Joining and Forming by Plastic Deformation

Work area

The focus of the research in joining by deformation is on questions relating to the joining of lightweight construction materials, such as fibre reinforced plastics or wrought aluminium alloys both as joints using purely deformation and in combination with adhesive bonding. The main fields of application for the joining methods in question are within the mobility sector (aircraft, rail and automotive industries).

© Fraunhofer IGP

The research covers both the initial qualification of the deformation or setting process of the joint and the analysis of the load-bearing capacity of the joint under static and cyclic loading and in the event of a crash. A particular focus here is on the fracture-mechanical evaluation of the joints with respect to crack initiation, crack propagation and fracture behaviour. Furthermore, the properties of the joints are analysed over the service life, and topics such as corrosion resistance, leak tightness, electrical conductivity or the possibilities of (non-destructive) testing (NDT) are examined.

 

The focus of the research into forming by plastic deformation centres on fundamental questions of forming and deformation of component structures. The main emphasis here is on the development of prediction models and the derivation of process control concepts for cold and hot plastic forming, predominantly for the forming of large steel plates with material thicknesses of more than 5 mm. These have to be evaluated and optimised with respect to their real-time capability for integration into machine control systems.

Project overview

At what point does the clinch joint break?

FRICTION-BASED CRACK INITIATION

Due to their efficiency, deformation joining processes requiring no pre-holing are increasingly used in the mobility sector. The focus is on processes that do not require the use of an auxiliary joining part, such as clinching. There is currently an acceptance problem in the field of aircraft construction, due in part to a lack of knowledge on the failure-behaviour of clinch-bonded connections under cyclic loading. The aim of the research project is therefore the in-depth analysis of crack initiation on deformation joined clinch-bonded connections and the prediction of the location and crack-related service life of these connections. A central task is to demonstrate the impact of friction-based crack initiation on the failure behaviour of clinch connections.

Improving the management of rolling rounds for SMEs in the long term

SIMPLIFIED REPLACEMENT MODEL FOR PROCESS CONTROL FOR ROLL BENDING LARGE SHEET THICKNESSES

The industrial rolling of heavy plates in small batches is currently controlled exclusively manually. This has the consequence that the efficiency and economy of the forming process is dependent on the experience of the system operator. Consequently, in order to optimise the process, an objective real-time-enabled control approach based on a simplified substitute model is being developed in the context of the research project. With the help of experimental and numerical investigations plus a sensitivity analysis of the influencing factors, the substitute model can be specifically adapted for industrially relevant space parameters. Using the substitute model leads to a sustainable improvement in control of the rolling process, especially for SMEs.

Damage analysis of a joint

Damage and failure behaviour of punch-riveted fibre-plastic composites under cyclic loading

Semi-tubular self-pierce riveting is an efficient joining process established in the structural assembly of motor vehicles. When joining high-performance fibre-plastic composites (FRP) and metals, process-related damage, such as delamination, results. The influence of this damage on the joining properties, especially under cyclical load, must be taken into account.

An essential part of the project is the analysis of the cyclical damage and failure behaviour of the individual components of the joint and the transfer of these to the damage analysis of the joint. As a consequence, correlations between the joint characteristics and the properties under cyclic loading can be derived, which increases the acceptance of the joint principle with FKV and ensures a safe design.

Analysis and networking of production steps

CONCEPTION OF AN ADAPTIVE PROCESS CHAIN FOR MECHANICAL JOINING

Production-related fluctuations in component
production lead to increasingly smaller tolerance
zones in the production process and therefore to
higher costs. The networking of production data
for individual production steps is insufficient and correlations between these data are unknown.
It therefore also follows that the potential for expanding the tolerance range is also unknown. The aim of this research project is the analysis and networking of the production steps of a selected product on the basis of the production data.


To achieve this, experimental and numerical analyses are carried out along the production chain. The production data are first subjected to a sensitivity analysis and then the correlation between production steps is analysed. In this way, tolerance specifications can be extended and costs reduced.

Projects

FKV-Metallverbindungen
(Laufzeit: '17-'18)
Modellierungsstrategie zur anwendungsgerechten Simulation stanzender Fügerverfahren in FKV-Metall-Verbindungen-FKV-Stanznietsimulation
Fügestellendynamik
(Laufzeit: '17-'18)
Fügestellendynamik - Einfluss mechanischer Fügeverbindungen auf das Dämpfungsverhalten stahlbaulicher Tragwerkstrukturen
Gewindeeinsätze für Leichtmetallverschraubungen
(Laufzeit: '16-'19)
Gewindeeinsätze für Leichtmetallverschraubungen
Setzverfahren
Blindnietmutterverbindungen (BNM)

