General Microhardness Indentation Theory for Multilayer Contacts

1997 ◽  
Vol 119 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Peter A. Engel ◽  
Qian Yang
Keyword(s):  
Iterative Procedure ◽  
Microhardness Measurement ◽  
Computational Method ◽  
Experimental Investigations ◽  
Load Range ◽  
Composite Action ◽  
Refined Method ◽  
General Rules ◽  
Microhardness Indentation ◽  
Multilayer Materials

A refined method for interpreting the Vickers composite microhardness measurement for multilayer materials having layers of arbitrary plating thickness is first presented. The position of an “effective substrate” is found using the concept of the “plastic boundary,” and the depth-wise deformation of each layer is considered in a double-iterative procedure which converges fast. This computational method is then extended from pyramidal indenters to conical and spherical indenters (e.g., Meyer’s). For its confirmation, experimental investigations are carried out for two configurations of Cu/Ni/Au sandwiches, using different diameter spherical indenters and spherical tipped cones, through and well above the microhardness load range. The general rules for composite action are established.

scholarly journals Compressive Creep Measurements of Fired Magnesia Bricks at Elevated Temperatures Including Creep Law Parameter Identification and Evaluation by Finite Element Analysis

Ceramics ◽  
2020 ◽  
Vol 3 (2) ◽  
pp. 210-222 ◽  
Author(s):  
Guenter Unterreiter ◽  
Daniel R. Kreuzer ◽  
Bernd Lorenzoni ◽  
Hans U. Marschall ◽  
Christoph Wagner ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Creep Behavior ◽  
Elevated Temperatures ◽  
Cell Model ◽  
Experimental Investigations ◽  
Load Range ◽  
Element Analysis ◽  
Compressive Creep ◽  
Creep Deformations

Creep behavior is very important for the selection of refractory materials. This paper presents a methodology to measure the compressive creep behavior of fired magnesia materials at elevated temperatures. The measurements were carried out at 1150–1500 °C and under compression loads from 1–8 MPa. Creep strain was calculated from the measured total strain data. The obtained creep deformations of the experimental investigations were subjected to detailed analysis to identify the Norton-Bailey creep law parameters. The modulus of elasticity was determined in advance to simplify the inverse estimation process for finding the Norton-Bailey creep parameters. In the next step; an extended material model including creep was used in a finite element analysis (FEA) and the creep testing procedure was reproduced numerically. Within the investigated temperature and load range; the creep deformations calculated by FEA demonstrated a good agreement with the results of the experimental investigations. Finally; a finite element unit cell model of a quarter brick representing a section of the lining of a ferrochrome (FeCr) electric arc furnace (direct current) was used to assess the thermo-mechanical stresses and strains including creep during a heat-up procedure. The implementation of the creep behavior into the design process led to an improved prediction of strains and stresses.

Perforated FRP Shear Connector for the FRP-Concrete Composite Bridge Deck

2007 ◽  
Vol 334-335 ◽  
pp. 381-384 ◽  
Author(s):  
Jeong Hun Nam ◽  
Soon Jong Yoon ◽  
Dong Min Ok ◽  
Sun Kyu Cho
Keyword(s):  
Bridge Deck ◽  
Experimental Investigations ◽  
Shear Connector ◽  
Composite Action ◽  
Shear Connectors ◽  
Load Carrying ◽  
Composite Bridge ◽  
New Type ◽  
Composite Bridge Deck ◽  
Push Out

In recent years, the FRP-concrete composite bridge deck system has been introduced because of its light-weight and durability. The FRP-concrete composite bridge deck is composed of FRP module and concrete, and they are connected with shear connectors. In order to insure the composite action between FRP module and concrete, appropriate types of shear connector need to be installed. In this study, new type of FRP shear connector was suggested and the experimental investigations are conducted based on the studies of Perfobond. In the experimental study, the push-out test was conducted and the load carrying mechanism was analyzed including the friction effect of sand coating. Considering the load carrying mechanism of perforated shear connector under shear force, the empirical equation for the prediction of shear strength of perforated FRP shear connector was suggested.

scholarly journals RESEARCH OF OPTOELECTRONIC VOLTAGE RELAY

2020 ◽  
Vol 2020 (3) ◽  
pp. 147-153
Author(s):  
E Abduraimov ◽  
◽  
A Rasulov ◽  
D Khalmanov ◽  
N Hamidova
Keyword(s):  
Power Supply ◽  
High Speed ◽  
Experimental Studies ◽  
Computational Method ◽  
Experimental Investigations ◽  
Theoretical Studies ◽  
Dynamic Circuits ◽  
Voltage Curve ◽  
Differential Condition ◽  
Executive Body

Article represents using theoretical analysis and experimental studies of nonlinear resistive circuits and it was developed that it is important to use such circuits as power contactless switching devices to ensure a quality power supply for consumers. The paper deals with the problems of designing lightweight, reliable, high-speed contactless optoelectronic voltage relays with extended service life, combining a responsive device and a strong executive body with a sinusoidal form of the load voltage curve. Theoretical studies of transients in nonlinear dynamic circuits result in the solution of differential condition equations by a computational method built on the basis of optoelectronic pressure relays with time delay. Experimental investigations and the operating theory of this relay are addressed.

scholarly journals Effects of Adhesive Connection on Composite Action between FRP Bridge Deck and Steel Girder

2017 ◽  
Vol 2017 ◽  
pp. 1-7
Author(s):  
Xu Jiang ◽  
Chengwei Luo ◽  
Xuhong Qiang ◽  
Henk Kolstein ◽  
Frans Bijlaard
Keyword(s):  
Adhesive Layer ◽  
Shear Stiffness ◽  
Experimental Investigations ◽  
Steel Girders ◽  
Plane Shear ◽  
Steel Girder ◽  
Composite Action ◽  
Four Point Bending ◽  
Frp Bridge Deck ◽  
Composite Bridge

