A new scheme for computational modeling of conical indentation in plastically graded materials

2004 ◽  
Vol 19 (6) ◽  
pp. 1703-1716 ◽  
Author(s):  
Yan Ping Cao ◽  
Jian Lu
Keyword(s):  
Inverse Problem ◽  
Computational Modeling ◽  
Apex Angle ◽  
Graded Materials ◽  
Plastic Properties ◽  
Acta Mater ◽  
Graded Surfaces ◽  
Plastically Graded ◽  
Stability Of The Solution ◽  
Conical Indentation

In this paper, a new scheme has been proposed for the computational modeling of conical indentation in plastically graded materials. Based on the new scheme and the work of Dao et al. [Acta Mater.49, 3899 (2001)], and taking the example of conical indentation with an indenter whose tip apex angle is θ = 70.3°, an analytical expression to predict the loading P - h curve for the indentation of plastically graded materials has been presented. A reverse algorithm has further been established to determine the plastic properties of a plastically graded surface. The existence, uniqueness, and stability of the solution to the inverse problem have been systematically investigated. The current work can be applied to the evaluation or optimization of various plastically graded surfaces.

scholarly journals Determination of plastic properties of metals by instrumented indentation using a stochastic optimization algorithm

2009 ◽  
Vol 24 (3) ◽  
pp. 936-947 ◽  
Author(s):  
I. Peyrot ◽  
P-O. Bouchard ◽  
R. Ghisleni ◽  
J. Michler
Keyword(s):  
Mechanical Properties ◽  
Optimization Algorithm ◽  
Plastic Material ◽  
Element Model ◽  
Optimization Approach ◽  
Plastic Properties ◽  
Acta Mater ◽  
Multiple Data Sets ◽  
Load Displacement ◽  
Commercial Solver

A novel optimization approach, capable of extracting the mechanical properties of an elasto-plastic material from indentation data, is proposed. Theoretical verification is performed on two simulated configurations. The first is based on the analysis of the load–displacement data and the topography of the residual imprint of a single conical indenter. The second is based on the load–displacement data obtained from two conical indenters with different semi-angles. In both cases, a semi-analytical approach [e.g., Dao et al., Acta Mater.49, 3899 (2001) and Bucaille et al., Acta Mater.51, 1663 (2003)] is used to estimate Young’s modulus, yield stress, and strain hardening coefficient from the load–displacement data. An inverse finite element model, based on a commercial solver and a newly developed optimization algorithm based on a robust stochastic methodology, uses these approximate values as starting values to identify parameters with high accuracy. Both configurations use multiple data sets to extract the elastic-plastic material properties; this allows the mechanical properties of materials to be determined in a robust way.

scholarly journals Characterization of homogenous and plastically graded materials with spherical indentation and inverse analysis

2011 ◽  
Vol 27 (1) ◽  
pp. 20-27 ◽  
Author(s):  
Charbel Moussa ◽  
Olivier Bartier ◽  
Gérard Mauvoisin ◽  
Philippe Pilvin ◽  
Guillaume Delattre
Keyword(s):  
Inverse Analysis ◽  
Spherical Indentation ◽  
Graded Materials ◽  
Image Position ◽  
Plastically Graded

Abstract

scholarly journals Computational Models of Face Perception

2017 ◽  
Vol 26 (3) ◽  
pp. 263-269 ◽  
Author(s):  
Aleix M. Martinez
Keyword(s):  
Computer Vision ◽  
Inverse Problem ◽  
Facial Expression ◽  
Computational Modeling ◽  
Face Perception ◽  
Computational Models ◽  
Emotional State ◽  
Current Understanding ◽  
Important Means ◽  
The Brain

Faces are one of the most important means of communication for humans. For example, a short glance at a person’s face provides information about his or her identity and emotional state. What are the computations the brain uses to acquire this information so accurately and seemingly effortlessly? This article summarizes current research on computational modeling, a technique used to answer this question. Specifically, my research tests the hypothesis that this algorithm is tasked with solving the inverse problem of production. For example, to recognize identity, our brain needs to identify shape and shading features that are invariant to facial expression, pose, and illumination. Similarly, to recognize emotion, the brain needs to identify shape and shading features that are invariant to identity, pose, and illumination. If one defines the physics equations that render an image under different identities, expressions, poses, and illuminations, then gaining invariance to these factors can be readily resolved by computing the inverse of this rendering function. I describe our current understanding of the algorithms used by our brains to resolve this inverse problem. I also discuss how these results are driving research in computer vision to design computer systems that are as accurate, robust, and efficient as humans.

The Elastic-Plastic Analysis of Functionally Graded Plate

2013 ◽  
Vol 275-277 ◽  
pp. 1040-1044
Author(s):  
Li Zhang ◽  
Yong Qi Yang ◽  
Xian Bin Tao
Keyword(s):  
Functionally Graded Materials ◽  
Functionally Graded ◽  
Flexible Design ◽  
Functionally Graded Plate ◽  
Graded Materials ◽  
Plastic Properties ◽  
Plastic Design ◽  
Continuous Structure ◽  
Elastic Plastic ◽  
Plastic Analysis

The elastic and plastic properties of functionally graded materials in our model are assumed to abide by the mixing law and a program package is developed based on the material subroutines in ABAQUS. Using this package, an elastic-plastic analysis is performed to study a plate made of functionally graded materials. Results of a flexible design and an elastic-plastic design, and those of a continuous structure and a layered structure are compared. It is found that the elastic-plastic design is more reasonable than the flexible design and the continuous structure is more in line with the design concept of functionally graded materials.

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