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Peter Hornberger, Diplom Physiker

Institutes

Fraunhofer Application Center for CT in Metrology

Academic Staff

ITC2 0.15

0991/3615-379

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Zeitschriftenartikel

  • M. Langhansl
  • J. Dörrstein
  • Peter Hornberger
  • C. Zollfrank

Fabrication of 3D-printed hygromorphs based on different cellulosic fillers

In: Functional Composite Materials vol. 2 pg. Article number: 4.

  • (2021)

DOI: 10.1186/s42252-020-00014-w

The aim of this work is to characterize the moisture-dependent actuation behavior of bioinspired and additively manufactured hygromorphs based by following deductive and inductive design approaches. Fused Filament Fabrication (FFF) is employed to print bilayered structures consisting of swellable active layers and rigid passive layers. The active layer is composed of a polylactic acid (PLA) matrix filled with different hygroscopic cellulosic materials (native and modified) up to a filler content of 50 m%. Acrylonitrile Butadiene Styrene (ABS) is used for the passive layer. The FFF process allows the generation of desired differential swelling properties in the composites upon moisture absorption. The moisture dependent actuation strain of the printed bilayers was determined by video analyses. Some influencing geometrical factors which contribute to the actuation were deduced from x-ray diffraction (XRD) and micro computed tomography (μCT). The investigation of the mean cellulose microfibril orientation on the surface of the active layer suggested a preferential orientation with respect to printing direction. Furthermore, a gradient of cellulosic material within a single printed layer was observed, which indicates fiber sedimentation. Comparison with the thermomechanical model derived from Timoshenko (1925) shows that the computational prediction of the moisture dependent actuation is considerably accurate for most selected cellulosic materials and filler contents.
  • Fraunhofer AWZ CTMT
  • NACHHALTIG
Zeitschriftenartikel

  • F. Heilmeier
  • R. Koos
  • Peter Hornberger
  • Jochen Hiller
  • K. Weraneck
  • M. Jakobi
  • A. Koch
  • W. Volk

Calibration of cast-in Fibre-Bragg-Gratings for internal strain measurements in cast aluminium by using neutron diffraction

In: Measurement vol. 163 pg. 107939.

  • (2020)

DOI: 10.1016/j.measurement.2020.107939

Fibre Bragg gratings (FBGs) are utilized to function as internal strain sensors during casting, solidification and cooling of two hypoeutectic Al alloys and technically pure Al. In situ neutron diffraction experiments were conducted simultaneously onsite the STRESS-SPEC instrument at the Research-Neutron Source (MLZ) in Garching. The experimental data correlated with structural finite element simulation and X-ray micro tomography (CT) elucidates the mechanisms of this measurement system. The presented work offers a new practical approach to measure in-situ strains during casting of Al alloys by using FBG-based sensors. The FBG strain results correlate with the Al(311) peak obtained by neutron diffraction which is furthermore used for calibration. The examination of interactions between fibres and surrounding cast Al by finite element simulation and CT of the cast specimens enables the application of the sensors for unequivocal strain measurements in castings as well as the characterization of alloys during solidification.
  • Maschinenbau und Mechatronik
  • Fraunhofer AWZ CTMT
  • DIGITAL
Zeitschriftenartikel

  • F. Heilmeier
  • R. Koos
  • M. Singer
  • C. Bauer
  • Peter Hornberger
  • Jochen Hiller
  • W. Volk

Evaluation of Strain Transition Properties between Cast-In Fibre Bragg Gratings and Cast Aluminium during Uniaxial Straining

In: Sensors vol. 20 pg. 6276.

  • (2020)

DOI: 10.3390/s20216276

Current testing methods are capable of measuring strain near the surface on structural parts, for example by using strain gauges. However, stress peaks often occur within the material and can only be approximated. An alternative strain measurement incorporates fibre-optical strain sensors (Fiber Bragg Gratings, FBG) which are able to determine strains within the material. The principle has already been verified by using embedded FBGs in tensile specimens. The transition area between fibre and aluminium, however, is not yet properly investigated. Therefore, strains in tensile specimens containing FBGs were measured by neutron diffraction in gauge volumes of two different sizes around the Bragg grating. As a result, it is possible to identify and decouple elastic and plastic strains affecting the FBGs and to transfer the findings into a fully descriptive FE-model of the strain transition area.We thus accomplished closing the gap between the external load and internal straining obtained from cast-in FBG and generating valuable information about the mechanisms within the strain transition area.It was found that the porosity within the casting has a significant impact on the stiffness of the tensile specimen, the generation of excess microscopic tensions and thus the formation of permanent plastic strains, which are well recognized by the FBG. The knowledge that FBG as internal strain sensors function just as well as common external strain sensors will now allow for the application of FBG in actual structural parts and measurements under real load conditions. In the future, applications for long-term monitoring of cast parts will also be enabled and are currently under development.
  • Fraunhofer AWZ CTMT
  • Maschinenbau und Mechatronik
  • DIGITAL
Zeitschriftenartikel

  • Simon Zabler
  • M. Maisl
  • Peter Hornberger
  • Jochen Hiller
  • C. Fella
  • R. Hanke

X-ray imaging and computed tomography for engineering applications . Röntgenbildgebung und Computertomografie für technische Anwendungen

In: tm - Technisches Messen vol. 87 pg. 211-226.