(Laufzeit: '15-'17)
Vergleich und Analyse verschiedener Setzverfahren zur Herstellung qualitätsgerechter Blindnietmutterverbindungen (BNM)
HakU
(Laufzeit: '16-'20)
Handhabungssystem für die kaltplastische Umformung – HakU
PLUGZ
(Laufzeit: '15-'16)
Erhöhung der Fügepunktsteifigkeit durch Z-Pins beim mechanischen Fügen von FVK-Metall-Hybridstrukturen – PLUGZ
Fügeverbindungen SRB
(Laufzeit: '14-'17)
Fügeverbindungen mit Schließringbolzen (SRB) unter atmosphärischen Belastungen
Gittertürme WEA
(Laufzeit: '13-'15)
Einsatz von wartungsfreien Gittertürmen für Windenergieanlagen (WEA)
Setzprozessunregelmäßigkeiten
bei Schließringbolzensystemen (Laufzeit '13-'15)
Numerische und experimentelle Untersuchung von Setzprozessunregelmäßigkeiten bei Schließringbolzensystemen
FVK
(Laufzeit: '13-'14)
Simulation des Halbhohlstanznietprozesses von FVK durch mehrskalige Modellierung
Laser- und ultraschallgestütztes Clinchen
(Laufzeit: '13-'14)
Laser- und ultraschallgestütztes Clinchen von hochfesten Stahl/Aluminium-Mischverbindungen
Tragverhalten FVK
(Laufzeit: '11-'13)
Tragverhalten vorgespannter, scherbeanspruchter mechanischer Fügeverbindungen in Strukturbauteilen aus Faserverbund-kunststoffe (FVK)
Stanznieten von Großstrukturen
(Laufzeit: '09-11')
Kostenoptimiertes robotergestütztes Stanznieten von Großstrukturen
Fügeprozessicherheit
(Laufzeit: '08-'10)
Fügeprozesssicherheit von Blindniet-Setzvorgängen bei Montage- und Bauteilunregelmäßigkeiten
Zerstörungsfreie Bauteilprüfung
(Laufzeit: '06-'08)
Zerstörungsfreie Bauteilprüfung von Schließringbolzen- und Blindnietverbindungen mit Aktor-Sensor-System
Korrelation zwischen Fertigungsparametern und Tragfähigkeit
(Laufzeit: '06-'08)
Korrelation zwischen Fertigungsparametern und Tragfähigkeit für kraft-und formschlüssige Schließring-und Blindbolzenverbindungen
Blindgenietete Funktionselemente
(Laufzeit: '06-'08)
Einsatz von blindgenieteten Funktionselementen in ausgewählten Bauteilwerkstoffen
Hochleistungstechnologien Fügen - TP9
(Laufzeit: '06 - '08)
Hochleistungstechnologien zum Fügen in schiffbaulichen Vorfertigungs-Montage-und Ausrüstungsprozessen zum mechanischen und wärmereduzierten Fügen sowie Kleben in Ausrüstungsprozessen
Huck-Spin- und Schraubenverbindungen
(Laufzeit: '06-'07)
Vergleichende statische und dynamische Festigkeitsuntersuchungen an Huck-Spin- und Schraubenverbindungen
Vorspannkraft und Relaxationsverhalten von Schließringbolzen in Aluminium-Strangpressprofilen
(Laufzeit: '06)
Vorspannkraft und Relaxationsverhaltenvon Schließringbolzen in Aluminium-Strangpressprofilen
Hemlok-Blindniet-Verbindungen
(Laufzeit: '05-'07)
Quasi-statische und dynamische Festigkeitsuntersuchungen an HEMLOK-Blindniet-Verbindungen
Tragverhalten von Schließringbolzenverbindungen
(Laufzeit: '04-'06)
Einfluss von werkstofflichen und geometrischen Parametern auf das Tragverhalten einer Schließringbolzenverbindung
Wöhlerversuche an Stanznietverbindungen
(Laufzeit: '04-'05)
Durchführung von Wöhlerversuchen an Stanznietverbindungen mit verschiedenen Materialkombinationen
Clinchen von Stahl- und Aluminiumwerkstoffen unter Einwirkung von Ultraschall
(Laufzeit: '03-'05)
Clinchen von Stahl- und Aluminiumwerkstoffen unter Einwirkung von Ultraschall
Fügeverfahren im Schiffbau
(Laufzeit: '02-'04)
Untersuchungen zum wirtschaftlichen Einsatz moderner mechanischer Fügeverfahren für ausgewählte Montageaufgaben im Schiffbau
Hucklok Blindnieten
(Laufzeit: '02-'03)
Festigkeits- und Korrosionsuntersuchungen an neuartigen Hucklok Blindnietsystemen
Auslegung von Schließringbolzenverbindungen
(Laufzeit: '02-'03)
Auslegung von Schließringbolzenverbindungen bei Mischbauweisen unter thermischer Beanspruchung
Beanspruchung von Schließringbolzenverbindungen
(Laufzeit: '99-'01)
Festigkeitseigenschaften von Schließringbolzenverbindungenbei statischer und dynamischer Beanspruchung

Services

  • Application-specific development and optimisation of deformation joining processes of lightweight construction materials
  • Process integration of joining by deformation through joint sampling, innovative setting device concepts and ergonomic workplace design
  • Establishment of quality assurance procedures, for example by monitoring the setting process or by NDT methods
  • Material and joining testing under mechanical load (static, cyclic, mechanical cracking)
  • Transformation of heavy plates and development of simplified
  • predictive models for technical control integration
  • Development of self-learning systems for joining and forming by plastic deformation processes (AI)
  • Process simulation during joining and forming by means of numerical FEM (ANSYS, LS-Dyna, etc.)
  • Analysis methods for sensitivity and damage analysis during joining and forming (material and metallography)

Equipment

Test laboratory

  • Static universal testing machines (up to 1000 kN)
  • Dynamic pulsators (0.1...100 kN; 0.1...100 Hz)
  • Torque test bench up to 500 Nm
  • Corrosion test chambers/UV irradiation facilities
  • Climate chambers for samples and component tests (90 m³, -50...60 °C)

Production Engineering

  • NC workshop for sample preparation and fixture construction
  • Test stand for conventional and ultrasonic-supported clinching up to max. 50 kN
  • Test stand for solid and semi-tubular self-pierce riveting
  • Process monitoring for setting processes (force / travel torque / angle of rotation)

Analytics laboratory

  • Incident and transmitted light microscopes
  • Spark Emission Spectrometry
  • Helium leak tester
  • Hardness tester

Software used

  • Catia V5
  • LS-Dyna
  • ABAQUS (Forschungslizenz)
  • Ansys Workbench V12