination and exploitation, and (6) Project management. The work packages integrate all activities that will lead to the accomplishment of all the project objectives within 66 months.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The applications and user requirements for the proposed ECSASDPE technologies have been defined. The fundamentals for helical drilling including damage mechanism and suppression methods, machining quality characterisation and evaluation methods, and machining parameter optimisation have been developed. The analytical model of cutting forces under steady state conditions has been developed for a special milling tool, which integrates the differential cutting forces along the cutter axis and considers the peripheral and bottom edges that participated in the cutting simultaneously. A number of cutting experiments are conducted for Ti–6Al–4V. The validity of the analytical model has been demonstrated by a series of cutting-verified tests. The influence of cutting variables on the cutting force during helical milling of CFRP has been analyzed based on the cutting experiments. The influence of tool wear on the cutting force is also analyzed. An investigation has been done to study the time varying temperature of the CFRP workpiece in helical milling process under various cutting conditions. The proposed temperature prediction model is capable of simulating the temperature distribution of CFRP workpiece with the movement of end mill. The effect of cutting conditions on machined CFRP surface integrity has been investigated using Taguchi DoE methods. The machining process has induced changes in the CFRP surface roughness, surface void fraction and depth of subsurface affected zone. A comparative study was conducted on different hole making methods for Al 2024-T3/Ti-6Al-4V stacks. The impacts of different hole making methods with constant or varied machining parameters across the stacked structures have been investigated. The resulting exit burr, hole surface roughness/microstructural change and fatigue behaviour of the machined stacks have been characterized. Results show that the exit burr formation is most severe for conventional drilling and least burr is produced in helical milling coupons.
We have filed 4 patents in terms of the hybrid robot error identification and compensation methodology, surface integrity and quality evaluation, and machining quality characterisation. These achieved techniques have significant potentials for the commercial exploitation.Great efforts on the exploitation have been made, e.g. workshops and conferences. Especially, through the industrial partner’s contribution, the further exploitation of the developed techniques has been implemented to benefit the end-users including the aircraft manufactures. Based on the research achievement and outcomes, the Trimule robot has been produced by a SME ‘Yangtian Science and Technology Ltd’ for the manufacturing and automation applications.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Overconstrained 1T2R parallel mechanisms can be visualized as being composed of a spatial limb plus a member of a class of planar symmetrical linkages. Drawing directly on the structures and evaluation criteria proposed here, a novel 5-DOF hybrid PKM module named TriMule is presented. A significant potential advantage of the new design over the established Tricept design arises because its geometry enables the integration of all the joints connecting to the base link of its planar linkage into a single compact part, thereby allowing the module weight to be dramatically reduced. Having determined with confidence that the TriMule design is competitive with the established Tricept design, its kinematic, static, and dynamic analyses have been fully investigated and reported.
A screw theory based approach for error modeling of the hybrid robot has been established by considering all possible source errors including the encoder offsets, the structural errors in joint and links, and the rigid body misalignments of the machine frame with respect to the workpiece frame. The experimental results show that the maximum volumetric position/orientation errors of 60um/0.04° within a task workspace of can be ensured after the fine calibration.

General introduction of ECSASDPE