Data-Driven Characterization of Composites Based on Virtual Deterministic and Noisy Multiaxial Data

Volume 3: 28th Computers and Information in Engineering Conference, Parts A and B ◽

10.1115/detc2008-49940 ◽

2008 ◽

Cited By ~ 3

Author(s):

J. G. Michopoulos ◽

T. Furukawa ◽

S. G. Lambrakos

Keyword(s):

Linear Equations ◽

Testing Machine ◽

Noisy Data ◽

Loading Path ◽

External Work ◽

Design Variables ◽

Characterization Of Materials ◽

Value Decomposition ◽

Loading Path Design

This paper presents an inverse methodology capable of identifying the elastic moduli of laminated composites from both deterministic and noisy data originating from virtual multiaxial tests. Unlike the conventional uniaxial characterization of materials, the methodology exploits the energy balance between the increment of external work and the corresponding increment of strain energy. It then formulates an overdetermined system of linear equations that are solved using Singular Value Decomposition (SVD) to compute the associated pseudoinverse array. The proposed methodology further controls the multiaxial testing machine by utilizing performance measures of the SVD process to construct objective functions that are maximized in order to compute loading path design variables. Numerical examples investigate the significance, robustness and efficiency of the proposed methodology. Deterministic and noisy data are synthesized in order to demonstrate the applicability of the technique with respect to realistic characterization problems. The effect of noisy data in the characterization process has been examined in a manner that leads to a demonstration of the practicality of the approach.

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Mechanical characterization of materials for bulk forming using a drop weight testing machine

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1243/09544062jmes2020 ◽

2010 ◽

Vol 224 (9) ◽

pp. 1795-1804 ◽

Cited By ~ 2

Author(s):

C M A Silva ◽

P A R Rosa ◽

P A F Martins

Keyword(s):

Flow Stress ◽

Mechanical Characterization ◽

Low Cost ◽

Testing Machine ◽

Operating Conditions ◽

Proportional Loading ◽

Bulk Forming ◽

Drop Weight ◽

Characterization Of Materials

The main limitation of mechanical testing equipments is nowadays centred in the characterization of materials at medium loading rates. This is particularly important in bulk forming because strain rate can easily reach values within the aforesaid range. The aim of this article is twofold: (a) to present the development of a low-cost, flexible drop weight testing equipment that can easily and effectively replicate the kinematic behaviour of presses and hammers and (b) to provide a new level of understanding about the mechanical characterization of materials for bulk forming at medium rates of loading. Special emphasis is placed on the adequacy of test operating conditions to the functional characteristics of the presses and hammers where bulk forming takes place and to its influence on the flow stress. This is needed because non-proportional loading paths during bulk forming are found to have significant influence on material response in terms of flow stress. The quality of the flow curves that were experimentally determined is evaluated through its implementation in a finite-element computer program and assessment is performed by means of axisymmetric upset compression with friction. Results show that mechanical characterization of materials under test operating conditions that are similar to real bulk forming conditions is capable of meeting the increasing demand of accurate and reliable flow stress data for the benefit of those who apply numerical modelling of process design in daily practice.

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Indexing of powder diffraction patterns by iterative use of singular value decomposition

Journal of Applied Crystallography ◽

10.1107/s0021889802019878 ◽

2003 ◽

Vol 36 (1) ◽

pp. 86-95 ◽

Cited By ~ 385

Author(s):

A. A. Coelho

Keyword(s):

Singular Value Decomposition ◽

Powder Diffraction ◽

Present Method ◽

Linear Equations ◽

Noisy Data ◽

Simulated Data ◽

Singular Value ◽

Fast Method ◽

Diffraction Patterns ◽

Value Decomposition

A fast method for indexing powder diffraction patterns has been developed for large and small lattices of all symmetries. The method is relatively insensitive to impurity peaks and missing highd-spacings: on simulated data, little effect in terms of successful indexing has been observed when one in threed-spacings are randomly removed. Comparison with three of the most popular indexing programs, namelyITO,DICVOL91andTREOR90, has shown that the present method as implemented in the programTOPASis more successful at indexing simulated data. Also significant is that the present method performs well on typically noisy data with large diffractometer zero errors. Critical to its success, the present method uses singular value decomposition in an iterative manner for solving linear equations relatinghklvalues tod-spacings.

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Development of an Optimized Loading Path for Material Parameters Identification

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.554-557.2200 ◽

2013 ◽

Vol 554-557 ◽

pp. 2200-2211 ◽

Cited By ~ 1

Author(s):

Elisabete Ferreira ◽

Joaquim Pinho-da-Cruz ◽

António Andrade-Campos

Keyword(s):

