Determination of Fracture Toughness by Single and Double Action Tensile Impact Fracture Tests

2016 ◽  
Vol 715 ◽  
pp. 101-106
Author(s):  
Zoltan Major ◽  
Matei Miron ◽  
Imre Kallai
Keyword(s):  
Fracture Toughness ◽  
Fracture Behavior ◽  
Loading Rate ◽  
Testing Machine ◽  
Peak Load ◽  
High Rate ◽  
Test Set ◽  
Data Scatter ◽  
Fracture Tests ◽  
Set Up

The characterization of the loading rate dependence of the fracture behavior of polymers is of prime theoretical and practical interest for supporting demanding engineering applications. To gain more insight into the high rate fracture behavior of polymers, fracture tests were performed under tensile loading conditions up to 12 m/s loading rate using a neat model polymer (PVC grey) in this study. A conventional single actuator test set-up for compact tension C(T) specimens was developed based on the previous experience of the authors and implemented on a new high rate servohydraulic testing machine. In addition, a novel double action test set-up was developed by applying two twin actuators and implemented in a rigid horizontal test frame. The conventional load and force measurement was extended by instrumented test specimens and by a high speed optical strain analysis system for both set-ups. Force based fracture toughness values using the peak load values, KIcPL and displacement based values using the critical crack opening displacement (CTOD) KICCTOD were determined up to a loading rate of 10 m/s. While the KIcPL values decreased up to a loading rate 103 MPam1/2s-1 an increase with a high data scatter was observed above them. Corresponding to the CTOD values the calculated KICCTOD values revealed a slight decrease and moderate data scatter up to the maximal loading rate.

Fracture assessment of polycarbonate parts produced by fused deposition modeling in the out-of-plane printing direction – effect of raster angle

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Iman Sedighi ◽  
Majid R. Ayatollahi ◽  
Bahador Bahrami ◽  
Marco A. Pérez-Martínez ◽  
Andrés A. Garcia-Granada
Keyword(s):  
Fracture Toughness ◽  
Finite Element ◽  
Fracture Behavior ◽  
Fused Deposition Modeling ◽  
Mode I ◽  
Content Type ◽  
Fused Deposition ◽  
Out Of Plane ◽  
Deposition Modeling ◽  
Fracture Tests

Purpose The purpose of this paper is to study the Mode I fracture behavior of polycarbonate (PC) parts produced using fused deposition modeling (FDM). The focus of this study is on samples printed along the out-of-plane direction with different raster angles. Design/methodology/approach Tensile and Mode I fracture tests were conducted. Semi-circular bend specimens were used for the fracture tests, which were printed in four different raster patterns of (0/90), (15/−75) (30/−60) and (45/−45). Moreover, the finite element method (FEM) was used to determine the applicability of linear elastic fracture mechanics (LEFM) for the printed PC parts. The fracture toughness results, as well as the fracture path and the fracture surfaces, were studied to describe the fracture behavior of the samples. Findings Finite element results confirm that the use of LEFM is allowed for the tested PC samples. The fracture toughness results show that changing the direction of the printed rasters can have an effect of up to 50% on the fracture toughness of the printed parts, with the (+45/−45) and (0/90) orientations having the highest and lowest resistance to crack propagation, respectively. Moreover, except for the (0/90) orientation, the other samples have higher crack resistance compared to the bulk material. The fracture toughness of the tested PC depends more on the toughness of the printed sample, rather than its tensile strength. Originality/value The toughness and the energy absorption capability of the printed samples (with different raster patterns) were identified as the main properties affecting the fracture toughness of the AM PC parts. Because the fracture resistance of almost all the samples was higher than that of the base material, it is evident that by choosing the right raster patterns for 3D-printed parts, very high resistance to crack growth may be obtained. Also, using FEM and comparing the size of the plastic zones, it was concluded that, although the tensile curves show nonlinearity, LEFM is still applicable for the printed parts.

FRACTURE BEHAVIOR OF Zr-BASED BULK METALLIC GLASS UNDER IMPACT LOADING

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4359-4364 ◽  
Author(s):  
HYUNG-SEOP SHIN ◽  
KI-HYUN KIM ◽  
SANG-YEOB OH
Keyword(s):  
Fracture Toughness ◽  
Crack Initiation ◽  
Fracture Energy ◽  
Impact Loading ◽  
Static Loading ◽  
Fracture Behavior ◽  
Loading Rate ◽  
Shear Bands ◽  
Maximum Load ◽  
Cu Alloy

The fracture behavior of a Zr -based bulk amorphous metal under impact loading using subsize V-shaped Charpy specimens was investigated. Influences of loading rate on the fracture behavior of amorphous Zr - Al - Ni - Cu alloy were examined. As a result, the maximum load and absorbed fracture energy under impact loading were lower than those under quasi-static loading. A large part of the absorbed fracture energy in the Zr -based BMG was consumed in the process for crack initiation and not for crack propagation. In addition, fractographic characteristics of BMGs, especially the initiation and development of shear bands at the notch tip were investigated. Fractured surfaces under impact loading are smoother than those under quasi-static loading. The absorbed fracture energy appeared differently depending on the appearance of the shear bands developed. It can be found that the fracture energy and fracture toughness of Zr -based BMG are closely related with the extent of shear bands developed during fracture.

