Practical Evaluation of the Strain Rate and Temperature Effects on Fracture Toughness of Steels

2015 ◽  
Author(s):  
Koji Gotoh
Keyword(s):  
Fracture Toughness ◽  
Strain Rate ◽  
Static Loading ◽  
Temperature Effects ◽  
Loading Condition ◽  
Temperature Shift ◽  
Evaluation Procedure ◽  
Practical Evaluation ◽  
Temperature Parameter ◽  
Properties Of Materials

Overview of the quantitative evaluation procedure of strain rate and temperature effects on fracture toughness proposed by the authors is introduced. Important concept of former researches is that the fracture toughness is a function of the strain rate-temperature parameter (R), which enables to unify both strain rate and temperature effects for the mechanical properties of materials. Using this knowledge, the equivalent temperature shift values at arbitrary strain rate from static loading condition are proposed.

Microstructural and fractographic characterization of B4C-Al cermets tested under dynamic and static loading

1989 ◽  
Vol 47 ◽  
pp. 562-563
Author(s):  
Gyeung Ho Kim ◽  
Mehmet Sarikaya ◽  
D. L. Milius ◽  
I. A. Aksay
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Static Loading ◽  
Carbon Deposition ◽  
Full Density ◽  
Unique Combination ◽  
Strong Component ◽  
Reaction Products

Cermets are designed to optimize the mechanical properties of ceramics (hard and strong component) and metals (ductile and tough component) into one system. However, the processing of such systems is a problem in obtaining fully dense composite without deleterious reaction products. In the lightweight (2.65 g/cc) B4C-Al cermet, many of the processing problems have been circumvented. It is now possible to process fully dense B4C-Al cermet with tailored microstructures and achieve unique combination of mechanical properties (fracture strength of over 600 MPa and fracture toughness of 12 MPa-m1/2). In this paper, microstructure and fractography of B4C-Al cermets, tested under dynamic and static loading conditions, are described.The cermet is prepared by infiltration of Al at 1150°C into partially sintered B4C compact under vacuum to full density. Fracture surface replicas were prepared by using cellulose acetate and thin-film carbon deposition. Samples were observed with a Philips 3000 at 100 kV.

Comparative Analysis of Fracture Toughness Obtained by Different Techniques in Alumina Matrix - Dispersed TZP Zirconia Composites

2016 ◽  
Vol 869 ◽  
pp. 46-51
Author(s):  
Daniel Alessander Nono ◽  
Eron Fernandes da Silva ◽  
Maria do Carmo de Andrade Nono ◽  
Francisco Piorino Neto ◽  
Sergio Luiz Mineiro
Keyword(s):  
Fracture Toughness ◽  
Tetragonal Zirconia ◽  
Ceramic Composites ◽  
Alumina Matrix ◽  
Single Edge ◽  
Chemical Inertness ◽  
Edge Notch ◽  
Properties Of Materials ◽  
Experimental Values ◽  
Benefit Cost

The fracture toughness is one of the requirements for mechanical properties of materials for use in satellites. The ceramic TZP zirconia (tetragonal zirconia polycrystals) have been investigated for applications in ballistic armor. Due to the chemical inertness and fracture toughness, this material has the potential to act as a screen against impacts of micrometeorites and space debris. The ceramic composites of alumina-zirconia 3Y-TZP (tetragonal zirconia polycrystals doped with 3 mol% ytria ) are the materials with the best benefit / cost for this application. This paper presents and discusses the results obtained from the use of two techniques for determining fracture toughness. The composite alumina - 18.5% of 3Y-TZP zirconia nanoparticles obtained from deflocculated powders have been tested for Vickers and the SEVNB penetration method (Single-Edge-Notch Beam V) to obtain the fracture toughness values (KIC). The KIC values obtained were analyzed due to the lower dispersion of experimental values. The SEVNB method showed better reliability in determining the toughness values in the studied ceramics.

A Newly Developed Clamping Device for the Tension/Compression Test at Various Strain Rates

2014 ◽  
Vol 626 ◽  
pp. 353-358
Author(s):  
Geun Su Joo ◽  
Min Kuk Choi ◽  
Hoon Huh
Keyword(s):  
Strain Rate ◽  
Sheet Metal ◽  
Metal Forming ◽  
Loading Condition ◽  
Strain Rates ◽  
Compression Tests ◽  
Compression Behavior ◽  
Compression Loading ◽  
Hardening Behavior ◽  
Clamping Device

The tension/compression hardening behavior is important in sheet metal forming processes because of complicated loading paths. Experimental methods to measure the tension/ compression behavior have not considered the effect of the strain rate although the strain rate is related to the hardening behavior of sheet metal. The tension/compression tests need to be conducted considering the strain rate to acquire accurate hardening behavior.This paper deals with an experimental technique to measure the tension/compression behavior of sheet metal at various strain rates. A new clamping device was developed to prevent a sheet specimen from buckling under compression loading condition. Compared to previous clamping devices, the clamping device was devised to uniformly impose a clamping force and easily measure the strain from side of a specimen. Tension/compression tests have been conducted at various strain rates for SPCC and DP590 with displacement of 10%. Hardening curves under the tension or compression loading condition were obtained and analyzed with respect to the strain rate.