The FRP-steel girder composite bridge system is increasingly used in new constructions of bridges as well as rehabilitation of old bridges. However, the understanding of composite action between FRP decks and steel girders is limited and needs to be systematically investigated. In this paper, depending on the experimental investigations of FRP to steel girder system, the Finite Element (FE) models on experiments were developed and analyzed. Comparison between experiments and FE results indicated that the FE models were much stiffer for in-plane shear stiffness of the FRP deck panel. To modify the FE models, rotational spring elements were added between webs and flanges of FRP decks, to simulate the semirigid connections. Numerical analyses were also conducted on four-point bending experiments of FRP-steel composite girders. Good agreement between experimental results and FE analysis was achieved by comparing the load-deflection curves at midspan and contribution of composite action from FRP decks. With the validated FE models, the parametric studies were conducted on adhesively bonded connection between FRP decks and steel girders, which indicated that the loading transfer capacity of adhesive connection was not simply dependent on the shear modulus or thickness of adhesive layer but dominated by the in-plane shear stiffness K.

scholarly journals Manufacture of silicon carbide reinforced aluminium 6061 metal matrix composites for enhanced sliding wear properties

2019 ◽  
Vol 6 ◽  
pp. 24
Author(s):  
Avinash Bhat ◽  
Ganesh Kakandikar
Keyword(s):  
Tribological Properties ◽  
Stir Casting ◽  
Experimental Investigations ◽  
Matrix Composites ◽  
The Novel ◽  
Wear Properties ◽  
Load Range ◽  
Mechanical And Tribological Properties ◽  
Hardness Tester ◽  
Pin On Disc

Composite materials have the capability of being customised to provide specific mechanical and tribological properties. This paper presents the manufacture of a novel composite of Al6061 with 5% SiC (50 μm size) by the stir casting method. Experimental investigations of mechanical and tribological properties of SiC reinforced Al6061 are discussed. Investigations with a Rockwell hardness tester revealed that this composite had enhanced hardness. Wear characteristics were investigated for Al6061 and the novel composite Al6061 + SiC with a Pin on disc tribometer for a load range of 5N-200N and RPM varying from 200 to 1500. The effect of crucial parameters such as load and RPM on the wear of the novel composite were presented with sensitivity analysis. The results obtained are encouraging, showing the novel composite having a lower wear rate.

scholarly journals Exhaustive reconstruction of the CRISPR locus in Mycobacterium tuberculosis complex using short reads

2019 ◽  
Author(s):  
Christophe Guyeux ◽  
Christophe Sola ◽  
Guislaine Refrégier
Keyword(s):  
Mycobacterium Tuberculosis ◽  
In Silico ◽  
Structural Characteristics ◽  
Computational Method ◽  
Direct Repeats ◽  
Crispr Locus ◽  
Short Read ◽  
General Rules ◽  
Genetic Mechanisms

AbstractSpoligotyping, a graphical partial display of the CRISPR locus that can be produced in vitro or in silico, is an important tool for analyzing the diversity of given Mycobacterium tuberculosis complex (MTC) isolates. As other CRISPR loci, this locus is made up of an alternation between direct repeats and spacers, and flanked by cas genes. Unveiling the genetic mechanisms of its evolution requires to have a fairly large amount of fully reconstructed loci among all MTC lineages.In this article, we point out and resolve the problem of CRISPR reconstruction based on short read sequences. We first show that more than 1/3 of the currently assembled genomes available for this complex contain a CRISPR locus erroneously reconstructed, and errors can be very significant. Second, we present a new computational method allowing this locus to be reconstructed extensively and reliably in silico using short read sequencing runs. Third, using this method, we describe new structural characteristics of CRISPR locus by lineages. We show how both the classical experimental in vitro approach and the basic in silico spoligotyping provided by existing analytic tools miss a whole diversity of this locus in MTC, by not capturing duplications, spacer and direct repeats variants, and IS6110 insertion locations. This description is extended in a second article that presents general rules for the evolution of the CRISPR locus in MTC.This work opens new perspectives for a larger exploration of CRISPR loci diversity and of mechanisms involved in its evolution and its functionality.

Experimental Investigations on Noise Attenuation of a Twin Cylinder Stationary Diesel Engine with Different Types of Mufflers

1999 ◽  
Vol 121 (3) ◽  
pp. 351-354
Author(s):  
B. K. Venkanna ◽  
Swati B. Wadawadagi
Keyword(s):  
Diesel Engine ◽  
Engine Performance ◽  
Noise Pollution ◽  
Sound Attenuation ◽  
Control Measures ◽  
Experimental Investigations ◽  
Human Society ◽  
Load Range ◽  
Wide Range ◽  
Exhaust Line

Together with atmospheric and water pollution, noise pollution is threatening human society with vehicles constituting the major source of noise. The available literature on control measures (1, 2, 3) indicates purely reactive mufflers in general are of more use for fixed speed machinery and dissipative attenuators have the ability to filler out acoustic energies over a wide range of frequencies. This paper presents cm attempt made to use a combination of these major types of mufflers fitted in the exhaust line of a four stroke, twin cylinder stationary diesel engine to attenuate exhaust noise to an acceptable level. A sound attenuation of 19 dBA has been obtained for combined reactive and dissipative (Model—M2, loosely packed with glass wool) attenuator through entire the load range without affecting the engine performance and a sound attenuation of 21 dBA has been obtained for reactive (with baffle plate. Model—M3) muffler through the entire load range with a nominal increase in BSFC at higher loads.

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