Fracture Toughness Testing on Bars Under Opposite Cylinder Loading

2004 ◽  
Vol 126 (1) ◽  
pp. 50-54
Author(s):  
T. Fett ◽  
D. Munz ◽  
G. Thun
Keyword(s):  
Fracture Toughness ◽  
Stress Intensity Factor ◽  
Ceramic Materials ◽  
Resistance Curve ◽  
Alumina Ceramics ◽  
Practical Applications ◽  
T Stress ◽  
Toughness Testing ◽  
Concentrated Forces

Bars loaded by opposite concentrated forces via rollers are appropriate test specimens for the determination of the fracture toughness, KIc, and the crack resistance curve (R-curve) of ceramic materials. In this paper stress solutions for the proposed test specimens are provided, as well as the stress intensity factor and the T-stress solutions. As practical applications, R-curves are determined for a soft PZT ceramic and several alumina ceramics.

Fracture Toughness Testing on Bars Under Opposite Cylinder Loading

2002 ◽  
Author(s):  
Theo Fett ◽  
Dietrich Munz ◽  
Gerhard Thun
Keyword(s):  
Fracture Toughness ◽  
Stress Intensity Factor ◽  
Ceramic Materials ◽  
Resistance Curve ◽  
Alumina Ceramics ◽  
Practical Applications ◽  
T Stress ◽  
Toughness Testing ◽  
Concentrated Forces

Bars loaded by opposite concentrated forces via rollers are appropriate test specimens for the determination of the fracture toughness, KIc, and the crack resistance curve (R-curve) of ceramic materials. In this paper stress solutions for the proposed test specimens are provided, as well as the stress intensity factor and the T-stress solutions. As practical applications, R-curves are determined for a soft PZT ceramic and several alumina ceramics.

Wafer-Level Strength and Fracture Toughness Testing of Surface-Micromachined MEMS Devices

1999 ◽  
Vol 605 ◽  
Author(s):  
H. Kahn ◽  
N. Tayebi ◽  
R. Ballarini ◽  
R.L. Mullen ◽  
A.H. Heuer
Keyword(s):  
Fracture Toughness ◽  
Tensile Strength ◽  
Microelectromechanical Systems ◽  
Reliability Prediction ◽  
Bend Strength ◽  
Mems Devices ◽  
Wafer Level ◽  
Toughness Testing ◽  
Loading Devices

AbstractDetermination of the mechanical properties of MEMS (microelectromechanical systems) materials is necessary for accurate device design and reliability prediction. This is most unambiguously performed using MEMS-fabricated test specimens and MEMS loading devices. We describe here a wafer-level technique for measuring the bend strength, fracture toughness, and tensile strength of MEMS materials. The bend strengths of surface-micromachined polysilicon, amorphous silicon, and polycrystalline 3C SiC are 5.1±1.0, 10.1±2.0, and 9.0±1.0 GPa, respectively. The fracture toughness of undoped and P-doped polysilicon is 1.2±0.2 MPa√m, and the tensile strength of polycrystalline 3C SiC is 3.2±1.2 GPa. These results include the first report of the mechanical strength of micromachined polycrystalline 3C SiC.

Determination of the Fracture Toughness Parameters for an MDF Cement Composite

1985 ◽  
Vol 64 ◽  
Author(s):  
M. Arzamendi ◽  
R. L. Sierakowski ◽  
W. E. Wolfe
Keyword(s):  
Fracture Toughness ◽  
Cement Composite ◽  
Compact Tension ◽  
Test Methods ◽  
Standard Test ◽  
Elastic Behavior ◽  
Hardened Cement ◽  
Linear Elastic ◽  
Toughness Testing

ABSTRACTThe experimental results of fracture toughness testing of a Macro Defect (MDF) Free cement are presented. The material, a hydraulic cement with hydrolyzed polyvinyl polymers, behaves much like a hardened ceramic with measured maximum compressive and tensile strengths of 380 MN/m2 and 69 MN/m2 respectively. Fracture toughness tests were performed on compact tension (CT) and single edge notched beam (SENB) specimens cut from test panels which were supplied in 3mm, 5mm and 10mm thicknesses. The results were evaluated with respect to the fracture toughness parameter Kic using a modification of standard test methods as determined by observed natural behavior. The MDF material exhibited an essentially linear elastic behavior with a fracture toughness slightly higher than typical values recorded for hardened cement paste.

