Representative Strain of Indentation Analysis

2005 ◽  
Vol 20 (8) ◽  
pp. 2225-2234 ◽  
Author(s):  
Nagahisa Ogasawara ◽  
Norimasa Chiba ◽  
Xi Chen
Keyword(s):  
Mechanical Properties ◽  
Stress State ◽  
Work Hardening ◽  
Biaxial Loading ◽  
Representative Strain ◽  
Indentation Analysis ◽  
Reverse Analysis ◽  
Engineering Materials ◽  
Definition Of ◽  
New Formulation

Indentation analysis based on the concept of representative strain offers an effective way of obtaining mechanical properties, especially work-hardening behavior of metals, from reverse analysis of indentation load–displacement data, and does not require measuring of the projected contact area. The definition of representative strain adopted in previous studies [e.g., Dao et al., Acta Mater.49, 3899 (2001)] has a weak physical basis, and it works only for a limited range in some sense of engineering materials. A new indentation stress-state based formulation of representation is proposed in this study, which is defined as the plastic strain during equi-biaxial loading. Extensive numerical analysis based on the finite element method has shown that with the new formulation of representative strain and representative stress, the critical normalized relationship between load and material parameters is essentially independent of the work-hardening exponent for all engineering materials, and the results also hold for three distinct indenter angles. The new technique is used for four materials with mechanical properties outside the applicable regime of previous studies, and the reverse analysis has validated the present analysis. The new formulation based on indentation stress-state based definition of representative strain has the potential to quickly and effectively measure the mechanical properties of essentially all engineering materials as long as their constitutive behavior can be approximated into a power-law form.

scholarly journals Reverse Analysis for Determining the Mechanical Properties of Zeolite Ferrierite Crystal

2008 ◽  
Vol 2008 ◽  
pp. 1-7 ◽  
Author(s):  
J. Lin ◽  
X. Y. Niu ◽  
X. F. Shu
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Single Crystal ◽  
Numerical Simulations ◽  
Work Hardening ◽  
Mechanical Parameters ◽  
Stress Strain Relation ◽  
Work Hardening Rate ◽  
Nanoindentation Experiment ◽  
Reverse Analysis

In order to explore more mechanical properties of zeolite Ferrierite (FER) single crystal, a method of determining its mechanical properties—nanoindentation reverse analysis—was obtained based on the nanoindentation experiment and numerical simulations, and this will be presented in this paper. The yield stress and the characteristic work-hardening rate were gained if its stress-strain relation was a bilinear constitutive relation. The mechanical parameters obtained by reverse analysis have been compared with ones gained by nanoindentation finite-element numerical simulations.

Further investigation on the definition of the representative strain in conical indentation

2006 ◽  
Vol 21 (7) ◽  
pp. 1810-1821 ◽  
Author(s):  
Yanping Cao ◽  
Norbert Huber
Keyword(s):  
Material Properties ◽  
Limited Range ◽  
Representative Strain ◽  
Plastic Materials ◽  
Acta Mater ◽  
Engineering Materials ◽  
Definition Of ◽  
High Level ◽  
Highly Elastic Materials ◽  
Conical Indentation

Further investigation on the definition of the representative strain in conical indentation was performed in this work. In particular, the representative strains proposed in the work of Cao et al. [J. Mater. Res.20, 1194 (2005)] and Ogasawara et al. [J. Mater. Res.20, 2225 (2005)] were discussed in detail. For the method using the energy-based representative strain [Cao et al., J. Mater. Res.20, 1194 (2005)], it is shown that it can be extended to a wider range of material properties (from nearly fully plastic materials to highly elastic materials). For the stress-state-based definition of the representative strain, we found, in contrast with the results reported in the work of Ogasawara et al. [J. Mater. Res.20, 2225 (2005)], that similar to the constant representative strain reported by Dao et al. [Acta Mater.49, 3899 (2001)], it works well only for a limited range of engineering materials. Based on this premise, novel definitions of the representative strain, which can lead to a one-to-one relationship with high level of accuracy between the reduced Young's modulus, the indentation loading curvature, and the representative stress are further presented. Detailed numerical analysis performed on nine kinds of engineering materials verified the effectiveness of the proposed representative strains and corresponding dimensionless functions. Experimental verification using the data for the ultrafine crystalline Ni further showed that the results reported in this paper have the potential to be applied in practice.

scholarly journals Discrete Element Simulation Analysis of Biaxial Mechanical Properties of Concrete with Large-Size Recycled Aggregate

2021 ◽  
Vol 13 (13) ◽  
pp. 7498
Author(s):  
Tan Li ◽  
Jianzhuang Xiao
Keyword(s):  
Mechanical Properties ◽  
Stress State ◽  
Strain Curve ◽  
Confining Pressure ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Aggregate Model ◽  
Large Size

Concrete made with large-size recycled aggregates is a new kind of recycled concrete, where the size of the recycled aggregate used is 25–80 mm, which is generally three times that of conventional aggregate. Thus, its composition and mechanical properties are different from that of conventional recycled concrete and can be applied in large-volume structures. In this study, recycled aggregate generated in two stages with randomly distributed gravels and mortar was used to replace the conventional recycled aggregate model, to observe the internal stress state and cracking of the large-size recycled aggregate. This paper also investigated the mechanical properties, such as the compressive strength, crack morphology, and stress–strain curve, of concrete with large-size recycled aggregates under different confining pressures and recycled aggregate incorporation ratios. Through this research, it was found that when compared with conventional concrete, under the confining pressure, the strength of large-size recycled aggregate concrete did not decrease significantly at the same stress state, moreover, the stiffness was increased. Confining pressure has a significant influence on the strength of large-size recycled aggregate cocrete.

