Identifying Elastic Properties of Isotropic Materials by Finite Element Analyses and Vibration Data

2007 ◽  
Vol 345-346 ◽  
pp. 1327-1330 ◽  
Author(s):  
Marco Alfano ◽  
Leonardo Pagnotta ◽  
Giambattista Stigliano
Keyword(s):  
Finite Element ◽  
Error Function ◽  
Finite Element Analyses ◽  
Vibration Testing ◽  
Isotropic Materials ◽  
Vibration Data ◽  
The Difference ◽  
Optimizing Algorithm ◽  
Non Destructive

The use of non destructive techniques for the elastic characterization of isotropic materials is continuously increasing and those based on the modal vibration testing of plate-like specimens is very widespread. In the present paper, an optimized search procedure is proposed which allows the material constants of isotropic plates to be non-destructively identified from vibration testing data and using finite element analyses. The identification process is performed by an optimizing algorithm in which the error function to be minimized depends on the difference between the natural frequencies obtained by finite element analyses and the measured ones. In order to verify the proposed identification procedure a comparison with the results reported in literature has been made.

Characterization of Ni- and Ni(Pt)-Silicide Formation on Narrow Polycrystalline Si Lines by Raman Spectroscopy

1999 ◽  
Vol 591 ◽  
Author(s):  
P. S. Lee ◽  
D. Mangelinck ◽  
K. L. Pey ◽  
J. Ding ◽  
T. Osipowicz ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Raman Spectroscopy ◽  
Raman Mapping ◽  
Silicide Formation ◽  
Nucleation Sites ◽  
The Difference ◽  
The Stability ◽  
Non Destructive ◽  
Thermal Stability Of

ABSTRACTThe formation and thermal stability of Ni- and Ni(Pt) silicide on narrow polycrystalline Si (poly-Si) lines have been investigated using the non-destructive micro-Raman technique. The presence of Ni or Ni(Pt)Si on poly-Si lines with linewidths ranging from 0.5 gtm to 0.25 μm has been monitored by a distinct Raman peak at around 215 cm−1. Ni(Pt)Si was clearly identified to be present up to a RTA temperature of 900°C on narrow poly-Si lines as compared to pure NiSi which was found only up to 750°C. Raman scattering from the 100×100 μm2 poly-Si pads showed the formation of NiSi2 at 750°C for pure Ni-salicidation and 900°C for Ni(Pt)-salicidation respectively. The difference in the stability of NiSi on the poly-Si pads and lines is discussed in terms of agglomeration, inversion and/or nucleation of NiSi2that could be due to difference in nucleation sites and/or stress. In addition, a correlation between the line sheet resistance and the presence of Ni silicide was found using micro-Raman mapping along single poly-Si lines.

Finite Element Analyses of Elasto-Plastic Deformation in Pearlite Lamellar and Colony Structures

2014 ◽  
Vol 626 ◽  
pp. 307-310 ◽  
Author(s):  
Roslan Lidyana ◽  
Tetsuya Ohashi ◽  
Yohei Yasuda ◽  
Kohsuke Takahashi ◽  
Chikara Suruga
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
Plastic Strain ◽  
Thickness Ratio ◽  
Lamellar Thickness ◽  
Finite Element Analyses ◽  
Lamellar Orientation ◽  
The Difference

Elasto-plastic tensile deformations in pearlite lamellar and two-colony structures are studied by finite element analyses to investigate the effects of lamellar thickness ratio and difference of lamellae orientation of two colonies in pearlite microstructure. The results obtained from plastic strain distributions in lamellar and colony structures show that plastic deformation in cementite lamellar stabilized when ferrite lamellar is thicker than cementite lamellar thickness and plastic strain concentrates when the difference between cementite lamellar orientation in two colonies are larger than 45°.

scholarly journals Finite element modeling of nanoindentation on an elastic-plastic microsphere

2020 ◽  
Author(s):  
Jialian Chen ◽  
Hongzhou Li
Keyword(s):  
Finite Element ◽  
Mechanical Behavior ◽  
Computational Study ◽  
Theoretical Method ◽  
Finite Element Analyses ◽  
Structured Materials ◽  
Elastic Plastic ◽  
Element Simulation ◽  
Insight Into

Abstract The understanding of the mechanical indentation on a curved specimen (e.g., microspheres and microfibers) is of paramount importance in the characterization of curved micro-structured materials, but there has been no reliable theoretical method to evaluate the mechanical behavior of nanoindentation on a microsphere. This article reports a computational study on the instrumented nanoindentation of elastic-plastic microsphere materials via finite element simulation. The finite element analyses indicate that all loading curves are parabolic curves and the loading curve for different materials can be calculated from one single indentation. The results demonstrate that the Oliver-Pharr formula is unsuitable for calculating the elastic modulus of nanoindentation involving cured surfaces. The surface of the test specimen of a microsphere requires prepolishing to achieve accurate results of indentation on a micro-spherical material. This study provides new insight into the establishment of nanoindentation models that can effectively be used to simulate the mechanical behavior of a microsphere.