Constraint Based Assessments of Large-Scale Cracked Straight Pipes and Elbows

2015 ◽  
Author(s):  
Marius Gintalas ◽  
Robert A. Ainsworth
Keyword(s):  
Fracture Toughness ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Large Scale ◽  
Initiation Point ◽  
T Stress ◽  
Advanced Analysis ◽  
Material Fracture ◽  
Fracture Toughness Specimen

The paper presents T-stress solutions developed to characterize constraint levels in large-scale cracked pipes and elbows. Stress intensity factor, KI, solutions for pipes and elbows are normalised by material fracture toughness to define the Kr parameter in fitness-for-service procedures, such as R6. Adding knowledge on levels of T-stress allows more advanced analysis through a normalised constraint parameter βT. The paper presents analyses for 6 pipes and 8 elbows. Values of the normalised constraint parameter βT are calculated for each pipe and elbow at the experimentally measured crack initiation point. Comparison of constraint levels in the pipes and elbows with those in various types of fracture toughness specimen are used to predict the initiation loads using the R6 method and to provide guidelines for transferability.

Determination of J Resistance Curves From CWP Specimens

2012 ◽  
Author(s):  
Fan Zhang ◽  
Honggang Zhou ◽  
Yong-Yi Wang ◽  
Ming Liu ◽  
Yaxin Song
Keyword(s):  
Fracture Toughness ◽  
Crack Growth ◽  
J Integral ◽  
Resistance Curve ◽  
Constraint Condition ◽  
Longitudinal Loading ◽  
Resistance Curves ◽  
Unloading Compliance ◽  
Girth Welds

A crack is highly constrained in traditional toughness tests, e.g., CVN and SE(B). However, a crack in the girth welds of pipelines under longitudinal loading is low constrained. Curved wide plate (CWP) test provides similar constraint condition as that of pipeline girth weld. CWP tests are being used recently for strain-based design. One of the desirable outcomes from those tests is fracture toughness resistance curves. The resistance curve consists of two components, the crack growth and the toughness measure, such as J-integral or CTOD. The paper describes the development of procedures for the determination of those two components. A normalized equation was developed to estimate the crack growth from the experimentally measured unloading compliance. The equation was verified by multiple FEA simulations with different pipe geometries and materials. The second set of equations was developed to evaluate the J-integral through an incremental frame based on the instantaneous crack growth and the load-CMOD record. The application of the resistance curve procedures was demonstrated through CWP tests of X80 and X100 welds.

scholarly journals Notes on the experimental measurement of fracture toughness of shape memory alloys

2019 ◽  
Vol 31 (3) ◽  
pp. 475-483 ◽  
Author(s):  
Jasdeep Makkar ◽  
Theocharis Baxevanis
Keyword(s):  
Fracture Toughness ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Measurement Accuracy ◽  
Test Method ◽  
Specimen Thickness ◽  
Resistance Curve ◽  
Ductile Materials ◽  
Induced Changes

A mechanics-aided test method for measuring the fracture toughness of shape memory alloys, the deformation/failure response of which violates basic assumptions of ASTM standards for measuring fracture toughness in conventional ductile materials, has been recently proposed. The proposed methodology relies on the resistance curve format of ASTM standards, but differs from it in the determination of the elastic part of the J value, for both stationary and advancing cracks, in an effort to accommodate the transformation/orientation-induced changes in the apparent elastic properties. This article discusses the proposed modifications to ASTM standards, that is, the expected degree of improvement in the measurement accuracy, the need for further ones regarding the uncertainty as to where to specify the fracture point on the obtained resistance curve, the specimen thickness requirement to ensure a conservative, constraint-independent measurement, and the temperature dependence of the measurements.

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