scholarly journals Application of indentation fracture mechanics approach for determination of fracture toughness of brittle polymer systems

2007 ◽  
Vol 26 (1) ◽  
pp. 51-59 ◽  
Author(s):  
Ralf Lach ◽  
Lada Antonova Gyurova ◽  
Wolfgang Grellmann
Keyword(s):  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Indentation Fracture ◽  
Polymer Systems ◽  
Brittle Polymer

scholarly journals Fracture Toughness Evaluation of S355 Steel Using Circumferentially Notched Round Bars

2018 ◽  
Vol 47 (2) ◽  
pp. 91-95 ◽  
Author(s):  
Fatih Bozkurt ◽  
Eva Schmidová
Keyword(s):  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Compact Tension ◽  
Compact Tension Specimen ◽  
Fracture Load ◽  
Alternative Methods ◽  
Test Procedures ◽  
Toughness Evaluation ◽  
Fracture Toughness Evaluation

In engineering applications, steels are commonly used in various areas. The mechanical members are exposed to different loading conditions and this subject can be investigated in fracture mechanics. Fracture toughness (KIC) is the important material property for fracture mechanics. Determination of this properties is possible using a compact tension specimen, a single edge notched bend or three-point loaded bend specimen, which are standardized by different institutions. Researchers underline that these standardized methods are complex, the manufacturing process is difficult, they require special fixtures for loading during the experiment and the test procedures are time consuming. Alternative methods are always being sought by researchers. In this work, two different approaches are investigated for S355 steels. In the first method, a circumferentially cracked round bar was loaded in tensile mode and pulled till failure. Using suitable equations, fracture toughness can be calculated. In the second method, a circumferentially notched bar specimen without fatigue pre-cracking was loaded in a tensile machine. By means of fracture load values, fracture toughness was determined by the proposed equations. It can be stated that these two different approaches for calculating fracture toughness are simple, fast and economical.

Nanoindentation Assessed Fracture Toughness of Cement Paste

2016 ◽  
Vol 368 ◽  
pp. 186-189 ◽  
Author(s):  
Jiří Němeček ◽  
Vladimír Hrbek
Keyword(s):  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Fracture Energy ◽  
Cement Paste ◽  
Quantitative Data ◽  
Brittle Materials ◽  
Fracture Properties ◽  
Micro Scale ◽  
Energetic Approach

This paper deals with fracture properties of microlevel components of hydrated cementpaste. Determination of fracture energy and fracture toughness for quasi-brittle materials hasbecome a challenge for many years on both macro- and micro-scales. Limited number of quantitative data can be found in the literature for the micro-scale. This work uses energetic approach and decomposition of work of indentation into plastic and other parts. Based on simplified assumptions fracture energy and fracture toughness are calculated for individual microstructural phases of cement paste with the aid of nanoindentation, statistical deconvolution and fracture mechanics.

Analysis of the Influence of Microstructure Heterogeneity and Mechanical Properties of Welded Joint Constituents on Fracture Toughness for Plane Strain, KIc

2011 ◽  
Vol 488-489 ◽  
pp. 617-620
Author(s):  
Ivica Čamagić ◽  
Nemanja Vasić ◽  
Zijah Burzić ◽  
Aleksandar Sedmak
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Plane Strain ◽  
Welded Joint ◽  
Crack Tip ◽  
Critical Areas ◽  
Theoretical Assumptions ◽  
Geometrical Form

The problem of fracture toughness, KIc, determination at a crack tip localized in a welded joint is placed in principle because fracture mechanics assumes homogenous material, not only around the crack tip but on a distance from it, in order to maintain valid theoretical assumptions and importance of the fracture toughness as the property measured by some of the fracture mechanics methods. Welded joint, as an integral part of a structure, represents inhomogeneity by microstructure and mechanical properties, often by geometrical form, and by the stress field as well, which are affected by various factors as well as residual stresses after welding [1]. However, these general difficulties did not disenable experimental determination of the fracture toughness under plane strain, KIc, in certain critical areas of a welded joint, or welded joint as a whole, but rather there are difficulties in interpreting the meaning of the measured values. Specimens for the fracture mechanics parameters determination are specimens with cracks, and cracks appears in welded joints as the most critical defects.

Comparison of R-Curve Behavior of Si3N4 Measured by Indentation Method and Single-Edge V-Notched Beam Technique (SEVNB)

2009 ◽  
Vol 409 ◽  
pp. 308-312
Author(s):  
Jana Špaková ◽  
Ján Dusza
Keyword(s):  
Fracture Toughness ◽  
Crack Opening ◽  
Single Edge ◽  
Indentation Fracture ◽  
Indentation Method ◽  
Indentation Toughness ◽  
Indentation Fracture Toughness ◽  
Beam Technique

Study compare R-curve behaviour of silicon nitride obtained using Vickers indented beam specimens and single edge V-notched beam (SEVNB). R-curve measurement realized by Vickers indented beam was reported by Krause. Crack growth using single edge V-notched beam was observed in situ. The indentation experiments, in comparison with SEVNB method revealed higher R-curve values (KR=3.3 – 4.8 MPa.m1/2). The discrepancy in the R-curve results is attributed to inaccuracy related to the determination of indentation toughness. The indentation fracture toughness may include the aspects of crack opening behaviour, residual indentation stress intensity.

scholarly journals Fracture toughness of old bridge steel

2013 ◽  
Vol 12 (1) ◽  
pp. 251-258
Author(s):  
Eliza Mytych-Kumańska ◽  
Paweł Kossakowski
Keyword(s):  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Critical Values ◽  
Steel Bridge ◽  
Railway Bridge ◽  
Bridge Steel ◽  
The Subject ◽  
Material Fracture

The subject of paper is related to problems the of fracture toughness of old steel bridge which was taken from the railway bridge, that was loaded during more than 100 years. The basic problems of fracture mechanics, as well as detailed information on the procedures of determination of material fracture toughness, which were used in the steel bridge research, are presented. The results of the study, the critical values of JQ integral, defining the fracture toughness of investigated steel are discussed.

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