Temperature effects on anaphase chromosome movement in the spermatocytes of two species of crane flies (Nephrotoma suturalis Loew and Nephrotoma ferruginea Fabricius)

1979 ◽  
Vol 39 (1) ◽  
pp. 29-52
Author(s):  
C.J. Schaap ◽  
A. Forer
Keyword(s):  
Sex Chromosomes ◽  
Temperature Effects ◽  
Sex Chromosome ◽  
Beat Frequency ◽  
General Pattern ◽  
Force Production ◽  
Temperature Shift ◽  
Ciliary Beat Frequency ◽  
Chromosome Movement ◽  
Flagellar Beat

Using phase-contrast cinemicrography on living crane fly (Nephrotoma suturalis Loew and Nephrotoma ferruginea Fabricius) spermatocytes, we have studied the effects of a range of temperatures (6–30 degrees C) on the anaphase I chromosome-to-pole movements of both autosomes and sex chromosomes. In contrast to previous work we have been able to study chromosome-to-pole velocities of autosomes without concurrent pole-to-pole elongation. In these cells we found that the higher the temperature, the faster was the autosomal chromosomes movement. From reviewing the literature we find that the general pattern of the effects of temperature on chromosome movement is similar whether or not pole-to-pole elongation occurs simultaneously with the chromosome-to-pole movement. Changes in cellular viscosities calculated from measurements of particulate Brownian movement do not seem to be able to account for the observed velocity differences due to temperature. Temperature effects on muscle contraction speed, flagellar beat frequency, ciliary beat frequency, granule flow in nerves, and chromosome movement have been compared, as have the activation energies for the rate-limiting steps in these motile systems: no distinction between possible mechanisms of force production is possible using these comparisons. The data show that even the different autosomes within single spermatocytes usually move at different speeds. These velocity differences cannot simply be related to chromosome size as the autosomes are visually indistinguishable. The sex chromosomes start their anaphase poleward movement after that of the autosomes, and move more slowly (by a factor of about 4), but their velocities appear to be affected by temperature in the same fashion as those of the autosomes. The interval between the onset of autosome anaphase and sex chromosome anaphase is also affected by temperature: the higher the temperature, the shorter the interval between the 2 stages. We have observed abnormalities in sex chromosome segregation, which may be due to temperature, but have not determined what the exact temperature shift conditions are that cause these abnormalities.

scholarly journals Rate-dependent ductile fracture under plane strain tension: experiments and simulations

2018 ◽  
Vol 183 ◽  
pp. 02022
Author(s):  
Vincent Grolleau ◽  
Vincent Lafilé ◽  
Christian C. Roth ◽  
Bertrand Galpin ◽  
Laurent Mahéo ◽  
...  
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Plane Strain ◽  
Static Loading ◽  
High Strain ◽  
Fracture Initiation ◽  
Surface Strain ◽  
Experimental Program ◽  
Loading Conditions ◽  
Plane Strain Tension

Among all other stress states achievable under plane stress conditions, the lowest ductility is consistently observed for plane strain tension. For static loading conditions, V-bending of small sheet coupons is the most reliable way of characterising the strain to fracture for plane strain tension. Different from conventional notched tension specimens, necking is suppressed during V-bending which results in a remarkably constant stress state all the way until fracture initiation. The present DYMAT talk is concerned with the extension of the V-bending technique from low to high strain rate experiments. A new technique is designed with the help of finite element simulations. It makes use of modified Nakazima specimens that are subjected to V-bending. Irrespective of the loading velocity, plane strain tension conditions are maintained throughout the entire loading history up to fracture initiation. Experiments are performed on specimens extracted from aluminum 2024-T3 and dual phase DP450 steel sheets. The experimental program includes quasi static loading conditions which are achieved on a universal testing machine. In addition, high strain rate experiments are performed using a specially-designed drop tower system. In all experiments, images are acquired with two cameras to determine the surface strain history through stereo Digital Image Correlation (DIC). The experimental observations are discussed in detail and also compared with the numerical simulations to validate the proposed experimental technique

scholarly journals Strain rate and temperature effects on the selection of primary and secondary slip and twinning systems in HCP Zr

2015 ◽  
Vol 88 ◽  
pp. 55-73 ◽  
Author(s):  
Marko Knezevic ◽  
Milovan Zecevic ◽  
Irene J. Beyerlein ◽  
John F. Bingert ◽  
Rodney J. McCabe
Keyword(s):  
Strain Rate ◽  
Temperature Effects ◽  
Secondary Slip ◽  
Selection Of
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