scholarly journals Determination of Static Fracture Toughness of Nettle Fibre (Urtica Dioica)/Polymethyl-methacrylate Composites Using Different Fracture Methods

Mechanika ◽  
2020 ◽  
Vol 26 (2) ◽  
pp. 95-102
Author(s):  
Kenan Büyükkaya ◽  
Faruk Güner
Keyword(s):  
Fracture Toughness ◽  
Bending Strength ◽  
Tensile Tests ◽  
Compact Tension ◽  
Fibre Reinforcement ◽  
Bending Stresses ◽  
Static Fracture ◽  
Compact Tension Test ◽  
Point Bend

In this study, the breaking behaviour of polymethylmethacrylate reinforced with nettle fibre was investigated experimentally. Single edge notched bending (SENB) and compact test(CT)  specimens were produced to include notches in various ratios. The Mode I fracture behaviour of samples were determined utilizing static frac-ture toughness experiments such as the Three Point Bend-ing (TPB) and Compact Tensile tests. The fracture tough-ness (KIC) was investigated using the TPB Test (Compli-ance and Initial notch method), and Compact Tension test. The bending module and bending stresses were also determined. It was found that nettle-fibre reinforcement improves the bending strength of the composite by 60% and improves the fracture toughness more than two-fold.

Comparison of fracture toughness values of normal and high strength concrete determined by three point bend and modified disk-shaped compact tension specimens

2017 ◽  
Author(s):  
Stanislav Seitl ◽  
José D. Ríos ◽  
Hector Cifuentes
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
High Strength Concrete ◽  
High Strength ◽  
Compact Tension ◽  
Tension Test ◽  
Test Method ◽  
Strength Concrete ◽  
Compact Tension Test ◽  
Point Bend

The modified disk shaped compact tension test is a configuration derived from standard compact tension test that is used for measuring fracture mechanical properties of primarily metallic materials. The compact tension configuration is commonly used for measurement fracture mechanical properties as e.g. fracture toughness, Young’s modulus, work of fracture etc. The modified compact tension tests imply significant modifications of the specimen morphology in order to avoid premature failure. The modified compact tension test is not proper for quasi-brittle materials due to its complicated shape (steel-concrete interface), but it is easily extracted from drill core and we do not need large amount of material for obtaining fracture properties as we need for e.g. three- or four- point bend test. Since it is a new test method, a wide range of tests is needed to be done before it can be applied. In the paper the selected outputs of the experiments performed on normal and high strength concrete will be processed and the values of fracture mechanical parameters will be discussed.

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.

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.

Experiments on a Ring Tension Setup and FE Analysis to Evaluate Transverse Mechanical Properties of Tubular Components

2017 ◽  
pp. 91-115
Author(s):  
M.K. Samal ◽  
K.S. Balakrishnan
Keyword(s):  
Mechanical Properties ◽  
Strain Curve ◽  
Tensile Tests ◽  
Stress Strain ◽  
Element Analysis ◽  
Integrity Assessment ◽  
Bending Stresses ◽  
Heavy Water Reactor ◽  
Tubular Components

Determination of transverse mechanical properties from ring specimens machined from tubular components is not straightforward due to presence of combined tension and bending stresses. Zircaloy tubes as used in nuclear reactors are manufactured through a complicated process of pilgering and heat-treatment and hence, the properties need to be determined in the as-manufactured condition. In this work, the authors perform ring-tensile tests on specimens of Zircaloy pressure tubes of Indian pressurized heavy water reactor in order to carry out integrity assessment of these tubes. As the loading condition in this test imposes both membrane and bending stresses in the cross-section of the ring, 3-D finite element analysis of the test setup was carried out in order to determine material stress-strain curve using an iterative technique. The effect of the design of the loading mandrel on the experimental stress-strain data has been investigated in detail. To validate the methodology, miniature tensile specimens have been tested and the data has been compared to those of ring specimens.

Influence of Crack Orientation and Crosshead Speed on the Fracture Toughness of PVC Pipe Materials

2004 ◽  
Vol 126 (4) ◽  
pp. 489-496 ◽  
Author(s):  
Tarek M. El-Bagory ◽  
Mohamed S. El-Fadaly ◽  
Maher Y. A. Younan ◽  
Lotfi A. Abdel-Latif
Keyword(s):  
Fracture Toughness ◽  
Experimental Work ◽  
Compact Tension ◽  
Specimen Thickness ◽  
Crosshead Speed ◽  
Operation Conditions ◽  
Pvc Pipe ◽  
Point Bend ◽  
Materials Used ◽  
Pipe Materials

In many modern engineering applications, designers and manufacturers of Polyvinyl chloride (PVC) pipes are interested in the evaluation of fracture toughness under several operation conditions. The aim of the present work is to investigate the fracture toughness of commercial amorphous thermoplastic PVC materials used in piping applications. The experimental work is carried out using three different specimens’ types: Taper Double Cantilever Beam (TDCB), Three Point Bend (TPB), and Compact Tension (CT). Tests are conducted on specimens with thickness (17, 20, 22, and 26 mm), longitudinal and transverse extrusion orientations, at different crosshead speeds (50–500 mm/min) to calculate the fracture toughness of PVC pipe materials. The experimental work has revealed that the crosshead speed has a significant effect on the fracture toughness at low speed rates. This effect, however, becomes insignificant at high rates since, the fracture behavior becomes brittle. The stress intensity factor KQ is approximately the same in both longitudinal and transverse orientations. The fracture toughness decreases as the specimen thickness increases.

Acoustic Emission Entropy for Evaluation of Fracture Toughness of HSLA Steel Welded Joint

2017 ◽  
Author(s):  
Mengyu Chai ◽  
Weijie Wu ◽  
Zaoxiao Zhang ◽  
Guangxu Cheng ◽  
Quan Duan
Keyword(s):  
Fracture Toughness ◽  
Acoustic Emission ◽  
Welded Joint ◽  
Hsla Steel ◽  
Amplitude Distribution ◽  
Compact Tension ◽  
Compact Tension Specimen ◽  
New Approach ◽  
Astm Standard

In this investigation, fracture toughness behavior of high strength low alloy (HSLA) steel welded joint was studied using acoustic emission (AE) monitoring. For the design of new structures and for the safety and reliability analyses of operating components, fracture toughness (KIC) values of materials play an essential role. Acoustic emission technique (AET) has been used for determination of fracture toughness based on some observable changes of AE evolutions. However, the occurrence of appreciable plasticity in materials, the friction between the crack surfaces and mechanical noise could generate high emission and may result in some difficulties in precise determination of fracture toughness. Thus, the objective of this study is to propose a new approach to evaluate fracture toughness values and to characterize the fracture process based on AE entropy. Specimens were selected from 2.25Cr-1Mo-0.25V steel welded joint which were thermally aged at 978 K for 8 h. The AE signals generated during fracture processes were recorded and the corresponding AE entropy was calculated based on the probability amplitude distribution from each original AE waveform. The point of crack initiation was identified by the occurrence of sudden rise of AE entropy and the corresponding critical load was used to estimate fracture toughness value. The estimated values obtained from the proposed new approach were compared with those determined by the methodology proposed by compact tension specimen testing according to ASTM standard E399. The results showed that the estimated values were in close agreement with those gained from ASTM standard. It was concluded that AE entropy was an effective parameter to estimate fracture characteristics and fracture toughness values.

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