J-R Fracture Toughness of Nuclear Piping Materials Under Excessive Seismic Loading Condition

2016 ◽  
Author(s):  
Jin Weon Kim ◽  
Myung Rak Choi ◽  
Sang Bong Lee ◽  
Yun Jae Kim
Keyword(s):  
Fracture Toughness ◽  
Cyclic Loading ◽  
Fracture Resistance ◽  
Cyclic Load ◽  
Fracture Behavior ◽  
Loading Rate ◽  
Seismic Loading ◽  
Monotonic Loading ◽  
Rate Effect ◽  
Loading Conditions

This study investigated the loading rate effect on the fracture resistance under cyclic loading conditions to clearly understand the fracture behavior of piping materials under excessive seismic conditions. J-R fracture toughness tests were conducted under monotonic and cyclic loading conditions at various displacement rates at room temperature (RT) and the operating temperature of nuclear power plants (NPPs), i.e., 316°C. SA508 Gr. 1a lo w-alloy steel (LAS) and SA312 TP316 stainless steel (SS) piping materials were used for the tests. The fracture resistance under a reversible cyclic load was considerably lower than that under monotonic load regardless of test temperature, material, and loading rate. Under both cyclic and monotonic loading conditions, the fracture behavior of SA312 TP316 SS was independent of the loading rate at both RT and 316°C. For SA508 Gr. 1a LAS, the loading rate effect on the fracture behavior was appreciable at 316°C under both cyclic and monotonic loading conditions. However, the loading rate effect diminished when the cyclic load ratio (R) was −1. Thus, it was recognized that the fracture behavior of piping materials, including seismic loading characteristics, can be evaluated when tested under a cyclic load of R = −1 at a quasi-static loading rate.

Characterization of the Loading Rate Dependent Fracture Behavior over a Wide Loading Rate Range Using Charpy Specimens

2014 ◽  
Vol 566 ◽  
pp. 286-291
Author(s):  
Zoltan Major ◽  
Martin Reiter
Keyword(s):  
Fracture Toughness ◽  
Fracture Behavior ◽  
Loading Rate ◽  
Polymeric Materials ◽  
Bending Test ◽  
Rate Range ◽  
Rate Dependent ◽  
Engineering Polymers ◽  
Dynamic Key

The fracture behavior of engineering polymers is usually characterized at high loading rates using Charpy specimens. However, due to the presence of dynamic effects the conventional force based analysis for determining fracture toughness values is applicable only up to 1 m/s using tree point bending test configurations. This difficulty can be overcome in principle, by applying dynamic analysis methods (e.g. dynamic key curve (DKC) analysis) or by applying tensile loading fracture configurations. The applicability of pre-cracked Charpy specimens for determining fracture toughness values for polymeric materials over a wide loading rate range is investigated in this study.

Fracture Behavior of Micro-Sized Ni-P Amorphous Alloy Specimens

1999 ◽  
Vol 605 ◽  
Author(s):  
Y. Ichikawa ◽  
S. Maekawa ◽  
K. Takashima ◽  
M. Shimojo ◽  
Y. Higo ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Stress Concentration ◽  
Amorphous Alloy ◽  
Fracture Behavior ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Testing Machine ◽  
The Other ◽  
Root Radius ◽  
The Difference

AbstractFracture behavior of micro-sized Ni-P Amorphous alloy specimens has been investigated using a newly developed mechanical testing machine. Specimens with dimensions of 10 × 12 × 50 μm were prepared by focused ion beam machining. Two types of specimens with different crack geometries were prepared. One specimen has a notch with root radius is 0.25 μtm and the other has a fatigue pre-crack. The shapes of the loaddisplacement curves are different for each type of specimen. The fracture strength of the specimens with a notch is higher than that with a fatigue pre-crack and the fracture surfaces of the specimens are also different for each type of specimen. This may be due to the difference in stress concentration at the crack (notch) tip, and indicates that even a notch with a root radius of 0.25 μm is not able to be regarded as a crack for micro-sized specimens. Therefore, the introduction of a fatigue pre-crack is essential for the evaluation of fracture toughness for such micro-sized specimens.