Thin Sheet ◽

Testing Machine ◽

Optimization Method ◽

Mechanical Tests ◽

Loading Path ◽

Objective Criterion ◽

Element Analysis ◽

Material Parameters ◽

Value Decomposition ◽

Material Parameters Identification

Nowadays, the characterization of material is becoming increasingly important due to ma\-nu\-fac\-tu\-ring of new materials and development of computational analysis software intending to reproduce the real behaviour which depends on the quality of the models implemented and their material parameters. However, a large number of technological mechanical tests are carried out to characterize the mechanical properties of materials and similar materials may also have properties and parameters similar. Therefore, many researchers are often confronted with the dilemma of what should be the best set of numerical solution for all different results. Currently, such choice is made based on the empirical experience of each researcher, not representing a severe and objective criterion. Hence, via optimization it is possible to find and classify the most unique and distinguishable solution for pa\-ra\-me\-ters identification. The aim of this work is to propose a methodology that numerically designs the loading path of multiaxial testing machine to characterize metallic thin sheet behavior. This loading path has to be the most informative, exhibiting normal and shear strains as distinctly as possible. Thus, applying Finite Element Analysis (FEA) and Singular Value Decomposition (SVD), the loading path can be evaluated in terms of distinguishability and uniqueness. Consequently, the loading path that leads to the most distinguish and unique set of material parameters can be found using a standard optimization method and the approach proposed. This methodology has been validated to characterize the elastic moduli for an anisotropic material and extrapolated for an hyperelastic material.

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Biaxial Testing Machine: Development and Evaluation

Machines ◽

10.3390/machines8030040 ◽

2020 ◽

Vol 8 (3) ◽

pp. 40

Author(s):

António B. Pereira ◽

Fábio A.O. Fernandes ◽

Alfredo B. de Morais ◽

João Maio

Keyword(s):

Testing Machine ◽

Tensile Tests ◽

Uniaxial Tensile ◽

Anisotropic Behavior ◽

Biaxial Testing ◽

Universal Testing ◽

Characterization Of Materials ◽

Biaxial Mechanical Testing ◽

New Machine

Biaxial mechanical testing gained increased importance for characterization of materials that present anisotropic behavior and/or different responses when subjected to tensile and compression loadings. In this work, a new biaxial testing machine was developed. The various systems and components were designed, manufactured, assembled, and assessed. Uniaxial tensile tests were performed to validate the device, showing results consistent with those obtained on a universal testing machine. Finally, biaxial tensile tests were also performed on polypropylene cruciform specimens. The results revealed high precision levels, thus showing the potential of this new machine.

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Some applications of electron beam microanalysis techniques in VLSI process evaluation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010007463x ◽

1983 ◽

Vol 41 ◽

pp. 160-161

Author(s):

Simon Thomas

Keyword(s):

Integrated Circuits ◽

Process Evaluation ◽

Large Scale ◽

Technology Development ◽

Analytical Techniques ◽

Successful Implementation ◽

Analysis Of Failures ◽

Characterization Of Materials ◽

Circuits Vlsi

Trends in the technology development of very large scale integrated circuits (VLSI) have been in the direction of higher density of components with smaller dimensions. The scaling down of device dimensions has been not only laterally but also in depth. Such efforts in miniaturization bring with them new developments in materials and processing. Successful implementation of these efforts is, to a large extent, dependent on the proper understanding of the material properties, process technologies and reliability issues, through adequate analytical studies. The analytical instrumentation technology has, fortunately, kept pace with the basic requirements of devices with lateral dimensions in the micron/ submicron range and depths of the order of nonometers. Often, newer analytical techniques have emerged or the more conventional techniques have been adapted to meet the more stringent requirements. As such, a variety of analytical techniques are available today to aid an analyst in the efforts of VLSI process evaluation. Generally such analytical efforts are divided into the characterization of materials, evaluation of processing steps and the analysis of failures.

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Applications of ultramicrotomy for materials characterization

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100147004 ◽

1993 ◽

Vol 51 ◽

pp. 232-233

Author(s):

R.T. Blackham ◽

J.J. Haugh ◽

C.W. Hughes ◽

M.G. Burke

Keyword(s):

Materials Science ◽

Microstructural Analysis ◽

Analytical Electron Microscopy ◽

Austenitic Stainless Steels ◽

Specimen Preparation ◽

Preparation Technique ◽

Thermally Induced ◽

Radiation Induced ◽

Characterization Of Materials

Essential to the characterization of materials using analytical electron microscopy (AEM) techniques is the specimen itself. Without suitable samples, detailed microstructural analysis is not possible. Ultramicrotomy, or diamond knife sectioning, is a well-known mechanical specimen preparation technique which has been gaining attention in the materials science area. Malis and co-workers and Glanvill have demonstrated the usefulness and applicability of this technique to the study of a wide variety of materials including Al alloys, composites, and semiconductors. Ultramicrotomed specimens have uniform thickness with relatively large electron-transparent areas which are suitable for AEM anaysis.Interface Analysis in Type 316 Austenitic Stainless Steel: STEM-EDS microanalysis of grain boundaries in austenitic stainless steels provides important information concerning the development of Cr-depleted zones which accompany M23C6 precipitation, and documentation of radiation induced segregation (RIS). Conventional methods of TEM sample preparation are suitable for the evaluation of thermally induced segregation, but neutron irradiated samples present a variety of problems in both the preparation and in the AEM analysis, in addition to the handling hazard.

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