Main research activities

1- Analysing X-ray tomography images using dedicated 3D image processing and analysis algorithms

1.1- Using X-ray tomography to investigate granular flow during silo discharging process

  • Surrounded by silo container, yet don't master the design w.r.t. type of granular material to handle
  • difficult to predict precisely flow pattern, local movement of grains
What we do know
  • granular materials are very good candidates for X-ray tomography investigation
  • Mechanical properties, cohesiveness of particles and silo structure (hopper angle, wall roughness) play important roles in flow pattern and discharge velocity
  • Discrete Element Method (DEM) is often used to predict granular flow
  • Design versatile silo that can generate wide variety of flow conditions
  • Investigate various materials and carry out mechanical propoerty measurements
  • Carry out time-lapse X-ray tomography study of silo discharge for different materials
  • Comparison between X-ray tomography data and structural-faithful DEM simulation
Info and data
  • Funds: Polish National Science Centre (NCN) - OPUS10 - 320 000 PLN (July 2016- Decembre 2018)
  • Team: L. Babout (coordinator), K. Grudzień, S. Waktola (PhD), K. Miśkiewicz (PhD)
  • Collaboration: Gdansk Univ. Technolog. (M. Szkodo, M. Niedostatkiewicz) / PAN Lublin (J. Wiącek) / INSA-Lyon (E. Maire, J. Adrien)
  • Open data: different studied granular packing can be found here and free of use under ODC licence.

versatile silo

Movie: a glimpse into X-ray CT experiment

reconstructed coronal views of silo discharge (sorghum, eccentric mass flow)

comparison between 3D tomography and DEM

1.2- Localising bridge ligaments along intergranular stress corrosion cracks

  • cracking has non-negligible social and economical impact on our lives
  • difficult to predict, even understand
What we do know
  • strong interaction between crack and material microstructure
  • in each case of damage accumulation the crack path is interrupted, deflected and bridged (see fig. top)
  • bridging ligaments can slow down crack propagation and increase lifetime
  • case of intergranular stress corrosion cracking (IGSCC)
  • extract bridges for geometrical characterisation
  • localise bridges wrt. crack front
  • comparison with results from Diffraction Contrast Tomography
Main achievements
  • development of hole filling algorithm (HFA) to localise and extract bridges (see fig. middle)
  • image registration approach to follow full process of bridging creation and failure towards sample fracture (bottom animation)
Collaborations: Univ. Manchester/Univ. Oxford, ESIEE-Paris (DENIDIA project)

2D reconstructed image: bridges (marked in red) along crack (black) in material (grey)

3D image: bridges (red) along 3D crack (yellow) after HFA

animation showing crack history up to fracture of specimen (grey)

1.3- Segmenting microstructure to correlate with crack path: case study of lamellar titanium alloy

  • titanium alloy: a myriad of applications (e.g. biomedical, areonautics)
  • very good performance at high temperature
  • strong dependance on microstructure
What we do know:
  • strong interaction between crack and material microstructure
  • in the case of lamellar microstructure (see fig. top), strong influence of α-colony and β grain boundaries on crack path
  • revealed by X-ray microtomography and EBSD
  • segment α-colony in 3D
  • segment β grain boundaries in 3D
  • segment crack
  • correlate crack with the other features
Main achievements
  • Creation of CHG directional filter bank to classify α-colonies of different directionality (13 different directions). (see fig. middle)
  • Segmentation of β-gb and crack also based on CHG filtering. Here mainy used to remove defects from the surface (directional filtering)
  • Quantitative characterization of the type of cracking (trans-/inter-lamellar) made possible (see fig. down)
Funds: Polish Ministry of Science and Higher Education (MS&HE) - 200 000 PLN (April 2011-Sept 2013)
PhD of L. Jopek (segmentation of α-colony using CHG)

segmentation of α-lamellae using CHG-based method in the case of Ti alloy. Red boundaries correspond to β-gb and balck to some α-colony boundaries

3D view showing how superpostion of crack (grey) with α-lamellae and β-gb (yellow) can help understanding cracking phenomenon

1.4- Software for quantitative analysis of bronchial tubes

  • increased number of patients suffering from asthma problems
  • CT scans helps in the diagnosis
  • difficulty in follow-up procedure, due to lack of quantitative method
  • software to quantify airway tree
  • localise tree cross-sections with potential closure problems
  • facilitate follow-up procedure for the doctor with pseudo-automatic diagnostic
  • defect correction for wall segmentation using HFA-based method
  • tree partitioning after skeletonization (see fig. top)
  • robust tangent estimator to reconstruct local cross-sections
  • quantitative analysis of local bronchi size and wall thickness (see fig. bottom)
Funds: Polish Ministry of Science and Higher Education (MS&HE) - 200 000 PLN (leader: dr M. Janaszewski. April 2011-April 2013)
PhD of M. Postolski (Co-supervised with Prof. M. Couprie (ESIEE, Paris)

partitioning of the bronchi after skeletonization and graph representation

view and analysis of a reconstructed bronchi section

1.5- Others

I have also been working on quantitative analysis of other materials science applications such as auxetic deformation of open-cell foams and analysis of defects in welding processes. More details here.

2- Electrical capacitance tomography: improvement of image accuracy

  • ECT: fast and cheap tomography method
  • main problem: reliability in data due to limited amount of measurements(image)
  • increasing the number of electrodes is not an issue
  • design rotatable sensor to increase no. of measurement
  • study sensor response in static and dynamic modes
  • sensors with 16 elecrodes wich fits to flow installation (see fig. top)
  • evident image accuracy improvement on static phantom as no. of rotation steps increases (see fig. bottom)
Current work:
  • improve image acquistion and reconstruction
  • feasibility study during dynamic measurements of pneumatic conveying
Main investigator: dr Z. Liu

sensor mounted on flow installation

comparision with 32-electrodes sensor. RS - rotation step