scholarly journals Large-Eddy Simulation Analyses of Heated Urban Canyon Facades

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3078
Author(s):  
Carlo Cintolesi ◽  
Francesco Barbano ◽  
Silvana Di Sabatino
Keyword(s):  
Urban Canopy ◽  
Pollutant Removal ◽  
Present Contribution ◽  
Convective Flows ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Isothermal Case ◽  
Definition Of ◽  
New Formulation ◽  
Heating Up

Thermal convective flows are common phenomena in real urban canyons and strongly affect the mechanisms of pollutant removal from the canyon. The present contribution aims at investigating the complex interaction between inertial and thermal forces within the canyon, including the impacts on turbulent features and pollutant removal mechanisms. Large-eddy simulations reproduce infinitely long square canyons having isothermal and differently heated facades. A scalar source on the street mimics the pollutant released by traffic. The presence of heated facades triggers convective flows which generate an interaction region around the canyon-ambient interface, characterised by highly energetic turbulent fluxes and an increase of momentum and mass exchange. The presence of this region of high mixing facilitates the pollutant removal across the interface and decreases the urban canopy drag. The heating-up of upwind facade determines favourable convection that strengthens the primary internal vortex and decreases the pollutant concentration of the whole canyon by 49% compare to the isothermal case. The heating-up of the downwind facade produces adverse convection counteracting the wind-induced motion. Consequently, the primary vortex is less energetic and confined in the upper-canyon area, while a region of almost zero velocity and high pollution concentration (40% more than the isothermal case) appears at the pedestrian level. Finally, numerical analyses allow a definition of a local Richardson number based on in-canyon quantities only and a new formulation is proposed to characterise the thermo-dynamics regimes.

Analysis of Two Cross Arm of Reactive Powder Concrete Pole Design with Structure Materials in Civil Engineering

2012 ◽  
Vol 568 ◽  
pp. 39-42
Author(s):  
Yu Zhuo Jia ◽  
Li Lin
Keyword(s):  
Mechanical Properties ◽  
Stress State ◽  
Structural Analysis ◽  
Transmission Line ◽  
Operating Conditions ◽  
Reactive Powder Concrete ◽  
Analysis Software ◽  
Technical Performance ◽  
Reduced Height ◽  
Reactive Powder

SAP2000 structural analysis software is used to designed two of 500kV partially prestressed reactive powder concrete pole cross arm; moreover, poles of the two cross arm program have been compared. The results show that the triangular truss cross arm has good mechanical properties, improving the main mate’rial of the stress state, the pole reduced height 10m, by the analysis of the structure shows, this cross arm has higher reliability under the operating conditions, which can be used in 500kV transmission line; from economic and technical performance, the pole cost of this program is greatly reduced, while speeding up the construction progress and improving the comprehensive benefits of the poles in the transmission line.

Effect of Ferrite Volume Fraction on Mechanical Properties of X80 Pipeline Steel

2014 ◽  
Vol 989-994 ◽  
pp. 212-215
Author(s):  
J. Liu ◽  
G. Zhu ◽  
W. Mao
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Work Hardening ◽  
Single Phase ◽  
Volume Fraction ◽  
Pipeline Steel ◽  
X80 Pipeline Steel ◽  
Hardening Behavior ◽  
Two Phases ◽  
Better Than

The effect of volume fraction of ferrite on the mechanical properties including strength, plasticity and wok hardening was systematically investigated in X80 pipeline steel in order to improve the plasticity. The microstructures with different volume fraction of ferrite and bainite were obtained by heat-treatment processing and the mechanical properties were tested. The work hardening behavior was analyzed by C-J method. The results show that the small amount of ferrite could effectively improve the plasticity. The work hardening ability and the ratio of yield/tensile strength with two phases of ferrite/bainite would be obviously better than that with single phase of bainite. The improvement of plasticity could be attributed to the ferrite in which more plastic deformation was afforded.

scholarly journals Influence of Steel Grain Size on Residual Stress in Grinding Processing

2010 ◽  
Vol 638-642 ◽  
pp. 2389-2394 ◽  
Author(s):  
Masahide Gotoh ◽  
Katsuhiro Seki ◽  
M. Shozu ◽  
Hajime Hirose ◽  
Toshihiko Sasaki
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Grain Size ◽  
Stress State ◽  
Mechanical Grinding ◽  
Fine Grained ◽  
Residual Stress State ◽  
Analysis Methods ◽  
Average Grain Size ◽  
Fine Grained Steels

The fine-grained rolling steels NFG600 and the conventional usual rolling steels SM490 were processed by sand paper polishing and mechanical grinding to compare the residual stress generated after processing. The average grain size of NFG600 and SM490 is 3 μm and 15μm respectively. Therefore improvement of mechanical properties for such fine-grained steels is expected, it is important to understand the residual stress state of new fine-grained materials with processing. In this study, multi axial stresses of two kinds of specimens after polishing and grinding were measured by three kinds of analysis methods including cos-ψ method. As a result, as for σ33, the stress of NFG was compression, though that of SM490 was tension.

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