Solid State Joining Processes
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Photo: HZG/Christian Schmid

Advanced Polymer-Metal Hybrid Structures

The development of new materials and fabrication techniques has become a matter of success for different industries, such as transportation, medical appliances and civil engineering. The development of new lightweight alloys, such as aluminium, magnesium and titanium, as well as of advanced polymer-based materials, such as Fiber Reinforced Plastics (FRP) and nanocomposites, has changed the current paradigm in the design of lightweight constructions.

In this way, advanced engineered composites are being increasingly mixed with lightweight metals aiming to increase the weight-to-strength structural performance of transportation components for reducing fuel consumption and gas emission. Therefore, alternative and advanced joining technologies are required to to join such multi-material structures.

Joining Dissimilar Materials

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Prize winning joining techniques recently developed at Helmholtz-Zentrum Geesthacht (HZG), such as FricRiveting, Injection Clinching Joining (ICJ) and Friction Spot Welding/Joining (FSpW/J) have been devised in order to try to overcome or attenuate the limitations found in current polymer-metal joining methods.

In this way, the performance of polymer-metal hybrid components fabricated by these new joining technologies could be improved in a reliable, faster and more environmental friendly manner. Therefore the Young Investigator Group “Advanced Polymer-Metal Hybrid Structures” aims to face the scientific and technological challenges involved in joining the new polymer-metal hybrid structures in engineering applications.

Projects

Friction Spot Joining of CFRP/Lightweight Metal Alloys Hybrid Structures

Goushegir Projects

The current project aims to investigate the mechanical integrity and corrosion resistance of metal-composite friction spot joints for future aircraft and automotive applications. Previous investigations have attained high level of understanding on the friction spot joints bonding mechanisms. Additionally, high mechanical strength of the coupon friction spot joints has been reported. In this way, these studies fully demonstrated the promising application of the FSpJ technique in lightweight structures. Nevertheless, the industrial transferability of a new technology requires further assessment to comply with the safety and operational requirements for certification on aircraft and automotive applications. For this purpose, an evaluation of damage tolerance, impact resistance, stress relaxation and residual stresses should demonstrate that joint catastrophic failure can be avoided throughout the service life of the friction spot joined structures. Furthermore, the susceptibility of intergranular, exfoliation, maintenance chemicals and fluids corrosion will be investigated for coupon friction spot joints. Thus, the validation of FSpJ for aircraft and automotive structural applications is intended.

Development of Injection Clinching Joining

Abibe Projects

The goal of this project is to develop and understand new ICJ process approaches to obtain reliable, sound polymer-metal spot joints for lightweight structures. Development of different and new joining tools and equipment, along with their characterization and optimization are the key strategies for this project. Investigation on joining energy source, tool and joint geometries, and effects of the process parameters are used to optimize the techniques for production of better joints. In order to evaluate the process, global and localized mechanical properties of the joints, microstructural effects on the materials, and interface investigations are performed.

Innovating Materials in Bridge Construction

Blaga Projects

The research emphasises on the problematic of joining fiber reinforced polymeric composites with application in civil engineering and bridge construction. The motivation of the work is the construction of lightweight Glass Fiber Reinforced Plastics (GFRP) emergency bridges while the scope is to develop innovative connection technologies for GFRP profiles. The feasibility of Friction Riveting is being studied, as well as its joint mechanical performance, for different material combinations. Finite Element structural analysis is undertaken in order to model friction riveted GFRP bridges.

Design and Mechanical Performance of Friction-Riveted Multi-material Joints for Aircraft Structures

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The research focuses on the optimisation of Friction Riveting process in terms of quasi-static and cyclic mechanical performance, for hybrid (metal and high performance polymer composites) joints with application in multi-material aircraft structures. At coupon-level, a design guideline for single overlap joints is proposed, as well as an investigation into the effects of environmental conditions and stress relaxation on the mechanical performance of the joint. Furthermore, part of the scope of this investigation, is the study of damage tolerance under static and dynamic loading. On a sub-component level, combining the use of finite element analysis and experimental results, it is expected to fill the present knowledge gap and support industrial transfer of FricRiveting. The output of this project aims at optimising friction-riveted connection design, new joining solutions and towards the fulfilling of basic requirements for industrial application.

Design and Mechanical Performance of Friction-Riveted Multi-material Joints for Aircraft Structures

Eduardo Projects2

This project aims at manufacturing future damage-tolerant and crash-resistant metal-composite hybrid lightweight structures through a new direct assembly methodology known as U-Joining (patent EP 3 078 480 A1). Understanding the fundamentals of U-Joining and the joint formation mechanisms are the key strategies to optimize the mechanical performance of the ultrasonically joined hybrid joints. This can be achieved by focusing on the evaluation of microstructural features and interface properties. The process feasibility has been demonstrated for Ti-6Al-4V with conical reinforcing-pins produced by metal injection molding, and glass-fiber reinforced polyetherimide laminates, two commercial available materials used by the transportation sector. The following steps of the project includes: evaluation of bonding mechanisms, metal-composite interface characteristics, determination of the correlation between process parameters and joints properties, as well as prediction of joints properties by statistical modeling.

Groupleader


Lucian A. Blaga

Institute of Materials Research, Material Mechanics

Helmholtz-Zentrum Geesthacht
Max-Planck Straße 1
21502 Geesthacht

Phone: +49 (0)4152 87 - 2055

E-mail contact