Biaxial Fracture Behavior of Polycrystalline Alumina

2005 ◽  
Vol 475-479 ◽  
pp. 1329-1332
Author(s):  
Masayuki Tsukada ◽  
Eiichi Sato ◽  
Kazuhiko Kuribayashi
Keyword(s):  
Fracture Toughness ◽  
Mixed Mode ◽  
Fracture Behavior ◽  
Mixed Mode Fracture ◽  
Polycrystalline Alumina ◽  
Mode Fracture ◽  
Multiaxial Stress State ◽  
Four Point Bending ◽  
Biaxial Tests ◽  
Fracture Tests

Fracture behavior under multiaxial stress state of polycrystalline alumina was studied from the view point of an artificial crack propagation and fracture from a natural flaw. The former was studied by mixed-mode fracture toughness tests; asymmetric four-point bending and diametral compression techniques were carried out using precracked and notched specimens. The latter was studied by biaxial fracture tests in compression and torsion loading; multiaxial fracture statistics was applied to the measured fracture envelope. The ratio KIIC/KIC obtained from the biaxial tests was higher than that obtained by the mixed-mode fracture toughness tests. It revealed that the fracture from an artificial flaw does not simulate the fracture from a naturall flaw in polycrystalline ceramics.

Microscale Fracture Testing of Mg-Zn-Y

2009 ◽  
Vol 1225 ◽  
Author(s):  
Shun Matsuyama ◽  
Tetsuya Sakamoto ◽  
Masaaki Otsu ◽  
Kazuki Takashima ◽  
Yoshihito Kawamura
Keyword(s):  
Fracture Toughness ◽  
Room Temperature ◽  
Focused Ion Beam ◽  
Volume Fraction ◽  
Ion Beam ◽  
Testing Machine ◽  
Alloy Specimen ◽  
Testing Technique ◽  
Lpso Phase ◽  
Fracture Tests

AbstractA microfracture testing technique was applied for investigating the fracture properties of Mg-Zn-Y alloys with a long-period stacking ordered (LPSO) phase. Microsized cantilever beam specimens with dimensions ≈ 10×20×50 μm3 were prepared from Mg-Zn-Y alloys by focused ion beam (FIB) machining. Notches with widths of 0.5 μm and depths of 3.5–5 μm were also introduced into the specimens by FIB machining. In this study, three types of Mg-Zn-Y alloys―Mg99.2Zn0.2Y0.6, Mg97Zn1Y2, and Mg88Zn5Y7―were used. Fracture tests were successfully conducted using a mechanical testing machine for microsized specimens at room temperature. The fracture toughness values (KIC) could not be obtained as the specimen size was too small to satisfy the plane strain condition. Hence, provisional KQ values were considered. The KQ values of the Mg97Zn1Y2 alloy were 0.8–1.2 MPam½, and those of the Mg88Zn5Y7 alloy were 1.2–3.0 MPam½. As the fracture in the Mg99.2Zn0.2Y0.6 alloy specimen occurred in a ductile plastic deformation, it was impossible to evaluate KQ values of this specimen. The increasing volume fraction of the LPSO phase indicates that the fracture toughness of Mg-Zn-Y alloys increases in LPSO phase.

scholarly journals The Loading Rate Effect on the Fracture Toughness of Marble Using Semicircular Bend Specimens

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Fengqiang Gong ◽  
Yunliang Wang ◽  
Shanyong Wang
Keyword(s):  
Fracture Toughness ◽  
Dynamic Fracture ◽  
Loading Rate ◽  
Testing Machine ◽  
Continuous Model ◽  
Dynamic Fracture Toughness ◽  
Rate Effect ◽  
High Loading ◽  
Quantitative Relation ◽  
Dynamic Increase Factor

A series of dynamic fracture experiments on semicircular bend (SCB) marble specimens were conducted to characterize the loading rate effect using the INSTRON testing machine and the modified SHPB testing system. The fracture toughness of the marble specimens was measured from a low loading rate to a high loading rate (10-3~106 MPa·m1/2s-1). The results show that the fracture toughness will increase with the loading rate. Since the fracture toughness at a magnitude of 10-3 MPa·m1/2s-1 is regarded as the static fracture toughness, the specific value of DI F f (the dynamic increase factor of fracture toughness) can be obtained at the other loading magnitudes from dynamic fracture tests. To describe the variation in DI F f from low to high loading rates, a new continuous model of DI F f was put forward to express the quantitative relation between the loading rate and rock dynamic fracture toughness. It is shown that the new DI F f model can accurately describe the loading rate effect on the dynamic fracture testing data for rock materials.

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