Logo SFB 871 Produkt-Regeneration
Logo: SFB 871
Logo SFB 871 Produkt-Regeneration
Logo: SFB 871
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B Interaction between production processes and the product´s functional characteristics

In Project Area B, repair techniques are researched for restoring the functional characteristics of complex capital goods and computational techniques are developed for predicting the functional impact of usage, wear, and of the repair process. Those regeneration technologies are investigated in which there is a strong interaction between the regeneration technologies are investigated in which there is a strong interaction between the regeneration technology and the functional characteristics. Beyond the isolated consideration of individual process strategies, process chains, i.e. chains of regeneration steps, will be studied that principally involve adding material, e.g. by coating, brazing, or welding, and removing excess material from the repair process by re-contouring the shape of components.

The subprojects of project area B are:

B1Near Net Shape Turbine Blade Repair
B2Dexterous Regeneration Cell
B3Loss Behavior of Complex Surface Structures
B4Stochastic Structural Analysis
B5Single Crystalline Laser Welding
B6Arc Welding of Titanium-alloys
T1Magnetic Bearing of Rotary Axis (finished 2016)


B1 Near Net Shape Turbine Blade Repair

Near Net Shape Turbine Blade Repair

Near Net Shape Turbine Blade Repair using a Coating and Joining Hybrid Process
In subproject B1 the developed hybrid process for nickel-base alloys will be enhanced. The focus is on the process combination brazing/alitizing with γ‘-precipitation hardening with the brazing process being integrated into the CVD-alitizing process. Furthermore, this project focuses on the further development of the near net-shape coating-technology with covers and templates. The developed hybrid process will be extended to titanium-alloys to adapt this repair-technology for blisks and low pressure compressors.


B2 Regeneration Cell

Dexterous Regeneration Cell

Dexterous Regeneration Cell
With the aircraft engine as the representative for complex goods, the repair parts are mostly complex-shaped and prone to vibrations. Thus, it is the main goal to investigate and finally realize the derived conceptual machine tool design and to provide new features for a dexterous machining operation of vibration-prone parts. Besides, different technologies along the repair process chain are integrated into the cell, which allows a fundamental survey of interactions between the different technologies.


B3 Loss Behavior of Complex Surface Structures

Direct Numerical Simulation (DNS) of Complex Surface Structures

Influence of Complex Surface Structures on the Aerodynamic Loss Behavior of Blades
The complex surface roughness structures of compressor blades formed during normal operation and regeneration processes will be characterized and parameterized based on optical measurements. Representative surface structures will be selected for further investigations on the interaction between the wall-bounded flow and the complex surface structures by means of Large-Eddy-Simulations. Additionally, experimental investigations will be conducted in a flow channel using Particle Image Velocimetry. The influence of complex surface roughness on the aerodynamic losses of compressor blades will be investigated in a linear-cascade wind tunnel by measuring surface pressure distribution on the blade and velocity profile in the wake.


B4 Stochastic Structural Analysis

Stochastic Structural Analysis

Dynamical Behavior and Strength of Structural Elements with Regeneration-induced Imperfections and Residual Stresses
In subproject B4 the methods used in the first funding period will initially be transferred to a “perfect” blisk. In addition, the physical phenomena of large deformations and creep rupture stress will be examined in the deterministic model. In pre-processors the local geometric and material imperfections, as well as the local residual stresses under consideration of their dependences will be statistically represented and coupled. The sensitivity and robustness of the structural properties compared to the defects will result from statistic analyses. Finally, probabilistic analyses by means of developed, semi-analytic methods will be conducted.


B5 Laser Welding

Epitaxial Crack-cladding of Single-crystal Nickel Base Superalloy CMSX-4

Single Crystalline Laser Welding
Based on the results of the first funding period, research project B5 will develop a procedure for similar single crystal regeneration of defects oriented perpendicular towards the basic crystal morphology. The development regarding epitaxial solidification within the defect area will be supported by initial and continuous numerical analysis of the process. Selected substrates shall enable a stepwise adaptation of the heat conduction and simplify the process development. Finally, the process will be transferred to the treatment of a turbine blade. The verification of the single crystal morphology will be done using metallographic and Electron Backscatter Diffraction analyses. All investigations will be done with regard to the long term perspective of being integrated into a full process chain.


B6 Arc welding of titanium-alloys

Repair methods of high-performance titanium-alloys components by arc welding processes
The scope of research project B6 comprises the investigation of innovative high-performance and low-energy arc welding processes for deposition welding of titanium alloys and welding on patches to blades or blisks. The studies focus on the properties after welding and heat treatment processes, including the residual stresses and deformations and also the microstructure of the heat-affected zone and welded zone. The properties of the welding seam are to be adjusted to regenerate turbine components and investigate the fatigue behavior of the joining zone.


T1 Magnetic Bearing of Rotary Axis (finished 2016)

Magnetic Bearing of Rotary Axis

Magnetic Bearing of Rotary Axis for the Application in Product Regeneration
Within the project ‚Dexterous Regeneration Cell‘ (B2) the sensory capabilities of  an active magnetic guide have been investigated and used for force-controlled adaptive milling operations.  Here, these adaptive machining solutions are transferred to a workpiece-sided use with an electromagnetic guided rotary table.
A prototype will be developed and assembled in collaboration with industrial partners and Application-oriented functions, e.g. precise positioning and sensory capabilities, will be integrated. Re-contouring of cylindrical frame engine components as well as further complex geometries will be investigated.