Hellen Altendorf

Mines Paris, PSL University | ParisTech · Centre de Morphologie Mathématique (CMM)

In the context of automated analyses of electron-backscattered-diffraction images, we present in this paper a novel method to automatically extract morphological properties of prior austenitic grains in martensitic steels based on raw crystallographic orientation maps. This quantification includes the estimation of the mean chord length in specific...

This work focuses on the linear elastic and thermal properties of real and virtual, computer-generated fibrous composites. A stochastic microstructure model is used to generate densely-assembled 3D systems of curved, non overlapping fibers with specific orientation distributions. This model is first optimized to approach the characteristics of a re...

In the area of tessellation models, there is an intense activity to fully understand the classical models of Voronoi, Laguerre and Johnson-Mehl. Still, these models are all simulations of isotropic growth and are therefore limited to very simple and partly convex cell shapes. The here considered microstructure of martensitic steel has a much more c...

For the simulation of fiber systems, there exist several stochastic models: systems of straight non overlapping fibers, systems of overlapping bending fibers, or fiber systems created by sedimentation. However, there is a lack of models providing dense, non overlapping fiber systems with a given random orientation distribution and a controllable le...

The recent booming of multiphoton imaging of collagen fibrils by means of second harmonic generation microscopy generates the need for the development and automation of quantitative methods for image analysis. Standard approaches sequentially analyse two-dimensional (2D) slices to gain knowledge on the spatial arrangement and dimension of the fibri...

Thèse en co-tutelle : école nationale supérieure des mines de Paris, France et Technische Universität Kaiserlautern, Deutschland

Stochastic modeling of a material microstructure is in general composed of multiple steps. First, geometric properties of the sample are measured by image analysis. Second, an appropriate stochastic model is chosen and model parameters are estimated from the geometric properties. Third, additional characteristics are computed on the data set and on...

For the simulation of fiber systems, there exist several stochastic models: systems of straight nonoverlapping fibers, systems of overlapping bending fibers, or fiber systems created by sedimentation. However, there is a lack of models providing dense, nonoverlapping fiber systems with a given random orientation distribution and a controllable leve...

For the simulation of fiber systems, there exist several stochastic models: systems of straight non-overlapping fibers, systems of overlapping bending fibers or fiber systems created by sedimentation. However, there is a lack of models providing dense, non-overlapping fiber systems with a given random orientation distribution and a controllable lev...

In this paper we present algorithms for measuring local characteristics of random fiber systems. The calculation of the local directions and radii is based on directional distance transforms and evaluation of the inertia moments and axes of the resulting extremities of the centralized, directed chords. The method provides continuous results while m...