  • (2020)

DOI: 10.1515/teme-2019-0151

After an incremental development which took place over four decades, X-ray imaging has become an important tool for non-destructive testing and evaluation. Computed Tomography (CT) in particular beholds the power of determining the location of flaws and inclusions (e. g. in castings and composites) in three-dimensional object coordinates. Therefore, and thanks to a speed-up of the measurement, CT is now routinely considered for in-line inspection of electronics, castings and composites. When precision and not speed is important, Micro-CT (μCT) can be employed for Dimensional Measurements (DM, e. g. quality assurance and shape verification), as well as for in situ testing, and for characterizing micro-structures in metals and composites. Using appropriate image processing and analysis μCT can determine the local fibre orientation in composites, the granular morphology of battery cathodes or the inter-connectivity of certain phases in casting alloys. Today, the large variety of X-ray instruments and methods poses an application problem which requires experience and a lot of knowledge for deciding which technique applies best to the task at hand. Application-specific guidelines exist for X-ray radiography testing (RT) only, whereas standardization has been applied to CT, unfortunately leaving out high resolution subμ CT, and nano-CT. For the latter exist an equally high number of NDT applications, however these instruments still necessitate a profound expertise. The task is to identify key industrial applications and push CT from system standardization to application specific automation.
  • Maschinenbau und Mechatronik
  • Fraunhofer AWZ CTMT
  • DIGITAL
Zeitschriftenartikel

  • Peter Hornberger
  • A. Sigl
  • Jochen Hiller
  • Simon Zabler

Kleiner als ein Mikrometer: Entwicklung einer kompakten, hochauflösenden 3D-Röntgen-CT für die Materialanalyse

In: VDI-Z (Sonderteil Additive Fertigung) pg. 52 ff..

  • (2019)
  • Maschinenbau und Mechatronik
  • Fraunhofer AWZ CTMT
  • DIGITAL
  • NACHHALTIG
Beitrag in Sammelwerk/Tagungsband

  • Jochen Hiller
  • Peter Hornberger
  • Thomas Miller

Dimensional Metrology for Industrial Computed Tomography

In: Handbook of X-ray Imaging - Physics and Technology. null (Series in medical physics and biomedical engineering) pg. 949-958.

Boca Raton, FL, USA

  • (2017)
  • Maschinenbau und Mechatronik
  • Fraunhofer AWZ CTMT
  • DIGITAL
Beitrag in Sammelwerk/Tagungsband

  • Peter Hornberger
  • Christian Aichinger
  • Jochen Hiller

Dimensionelles Messen mit Computertomographie

pg. 285-291.

  • (2017)
  • Fraunhofer AWZ CTMT
  • Maschinenbau und Mechatronik
  • DIGITAL
Vortrag

  • Mario Salzinger
  • Peter Hornberger
  • Jochen Hiller

Analysis and comparison of the surface filtering characteristics of computed tomography and tactile measurements

In: 6th Conference on Industrial Computed Tomography (iCT 2016)

Wels, Österreich

  • 09.-12.02.2016 (2016)
  • Fraunhofer AWZ CTMT
  • Maschinenbau und Mechatronik
  • DIGITAL
Zeitschriftenartikel

  • Jochen Hiller
  • Peter Hornberger

Measurement accuracy in X-ray computed tomography metrology: Toward a systematic analysis of interference effects in tomographic imaging

In: Precision Engineering vol. 45 pg. 18-32.

  • https://www.sciencedirect.com/science/article/pii/S0141635915002238 (2016)

DOI: 10.1016/j.precisioneng.2015.12.003

In this paper an investigation of interference effects leading to limitations of metrological performance of X-ray computed tomography (CT) used as a coordinate measuring technique is presented. Using reconstruction data, image quality metrics, and calculations of artifact formation, a deeper understanding and explanation of the physical and technical limitations of CT used in dimensional metrology is given. This is demonstrated in a case study using a simple hollow cylinder made of steel as a test object and calibration measurements from a tactile coordinate measuring machine (CMM). Two different threshold determination strategies for surface computation are applied. Within the study it is also shown that CT image properties, threshold determination strategies, and systematic and random measurement errors must have a definite correlation. As a conclusion it is recommended to focus more strongly on the correlation of local CT image quality and data evaluation operations in order to reduce systematic errors in surface computation and to increase repeatability of dimensional CT measurements.
  • Maschinenbau und Mechatronik
  • Fraunhofer AWZ CTMT
  • DIGITAL
Beitrag in Sammelwerk/Tagungsband

  • Mario Salzinger
  • Peter Hornberger
  • Jochen Hiller

Analysis and comparison of the surface filtering characteristics of computed tomography and tactile measurements

  • (2016)