The Destructive High Pressure Tests of Cylindrical Shells

2002 ◽  
Author(s):  
Yasumi Kitajima ◽  
Satoru Shibata
Keyword(s):  
Finite Element ◽  
Prestressed Concrete ◽  
General Structure ◽  
Limit State ◽  
Cylindrical Shells ◽  
Weld Line ◽  
Finite Element Analyses ◽  
State Tests ◽  
The Difference ◽  
State Pressure

We conducted the limit state tests of cylindrical shells to establish criteria for the occurrence of steel wall/liner tearing in the reactor containment vessels (such as Steel Containment Vessels (SCV), Prestressed Concrete Containment Vessels (PCCV) and Reinforced Concrete Containment Vessels (RCCV)) under the limit state pressure. In the tests, precisely manufactured cylindrical shell vessels (about 800 mm in height and 300 mm in diameter) were pressurized to the failure using water. We also conducted the finite element analyses. The conclusions are as follows: 1. We obtained good agreement (within 2–3%) between the tests and the analyses in structural behavior such as internal pressure loading vs. displacement and strain to the failure. However, in the case of the test piece which included weld line on the cylindrical wall, the difference between the tests and the analyses was larger (about 1.5 times) than the rest. 2. The localized strains began to increase when radial strains in general structure reached 5–10%. We are intended to apply these results to the finite element analyses and the integrity evaluation of containment vessels (SCV, PCCV and RCCV).

scholarly journals Effects of Flotage on Immersion Indentation Results of Bone Tissue: An Investigation by Finite Element Analysis

2017 ◽  
Vol 2017 ◽  
pp. 1-7
Author(s):  
Mingxing Zhou ◽  
Zunqiang Fan ◽  
Zhichao Ma ◽  
Yue Guo ◽  
Liguo Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Nanoindentation Test ◽  
Liquid Media ◽  
Depth Sensing ◽  
Element Analysis ◽  
Fea Simulation ◽  
The Difference

In reality, nanoindentation test is an efficient technique for probing the mechanical properties of biological tissue that soaked in the liquid media to keep the bioactivity. However, the effects of flotage imposed on the indenter will lead to inaccuracy when calculating mechanical properties (for instance, elastic modulus and hardness) by using depth-sensing nanoindentation. In this paper, the effects of flotage on the nanoindentation results of cortical bone were investigated by finite element analysis (FEA) simulation. Comparisons of nanoindentation simulation results of bone samples with and without being soaked in the liquid media were carried out. Conclusions show that the difference of load-displacement curves in the case of soaking sample and without soaking sample conditions varies widely based on the change of indentation depth. In other words, the nanoindentation measurements in liquid media will cause significant error in the calculated Young’s modules and hardness due to the flotage. By taking into account the effect of flotage, these errors are particularly important to the accurate biomechanics characterization of biological samples.

New Development in Studies on the Characteristics of Bolted Pipe Flange Connections in JPVRC

2005 ◽  
Vol 128 (1) ◽  
pp. 103-108 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Satoshi Nagata ◽  
Hirokazu Tsuji
Keyword(s):  
Finite Element ◽  
Contact Stress ◽  
Bending Moment ◽  
Stress Distributions ◽  
Finite Element Analyses ◽  
Flange Connection ◽  
Load Factors ◽  
Bolt Preload ◽  
New Development ◽  
The Difference

This paper deals with some studies carried out in the bolted flanged connection committee (BFC) in Japan Pressure Vessel Council (JPVRC) on the stress analysis of a pipe flange connection using the elastoplastic finite element method. The characteristics of the connections with the different nominal diameters from 2in. to 20in. such as the contact gasket stress distribution, the hub stress, and the load factors were examined. The results from the finite element analyses were fairly consistent with the experimental results concerning the variation in the axial bolt force. By using the contact stress distributions and the results of the leakage test, the new gasket constants were evaluated. As a result, it was found that the variations in the contact stress distributions were substantial due to the flange rotation in the pipe flange connections with the larger nominal diameter. A method to determine the bolt preload for a given tightness parameter was demonstrated and the difference in the bolt preload between our research and PVRC was shown. In addition, the characteristics of pipe flange connection under a bending moment and internal pressure were also discussed and a newly developed bolt tightening method was demonstrated.

scholarly journals Analysis of the Main Aspects Affecting Bonding in Stainless Steel Rebars Embedded in a Hydraulic Medium

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 786
Author(s):  
Fernando Ancio ◽  
Esperanza Rodriguez-Mayorga ◽  
Beatriz Hortigon
Keyword(s):  
Finite Element ◽  
Stainless Steel ◽  
Boundary Conditions ◽  
Masonry Structures ◽  
Finite Element Analyses ◽  
Pull Out ◽  
Mathematical Expressions ◽  
Special Circumstances ◽  
Steel Rebars

The use of stainless steel rebars to reinforce masonry structures has become established as an eminently efficient methodology. From among the numerous techniques available, bed-joint structural repointing and superficial reinforcement with rebars or meshes attached to surfaces have become widespread, thanks to the excellent results they have produced in recent decades. Both techniques imply the use of diameters less than 6 mm and thin coverings. This article deals with the characterization of the bonding behavior of the rebar under these special circumstances. To this end, several finite element analyses have been carried out to identify the possible relationships between pull-out forces in various situations. These models allow certain conclusions to be drawn regarding the influence of the thickness of covering, boundary conditions, and geometrical aspects of the rebars in bonding. Certain mathematical expressions that relate the various conclusions from this research are finally laid out.

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