Journal ArticleDOI
Identification of elastic-plastic material parameters from pyramidal indentation of thin films
TLDR
In this article, the authors proposed a neural network-based method for the determination of the reduced modulus as well as the nonlinear hardening behavior of both the film and substrate materials.Abstract:
The indentation experiment is a popular method for the investigation of mechanical properties of thin films. By application of conventional methods, the hardness and the stiffness of the film material can be determined by limiting the indentation depth to well below the film thickness so that the substrate effects can be eliminated. In this work a new method is proposed, which allows for a determination of the reduced modulus as well as the nonlinear hardening behaviour of both the film and substrate materials. To this end, comparable deep indentations are made on the film/substrate composite to obtain sufficient information on the mechanical properties of both materials. The inverse problem is solved by training neural networks on the basis of finite–element simulations using only the easily measurable hardness and stiffness behaviour as input data. It is shown that the neural networks are very robust against noise in the load and depth. The identification of the material parameters of aluminium films on different substrates results in a significant increase in yield stress and initial work–hardening rate for a reduction of the film thickness from 1.5 to 0.5 µm, while the elastic modulus and the extent of work hardening remain constant.read more
Citations
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Journal ArticleDOI
Review of Instrumented Indentation
TL;DR: An overview of instrumented indentation is given with regard to current instrument technology and analysis methods and research efforts at the National Institute of Standards and Technology aimed at improving the related measurement science are discussed.
Journal ArticleDOI
Analytical and experimental determination of the material intrinsic length scale of strain gradient plasticity theory from micro- and nano-indentation experiments
TL;DR: In this paper, a micromechanical model that assesses a nonlinear coupling between statistically stored dislocations (SSDs) and geometrically necessary dislocation (GNDs) is used to derive an analytical form for the deformation-gradient-related intrinsic length-scale parameter in terms of measurable microstructural physical parameters.
Journal ArticleDOI
A Review of the Application of Machine Learning and Data Mining Approaches in Continuum Materials Mechanics
Frederic E. Bock,Roland C. Aydin,Christian J. Cyron,Christian J. Cyron,Norbert Huber,Norbert Huber,Surya R. Kalidindi,Benjamin Klusemann,Benjamin Klusemann +8 more
TL;DR: It is shown that experiment- and simulation-based data mining in combination with machine leaning tools provide exceptional opportunities to enable highly reliant identification of fundamental interrelations within materials for characterization and optimization in a scale-bridging manner.
Journal ArticleDOI
A physically based gradient plasticity theory
TL;DR: In this article, a physically motivated mathematical form for the gradient plasticity was derived to interpret the size effects observed experimentally, and a physically sound relation for the material length scale parameter was obtained as a function of the course of plastic deformation, grain size, and macroscopic and microscopic physical parameters.
Journal ArticleDOI
Material model calibration by indentation, imprint mapping and inverse analysis
TL;DR: In this article, the identification of elastic-plastic material parameters by means of indentation tests and their finite element simulation is considered with the innovative provision of measuring the imprint geometry besides the indentation curves.
References
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Journal ArticleDOI
An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments
Warren C. Oliver,George M. Pharr +1 more
TL;DR: In this paper, the authors used a Berkovich indenter to determine hardness and elastic modulus from indentation load-displacement data, and showed that the curve of the curve is not linear, even in the initial stages of the unloading process.
Book
Neural networks for pattern recognition
TL;DR: This is the first comprehensive treatment of feed-forward neural networks from the perspective of statistical pattern recognition, and is designed as a text, with over 100 exercises, to benefit anyone involved in the fields of neural computation and pattern recognition.
Book ChapterDOI
Neural Networks for Pattern Recognition
Suresh Kothari,Heekuck Oh +1 more
TL;DR: The chapter discusses two important directions of research to improve learning algorithms: the dynamic node generation, which is used by the cascade correlation algorithm; and designing learning algorithms where the choice of parameters is not an issue.
Proceedings ArticleDOI
A direct adaptive method for faster backpropagation learning: the RPROP algorithm
Martin Riedmiller,Heinrich Braun +1 more
TL;DR: A learning algorithm for multilayer feedforward networks, RPROP (resilient propagation), is proposed that performs a local adaptation of the weight-updates according to the behavior of the error function to overcome the inherent disadvantages of pure gradient-descent.
Book
The Hardness of Metals
TL;DR: Hardness measurements with conical and pyramidal indenters as mentioned in this paper have been used to measure the area of contact between solids and the hardness of ideal plastic metals. But they have not yet been applied to the case of spherical indenters.
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