Analysis and comparison of the surface filtering characteristics of computed tomography and tactile measurementsMario Salzinger, Peter Hornberger, Jochen HillerFraunhofer Application Center for Computed Tomography in Metrology CTMT, Deggendorf, Germany, e-mail: mario.salzinger@iis.fraunhofer.de, peter.hornberger@iis.fraunhofer.de, jochen.hiller@iis.fraunhofer.deAbstractThe use of industrial computed tomography for dimensional measurements is still met with considerable suspicion because of the numerous factors that influence the measurement uncertainty, which thus is hardly describable by a mathematical model. As a consequence, reference measurements with a tactile coordinate measuring machine (CMM) are usually performed. Image unsharpness when using computed tomography (CT) can be seen as low pass filter and therefore is one among many factors that influence the metrological performance of a CT system. However, it is also known that the geometry of the probe tip acts as a mechanical filter when using tactile CMMs. The studies in this work are performed with the help of a simple specimen which includes a number of surfaces of different waviness and roughness. Capturing the surfaces using both systems and comparing the results allows a deeper analysis and understanding of the filtering effects. The measurements are performed with probe balls of different diameters on a CMM. TheCT measurements are performed using various spatial resolution settings, resulting in different surface filtering characteristics. Additionally, surface measurements using a stylus instrument are performed. The comparison of these measurements shows that the CMM is more accurate when measuring form deviations of higher order. However, it also shows that the metrological performance, when measuring dimensional and geometrical measurands using the two systems, is comparable in many cases. Keywords: CMM, CT, metrology, roughness, surface, waviness
  • Maschinenbau und Mechatronik
  • Fraunhofer AWZ CTMT
  • DIGITAL
Beitrag in Sammelwerk/Tagungsband

  • Jochen Hiller
  • Peter Hornberger
  • Mario Salzinger

Bewertung technischer Oberflächen mit Röntgen-Computertomographie

In: Leitfaden zur Inspektion und Charakterisierung von Oberflächen mit Bildverarbeitung. null (Vision-Leitfaden)

Stuttgart

  • (2016)
  • Maschinenbau und Mechatronik
  • Fraunhofer AWZ CTMT
  • DIGITAL
Beitrag in Sammelwerk/Tagungsband

  • Simon Rettenberger
  • Peter Hornberger
  • A. Tissen
  • Jochen Hiller
  • Simon Zabler

Messtechnik und Materialprüfung an belasteten Bauteilen mit In-situ-Computertomographie

In: Leitfaden zur industriellen Röntgentechnik. Zerstörungsfreie Prüfung mit Bildverarbeitung (Vision)

  • (2015)
  • Maschinenbau und Mechatronik
  • Fraunhofer AWZ CTMT
  • DIGITAL
Beitrag in Sammelwerk/Tagungsband

  • Peter Hornberger
  • Christian Aichinger
  • Jochen Hiller

Dimensionelles Messen mit Computertomographie

In: Leitfaden zur industriellen Röntgentechnik. Zerstörungsfreie Prüfung mit Bildverarbeitung (Vision)

  • (2015)
  • Fraunhofer AWZ CTMT
  • Maschinenbau und Mechatronik
  • DIGITAL
Vortrag

  • S. Kasperl
  • R. Schielein
  • R. Sukowski
  • Peter Hornberger
  • Andreas Gruber

CT simulation study to demonstrate material impact using hole plates

In: 11th European Conference on Non-Destructive Testing (ECNDT)

Prag, Tschechische Republik

  • 06.-10.10.2014 (2014)
  • Maschinenbau und Mechatronik
Zeitschriftenartikel

  • A. Tissen
  • Peter Hornberger
  • Jochen Hiller
  • Simon Zabler
  • B. Baudrit
  • S. Horlemann

Dimensionelles Messen und Materialprüfung an belasteten Bauteilen mit In-situ-CT

In: inspect vol. 15 pg. 54-56.

  • (2014)
Die Anwendung der Röntgen-Computertomographie (CT) als zerstörungsfreie Prüfung (zfP) entwickelt sich zunehmend zu einem unverzichtbaren bildgebenden Verfahren in der Qualitätssicherung. Seit dem letzten Jahrzehnt wird diese Technologie verstärkt auch in der dimensionellen Messtechnik eingesetzt.
  • Fraunhofer AWZ CTMT
  • Maschinenbau und Mechatronik
Vortrag

  • Roswitha Giedl-Wagner
  • Peter Hornberger
  • Thomas Miller
  • S. Müller

Entwicklung eines CT-Expertensystems in Kombination mit einer robotergesteuerten Automatisierung

In: DACH-Jahrestagung

Graz, Österreich

  • 17.-19.09.2012 (2012)
  • Maschinenbau und Mechatronik
Zeitschriftenartikel

  • Peter Hornberger

Die Wolfgang Pfeiffer Stiftung an der Hochschule Deggendorf

In: Technik in Bayern: Nachrichten aus Technik, Naturwissenschaft und Wirtschaft (VDI Bezirksverein München, Obb. u. Ndb.) pg. 39.

  • (2009)
  • Maschinenbau und Mechatronik
  • DIGITAL
Beitrag in Sammelwerk/Tagungsband

  • Peter Hornberger

Die Wolfgang Pfeiffer Stiftung an der Hochschule Deggendorf

pg. 39.

  • (2009)
  • Maschinenbau und Mechatronik