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Hornfeck C.,Neue Materialien Furth GmbH | Geiss C.,TU Munich | Rucker M.,IABG mbH | Grosse C.U.,TU Munich
Journal of Nondestructive Evaluation

This paper evaluates and compares the application of current state of the art methods and the new local acoustic resonance spectroscopy (LARS) method for nondestructive evaluation of damages in glass fiber reinforced polymers. The innovation of the LARS is the combination of the analysis of the acoustic signals and the force excitation. Generic plates of a standardized material (Vetronit EGS 619) and segments of rotor blades of wind turbines were tested. The generic specimens, 2 and 6 mm in thickness, were damaged with various impact energies caused by a spherical impactor with a diameter of 16 mm, which generated impact damages ranging from barely visible to clearly visible on the generic specimen as well as on segments of real rotorblades of windturbines. The impacts have been measured to account for damage diameter, form and area, indentation depth and bulge height. In addition, blind holes of different depths have been drilled to assess the depth of penetration of the methods tested. As observed in scientific literature as well as in current research, impact damages exhibit a peanut-shaped damage area when impacted with minimum threshold energy. The current research tested several of the specimens using X-ray computed tomography as a reference measurement. These results were compared to the data obtained by ultrasonic methods, LARS and optical lock-in thermography. Finally, all methods have been applied to evaluate rotor blades of wind turbines. The results are shortly discussed in respect to practical applications and accuracy. © 2015, Springer Science+Business Media New York. Source

Rettig R.,Friedrich - Alexander - University, Erlangen - Nuremberg | Ritter N.C.,Friedrich - Alexander - University, Erlangen - Nuremberg | Muller F.,Friedrich - Alexander - University, Erlangen - Nuremberg | Franke M.M.,Neue Materialien Furth GmbH | Singer R.F.,Friedrich - Alexander - University, Erlangen - Nuremberg
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science

A method for predicting the fastest possible homogenization treatment of the as-cast microstructure of nickel-based superalloys is presented and compared with experimental results for the single-crystal superalloy ERBO/1. The computational prediction method is based on phase-field simulations. Experimentally determined compositional fields of the as-cast microstructure from microprobe measurements are being used as input data. The software program MICRESS is employed to account for multicomponent diffusion, dissolution of the eutectic phases, nucleation, and growth of liquid phase (incipient melting). The optimization itself is performed using an iterative algorithm that increases the temperature in such a way that the microstructural state is always very close to the incipient melting limit. Maps are derived allowing describing the dissolution of primary γ/γ′-islands and the elimination of residual segregation with respect to temperature and time. © 2015 The Minerals, Metals & Materials Society and ASM International Source

University Breman Bccms, Neue Materialien Fürth GmbH and FutureCarbon GmbH | Date: 2013-04-19

An electric heating device (

Franke M.M.,Neue Materialien Furth GmbH | Hilbinger R.M.,Neue Materialien Furth GmbH | Konrad C.H.,University of Bayreuth | Glatzel U.,University of Bayreuth | Singer R.F.,Friedrich - Alexander - University, Erlangen - Nuremberg
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science

A numerical model was developed to estimate the solidification conditions and the secondary dendrite arm spacing of equiaxed solidified IN738LC investment castings. The model, composed of geometric data, thermophysical properties, and boundary conditions, was verified by a comparison of calculated and measured process temperatures obtained from casting experiments. The computation of the secondary dendrite arm spacing was carried out from temperature gradient G, solidification rate v, and an alloy-specific parameter M, determined by means of an inverse approach. The calculated secondary dendrite arm spacing was found to be in very good agreement with metallographic measurements. © 2010 The Minerals, Metals & Materials Society and ASM International. Source

Franke M.M.,Friedrich - Alexander - University, Erlangen - Nuremberg | Hilbinger R.M.,Neue Materialien Furth GmbH | Lohmuller A.,Neue Materialien Furth GmbH | Singer R.F.,Friedrich - Alexander - University, Erlangen - Nuremberg
Journal of Materials Processing Technology

Numerical methods were used to examine the influence of casting and baffle geometry, mold thickness as well as withdrawal speed on solidification conditions and resulting microstructure. Achievable thermal gradients, stability limits and primary dendrite arm spacings for Liquid Metal Cooling (LMC) and High Rate Solidification (HRS) process are reported. Calculations were compared with experimental results from the literature and good agreement was found. A thermal gradient almost 1.8 times higher was observed for the use of LMC in the case of simple cylindrical castings. In contrast, a thermal gradient up to three times higher was calculated with LMC compared to HRS for large section size castings. The numerical investigations indicate that the nature of the baffle has a stronger effect than the different mechanism of heat dissipation when HRS and LMC are compared. © 2013 Elsevier B.V. Source

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